U.S. patent application number 16/696267 was filed with the patent office on 2020-05-07 for control method for internal combustion engine.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Toshiaki Date, Nozomu Kamioka, Noriya Sagayama, Satoshi Wachi.
Application Number | 20200141342 16/696267 |
Document ID | / |
Family ID | 52812662 |
Filed Date | 2020-05-07 |
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United States Patent
Application |
20200141342 |
Kind Code |
A1 |
Sagayama; Noriya ; et
al. |
May 7, 2020 |
CONTROL METHOD FOR INTERNAL COMBUSTION ENGINE
Abstract
A throttle valve 11 that adjusts an amount of air flowing into
an intake passage of an internal combustion engine 1, a fuel
injection valve 9 that injects fuel into the internal combustion
engine 1, and a generator-motor 6 that drives the internal
combustion engine 1 via a drive belt 5 are controlled by an
internal combustion engine control unit 13. The internal combustion
engine control unit 13 opens the throttle valve 11 to a first
throttle opening after detecting a request to start the internal
combustion engine 1, then causes the fuel injection valve 9 to
inject fuel while maintaining the first throttle opening, and then
opens the throttle valve 11 to a second throttle opening that is
larger than the first throttle opening.
Inventors: |
Sagayama; Noriya; (Tokyo,
JP) ; Kamioka; Nozomu; (Tokyo, JP) ; Wachi;
Satoshi; (Tokyo, JP) ; Date; Toshiaki; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
52812662 |
Appl. No.: |
16/696267 |
Filed: |
November 26, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15022959 |
Mar 18, 2016 |
10513995 |
|
|
PCT/JP2013/077659 |
Oct 10, 2013 |
|
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16696267 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02D 41/0002 20130101;
Y02T 10/40 20130101; F02D 41/062 20130101; F02N 11/08 20130101;
F02D 41/3005 20130101; F02N 11/04 20130101; F02D 41/32 20130101;
F02D 2200/021 20130101; F02D 2200/0406 20130101; Y02T 10/42
20130101; F02B 63/04 20130101; F02D 11/10 20130101 |
International
Class: |
F02D 41/06 20060101
F02D041/06; F02D 41/00 20060101 F02D041/00; F02D 41/32 20060101
F02D041/32; F02B 63/04 20060101 F02B063/04; F02D 41/30 20060101
F02D041/30; F02N 11/08 20060101 F02N011/08 |
Claims
1. A control method for an internal combustion engine, comprising
the steps of: determining whether or not a request to start the
internal combustion engine has been issued; driving a
generator-motor that drives the internal combustion engine via a
belt after determining that the request has been issued; opening a
throttle valve provided in an intake passage of the internal
combustion engine to a first throttle opening; injecting fuel into
the internal combustion engine from a fuel injection valve while
maintaining a throttle opening of the throttle valve at the first
throttle opening; stopping the generator-motor; and opening the
throttle valve to a second throttle opening that is larger than the
first throttle opening.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 15/022,959, filed Mar. 18, 2016, which is a National Stage of
International Application No. PCT/JP2013/077659, filed on Oct. 10,
2013, the contents of all of which are incorporated herein by
reference in their entirety.
TECHNICAL FIELD
[0002] This invention relates to a control apparatus and a control
method for an internal combustion engine, and more particularly to
a control apparatus and a control method for an internal combustion
engine with which to reduce shock during startup of the internal
combustion engine.
BACKGROUND ART
[0003] In a conventional control apparatus for an internal
combustion engine installed in a vehicle, a throttle valve is
operated when executing cranking on the internal combustion engine
in order to start the internal combustion engine. As a result,
negative pressure is generated rapidly on a downstream side of the
throttle valve. Further, shock is suppressed during startup by
securing torque continuity.
[0004] PTL 1 describes an example of a conventional control
apparatus that performs this type of control. In PTL 1, a throttle
valve is fully closed when cranking is executed so that negative
pressure is generated rapidly on a downstream side of the throttle
valve. The throttle valve is then opened to a preset throttle
opening prior to a fuel injection timing. In so doing, an amount of
air taken in during startup of the internal combustion engine is
reduced, and as a result, an amount of torque generated during
complete combustion in the internal combustion engine is
suppressed. Further, torque continuity is secured by aligning a
timing at which negative pressure in an intake passage reaches a
peak with a timing at which the internal combustion engine reaches
a complete combustion state, and as a result, shock generation in
the internal combustion engine is prevented. Note that here, the
complete combustion state denotes a state of complete combustion
following the beginning of a startup operation in the internal
combustion engine.
