U.S. patent application number 10/202025 was filed with the patent office on 2003-02-06 for control device for hybrid vehicle.
This patent application is currently assigned to HONDA GIKEN KOGYO KABUSHIKI KAISHA. Invention is credited to Kamo, Tomoharu, Matsubara, Atsushi, Nakamoto, Yasuo, Nakaune, Kan, Wakashiro, Teruo.
Application Number | 20030028295 10/202025 |
Document ID | / |
Family ID | 19065625 |
Filed Date | 2003-02-06 |
United States Patent
Application |
20030028295 |
Kind Code |
A1 |
Wakashiro, Teruo ; et
al. |
February 6, 2003 |
CONTROL DEVICE FOR HYBRID VEHICLE
Abstract
A control device for a hybrid vehicle includes an actual intake
gas negative pressure detection unit which detects an intake air
negative pressure for the engine, an estimated intake gas negative
pressure calculation unit which estimates an intake air negative
pressure based on a revolution number of the engine and an opening
degree of a throttle, and an engine control unit which compares an
actual intake gas negative pressure obtained by the actual intake
gas negative pressure detection unit with an estimated intake gas
negative pressure obtained by the estimated intake gas negative
pressure calculation unit. The engine control unit prohibits a fuel
supply to the engine until the actual intake gas negative pressure
matches the estimated intake gas negative pressure, and carries out
the fuel supply to the engine when the actual intake gas negative
pressure matches the estimated intake gas negative pressure.
Inventors: |
Wakashiro, Teruo;
(Shioya-gun, JP) ; Matsubara, Atsushi;
(Utsunomiya-shi, JP) ; Kamo, Tomoharu;
(Kawachi-gun, JP) ; Nakaune, Kan; (Kawachi-gun,
JP) ; Nakamoto, Yasuo; (Utsunomiya-shi, JP) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN, PLLC
Suite 600
1050 Connecticut Avenue, N.W.
Washington
DC
20036-5339
US
|
Assignee: |
HONDA GIKEN KOGYO KABUSHIKI
KAISHA
|
Family ID: |
19065625 |
Appl. No.: |
10/202025 |
Filed: |
July 25, 2002 |
Current U.S.
Class: |
701/22 ;
180/65.26; 180/65.28; 903/905; 903/918; 903/919; 903/947 |
Current CPC
Class: |
B60W 10/06 20130101;
F02D 41/126 20130101; B60W 2510/0614 20130101; F02D 41/0087
20130101; B60W 2510/0619 20130101; B60W 2710/0605 20130101; B60W
2710/0616 20130101; B60W 2510/0638 20130101; Y02T 10/40 20130101;
B60K 6/543 20130101; B60W 20/00 20130101; Y10S 903/919 20130101;
B60W 20/10 20130101; B60K 6/485 20130101; Y02T 10/62 20130101; B60W
2510/0671 20130101; B60W 2520/10 20130101; F02D 2250/41 20130101;
Y02T 10/48 20130101; Y10S 903/918 20130101; F02D 37/02 20130101;
Y02T 10/6226 20130101; Y10S 903/905 20130101; B60L 2240/441
20130101; Y10S 903/947 20130101 |
Class at
Publication: |
701/22 ;
180/65.3 |
International
Class: |
B60K 006/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2001 |
JP |
P2001-233915 |
Claims
1. A control device for a hybrid vehicle provided with an engine
including a plurality of cylinders and a motor as driving sources,
in the vehicle a supply of fuel to the engine during a deceleration
state of the vehicle is stopped and a regeneration control is
performed by the motor in accordance with the state of
deceleration, and the engine is a cylinder deactivatable engine
capable of switching to an all cylinder operation state from a
cylinder deactivated operation state in which at least one of the
cylinders is deactivated, and vice versa, so that a cylinder
deactivated operation of the engine is carried out in accordance
with an operation state of the vehicle during deceleration, the
control device comprising: an actual intake gas negative pressure
detection unit which detects an intake air negative pressure for
the engine; an estimated intake gas negative pressure calculation
unit which estimates an intake air negative pressure based on a
revolution number of the engine and an opening degree of a
throttle, both the actual intake gas negative pressure detection
unit and the estimated intake gas negative pressure calculation
unit being used when the operation state of the engine is switched
to the all cylinder operation state from the cylinder deactivated
operation state, and a supply of fuel to the engine is about to be
restarted by a fuel supply amount control unit; and, an engine
control unit which compares an actual intake gas negative pressure
obtained by the actual intake gas negative pressure detection unit
with an estimated intake gas negative pressure obtained by the
estimated intake gas negative pressure calculation unit, the engine
control unit prohibits a fuel supply to the engine until the actual
intake gas negative pressure matches the estimated intake gas
negative pressure, and carries out the fuel supply to the engine
when the actual intake gas negative pressure matches the estimated
intake gas negative pressure.
2. A control device for a hybrid vehicle according to claim 1,
wherein an initial value of fuel injection amount smaller than a
normal fuel injection amount is set when the fuel supply is
restarted, and an amount of the fuel supply is gradually increased
until the fuel injection amount reaches the normal fuel injection
amount.
3. A control device for a hybrid vehicle according to claim 1,
wherein a predetermined amount ignition retard is carried out when
returned to the all cylinder operation state from the cylinder
deactivated operation state, and an ignition timing is gradually
returned to a normal ignition timing after restarting a fuel
injectino.
4. A control device for a hybrid vehicle according to claim 2,
wherein a predetermined amount ignition retard is carried out when
returned to the all cylinder operation state from the cylinder
deactivated operation state, and an ignition timing is gradually
returned to a normal ignition timing after restarting a fuel
injectino.
5. A control device for a hybrid vehicle according to claim 1,
wherein a driving force is assisted by the motor during a time
period between fuel supply prohibition and a restart of fuel supply
when returning to the all cylinder operation state from the
cylinder deactivated operation state.
6. A control device for a hybrid vehicle according to claim 2,
wherein a driving force is assisted by the motor during a time
period between fuel supply prohibition and a restart of fuel supply
when returning to the all cylinder operation state from the
cylinder deactivated operation state.
7. A control device for a hybrid vehicle according to claim 3,
wherein a driving force is assisted by the motor during a time
period between fuel supply prohibition and a restart of fuel supply
when returning to the all cylinder operation state from the
cylinder deactivated operation state.
8. A control device for a hybrid vehicle according to claim 4,
wherein a driving force is assisted by the motor during a time
period between fuel supply prohibition and a restart of fuel supply
when returning to the all cylinder operation state from the
cylinder deactivated operation state.
9. A control device for a hybrid vehicle provided with an engine
including a plurality of cylinders and a motor as driving sources,
in the vehicle a supply of fuel to the engine during a deceleration
state of the vehicle is stopped and a regeneration control is
performed by the motor in accordance with the state of
deceleration, and the engine is a cylinder deactivatable engine
capable of switching to an all cylinder operation state from a
cylinder deactivated operation state in which at least one of the
cylinders is deactivated, and vice versa, so that a cylinder
deactivated operation of the engine is carried out in accordance
with an operation state of the vehicle during deceleration, the
control device comprising: an actual intake gas negative pressure
detection unit which detects an intake air negative pressure for
the engine; an estimated intake gas negative pressure calculation
unit which estimates an intake air negative pressure based on a
revolution number of the engine and an opening degree of a
throttle, both the actual intake gas negative pressure detection
unit and the estimated intake gas negative pressure calculation
unit being used when the operation state of the engine is switched
to the all cylinder operation state from the cylinder deactivated
operation state, and a supply of fuel to the engine is about to be
restarted by a fuel supply amount control unit; and, an engine
control unit which compares an actual intake gas negative pressure
obtained by the actual intake gas negative pressure detection unit
with an estimated intake gas negative pressure obtained by the
estimated intake gas negative pressure calculation unit, the engine
control unit determines a fuel supply amount based on the actual
intake gas negative pressure when the actual intake gas negative
pressure is larger than the estimated intake gas negative pressure,
and determines the fuel supply amount based on the estimated intake
gas negative pressure when the estimated intake gas negative
pressure is larger than the actual intake gas negative pressure,
and carries out the fuel supply.
10. A control device for a hybrid vehicle according to claim 9,
wherein a fuel injection amount based on the actual intake gas
negative pressure is determined after returning to the all cylinder
operation state from the cylinder deactivated operation state and a
predetermined period of time has been elapsed.
11. A control device for a hybrid vehicle according to claim 9,
further comprising: an ignition timing control unit which controls
an ignition timing, wherein the ignition timing control unit
carries out an ignition timing control based on the actual intake
gas negative pressure and the estimated intake gas negative
pressure.
12. A control device for a hybrid vehicle provided with an engine
including a plurality of cylinders and a motor as driving sources,
in the vehicle a supply of fuel to the engine during a deceleration
state of the vehicle is stopped and a regeneration control is
performed by the motor in accordance with the state of
deceleration, and the engine is a cylinder deactivatable engine
capable of switching to an all cylinder operation state from a
cylinder deactivated operation state in which at least one of the
cylinders is deactivated, and vice versa, so that a cylinder
deactivated operation of the engine is carried out in accordance
with an operation state of the vehicle during deceleration, the
control device comprising: a basic fuel injection amount
calculation unit which calculates a basic fuel injection amount
based on an intake air negative pressure for the engine and a
revolution number of the engine; a fuel injection amount
calculation unit which calculates a fuel injection amount based on
the revolution number of the engine and an opening degree of a
throttle, both the basic fuel injection amount calculation unit and
the fuel injection amount calculation unit being used when the
operation state of the engine is switched to the all cylinder
operation slate from the cylinder deactivated operation state, and
a supply of fuel to the engine is about to be restarted by a fuel
supply amount control unit; and, an engine control unit which
compares a fuel injection amount calculated by the fuel injection
amount calculation unit with a basic fuel injection amount
calculated by the basic fuel injection amount calculation unit, and
carries out a fuel supply based on a comparison result obtained.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a control device for
parallel type hybrid vehicles in which the operation of a cylinder
can be stopped. More specifically, the present invention relates to
a control device for a hybrid vehicle which enables improvement in
fuel consumption efficiency while maintaining salability when the
vehicle is reaccelerated from a cylinder deactivated operation
state.
[0003] 2. Description of Related Art
[0004] Hybrid vehicles provided with a motor as an auxiliary
driving source for running the vehicle in addition to an engine
have been conventionally known. A parallel hybrid vehicle in which
output from an engine is auxiliary assisted by a motor is a
variation of the hybrid vehicles.
[0005] In the parallel hybrid vehicle, output from the engine is
auxiliary assisted by the motor when the vehicle is accelerated,
and various controls, such as charging of batteries using
deceleration regeneration, are performed when the vehicle is
decelerated so that the needs of the driver can be satisfied while
maintaining remaining charge (electric energy) of the batteries.
Also, the parallel hybrid vehicle, in terms of its structure, has a
mechanism in which the engine and the motor are arranged in series.
Accordingly, the parallel hybrid vehicle has advantages in that its
structure can be simplified to decrease the weight thereof and to
improve the degree of freedom in vehicle loading capacity.
[0006] The types of the parallel hybrid vehicle includes one in
which a clutch is provided between the engine and the motor in
order to eliminate the influence of engine friction (engine brake)
during deceleration regeneration as disclosed in, for instance, the
Japanese Unexamined Patent Application, First Publication No.
2000-97068, and one in which the engine, motor, and transmission
are connected in series in order to maximally simplify its
structure as disclosed in, for instance, the Japanese Unexamined
Patent Application, First Publication No. 2000-125405.
[0007] However, the former in which the clutch is provided between
the engine and the motor has disadvantages that its structure is
complicated due to the presence of the clutch, which in turn
deteriorates the loading capacity, and that its mechanical
efficiency of power transmission during a running mode is decreased
due to the used of the clutch. On the other hand, the latter in
which the engine, motor, and transmission are connected in series
has a regeneration amount decreased by the above-mentioned engine
friction, and hence the amount of electric energy obtained by
regeneration is reduced. Accordingly, it has problems in that the
driving auxiliary (i.e., the amount of assist) etc. is restricted
by the motor.
[0008] Also, in the former, a method for reducing engine friction
during deceleration is available in which the amount of
regeneration is increased by controlling a throttle valve to an
open side during deceleration using an electronic control throttle
mechanism in order to significantly decrease a pumping loss.
However, there is a problem that a large amount of new gas directly
flows into an exhaust system during deceleration to lower the
temperature of catalyst or an A/F sensor, and exhaust gas control
is adversely influenced.
[0009] With regard to the above, proposals have been made to solve
the problem by using a cylinder deactivation technique. However,
there is a problem in that smooth transition from a cylinder
deactivated state to an all cylinder operation state is
difficult.
SUMMARY OF THE INVENTION
[0010] Accordingly, an object of the present invention is to
provide a control device for a hybrid vehicle which enables a
smooth transition from the cylinder deactivated state to the all
cylinder operation state using a cylinder deactivation technique so
as to improve fuel consumption efficiency.
[0011] In order to achieve the above object, the present invention
provides a control device for a hybrid vehicle provided with an
engine (for instance, an engine E in an embodiment described later)
including a plurality of cylinders and a motor (for instance, a
motor M in the embodiment described later) as driving sources, in
the vehicle a supply of fuel to the engine during a deceleration
state of the vehicle is stopped and a regeneration control is
performed by the motor in accordance with the state of
deceleration, and the engine is a cylinder deactivatable engine
capable of switching to an all cylinder operation state from a
cylinder deactivated operation state in which at least one of the
cylinders is deactivated, and vice versa, so that a cylinder
deactivated operation of the engine is carried out in accordance
with an operation state of the vehicle during deceleration, the
control device comprising: an actual intake gas negative pressure
detection unit (for instance, an inlet pipe negative pressure
sensor S1 in the embodiment described later) which detects an
intake air negative pressure for the engine; an estimated intake
gas negative pressure calculation unit (for instance, a step S201
shown in FIG. 5 in the embodiment described later) which estimates
an intake air negative pressure based on a revolution number of the
engine and an opening degree of a throttle, both the actual intake
gas negative pressure detection unit and the estimated intake gas
negative pressure calculation unit being used when the operation
state of the engine is switched to the all cylinder operation state
from the cylinder deactivated operation state, and a supply of fuel
to the engine is about to be restarted by a fuel supply amount
control unit (for instance, an FIECU 11 in the embodiment described
later); and an engine control unit (for instance, also the FIECU 11
in the embodiment described later) which compares an actual intake
gas negative pressure obtained by the actual intake gas negative
pressure detection unit with an estimated intake gas negative
pressure obtained by the estimated intake gas negative pressure
calculation unit, the engine control unit prohibits a fuel supply
to the engine until the actual intake gas negative pressure matches
the estimated intake gas negative pressure, and carries out the
fuel supply to the engine when the actual intake gas negative
pressure matches the estimated intake gas negative pressure.
[0012] According to the above control device for a hybrid vehicle,
it becomes possible, when returning to the all cylinder operation
state to the cylinder deactivated operation state, to stop the fuel
supply until the actual intake gas pressure matches the estimated
intake gas negative pressure, and to restart the fuel supply
quickly when the actual intake gas pressure matches the estimated
intake gas negative pressure. Accordingly, as compared with the
case where a fuel supply is restarted when the inlet pipe negative
pressure is completely recovered, it becomes possible to shorten
the time interval to the fuel supply and improve the salability
during reacceleration after returning from the cylinder deactivated
operation state.
[0013] In accordance with another aspect of the invention, in the
control device for a hybrid vehicle, an initial value of fuel
injection amount smaller than a normal fuel injection amount is set
when the fuel supply is restarted, and an amount of the fuel supply
is gradually increased until the fuel injection amount reaches the
normal fuel injection amount.
[0014] According to the above control device for a hybrid vehicle,
it becomes possible to suppress the generation of shock by
gradually increasing the amount of fuel supply which is started
when the actual intake gas negative pressure matches the estimated
intake gas negative pressure. Accordingly, the salability during
reacceleration can be improved.
[0015] In accordance with yet another aspect of the invention, in
the control device for a hybrid vehicle, a predetermined amount of
ignition retard is carried out when returned to the all cylinder
operation state from the cylinder deactivated operation state, and
an ignition timing is gradually returned to a normal ignition
timing after restarting a fuel injection.
[0016] According to the above control device for a hybrid vehicle,
it becomes possible to carry out an ignition retard of a
predetermined amount immediately after returning to the all
cylinder operation state from the cylinder deactivated operation
state, and the delay of the ignition timing can be gradually
returned to normal ignition timing. Accordingly, shock generated
when returned to the all cylinder operation state can be decreased,
and a smooth transition of the operation states can be
performed.
[0017] In accordance with another aspect of the invention, in the
control device for a hybrid vehicle, a driving force is assisted by
the motor during a time period between fuel supply prohibition and
a restart of fuel supply when returning to the all cylinder
operation state from the cylinder deactivated operation state.
[0018] According to the above control device for a hybrid vehicle,
it becomes possible to carry out acceleration using the motor
during the time period between the fuel supply prohibition and a
restart of the fuel supply when returning to the all cylinder
operation state form the cylinder deactivated operation state.
Accordingly, it becomes possible to maintain the acceleration
performance during a time period in which no fuel is supplied, and
hence, the salability can be improved.
[0019] The present invention also provides a control device for a
hybrid vehicle provided with an engine including a plurality of
cylinders and a motor as driving sources, in the vehicle a supply
of fuel to the engine during a deceleration state of the vehicle is
stopped and a regeneration control is performed by the motor in
accordance with the state of deceleration, and the engine is a
cylinder deactivatable engine capable of switching to an all
cylinder operation state from a cylinder deactivated operation
state in which at least one of the cylinders is deactivated, and
vice versa, so that a cylinder deactivated operation of the engine
is carried out in accordance with an operation state of the vehicle
during deceleration, the control device comprising: an actual
intake gas negative pressure detection unit which detects an intake
air negative pressure for the engine; an estimated intake gas
negative pressure calculation unit which estimates an intake air
negative pressure based on a revolution number of the engine and an
opening degree of a throttle, both the actual intake gas negative
pressure detection unit and the estimated intake gas negative
pressure calculation unit being used when the operation state of
the engine is switched to the all cylinder operation state from the
cylinder deactivated operation state, and a supply of fuel to the
engine is about to be restarted by a fuel supply amount control
unit; and an engine control unit which compares an actual intake
gas negative pressure obtained by the actual intake gas negative
pressure detection unit with an estimated intake gas negative
pressure obtained by the estimated intake gas negative pressure
calculation unit, the engine control unit determines a fuel supply
amount based on the actual intake gas negative pressure when the
actual intake gas negative pressure is larger than the estimated
intake gas negative pressure, and determines the fuel supply amount
based on the estimated intake gas negative pressure when the
estimated intake gas negative pressure is larger than the actual
intake gas negative pressure, and carries out the fuel supply.