CITATION LIST
Patent Literature
[0005] [PTL 1] JP 2010-203346 A
SUMMARY OF INVENTION
Technical Problem
[0006] With the conventional control apparatus described in PTL 1,
however, the following problems occur.
[0007] In the conventional control apparatus of PTL 1, as described
above, the throttle valve is initially fully closed when cranking
is executed on the engine. The throttle valve is then opened to the
preset opening prior to the fuel injection timing. As a result,
shock during startup is suppressed. However, in a situation where
it is necessary to prioritize startability in the internal
combustion engine, for example when a water temperature of the
internal combustion engine is extremely low, the intake air amount
is increased using following methods. In one method, control is
implemented to shorten a period in which the throttle valve is
closed. In another method, control is implemented to eliminate the
period in which the throttle valve is closed. By increasing an
absolute value of the peak of the negative pressure generated in
the intake passage in this manner, the intake air amount is
increased.
[0008] Here, in PTL 1, the period in which the throttle valve is
closed, a timing at which the valve is opened, and an opening to
which the valve is opened are determined from an estimated value of
the peak of the negative pressure in the intake passage. When
determining the period in which the throttle valve is closed, the
timing at which the valve is opened, and the opening to which the
valve is opened, it is necessary, in consideration of a deviation
between the estimated value of the peak of the negative pressure
and the actual peak value of the negative pressure, to ensure that
the internal combustion engine is started reliably by setting the
estimated value of the peak of the negative pressure at a higher
value than a minimum negative pressure value at which the internal
combustion engine can be started (in other words, a minimum
negative pressure value at which the internal combustion engine is
started reliably). Therefore, when startability is prioritized,
shock occurring in the engine during startup cannot be suppressed,
and as a result, a driver experiences discomfort.
[0009] Furthermore, in PTL 1, the throttle valve is opened prior to
the fuel injection timing, making it difficult to stabilize the
negative pressure in the intake passage during fuel injection.
Accordingly, a fuel injection amount determined on the basis of the
negative pressure in the intake passage cannot always be reduced to
a minimum required amount, and as a result, fuel may be injected in
an excessive amount such that a fuel consumption amount cannot be
suppressed.
[0010] Moreover, in PTL 1, a determination is not made as to
whether or not the internal combustion engine is rotating with
stability. Therefore, when the torque generated by the internal
combustion engine is insufficient, an engine starting apparatus may
be stopped, leading to a reduction in a rotation speed of the
internal combustion engine.
[0011] This invention has been made in order to solve the problems
described above, and an object thereof is to provide a control
apparatus and a control method for an internal combustion engine,
with which shock can be suppressed during startup of the internal
combustion engine, even in a situation where it is necessary to
prioritize startability, and with which a fuel consumption amount
can be suppressed following startup of the internal combustion
engine.
Solution to Problem
[0012] This invention is a control apparatus for an internal
combustion engine, including a throttle valve that adjusts an
amount of air flowing into an intake passage of the internal
combustion engine, a fuel injection valve that injects fuel into
the internal combustion engine, a generator-motor coupled to the
internal combustion engine via a belt in order to drive the
internal combustion engine, and an internal combustion engine
control unit that controls the throttle valve, the fuel injection
valve, and the generator-motor, wherein the internal combustion
engine control unit opens the throttle valve to a first throttle
opening after detecting a request to start the internal combustion
engine, then causes the fuel injection valve to inject fuel while
maintaining the throttle valve at the first throttle opening, and
then opens the throttle valve to a second throttle opening that is
larger than the first throttle opening.
Advantageous Effects of Invention
[0013] This invention is a control apparatus for an internal
combustion engine, including a throttle valve that adjusts an
amount of air flowing into an intake passage of the internal
combustion engine, a fuel injection valve that injects fuel into
the internal combustion engine, a generator-motor coupled to the
internal combustion engine via a belt in order to drive the
internal combustion engine, and an internal combustion engine
control unit that controls the throttle valve, the fuel injection
valve, and the generator-motor, wherein the internal combustion
engine control unit opens the throttle valve to a first throttle
opening after detecting a request to start the internal combustion
engine, then causes the fuel injection valve to inject fuel while
maintaining the throttle valve at the first throttle opening, and
then opens the throttle valve to a second throttle opening that is
larger than the first throttle opening. Therefore, shock can be
suppressed during startup of the internal combustion engine even in
a situation where it is necessary to prioritize startability, and a
fuel consumption amount can be suppressed following startup of the
internal combustion engine.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 is a view showing a configuration of a control
apparatus for an internal combustion engine according to a first
embodiment of this invention.
[0015] FIG. 2 is a flowchart showing an operation of the control
apparatus for an internal combustion engine according to the first
embodiment of this invention.
[0016] FIG. 3 is a timing chart showing timings of an operation of
the internal combustion engine according to the first embodiment of
this invention.
[0017] FIGS. 4A-4C are a view showing map tables used by the
control apparatus for an internal combustion engine according to
the first embodiment of this invention.
DESCRIPTION OF EMBODIMENTS
[0018] A control apparatus and a control method for an internal
combustion engine according to an embodiment of this invention will
be described below using the drawings. Note that in the drawings,
identical constituent elements have been allocated identical
reference symbols, and duplicate description thereof has been
omitted.
First Embodiment
[0019] FIG. 1 is a view showing a configuration of a control
apparatus for an internal combustion engine (referred to hereafter
simply as a control apparatus) according to a first embodiment of
this invention.
[0020] The control apparatus according to the first embodiment
controls an internal combustion engine 1. As shown in FIG. 1, the
control apparatus includes a crank pulley 2, a crank angle
detecting ring gear 3, a crank angle sensor 4, a drive belt 5, a
generator-motor 6, a generator-motor drive pulley 7, a fuel
injection valve 9, a throttle valve 11, a negative pressure
detector 12, an internal combustion engine control unit 13, and an
accelerator pedal 14.
[0021] The internal combustion engine 1 includes an intake passage
10 for supplying air to the internal combustion engine 1, and an
exhaust passage 8 for discharging exhaust gas from the internal
combustion engine 1 into the atmosphere. The crank angle detecting
ring gear 3 is directly connected to the internal combustion engine
1. Therefore, when the internal combustion engine 1 rotates, the
crank angle detecting ring gear 3 rotates. The crank angle sensor 4
determines a crank angle of the internal combustion engine 1 by
detecting the rotation of the crank angle detecting ring gear 3,
and in so doing detects a rotation speed of the internal combustion
engine 1. Rotation information relating to the internal combustion
engine 1, obtained by the crank angle sensor 4, is transmitted to
the internal combustion engine control unit 13.
[0022] The intake passage 10 includes a throttle valve 11. The
throttle valve 11 adjusts an amount of air flowing into the intake
passage 10 in accordance with the control executed by the internal
combustion engine control unit 13. As a result, intake air flows
into the interior of the internal combustion engine 1 through the
intake passage 10 in an amount adjusted by the throttle valve
11.
[0023] Negative pressure in the intake passage 10 is detected by
the negative pressure detector 12. Information indicating the
detected negative pressure is transmitted to the internal
combustion engine control unit 13.
[0024] The internal combustion engine control unit 13 calculates a
fuel injection amount of the fuel injection valve 9 on the basis of
the information indicating the negative pressure in the intake
passage 10, obtained by the negative pressure detector 12. The fuel
injection valve 9 injects fuel into the interior of the internal
combustion engine 1 in the fuel injection amount calculated by the
internal combustion engine control unit 13.
[0025] The accelerator pedal 14 is provided with an accelerator
position sensor (not shown) for detecting an amount (an accelerator
opening APS1) by which a driver depresses the accelerator pedal 14.
Accelerator opening information obtained by the accelerator
position sensor is transmitted to the internal combustion engine
control unit 13.
[0026] Exhaust gas generated when fuel is burned in the interior of
the internal combustion engine 1 is released into the atmosphere
through the exhaust passage 8.
[0027] The crank pulley 2 is coupled to the internal combustion
engine 1. The generator-motor drive pulley 7 is coupled to the
generator-motor 6. The crank pulley 2 and the generator-motor drive
pulley 7 are coupled by the drive belt 5. Accordingly, the
generator-motor 6 is coupled to the internal combustion engine 1
via the crank pulley 2, the drive belt 5, and the generator-motor
drive pulley 7. As a result, the internal combustion engine 1 can
be rotated by torque output from the generator-motor 6. Further,
the generator-motor 6 can be rotated by torque output from the
internal combustion engine 1.