[0020] According to the above control device for a hybrid vehicle,
it becomes possible to supply a fuel, when returning to the all
cylinder operation state from the cylinder deactivated state, based
on one of the actual intake gas negative pressure and the estimated
intake gas negative pressure, whichever is the greater, so that
acceleration performance can be secured and the salability can be
improved.
[0021] In accordance with another aspect of the invention, in the
control device for a hybrid vehicle, a fuel injection amount based
on the actual intake gas negative pressure is determined after
returning to the all cylinder operation state from the cylinder
deactivated operation state and a predetermined period of time has
elapsed.
[0022] According to the above control device for a hybrid vehicle,
a fuel injection amount based on the actual intake gas negative
pressure is determined after a predetermined time period has
elapsed even if a problem is caused, and hence reliability can be
improved.
[0023] In accordance with another aspect of the invention, the
control device for a hybrid vehicle further includes an ignition
timing control unit (for instance, the FIECU in the embodiment
described later) which controls an ignition timing, and the
ignition timing control unit carries out an ignition timing control
based on the actual intake gas negative pressure and the estimated
intake gas negative pressure.
[0024] According to the above control device for a hybrid vehicle,
it becomes possible to set a proper ignition timing corresponding
to the fuel supply, and hence, acceleration performance when
returned to the all cylinder operation state from the cylinder
deactivated operation state can be secured.
[0025] The present invention also provides a control device for a
hybrid vehicle provided with an engine including a plurality of
cylinders and a motor as driving sources, in the vehicle a supply
of fuel to the engine during a deceleration state of the vehicle is
stopped and a regeneration control is performed by the motor in
accordance with the state of deceleration, and the engine is a
cylinder deactivatable engine capable of switching to an all
cylinder operation state from a cylinder deactivated operation
state in which at least one of the cylinders is deactivated, and
vice versa, so that a cylinder deactivated operation of the engine
is carried out in accordance with an operation state of the vehicle
during deceleration, the control device comprising: a basic fuel
injection amount calculation unit (for instance, the FIECU 11 in
the embodiment described later) which calculates a basic fuel
injection amount (for instance, a basic fuel injection amount TiM
in the embodiment described later) based on an intake air negative
pressure for the engine and a revolution number of the engine; and
a fuel injection amount calculation unit (for instance, a step S401
shown in FIG. 12 in the FIECU 111 in the embodiment described
later) which calculates a fuel injection amount (for instance, a
fuel injection amount Ti in the embodiment described later) based
on the revolution number of the engine and an opening degree of a
throttle, both the basic fuel injection amount calculation unit and
the fuel injection amount calculation unit being used when the
operation state of the engine is switched to the all cylinder
operation state from the cylinder deactivated operation state, and
a supply of fuel to the engine is about to be restarted by a fuel
supply amount control unit; and an engine control unit which
compares a fuel injection amount calculated by the fuel injection
amount calculation unit with a basic fuel injection amount
calculated by the basic fuel injection amount calculation unit, and
carries out a fuel supply based on a comparison result
obtained.
[0026] According to the above control device for a hybrid vehicle,
it becomes possible to compare the fuel injection amount with the
basic fuel injection amount and a lower injection amount can be
selected and set. Accordingly, acceleration performance can be
secured while minimizing deterioration in the fuel consumption
efficiency when returned to the all cylinder operation state from
the cylinder deactivated operation state.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Some of the features and advantages of the invention have
been described, and others will become apparent from the detailed
description which follows and from the accompanying drawings, in
which:
[0028] FIG. 1 is a schematic structural diagram showing a hybrid
vehicle according to an embodiment of the present invention;
[0029] FIG. 2 is a flowchart showing a cylinder deactivated
operation switching process in an embodiment according to the
present invention;
[0030] FIG. 3 is a flowchart showing a cylinder deactivated
operation precondition determination process in an embodiment
according to the present invention;
[0031] FIG. 4 is a flowchart showing a cylinder deactivated
operation cancellation condition determination process in an
embodiment according to the present invention;
[0032] FIG. 5 is a flowchart showing a fuel gradual addition
coefficient calculation process in an embodiment according to the
present invention;
[0033] FIG. 6 is a flowchart showing a retard treatment when
returned from a cylinder deactivated operation in an embodiment
according to the present invention;
[0034] FIG. 7 is a graph showing a state where an actual intake gas
negative pressure matches an estimated intake gas negative pressure
in an embodiment according to the present invention;
[0035] FIG. 8 is a graph indicating a retard treatment in an
embodiment according to the present invention;
[0036] FIG. 9 is a diagram showing a front elevational view of a
variable valve timing mechanism used in an embodiment according to
the present invention;
[0037] FIG. 10A is a diagram showing a cross-sectional view of main
parts of the variable valve timing mechanism, which is used in an
embodiment according to the present invention, in a cylinder
operation state, and FIG. 10B is a diagram showing a
cross-sectional view of main parts of the variable valve timing
mechanism in a cylinder deactivated operation state;
[0038] FIG. 11 is a diagram showing an enlarged view of main parts
shown in FIG. 1;
[0039] FIG. 12 is a flowchart showing an estimated fuel injection
amount calculation process after returning to an all cylinder
operation state in an embodiment according to the present
invention; and
[0040] FIG. 13 is a flowchart showing a motor assist treatment in
an embodiment according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0041] The invention summarized above and defined by the enumerated
claims may be better understood by referring to the following
detailed description, which should be read with reference to the
accompanying drawings. This detailed description of a particular
preferred embodiment, set out below to enable one to build and use
one particular implementation of the invention, is not intended to
limit the enumerated claims, but to serve as a particular example
thereof.
[0042] FIG. 1 is a diagram showing a parallel hybrid vehicle
according to the first embodiment of the present invention. The
parallel hybrid vehicle shown in FIG. 1 has a structure in which an
engine E, a motor M, and a transmission T, are connected in series.
The driving force from both the engine E and the motor M are
transmitted to a front wheel Wf, which is a driving wheel, via the
transmission T (which can be a manual transmission), such as a CVT.
Also, when the driving force is transmitted to the motor M side
from the front wheel Wf during deceleration of the hybrid vehicle,
the motor M functions as a power generator to exert a regenerative
braking force so as to collect the kinetic energy of the vehicle as
an electric energy. In this embodiment, the regeneration control by
the motor M is carried out by taking into account an increased
amount of deceleration energy by a cylinder deactivated operation
which will be described later.
[0043] The actuation and regeneration operation of the motor M are
carried out by a power drive unit (PDU) 2 which receives a control
command from a motor CPU 1M of a motor ECU1. A high voltage type
nickel-hydrogen battery 3, which supplies and receives an electric
energy from the motor M, is connected to the power drive unit 2.
The battery 3 is formed by, for instance, a plurality of modules,
in each of which a plurality of cells are connected in series as
one unit, connected in series. A 12-volt auxiliary battery 4 for
driving various auxiliary machineries is mounted on the hybrid
vehicle, and the auxiliary battery 4 is connected to the battery 3
via a downverter 5 which is a DC-DC converter. The downverter 5,
which is controlled by a FIECU 11 (fuel supply amount control
means, engine control means, and ignition timing control means),
charges the auxiliary battery 4 by decreasing the voltage of the
battery 3. Also, the motor ECU 1 is provided with a battery CPU 1B
which protects, and calculates the remaining charge of, the battery
3. Moreover, the transmission T, which may be the above-mentioned
CVT, is connected to a CVTECU 21 which controls the transmission
T.
[0044] The FIECU 11, in addition to the motor ECU 1 and the
downverter 5, controls operation of a fuel injection valve (not
shown in the figure), which adjust the amount of fuel supplied to
the engine E, of a starter motor, and of ignition timing. For this
reason signals are input to the FIECU 11 from a speed sensor which
detects the vehicle's speed, an engine revolution number sensor
which detects the revolution number of the engine, a shift position
sensor which detects a shift position of the transmission T, a
brake switch which detects operation of a brake pedal, a clutch
switch which detects operation of a clutch pedal, throttle sensor
which detects an opening degree of a throttle valve 32, an inlet
pipe negative pressure sensor (actual depression at engine manifold
detection means) which detects inlet pipe negative pressure (actual
depression at engine manifold), and a knock sensor.
[0045] The letters BS shown in FIG. 1 indicate a booster which is
coupled to the brake pedal, and a sensor for detecting negative
pressure in a brake master power (hereinafter called negative
pressure in master power) is provided with the booster BS. Also,
the sensor for detecting negative pressure in master power is
connected to the FIECU 11.