[0028] In this embodiment, the generator-motor 6 is used as a
starting device (a starter motor) for starting the internal
combustion engine 1. More specifically, when the internal
combustion engine 1 is started, drive torque is transmitted from
the generator-motor 6 to the internal combustion engine 1 by the
drive belt 5 in order to start the internal combustion engine 1.
Note that the starting device for the internal combustion engine 1
is not limited to the generator-motor 6 shown in FIG. 1, and any
device capable of causing the internal combustion engine 1 to
rotate, such as a gear meshing type generator-motor or a gear
meshing type motor, may be used.
[0029] The information indicating the negative pressure detected by
the negative pressure detector 12, the information indicating the
accelerator opening of the accelerator pedal 14, and the rotation
information relating to the internal combustion engine 1, detected
by the crank angle sensor 4, are input into the internal combustion
engine control unit 13. The internal combustion engine control unit
13 uses at least one of these information to control driving of the
generator-motor 6, an opening of the fuel injection valve 9 (i.e.
the fuel injection amount), and a throttle opening of the throttle
valve 11. The internal combustion engine control unit 13 also
performs control for stopping the internal combustion engine 1.
[0030] Next, control performed during startup of the internal
combustion engine 1 will be described.
[0031] The control apparatus according to this embodiment performs
processing shown on a flowchart in FIG. 2 to control startup of the
internal combustion engine 1.
[0032] As shown in FIG. 2, a START condition is established while
the internal combustion engine 1 is stopped. The internal
combustion engine 1 is stopped by control performed by the internal
combustion engine control unit 13. The internal combustion engine 1
is stopped when, for example, an ignition is switched OFF, idling
is stopped or idling reduction is implemented, the internal
combustion engine control unit 13 stops the internal combustion
engine 1 intentionally for a particular reason, and so on.
[0033] In step S201, the internal combustion engine control unit 13
determines whether or not a request to start the internal
combustion engine 1 has been issued. Examples of conditions for
determining whether or not a start request has been issued include
whether or not the driver has depressed the accelerator pedal 14,
whether or not the driver has operated an ignition key or an
ignition switch, whether or not the driver has taken his/her foot
off a brake pedal, and so on. Any one of these conditions may be
employed as the condition for determining whether or not a start
request has been issued. When a request to start the internal
combustion engine 1 has been issued, the routine advances to step
S202. On the other hand, when a request to start the internal
combustion engine 1 has not been issued, a RETURN condition is
established and the startup control is terminated.
[0034] In step S202, the internal combustion engine control unit 13
determines the throttle opening of the throttle valve 11 during
startup of the internal combustion engine 1 as a first throttle
opening TH1.
[0035] The first throttle opening TH1 is determined using a map
table M401 shown in FIG. 4A, for example. On the map table M401
shown in FIG. 4A, the horizontal axis shows a water temperature of
cooling water in the internal combustion engine 1, and the vertical
axis shows the first throttle opening TH1 (the throttle opening
during startup of the internal combustion engine 1). A relationship
between the water temperature of the cooling water in the internal
combustion engine 1 and the first throttle opening TH1 is as shown
by a solid line 41 on the map table M401 of FIG. 4A. Hence, a value
of the first throttle opening TH1 is stored in advance on the map
table M401 for each water temperature of the cooling water in the
internal combustion engine 1. The first throttle opening TH1 is
therefore determined from the map table M401 on the basis of the
water temperature of the cooling water in the internal combustion
engine 1. Note that the first throttle opening TH1 is an opening of
the throttle valve 11 at which a minimum negative pressure (a
minimum negative pressure value V1) required to achieve complete
combustion in the internal combustion engine 1 can be generated. In
other words, as long as the throttle opening of the throttle valve
11 is maintained at the first throttle opening TH1, complete
combustion is achieved reliably in the internal combustion engine
1. Note that the first throttle opening TH1 is not limited to this
example, and may be determined using another method.
[0036] In step S203, the internal combustion engine control unit 13
determines the minimum negative pressure value V1 in the intake
passage 10 in order to determine a timing at which to start fuel
injection from the fuel injection valve 9. The minimum negative
pressure value V1 is the minimum required negative pressure at
which complete combustion can be achieved in the internal
combustion engine 1. In other words, as long as the value of the
negative pressure in the intake passage 10 reaches the minimum
negative pressure value V1, complete combustion is achieved
reliably in the internal combustion engine 1.
[0037] The minimum negative pressure value V1 is determined using a
map table M402 shown in FIG. 4B, for example. On the map table M402
shown in FIG. 4B, the horizontal axis shows the first throttle
opening TH1, and the vertical axis shows the minimum negative
pressure value V1. A relationship between the first throttle
opening TH1 and the minimum negative pressure value V1 is as shown
by a solid line 42 on the map table M402 of FIG. 4B. Hence, the
minimum negative pressure value V1 is stored in advance on the map
table M402 for each value of the first throttle opening TH1. The
minimum negative pressure value V1 is therefore determined from the
map table M402 on the basis of the first throttle opening TH1. The
minimum negative pressure value V1 in the intake passage 10 at
which complete combustion can be achieved in the internal
combustion engine 1 is set in this manner using the map table M402
shown in FIG. 4B. In this embodiment, the minimum negative pressure
value V1 is determined in the manner described above, whereupon a
determination is made in step S210, to be described below, as to
whether or not the negative pressure in the intake passage 10
during startup of the internal combustion engine 1 has reached the
minimum negative pressure value V1. After it is confirmed that the
negative pressure in the intake passage 10 has reached the minimum
negative pressure value V1, fuel injection can be started, and
therefore energy generated as a result of fuel combustion can be
used entirely to increase the rotation speed of the internal
combustion engine 1. As a result, shock can be suppressed during
complete combustion, and startability can be secured.
[0038] In step S204, the internal combustion engine control unit 13
calculates a driver requested torque TR2 requested by the driver
using Equation (1), shown below, on the basis of the accelerator
opening APS1 of the accelerator pedal 14. The driver requested
torque TR2 is a torque requested by the driver during startup of
the internal combustion engine 1. Note that a conversion factor is
set as appropriate in advance.
TR2=APS1.times.conversion factor (1)
[0039] Here, the driver requested torque TR2 is a torque required
from step S211 (the start of fuel injection), to be described
below, to step S216 (where the throttle opening is set at a second
throttle opening TH2), to be described below.
[0040] In step S205, the internal combustion engine control unit 13
determines a torque TR3 to be output by the internal combustion
engine 1 by means of fuel combustion between step S211 and step
S216. The internal combustion engine control unit 13 then
calculates a drive torque of the generator-motor 6 corresponding to
the driver requested torque TR2 as a first torque TR1 using
Equation (2), shown below, on the basis of the driver requested
torque TR2 and the torque TR3.
TR1=TR2-TR3 (2)
[0041] Note that the drive torque (the first torque TR1) of the
generator-motor 6 corresponding to the driver requested torque TR2
may be determined using a map table M403 shown in FIG. 4C without
using Equation (2). On the map table M403 of FIG. 4C, the
horizontal axis shows the driver requested torque TR2 and the
vertical axis shows the first torque TR1. A relationship between
the driver requested torque TR2 and the first torque TR1 is as
shown by a solid line 43 on the map table M403 of FIG. 4C. Hence, a
value of the first torque TR1 is stored on the map table M403 in
advance for each value of the driver requested torque TR2. The
first torque TR1 can therefore be determined from the map table
M403 on the basis of the driver requested torque TR2.
[0042] In step S206, a determination is made as to whether or not
the first torque TR1 (the drive torque of the generator-motor 6)
determined in step S205 is no greater than a maximum torque value
that can be output by the generator-motor 6. Note that the maximum
torque value is a design value of the generator-motor 6. When the
first torque TR1 exceeds the maximum torque value, the routine
advances to step S207. On the other hand, when the first torque TR1
does not exceed the maximum torque value, the routine advances to
step S208.
[0043] In step S207, the minimum negative pressure value V1 in the
intake passage 10, used to determine the fuel injection timing, is
reset at a higher value than the value determined in step S203.
Hence, the value of the minimum negative pressure value V1 when the
first torque TR1 exceeds the maximum torque value is higher than
the minimum negative pressure value V1 when the first torque TR1
does not exceed the maximum torque value. In a calculation method
used to reset the minimum negative pressure value V1, a preset
value is added to the minimum negative pressure value V1 determined
in step S203, for example. The added value is determined as
appropriate in advance on the basis of design values of the
internal combustion engine 1, experiment results, and so on. By
resetting the minimum negative pressure value V1 in this manner,
the fuel injection timing when the first torque TR1 exceeds the
maximum torque value is advanced relative to the fuel injection
timing when the first torque TR1 does not exceed the maximum torque
value. Accordingly, a period up to the beginning of startup of the
internal combustion engine 1 becomes shorter than that when the
first torque TR1 does not exceed the maximum torque value. As a
result, shock tends to occur during startup, but since the driver
has intentionally issued a torque request, the shock is
permitted.