[0046] In FIG. 1, for the sake of explanation, among the above
sensors, an inlet pipe negative pressure sensor (an inlet air
pressure detection means) S1, and a throttle sensor S2, which are
disposed at an inlet passage 30, a sensor for detecting negative
pressure inside master power at a communication passage 31, which
is connected to the inlet passage 30, and knock sensors S4 are
shown.
[0047] The inlet passage 30 is provided with a secondary air
passage 33 which connects an upstream side and a downstream side of
the throttle valve 32, and the secondary air passage 33 is provided
with a control valve 34 which opens and closes the secondary air
passage 33. The secondary air passage 33 is used to supply a small
amount of air into a cylinder even when the throttle valve 32 is
completely closed. The control valve 34 is opened and closed based
on a signal from the FIECU 11 in accordance with the inlet pipe
negative pressure which is detected by the inlet pipe negative
pressure sensor S1. Also, a POIL sensor S5, a solenoid of a spool
valve 71, and a TOIL sensor S6, which are described later, are also
connected to the FIECU 11. The knock sensors S4 are used to detect
a misfire state of a cylinder provided with a variable valve timing
mechanism VT.
[0048] The engine E is provided with three cylinders including a
variable valve timing mechanism for cylinder deactivated operation
at an inlet side and an exhaust side, and with one cylinder
including an ordinary valve train NT which does not carry out a
cylinder deactivated operation.
[0049] That is, the above-mentioned engine E is a cylinder
deactivatable engine which may be switched from an all cylinder
operation state in which the four cylinders including the three
stoppable cylinders are operated, to a cylinder deactivated
operation state in which the operation of three stoppable cylinders
are stopped. Hence, the engine E has a structure in which an inlet
valve IV and an exhaust valve EV of the stoppable cylinders can
stop the operation by the variable valve timing mechanism VT.
[0050] Next, the variable valve timing mechanism VT will be
described in detail with reference to FIGS. 9-11.
[0051] FIG. 9 is a diagram showing an example in which the variable
valve timing mechanism VT for cylinder deactivated operation is
applied to a SOHC type engine. The inlet valve IV and the exhaust
valve EV are provided with a cylinder (not shown in the figure),
and the inlet valve IV and the exhaust valve EV are urged towards a
direction closing an inlet and exhaust port (not shown in the
figure) by valve springs 51 and 51. On the other hand, the numeral
52 in FIG. 9 indicates a lift cam provided with a cam shaft 53, and
a rocker arm 54a for cam lift at the inlet valve side and a rocker
arm 54b for cam lift at the exhaust valve side, which are rotatably
supported via a rocker arm shaft 62, are coupled to the lift cam
52.
[0052] Also, rocker arms 55a and 55b for driving valves are
rotatably supported by the rocker arm shaft 62 adjacent to the
rocker arms 54a and 54b for cam lift. A rotation end of rocker arms
55a and 55b, respectively, pushes an upper end of the inlet valve
IV and the exhaust valve EV to perform an opening valve operation
for the inlet valve IV and the exhaust valve EV. Moreover, as shown
in FIGS. 10A and 10B, a base end side (i.e., opposite the valve
contacting portion side) of the rocker arms 55a and 55b are made so
as to slidably make contact with a round cam 531 provided with the
cam shaft 53.
[0053] FIGS. 10A and 10B are diagrams showing the rocker arm 54b
for the cam lift and the rocker arm 55b for driving the valve
viewed from the exhaust valve side.
[0054] In FIGS. 10A and 10B, a hydraulic chamber 56 for the rocker
arm 54b for the cam lift and the rocker arm 55b for driving the
valve is disposed at the opposite side of the lift cam 52. A pin
57a and a release pin 57b are slidably provided inside the
hydraulic chamber 56, and the pin 57a is urged towards the rocker
arm 54b side via a pin spring 58.
[0055] A hydraulic passage 59 (59a and 59b), which is separated by
a partition portion S, are formed inside the rocker arm shaft 62.
The hydraulic passage 59b communicates with the release pin 57b
side of the hydraulic chamber 56 via an opening portion 60 of the
hydraulic passage 59b, and a communication passage 61 of the rocker
arm 54b for the cam lift, and the hydraulic passage 59a
communicates with the pin 57a side of the hydraulic chamber 56 via
an opening portion 60 of the hydraulic passage 59a, and a
communication passage 61 of the rocker arm 55b for driving the
valve so that it can be connected to a drain passage which is not
shown in the figure.
[0056] When no oil pressure is exerted from the hydraulic passage
59b, the pin 57a is located at a position extending over both the
rocker arm 54b and the rocker arm 55b by the pin spring 58 as shown
in FIG. 10a. On the other hand, when oil pressure is exerted from
the hydraulic passage 59b based on a cylinder deactivation signal,
the pin 57a slides towards the rocker arm 55b together with the
release pin 57b against the pin spring 58 as shown in FIG. 10B, and
the pin 57a release the engagement of the rocker arm 54b with the
rocker arm 55b when the boundary portion with the release pin 57b
matches the boundary portion between the rocker arm 54b and the
rocker arm 55b. Note that the inlet valve side thereof has the same
structure. In this embodiment, the hydraulic passages 59a and 59b
are connected to an oil pump 70 via a spool valve 71 which secures
the oil pressure for the variable valve timing mechanism VT.
[0057] As shown in FIG. 11, a cylinder deactivation side passage 72
of the spool valve 71 is connected to the hydraulic passage 59b of
the rocker arm shaft 62, and a cylinder deactivation cancel side
passage 73 of the spool valve 71 is connected to the hydraulic
passage 59a. Here, the POIL sensor S5 is connected to the cylinder
deactivation cancel side passage 73. The POIL sensor S5 monitors
the oil pressure of the cylinder deactivation cancel side passage
73 in which the pressure level becomes low during the cylinder
deactivated state, and the pressure level becomes high during the
all cylinder operation state. Also, the TOIL sensor S6 (shown in
FIG. 1), which detects the temperature of oil, is connected to a
supply passage 74, which is a discharge side passage of the oil
pump 70 and is branched from a passage to the spool valve 71 to
supply hydraulic oil to the engine E, in order to monitor the
temperature of the hydraulic oil supplied.
[0058] Accordingly, when conditions for the cylinder deactivated
operation, which will be described later, are satisfied, the spool
valve 71 is operated based on a signal from the FIECU 11, and oil
pressure is applied to the hydraulic chamber 56 from the hydraulic
passage 59b at both the inlet valve side and the exhaust valve side
via the oil pump 70. Then, the pins 57a and 57a and the release
pins 57b and 57b, which have engaged the rocker arms 54a and 54b
for cam lift with the rocker arms 55a and 55b for driving the
valve, are slid towards the rocker arms 54a and 54b side so that
the rocker arms 54a and 54b are disengaged from the rocker arms 55a
and 55b.
[0059] Therefore, although the rocker arms 54a and 54b are driven
by the rotary movement of the lift cam 52, the movement is not
transmitted to the rocker arms 55a and 55b whose engagement with
the rocker arms 54a and 54b by means of the pins 57a and the
release pins 57b is released. As a result, since the rocker arms
55a and 55b at the inlet valve side and the exhaust valve side are
not operated, each of the valves IV and EV is kept closed to enable
a cylinder deactivated operation.
[0060] (Cylinder Deactivated Operation Switching Process)
[0061] Next, a cylinder deactivated operation switching process
will be explained with reference to FIG. 2.
[0062] In this embodiment, the term "cylinder deactivated
operation" means an operation in which the inlet valve and the
exhaust valve are closed using the variable valve timing mechanism
VT during deceleration regeneration under certain conditions, and
the cylinder deactivated operation is carried out to decrease
engine friction and increase a deceleration regeneration amount. In
the flowchart shown in FIG. 2, setting and resetting of a flag
(i.e., a cylinder deactivation performing flag F_DECCS) for
switching the cylinder deactivated operation and the all cylinder
operation, in which no cylinder deactivated operation is carried
out, take place in a certain period.
[0063] In step S100A, it is determined whether a deceleration G
excessive state cylinder deactivation cancel command flag F_GDECCS
is "1" or not. If it is determined that the result is "YES" in step
S100A, the process proceeds to step S114, and if it is determined
that the result is "NO", the process proceeds to step S100B.
[0064] In step S100B, it is determined whether a deceleration G
excessive state deceleration regeneration cancel command flag
F_GDECMA is "1" or not. If it is determined that the result is
"YES", the process proceeds to step S114, and if it is determined
that the result is "NO", the process proceeds to step S101.
[0065] The reason why the determination in step S100A is carried
out is because it is preferable not to carry out a cylinder
deactivated operation when stopping the vehicle is most preference.
Also, since the probability is high that the negative pressure in
master power is significantly decreased by a rapid deceleration G
braking and the state returns to the all cylinder operation state
thereafter during the cylinder deactivated operation, the cylinder
deactivated operation can be cancelled when such braking of high
deceleration G has taken place.
[0066] The reason why the determination in step S100B is carried
out is because it is preferable not to carry out a cylinder
deactivated operation from the view point of preventing slip of
wheels by regeneration during a rapid deceleration state.