[0044] In step S208, the internal combustion engine control unit 13
drives the generator-motor 6 in order to rotate the internal
combustion engine 1. At this time, the drive torque of the
generator-motor 6 is a torque at which the rotation speed of the
internal combustion engine 1 can be increased quickly to a preset
rotation speed. The drive torque at this time is therefore
different from the first torque TR1 (see the drive torque between a
time T301 and a time T302 in FIG. 3).
[0045] In step S209, the internal combustion engine control unit 13
opens the throttle valve 11 to the first throttle opening TH1
determined in step S202.
[0046] In step S210, the internal combustion engine control unit 13
determines on the basis of the negative pressure information from
the negative pressure detector 12 whether or not the detected value
of the negative pressure in the intake passage 10, detected by the
negative pressure detector 12, is equal to or less than the minimum
negative pressure value V1 determined in step S203 or step S207.
When the detected value of the negative pressure is equal to or
less than the minimum negative pressure value, the routine advances
to step S211. On the other hand, when the detected value of the
negative pressure is higher than the minimum negative pressure
value, the routine returns to step S210.
[0047] Hence, in step S210, the internal combustion engine control
unit 13 waits for the detected value of the negative pressure to
fall to or below the minimum negative pressure value. At this time,
as described above, the value of the minimum negative pressure
value V1 when the first torque TR1 exceeds the maximum torque value
is higher than the minimum negative pressure value V1 when the
first torque TR1 does not exceed the maximum torque value.
Therefore, a wait time when the first torque TR1 exceeds the
maximum torque value is shorter than the wait time when the first
torque TR1 does not exceed the maximum torque value. In either
case, however, it is possible to determine reliably, from the
determination of step S210, whether or not the detected value of
the negative pressure in the intake passage 10 is equal to or less
than the minimum negative pressure value at which the internal
combustion engine 1 can be started, and therefore the energy
generated as a result of fuel combustion can be used entirely to
increase the rotation speed of the internal combustion engine 1. As
a result, shock can be suppressed reliably during complete
combustion, and startability can be secured reliably.
[0048] In step S211, the internal combustion engine control unit 13
determines the fuel injection amount to be injected from the fuel
injection valve 9, and starts fuel injection by controlling the
fuel injection valve 9 on the basis thereof.
[0049] In step S212, the internal combustion engine control unit 13
modifies the drive torque of the generator-motor 6 to the first
torque TR1 calculated in step S205.
[0050] In step S213, the internal combustion engine control unit 13
determines on the basis of the output of the crank angle sensor 4
whether or not the rotation speed of the internal combustion engine
1, calculated from the crank angle, has reached a preset crank
angle threshold after the start of fuel injection. When the
rotation speed of the internal combustion engine 1 has not reached
the crank angle threshold, the routine advances to step S214. On
the other hand, when the rotation speed of the internal combustion
engine 1 exceeds the crank angle threshold, the routine advances to
step S215.
[0051] By increasing the crank angle threshold intentionally at
this time, a period in which the internal combustion engine 1 can
be operated while maintaining the throttle valve 11 at the first
throttle opening TH1 can be extended, and as a result, a fuel
consumption amount can be reduced in comparison with the
conventional control apparatus described in PTL 1.
[0052] Further, by setting the crank angle threshold intentionally
to be small in a case where the driver requested torque TR2 is
greater than the maximum torque of the generator-motor 6, a timing
at which the internal combustion engine 1 outputs the
driver-requested torque TR2 by means of fuel combustion can be
earlier, and as a result, the driver does not experience discomfort
caused by a torque deficiency.
[0053] In step S214, the internal combustion engine control unit 13
determines whether or not an elapsed time following the start of
fuel injection has reached or exceeded a predetermined time
threshold. When the elapsed time has not reached or exceeded the
time threshold, the routine returns to step S213. On the other
hand, when the elapsed time has reached or exceeded the time
threshold, the routine advances to step S215.
[0054] Here, by increasing the time threshold applied to the
elapsed time following the start of fuel injection intentionally,
the period in which the internal combustion engine 1 can be
operated while maintaining the throttle valve 11 at the first
throttle opening TH1 can be extended, and as a result, the fuel
consumption amount can be reduced in comparison with the
conventional control apparatus described in PTL 1.