[0067] In step S101, it is determined if assigned F/S (fail safe)
is already detected or not. If the detection result is "NO", the
process proceeds to step S102, and if the detection result is
"YES", the process proceeds to step S114. This is because the
cylinder deactivated operation should not be carried out if there
is any abnormality.
[0068] In step S102, it is determined whether a cylinder
deactivation solenoid flag F_DECCSSOL is "1" (i.e., the cylinder
deactivation solenoid of the spool valve 71 is ON) or not. If the
determination result is "YES", the process proceeds to step S105,
and if the determination result is "NO", the process proceeds to
step S103. In step S103, a cylinder deactivated operation
precondition determination (F_DECCSSTB_JUD), which will be
described later, is carried out and proceeds to step S104. The
cylinder deactivated operation is performed only when the
preconditions are met in the cylinder deactivated operation
precondition determination.
[0069] In step S104, it is determined whether a cylinder
deactivation standby flag F_DECCSSTB is "1" or not. The value of
this flag becomes "1" when the preconditions are met in the
determination made in step S103, and the value of the flag becomes
"0" when the preconditions are not met. It is determined if the
cylinder deactivated operation is carried out or not based on the
flag in accordance with the driving state of the vehicle. If the
determination result in step S104 is "YES", the process proceeds to
step S105 since the preconditions are met. If the determination
result in step S104 is "NO", the process proceeds to step S114
since the preconditions are not met.
[0070] In step S105, a cylinder deactivation cancellation condition
determination (F_DECCSSTP_JUD), which will be described later, is
carried out, and the process proceeds to step S106. If the
cancellation conditions are met in the cylinder deactivation
cancellation condition determination, the cylinder deactivated
operation is not performed. The cylinder deactivation cancellation
condition determination differs from the cylinder deactivation
precondition determination, and is always determined when the
process shown in FIG. 2 is carried out (i.e., continuous
monitoring).
[0071] In step S106, it is determined whether a cylinder
deactivation cancellation conditions met flag F_DECCSSTP is "1" or
not. The value of this flag becomes "1" when the cancellation
conditions are met in the determination made in step S105, and the
value of the flag becomes "0" when the cancellation conditions are
not met. It is determined if the cylinder deactivated operation is
cancelled or not based on the flag in accordance with the driving
state of the vehicle. If the determination result in step S106 is
"YES", the process proceeds to step S114 since the cancellation
conditions are met. If the determination result in step S106 is
"NO", the process proceeds to step S107 since the cancellation
conditions are not met.
[0072] In step S107, it is determined whether a solenoid ON delay
timer TDECCSDL1 is "0" or not. If the determination result is
"YES", the process proceeds to step S108 since a certain time
period has been elapsed. If the determination result in step S107
is "NO", the process proceeds to step S116 since a certain time
period has not elapsed.
[0073] In step S108, a predetermined value #TMDECCS2 is set for the
solenoid OFF delay timer TDECCSDL2 for the above-mentioned spool
valve 71, and the process proceeds to step S109. This is to secure
a certain time period, when the operation state is switched to the
all cylinder operation state from the cylinder deactivated
operation state, between the completion of the determination in
step S105 and the completion of the OFF operation of the solenoid
for the spool valve 71 in step S116, which will be described
later.
[0074] In step S109, "1" is set for a cylinder deactivation
solenoid flag F_DECCSSOL (i.e., the cylinder deactivation solenoid
for the spool valve 71 is turned on), and the process proceeds to
step S110.
[0075] In step S110, it is determined whether the oil pressure is
actually generated or not by the ON operation of the above solenoid
for the cylinder deactivated operation using the POIL sensor S5.
More specifically, it is determined whether the engine oil pressure
POIL is equal to or greater than a cylinder deactivated operation
determination oil pressure #POILCSH. If the pressure is
sufficiently high and the determination result is "YES". the
process proceeds to step S111. If the determination result is "NO"
(i.e., there is hysteresis), then the process proceeds to step
S118. Note that it is possible to make a determination by using an
oil pressure switch instead of the POIL sensor S5.
[0076] In step S111, it is determined whether a cylinder
deactivated operation delay timer TCSDLY1 is "0" or not in order to
secure time between the ON operation of the spool valve 71 and the
application of oil pressure. If the determination result is "YES",
the process proceeds to step S112. If the determination result is
"NO", then the process proceeds to step S120A.
[0077] In step S112, a timer value #TMNCSDL2 is table retrieved in
accordance with the engine revolution number NE, and a cylinder
deactivated operation cancellation delay timer TCSDLY2 is set. The
reason why the timer value is set in accordance with the engine
revolution number NE is because the change responsive time of the
oil pressure varies in accordance with the engine revolution number
NE. Accordingly, the timer value #TMNCSDL2 becomes larger as the
engine revolution number NE becomes smaller.
[0078] Then, in step S113, "1" is set for a cylinder deactivated
operation flag F_DECCS, and the control is terminated.
[0079] In step S114, it is determined whether the solenoid OFF
delay timer TDECCSDL2 is "0" or not. If the determination result is
"YES", the process proceeds to step S115 since a certain time
period has elapsed. If the determination result in step S114 is
"NO", then the process proceeds to step S109 since a certain time
period has not elapsed.
[0080] In step S115, a predetermined value #TMDECCS1 is set for the
solenoid ON delay timer TDECCSDL1 for the spool valve 71, and the
process proceeds to step S116. This is to secure a certain time
period, when the operation state is switched to the cylinder
deactivated operation state from the all cylinder operation state,
between the completion of the determination in step S105 and the
completion of the OFF operation of the solenoid for the spool valve
71 in step S109, which will be described later.
[0081] In step S1116, "0" is set for a cylinder deactivation
solenoid flag F_DECCSSOL (i.e., the cylinder deactivation solenoid
for the spool valve 71 is turned off), and the process proceeds to
step S117.
[0082] In step S117, it is determined whether the oil pressure is
actually cancelled or not by the OFF operation of the above
solenoid for the cylinder deactivation cancellation operation using
the POIL sensor S5. More specifically, it is determined whether the
engine oil pressure POIL is less than a cylinder deactivated
operation cancellation determination oil pressure #POILCSL. If the
pressure is low and the determination result is "YES", the process
proceeds to step S118. If the determination result is "NO" (i.e.
there is hysteresis), then the process proceeds to step S111. Note
that it is possible to make a determination by using an oil
pressure switch instead of the POIL sensor S5.
[0083] In step S118, it is determined whether a cylinder
deactivated operation cancellation delay timer TCSDLY2 is "0" or
not in order to secure time between the OFF operation of the spool
valve 71 and the release of the oil pressure. If the determination
result is "YES", the process proceeds to step S119. If the
determination result is "NO", then the process proceeds to step
S13.
[0084] In step S119, a timer value #TMNCSDL1 is table retrieved in
accordance with the engine revolution number NE, and a cylinder
deactivated operation delay timer TCSDLY1 is set. Then, the process
proceeds to step S120A. The reason why the timer value is set in
accordance with the engine revolution number NE is because the
change responsive time of the oil pressure varies in accordance
with the engine revolution number NE. Accordingly, the timer value
#TMNCSDL1 becomes smaller as the engine revolution number NE
becomes larger.
[0085] In step S120A, a timer value #TMCSCEND is set for a cylinder
deactivated operation compulsive cancellation timer TCSCEND, and
the process proceeds to step S120. The cylinder deactivated
operation compulsive cancellation timer TCSCEND is a timer by which
the cylinder deactivated operation is enforceably cancelled when a
certain period of time has been elapsed after the cylinder
deactivated operation is carried out.
[0086] Then, in step S120, "0" is set for a cylinder deactivated
operation flag F_DECCS, and the control is terminated.
[0087] (Cylinder Deactivated Operation Precondition Determination
Process)
[0088] Next, the cylinder deactivated operation precondition
determination process in step S103 shown in FIG. 2 will be
explained with reference to FIG. 3. Note that this process is
repeated periodically.
[0089] In step S131, it is determined whether outside air
temperature TA is within a predetermined range (i.e., a cylinder
deactivated operation lower limit outside air temperature
#TADECCSL.ltoreq.TA.ltoreq.cylinder deactivated operation upper
limit outside air temperature #TADECCSH). If it is determined in
step S131 that the outside air temperature TA is within the
predetermined range, the process proceeds to step S132. If it is
determined that the outside air temperature TA is not within the
predetermined range, the process proceeds to step S144. This is
because the engine becomes unstable if the cylinder deactivated
operation is carried out when the outside air temperature TA is
lower than the cylinder deactivated operation lower limit outside
air temperature #TADECCSL or higher than the cylinder deactivated
operation upper limit outside air temperature TADECCSH.
[0090] In step S132, it is determined whether coolant temperature
TW is within a predetermined range (i.e., a cylinder deactivated
operation lower limit coolant temperature
#TWDECCSL.ltoreq.TW.ltoreq.cylinder deactivated operation upper
limit coolant temperature #TWDECCSH). If it is determined in step
S132 that the coolant temperature TW is within the predetermined
range, the process proceeds to step S133. If it is determined that
the coolant temperature TW is not within the predetermined range,
the process proceeds to step S144. This is because the engine
becomes unstable if the cylinder deactivated operation is carried
out when the coolant temperature TW is lower than the cylinder
deactivated operation lower limit coolant temperature #TWDECCSL or
higher than the cylinder deactivated operation upper limit coolant
temperature TWDECCSH.
[0091] In step S133, it is determined whether the atmospheric
pressure PA is equal to or greater than a cylinder deactivated
operation upper limit atmospheric pressure #PADECCS. If the
determination result in step S133 is "YES" (i.e., high pressure),
the process proceeds to step S134, and if the determination result
is "NO", then the process proceeds to step S144. This is because it
is not preferable to carry out the cylinder deactivated operation
when the atmospheric pressure is low (i.e., there is a possibility,
for instance, that the negative pressure in master power of the
brake is not secured in a sufficient state when the brake is
activated).
[0092] In step S134, it is determined whether the voltage VB of the
12V auxiliary battery 4 is equal to or greater than a cylinder
deactivated operation upper limit voltage #VBDECCS. If the
determination result is "YES" (i.e., the voltage is large), the
process proceeds to step S135, and if the determination result is
"NO", the process proceeds to step S144. This is because the
response of the spool valve 71 is slowed when the voltage VB of the
12V auxiliary battery is smaller than the predetermined value.
Also, this has a meaning of countermeasures for battery voltage
lowering under low temperature conditions or battery
deterioration.
[0093] In step S135, it is determined whether a battery temperature
TBAT of the battery 3 is equal to or lower than a cylinder
deactivation upper limit battery temperature #TBDECCSH. If the
determination result is "YES", then the process proceeds to step
S1136, and if the determination result is "NO", then the process
proceeds to step S144.
[0094] In step S136, it is determined whether the battery
temperature TBAT is equal to or greater than a cylinder
deactivation lower limit battery temperature #TBDECCSL. If the
determination result is "YES", then the process proceeds to step
S137, and if the determination result is "NO", then the process
proceeds to step S144.
[0095] The reason for the above is because the cylinder deactivated
operation should not be carried out when the temperature of the
battery 3 is not within a certain range in step S135 and step
S136.
[0096] In step S137, it is determined whether it is in a
deceleration fuel cut state based on whether a deceleration fuel
cut flag F_FC is "1" or not. If the determination result is "YES",
then the process proceeds to step S138, and if the determination
result is "NO", then the process proceeds to step S144. This is
because it is necessary, when the cylinder deactivated operation is
carried out, that the supply of fuel be stopped in advance.
[0097] In step S138, it is determined whether oil temperature TOIL
is within a predetermined temperature range (i.e., a cylinder
deactivated operation lower limit oil temperature
#TODECCSL.ltoreq.TOIL.ltoreq.cylind- er deactivated operation upper
limit oil temperature #TODECCSH). If it is determined in step S138
that the oil temperature TOIL is within the predetermined
temperature range, the process proceeds to step S139. If it is
determined that the outside air temperature TA is not within the
predetermined range, the process proceeds to step S144. This is
because the responsiveness for switching engine activation from/to
cylinder deactivation is unstabilized if the cylinder deactivated
operation is carried out when the oil temperature TOIL is lower
than the cylinder deactivated operation lower limit oil temperature
#TODECCSL or is higher than the cylinder deactivated operation
upper limit oil temperature #TODECCSH.
[0098] In step S139, it is determined whether a cylinder
deactivation standby flag F_DECCSSTB, which is set as a result of
the process shown in FIG. 3, is "1" or not. If the determination
result is "YES", then the process proceeds to step S142, and if the
determination result is "NO", the process proceeds to step
S140.
[0099] In step S140, it is determined whether an inlet pipe
negative pressure PBGA is equal to or greater than a cylinder
deactivated operation upper limit negative pressure #PBGDECCS,
which is a table retrieved value determined in accordance with the
engine revolution number NE (i.e., a value which becomes smaller
(the negative pressure becomes larger) as the engine revolution
number becomes larger).
[0100] The reason of the above is because the cylinder deactivated
operation is not carried out immediately if the engine load is high
(i.e., the inlet pipe negative pressure is lower than the cylinder
deactivated operation upper limit negative pressure #PBGDECCS), and
the inlet pipe negative pressure is used in order to secure the
negative pressure in master power prior to the cylinder deactivated
operation. If the determination result in step S140 is "YES" (low
negative pressure), then the process proceeds to step S141, and if
the determination result is "NO" (high negative pressure), then the
process proceeds to step S143. In step S143, "1" is set for a
deceleration inlet pipe negative pressure increase flag F_DECPBUP,
and the process proceeds to step S145.
[0101] It is possible to make determination based on a negative
pressure in master power MPGA instead of the inlet pipe negative
pressure PBGA in step S140.
[0102] In step S141, "0" is set for the deceleration inlet pipe
negative pressure increase flag F_DECPBUP, and the process proceeds
to step S142. In step S142, since the cylinder deactivation
preconditions are met, "1" is set for the cylinder deactivation
standby flag F_DECCSSTB, and the control is terminated.
[0103] In step S144, on the other hand, "0" is set for the
deceleration inlet pipe negative pressure increase flag F_DECPBUP,
and the process proceeds to step S145. In step S145, since the
cylinder deactivation preconditions are not met, "0" is set for the
cylinder deactivation standby flag F_DECCSSTB, and the control is
terminated.
[0104] Here, if the flag value of the above-mentioned deceleration
inlet pipe negative pressure increase flag F_DECPBUP is "1", then
the secondary air passage 33 is closed under certain conditions,
and if the flag value is "0", the secondary air passage 33 is
opened under certain conditions.
[0105] That is, if it is determined that the load is high in step
S140, the secondary air passage 33 is closed because the negative
pressure is small (step S143), and the cylinder deactivated
operation is not carried out (step S145). Then, the process is
performed again from step S131, and when the inlet pipe negative
pressure PBGA becomes the predetermined value, the process proceeds
to step S141 and to step S142 using the inlet pipe negative
pressure as a trigger so that the preconditions for the cylinder
deactivated operation are met (i.e., cylinder deactivation standby
flag F_DECCSSTB=1).
[0106] (Cylinder Deactivation Cancellation Condition Determination
Process)
[0107] Next, the cylinder deactivation cancellation condition
determination process in step S105 shown in FIG. 2 will be
explained in detail with reference to FIG. 4. Note that this
process is repeated periodically.
[0108] In step S151, it is determined whether the cylinder
deactivated operation compulsive cancellation timer TCSCEND is "0"
or not. If the determination result is "YES", then the process
proceeds to step S169, and if the determination result is "NO",
then the process proceeds to step S152. This is because it is
necessary, when the cylinder deactivated operation compulsive
cancellation timer TCSCEND becomes "0", to cancel the cylinder
deactivated operation.
[0109] In step S152, it is determined whether the fuel cut flag
F_FC is "1" or not. If the determination result in step S152 is
"YES", then the process proceeds to step S153, and if the
determination result is "NO", then the process proceeds to step
S166. The reason why this determination is made is because the
purpose of the cylinder deactivated operation is to decrease engine
friction during the deceleration fuel cut and to increase the
regeneration amount by an amount corresponding to the decreased
engine friction amount.
[0110] In step S166, "0" is set for the cylinder deactivation
termination flag F_DECCSCEND, and the process proceeds to step
S169.
[0111] In step S153, it is determined whether the cylinder
deactivation termination flag F_DECCSCEND is "1" or not. If the
determination result is "YES", then the process proceeds to step
S169, and if the determination result is "NO", then the process
proceeds to step S154.
[0112] In step S154, it is determined if it is in a deceleration
regeneration state. If the determination result is "YES", the
process proceeds to step S155, and if the determination result is
"NO", then the process proceeds to step S169.
[0113] In step S155, it is determined whether a MT/CVT
determination flag F_AT is "1" or not. If the determination result
is "NO" (MT vehicle), the process proceeds to step S156. If the
determination result is "YES" (AT/CVT vehicle), then the process
proceeds to step S167.
[0114] In step S167, it is determined whether an in-gear
determination flag F_ATNP is "1" or not. If the determination
result is "NO" (in-gear), then the process proceeds to step S168.
If the determination result is "YES" (N/P range), then the process
proceeds to step S169.
[0115] In step S168, it is determined whether a reverse position
determination flag F_ATPR is "1" or not. If the determination
result is "YES" (reverse position), the process proceeds to step
S169. If the determination result is "NO" (other than the reverse
position), then the process proceeds to step S158.
[0116] By the treatment in steps S167 and S168, the cylinder
deactivated operation at the N/P range, reverse position is
cancelled.
[0117] In step S156, it is determined whether a previous gear
position NGR is at an Hi gear side with respect to a cylinder
deactivation continuation lower limit gear position #NGRDECCS (for
instance, third gear position). If the determination result is
"YES" (Hi gear side), then the process proceeds to step S157, and
if the determination result is "NO" (Lo gear side), then the
process proceeds to step S169. This is to prevent decrease in
regeneration rate at low gears or frequent switching of the
cylinder deactivation during, for instance, a traffic jam.