[0055] Note that when the driver requested torque TR2 is greater
than the maximum torque of the generator-motor 6, the timing at
which the internal combustion engine 1 outputs the torque requested
by the driver by means of fuel combustion can be advanced by
setting the time threshold applied to the elapsed time following
the start of fuel injection intentionally to be small, and as a
result, the driver does not experience discomfort caused by a
torque deficiency.
[0056] When either the determination condition of step S213 or the
determination condition of step S214 is satisfied, the routine
advances to step S215. More specifically, a determination as to
whether or not the internal combustion engine 1 is rotating with
stability is made on the basis of either the determination
condition of step S213 or the determination condition of step S214.
When it can be confirmed as a result of the determination that
either the rotation speed of the internal combustion engine 1 has
reached the threshold or that sufficient time has elapsed following
the start of fuel injection, the routine advances to step S215.
[0057] In step S215, since either the determination condition of
step S213 or the determination condition of step S214 is satisfied,
the internal combustion engine control unit 13 sets the drive
torque of the generator-motor 6 at zero. In other words, the
internal combustion engine control unit 13 stops the
generator-motor 6.
[0058] In step S216, at the same time as the generator-motor 6 is
stopped in step S215, the internal combustion engine control unit
13 opens the throttle valve 11 to a second throttle opening TH2
that is larger than the first throttle opening TH1. Note that the
second throttle opening TH2 is set at an optimum throttle opening
employed during idling in the internal combustion engine 1.
[0059] At this time, by setting the second throttle opening TH2 of
the throttle valve 11 to a throttle opening at which the drive
torque of the generator-motor 6 (the first torque TR1) over the
period from step S212 to step S215 can be secured, the drive torque
of the generator-motor 6 can be set at zero without causing the
torque TR2 output by the internal combustion engine 1 to vary, and
as a result, the RETURN condition can be established, whereby the
processing shown in FIG. 2 is completed.
[0060] FIG. 3 is a time chart of the startup control executed by
the control apparatus for an internal combustion engine according
to the first embodiment.
[0061] At the time T301, when the internal combustion engine
control unit 13 detects a startup request, the internal combustion
engine control unit 13 controls the throttle valve 11 to open the
throttle valve 11 to the first throttle opening TH1. Further, the
internal combustion engine control unit 13 controls the
generator-motor 6 such that the generator-motor 6 rotates, with the
result that the internal combustion engine 1 rotates and negative
pressure is generated in the intake passage 10. The drive torque of
the generator-motor 6 at this time is a torque at which the
rotation speed of the internal combustion engine 1 can be increased
quickly to a preset rotation speed.
[0062] At the time T302, when the negative pressure in the intake
passage 10 decreases to the minimum negative pressure value V1, the
internal combustion engine control unit 13 controls the fuel
injection valve 9 to start fuel injection. Note that the minimum
negative pressure value V1 is a negative pressure value at which
the internal combustion engine 1 can be started and shock during
complete combustion can be sufficiently suppressed. Further, at the
time T302, the internal combustion engine control unit 13 modifies
the drive torque of the generator-motor 6 to the first torque
TR1.
[0063] Hence, in a period from the time T302 to a time T304, the
internal combustion engine 1 is driven by the first torque TR1 and
the torque TR3. The first torque TR1 is the drive torque of the
generator-motor 6. The torque TR3 is the torque output by the
internal combustion engine 1 by means of fuel combustion.
[0064] At a time T303, a spark plug (not shown) is ignited, whereby
an air-fuel mixture taken into the internal combustion engine 1
undergoes complete combustion. At this time, the negative pressure
in the intake passage 10 remains in a reduced condition at the
minimum negative pressure value V1 at which complete combustion can
be achieved in the internal combustion engine 1 and shock can be
sufficiently suppressed during complete combustion. Therefore,
shock during complete combustion can be suppressed.
[0065] Further, at the time T303, the negative pressure in the
intake passage 10 reaches the minimum negative pressure value V1
set when the throttle valve 11 is at the first throttle opening
TH1. Accordingly, a timing of complete combustion and a timing of a
peak of the negative pressure match each other. As a result, shock
generated during complete combustion due to a mismatch between the
timing of complete combustion and the timing of the peak of the
negative pressure can also be suppressed.