[0118] In step S157, it is determined whether a half-clutch
determination flag F_NGRHCL is "1" (half-clutch) or not. If the
determination result is "YES" (half-clutch), then the process
proceeds to step S169. If the determination result is "NO". then
the process proceeds to step S159. Accordingly, it becomes
possible, for instance, to prevent unnecessary cylinder
deactivation by which generation of engine stall during a
half-clutch state to stop the vehicle, or problems due to which a
driver's need to accelerate the vehicle cannot be satisfied during
a half-clutch state for gear change.
[0119] In step S158, it is determined whether the rate of change in
the engine revolution number DNE is equal to or greater than the
cylinder deactivated operation continuation upper limit engine
revolution number rate of change #DNEDECCS. If the determination
result is "YES" (i.e., a decreasing rate of the engine revolution
number is large), the process proceeds to step S169. If the
determination result is "NO", then the process proceeds to step
S159. This is to prevent generation of engine stall during the
cylinder deactivated operation which is carried out when the
decreasing rate of the engine revolution number is large.
[0120] In step S159, it is determined whether a vehicle speed VP is
within the predetermined range (i.e., cylinder deactivated
operation continuation lower limit vehicle speed
#VPDECCSL.ltoreq.VP.ltoreq.cylinde- r deactivated operation
continuation upper limit vehicle speed #VPDECCSH) or not. As a
result of determination in step S159, if it is determined that the
vehicle speed VP is within a predetermined range, the process
proceeds to step S160. On the other hand, if it is determined that
the vehicle speed VP is not within the predetermined range, the
process proceeds to step S169. The cylinder deactivated operation
is cancelled when the vehicle speed VP is lower than the cylinder
deactivated operation continuation lower limit vehicle speed
#VPDECCSL or higher than the cylinder deactivated operation
continuation upper limit vehicle speed #VPDECCSH.
[0121] In step S160, it is determined whether the negative pressure
in master power MPGA is equal to or greater than a cylinder
deactivated operation continuation upper limit negative pressure
#MPDECCS or not. Here, the cylinder deactivate operation
continuation upper limit #MPDECCS is a table retrieved value which
is set in accordance with the speed of vehicle VP (a value which
becomes smaller (i.e., the negative pressure becomes larger) as the
speed of vehicle increases). This is because it is preferable that
the negative pressure in master power MPGA be set in accordance
with the kinetic energy of the vehicle, i.e., the speed of vehicle
VP, by taking into account the fact that the negative pressure in
master power MPGA is used to stop the vehicle.
[0122] As a result of the determination made in step S160, if the
negative pressure in master power MPGA is equal to or greater than
the cylinder deactivated operation continuation upper limit
negative pressure #MPDECCS (i.e., the negative pressure in master
power is large), the process proceeds to step S161. As a result of
the determination made in step S160, if the negative pressure in
master power MPGA is less than the cylinder deactivated operation
continuation lower limit negative pressure #MPACLS (i.e., the
negative pressure in master power is small), the process proceeds
to step S169. This is because it is not preferable to continue the
cylinder deactivated operation when a sufficient negative pressure
in master power MPGA cannot be obtained.
[0123] In step S161, it is determined whether a battery remaining
charge QBAT is within a predetermined range (i.e., cylinder
deactivated operation continuation lower limit remaining charge
#QBDECCSL.ltoreq.QBAT.ltoreq.cylinder deactivated operation
continuation upper limit remaining charge #QBDECCSH). As a result
of the determination made in step S161, if it is determined that
the battery remaining charge QBAT is within the predetermined
range, the process proceeds to step S162. If it is determined that
the battery remaining charge QBAT is not within the predetermined
range, the process proceeds to step S169. If the battery remaining
charge QBAT is lower than the cylinder deactivated operation
continuation lower limit remaining charge #QBDECCSL or higher than
the cylinder deactivated operation continuation upper limit
remaining charge #QBDECCSH, the cylinder deactivated operation is
cancelled. This is because energy required for auxiliary driving of
the engine by the motor M, which is carried out when returning from
the cylinder deactivated operation, cannot be secured if the
battery remaining charge QBAT is too small. Also, if the battery
remaining charge QBAT is too large, regeneration cannot be
performed.
[0124] In step S162, it is determined whether the engine revolution
number NE is within a predetermined range (i.e., cylinder
deactivated operation continuation lower limit engine revolution
number #NDECCSL.ltoreq.NE.ltor- eq.cylinder deactivated operation
continuation upper limit engine revolution number #NDECCSH). As a
result of the determination in step S162, if it is determined that
the engine revolution number NE is within the predetermined range,
the process proceeds to step S163. If it is determined that the
engine revolution number NE is not within the predetermined range,
the process proceeds to step S169. If the engine revolution number
NE is lower than the cylinder deactivated operation continuation
lower limit engine revolution number #NDECCSL or higher than the
cylinder deactivated operation continuation upper limit engine
revolution number #NDECCSH, the cylinder deactivated operation is
cancelled. This is because the regeneration efficiency may be low
or oil pressure for switching to the cylinder deactivated operation
cannot be secured if the engine revolution number NE is low. Also
if the engine revolution number NE is too large, it may not be
possible to switch to the cylinder deactivated operation due to
high oil pressure caused by the large engine revolution number, or
there is a danger that consumption of hydraulic oil for a cylinder
deactivated operation is deteriorated.
[0125] In step S163, it is determined whether an IDLE determination
flag F_THIDLMG is "1" or not. If the determination result is "YES"
(i.e., not completely closed), the process proceeds to step S169.
If the determination result is "NO" (i.e., completely closed), then
the process proceeds to step S164. This is to cancel the
continuation of the cylinder deactivated operation when the
throttle is opened at any degree from the completely closing state
thereof in order to improve salability.
[0126] In step S164, it is determined whether the engine oil
pressure POIL is equal to or larger than a cylinder deactivated
operation continuation lower limit oil pressure #PODECCS (with
hysteresis). If the determination result is "YES", then the process
proceeds to step S165. If the determination result is "NO", then
the process proceeds to step S169. This is because oil pressure for
enabling the cylinder deactivated operation (for instance, oil
pressure of activating the spool valve 71) cannot be obtained if
the engine oil pressure POIL is lower than the cylinder deactivated
operation continuation lower limit oil pressure #PODECCS.
[0127] In step S165, since the conditions for the cylinder
deactivated operation cancellation are not satisfied, "0" is set
for a cylinder deactivation cancellation conditions met flag
F_DECCSSTP in order to continue the cylinder deactivated operation,
and the control is terminated.
[0128] In step S169, it is determined whether a cylinder
deactivation cancellation conditions met flag F_DECCSSTP, which
shows a result of the process shown in the flowchart, is "0" or
not. If the determination result is "YES", then the process
proceeds to step S170. If the determination result is "NO", then
the process proceeds to step S171.
[0129] In step S170, "1" is set for a cylinder deactivation
termination flag F_DECCSCEND, and the process proceeds to step
S171. In step S171, since the cylinder deactivation cancellation
conditions are satisfied, "1" is set for the cylinder deactivation
cancellation conditions met flag F_DECCSSTP, and the control is
terminated.
[0130] Here, the above-mentioned cylinder deactivation termination
flag F_DECCSCEND is a flag provided for not canceling the cylinder
deactivation unless the deceleration fuel cut is once terminated
and returns to the all cylinder operation state, and the flag is
used to prevent hunting.
[0131] (Gradual Fuel Addition Coefficient Calculation Process After
Returning From Cylinder Deactivation F/C (Fuel Cut))
[0132] Next, a gradual fuel addition coefficient calculation
process after returning from a cylinder deactivation fuel cut will
be explained in detail with reference to FIG. 5. By this process,
since shock is caused if fuel is supplied immediately after
retuning to the all cylinder operation from the cylinder
deactivated operation, supply of fuel is prohibited until certain
conditions are satisfied in order to secure a smooth transition to
the all cylinder operation by gradually increasing the amount of
fuel supplied starting from an initial amount level which is less
than an ordinary amount.
[0133] In the process specifically explained below, setting of a
gradual fuel addition coefficient after returning from a cylinder
deactivation fuel cut (hereinafter simply referred to as a gradual
addition coefficient KADECC), and setting and resetting of a
gradual addition flag F_KADECCS for fuel, which mainly shows if a
gradual addition of fuel is carried out or not, are performed.
Here, the gradual addition coefficient KADECCS returned from the
fuel cut indicates a multiplying ratio to an ordinary fuel amount
and the maximum value thereof is 1.0. Accordingly, the supply of
fuel is stopped when the gradual addition coefficient KADECCS=0.
Note that this process is carried out periodically.
[0134] In step S201 (estimated intake gas negative pressure
calculation means), an estimated inlet pipe negative pressure
(estimated intake gas negative pressure) INFEPBG is retrieved from
a #INFEPBGM map based on the engine revolution number NE and a
throttle opening degree TH, and the process proceeds to step
S202.
[0135] In step S202, it is determined whether a MT/CVT
determination flag F_AT is "1" or not. If the determination result
is "YES" (AT vehicle, CVT vehicle), the process proceeds to step
S205. If the determination result is "NO" (MT vehicle), then the
process proceeds to step S203.