[0066] At the time T304, either the rotation speed of the internal
combustion engine 1 has reached the crank angle threshold following
the time 1302 or the elapsed time following the time 1302 has
reached or exceeded the time threshold, and therefore the internal
combustion engine control unit 13 determines that the internal
combustion engine 1 is rotating with stability. Therefore, at the
time T304, the internal combustion engine control unit 13 opens the
throttle valve 11 to the second throttle opening TH2, which is
larger than the first throttle opening TH1, and simultaneously
stops driving the generator-motor 6.
[0067] Here, in a period extending from the time T302 to the time
T304, the internal combustion engine 1 can be operated while
maintaining the throttle opening of the throttle valve 11 at the
first throttle opening TH1, at which the minimum negative pressure
value V1 enabling complete combustion in the internal combustion
engine 1 is obtained. Therefore, the amount of fuel consumed during
the period extending from the time T302 to the time T304 can be
reduced in comparison with the amount of fuel consumed in the
conventional control apparatus of PTL 1.
[0068] Hence, in this embodiment, the throttle opening of the
throttle valve 11 is set at the first throttle opening TH1 during
startup of the internal combustion engine 1. Fuel is then injected
from the fuel injection valve 9 at a fuel injection timing
calculated on the basis of the detected value of the negative
pressure in the intake passage 10 while maintaining the throttle
opening at the first throttle opening TH1. The throttle valve 11 is
then opened to the second throttle opening TH2. In so doing,
complete combustion can be achieved while maintaining the negative
pressure in the intake passage 10 in a favorable condition even in
a situation where it is necessary to prioritize startability in the
internal combustion engine 1, and as a result, shock occurring
during complete combustion can be suppressed.
[0069] Further, in the period where the rotation speed of the
internal combustion engine 1, which is calculated on the basis of
the crank angle, equals or exceeds the crank angle threshold
following the start of fuel injection or the elapsed time following
the start of fuel injection equals or exceeds the time threshold,
the internal combustion engine 1 can be rotated and driving of the
generator-motor 6 can be continued while maintaining the opening of
the throttle valve 11 at the first throttle opening TH1. As a
result, the fuel consumption amount can be reduced without the
driver sensing a torque deficiency.
[0070] Note that likewise when a request to start the internal
combustion engine 1 is issued by the driver by depressing the
accelerator pedal or the like, as long as the driver requested
torque TR2 does not exceed the maximum torque that can be output by
the generator-motor 6, shock can be suppressed during complete
combustion, and output torque can be secured in the internal
combustion engine 1 in accordance with the driver requested torque
TR2.
[0071] Furthermore, when a request to start the internal combustion
engine 1 is issued by the driver by depressing the accelerator
pedal or the like and the driver-requested torque TR2 exceeds the
maximum torque that can be output by the generator-motor 6, the
fuel injection timing can be advanced relative to the fuel
injection timing when the driver requested torque TR2 does not
exceed the maximum torque of the generator-motor 6 by setting the
minimum negative pressure value V1 in the intake passage 10, by
which the start timing of fuel injection is determined, to be
higher than the minimum negative pressure value V1 when the driver
requested torque TR2 does not exceed the maximum torque of the
generator-motor 6. As a result, a timing at which startup of the
internal combustion engine 1 is begun can be advanced relative to
the timing in a case where the driver-requested torque TR2 does not
exceed the maximum torque of the generator-motor 6.
[0072] In the control method for an internal combustion engine
according to this embodiment, as described above, the internal
combustion engine control unit 13 sets the throttle valve 11 at the
first throttle opening after detecting a request to start the
internal combustion engine 1, then causes the fuel injection valve
9 to inject fuel at a fuel injection timing determined using the
actual negative pressure in the intake passage 10, detected by the
negative pressure detector 12, while maintaining the first throttle
opening, and then opens the throttle valve 11 to the second
throttle opening TH2 that is larger than the first throttle opening
TH1. Accordingly, complete combustion can be achieved while
maintaining the negative pressure in the intake passage 10 in a
favorable condition. As a result, shock during startup can be
suppressed even in a situation where it is necessary to prioritize
startability in the internal combustion engine 1.
REFERENCE SIGNS LIST
[0073] 1 internal combustion engine, 2 crank pulley, 3 crank angle
detecting ring gear, 4 crank angle sensor, 5 drive belt, 6
generator-motor, 7 generator-motor drive pulley, 8 exhaust passage,
9 fuel injection valve, 10 intake passage, 11 throttle valve, 12
negative pressure detector, 13 internal combustion engine control
unit, 14 accelerator pedal.
* * * * *