[0136] In step S203, it is determined whether a neutral switch flag
F_NSW is "1" of not. If the determination result is "YES"
(neutral), the process proceeds to step S210. If the determination
result is "NO" (in-gear), then the process proceeds to step
S204.
[0137] A timer value #TMKACSWT is set for an inlet pipe negative
pressure determination permit timer TKACSWT in step S210, 1.0 is
set for the gradual addition coefficient KADECCS in step S211, "0"
is set for the gradual addition flag F_KADECCS in step S212, "0" is
set for a gradual addition initial value setting flag F_KADECCS2 in
step S213, and the above-explained process is repeated.
[0138] In step S204, it is determined whether a clutch switch flag
F_CLSW is "1" or not. If the determination result is "YES"
(disengage clutch), the process proceeds to step S210. If the
determination result is "NO" (engage clutch), then the process
proceeds to step S206.
[0139] In step S205, it is determined whether an in-gear
determination flag F_ATNP for CVT is "1" or not. If the
determination result is "YES" (N, P range), the process proceeds to
step S210. If the determination result is "NO" (in-gear), then the
process proceeds to step S206.
[0140] In step S206, it is determined whether a gradual addition
flag F_KADECCS set in this process is "1" or not. If the
determination result is "YES", the process proceeds to step S214,
and if the determination result is "NO", then the process proceeds
to step S207. Here, if the gradual addition flag F_KADECCS is "1",
it means that the gradual addition of fuel is carried out. On the
other hand, if the flag value is "0", it means that the gradual
addition of fuel is not carried out.
[0141] In step S207, it is determined whether the previous cylinder
deactivated operation flag F_DECCS is "1" or not. If the
determination result is "YES", the process proceeds to step S208,
and if the determination result is "NO", then the process proceeds
to step S210.
[0142] In step S208, it is determined whether the cylinder
deactivated operation flag F_DECCS is "1" or not. If the
determination result is "YES", the process proceeds to step S210,
and if the determination result is "NO", then the process proceeds
to step S209.
[0143] In step S209, "1" is set for the gradual addition flag
F_KADECCS, and the above-explained process is repeated.
[0144] In step S214, it is determined whether the gradual addition
initial value setting flag F_KADECCS2 is "1" or not. If the
determination result is "YES", the process proceeds to step S216,
and if the determination result is "NO", then the process proceeds
to step S215.
[0145] In step S215, it is determined whether the timer value of
the inlet pipe negative pressure determination permit timer TKACSWT
set in step S210 is "0" or not. If the determination result is
"YES", the process proceeds to step S216, and if the determination
result is "NO", then the process proceeds to step S218.
[0146] In step S216, a new gradual addition coefficient KADECCS is
set by adding a gradual addition value #DKAKECCS to the gradual
addition coefficient KADECCS, and the process proceeds to step
S217. Here, the gradual addition value #DKADECCS is a value which
increases as the throttle opening degree TH increases, and may be
obtained by, for instance, table retrieval.
[0147] In step S217, it is determined whether the gradual addition
coefficient KADECCS is "1.0" or not. If the determination result is
"YES", the process proceeds to step S210, and if the determination
result is "NO", then the above-explained process is repeated.
[0148] In step S218, it is determined whether an actual inlet pipe
negative pressure PBGA.gtoreq.estimated inlet pipe negative
pressure INFEPBG. If the determination result is "YES" (actual
negative pressure is larger), the process proceeds to step S220,
and if the determination result is "NO" (estimated negative
pressure is larger), then the process proceeds to step S219. That
is, the process proceeds to step S219 if the actual inlet pipe
negative pressure is larger than the estimated inlet pipe negative
pressure INFEPBG immediately after being switched to the all
cylinder operation state from the cylinder deactivated operation
state. Thereafter, when the actual inlet pipe negative pressure
PBGA becomes equal to or larger than the estimated inlet pipe
negative pressure INFEPBG, the process proceeds to step S220.
[0149] In step S219, "0" is set for the gradual addition
coefficient KADECCS, and the above process is repeated.
[0150] An initial value #KDECCSINI of the gradual addition
coefficient is set for the gradual addition coefficient KADECCS in
step S220, and "1" is set for the gradual addition initial value
setting flag F_KADECCS2 in step S221, and the above-explained
process is repeated.
[0151] Accordingly, if the operation state is switched to the all
cylinder operation state from the cylinder deactivated operation
state due to, for instance, reacceleration when the vehicle is in
the in-gear state, "1" is set for the gradual addition flag
F_KADECCS in step S209. Then, the process proceeds to step S206 to
step S214, and step S215 to step S218 since the timer value of the
inlet pipe negative pressure determination permit timer TKACSWT
initially set in step S210 is not "0". In step S218, the actual
inlet pipe negative pressure PBGA is compared with the estimated
inlet pipe negative pressure INFEPBG.
[0152] As indicated in the graph shown in FIG. 7, since the
estimated inlet pipe negative pressure INFEPBG is large (i.e., the
negative pressure is large) with respect to the actual inlet pipe
negative pressure PBGA immediately after being switched to the all
cylinder operation state to the cylinder deactivated operation
state, the determination result made in step 218 becomes "NO", and
"0" is set for the gradual addition coefficient KADECC in the
subsequent step S219.
[0153] Accordingly, since no wasteful fuel supply is made within
the range of time T1 shown in FIG. 7, the fuel is not consumed
uselessly, and hence this can be contributed to improve the fuel
consumption efficiency of the vehicle.
[0154] When the actual inlet pipe negative pressure PBGA becomes
equal to the estimated inlet pipe negative pressure TNFEPBG at the
point P shown in FIG. 7, the determination made in step S218
becomes "YES", and an initial value #KDECCSINI (for instance, 0.3)
of the gradual addition coefficient is set for the gradual addition
coefficient KADECCS in step S220. Note that an initial value less
than an ordinary fuel supply amount means a value obtained by
multiplying the ordinary fuel supply amount by the initial value
#KDECCSINI of the gradual addition coefficient.
[0155] Here, since the initial value #KDECCSINI of the gradual
addition coefficient is smaller than the gradual addition
coefficient KADECCS, which corresponds to the ordinary fuel supply
amount, the corresponding fuel supply amount becomes smaller than
the ordinary fuel supply amount. In this manner, it becomes
possible to prevent generation of shock to a minimum level.
[0156] Also, it becomes possible to quicken the timing of fuel
injection (T1<T0) as compared with the case where fuel is
supplied with an interval time T0 during which the actual inlet
pipe negative pressure PBGA completely recovers, and the slope of
the estimated inlet pipe negative pressure INFEPBG shown in FIG. 7
increases as the throttle opening degree increases where
acceleration demand is high. Accordingly, salability can be
improved by securing responsibility corresponds to the acceleration
demand of a driver during a reacceleration state since the time T1
until a restart of the fuel injection can be shortened.
[0157] Then, in step S221, "1" is set for the initial value
#KDECCSINI of the gradual addition coefficient, i.e., the gradual
addition initial value setting flag F_KADECCS2 which indicates
setting of an initial value of the fuel supply amount, and when
proceeds to step S214 from step S206, fuel is supplied, an amount
of which is increased by the gradual addition amount #DKADECCS, in
step S216 since the determination result in step S214 is "YES".
Thereafter, the amount of fuel supplied is gradually increased as
in the above-mentioned manner, and when the gradual addition
coefficient KADECCS reaches 1.0, i.e., the ordinary fuel supply
amount, in step S217, the inlet pip negative pressure determination
permit timer TKACSWT is set in step S210, "1.0" is set in the
gradual addition coefficient KADECCS in step S211, the gradual
addition flag F_KADECCS is set in step S212, the gradual addition
flag F_KADECCS is reset in step S212, and the gradual addition
initial value setting flag F_KADECCS2 is reset in step S213.
[0158] Accordingly, since the fuel supply can be quicker as
compared with the case where an ordinary amount of fuel is supplied
after the inlet pipe negative pressure is recovered, it becomes
possible to quickly accelerate the vehicle so as to corresponds to
the drivers' intention, and hence the salability thereof can be
improved. Also, since a fuel supply of ordinary amount is
prohibited until the actual inlet pipe negative pressure becomes
equal to the estimated inlet pipe negative pressure, it becomes
possible to prevent consumption of unnecessary fuel as compared
with the case where an ordinary amount of fuel is supplied though
sufficient inlet pipe negative pressure is not secured, and hence
the fuel consumption efficiency can be improved.
[0159] Also, since a smaller amount of fuel, as compared to an
ordinary amount of fuel, is supplied at the same time the vehicle
is reaccelerated, it a smooth acceleration can be realized.
Moreover, a proper amount of fuel corresponding to the inlet pipe
negative pressure can be supplied without wasting the fuel, as
compared with the case where an ordinary amount of fuel is supplied
during reacceleration, and hence the fuel consumption efficiency
can be improved.
[0160] Further, since the above-explained gradual addition value
#DKADECCS is a value which increases as the throttle opening degree
TH increases, the time for restarting the fuel injection can be
shortened further as the throttle opening degree TH becomes larger
where the acceleration demand is high. Accordingly, the salability
during reacceleration after returning from the cylinder
deactivation can be improved.
[0161] (Retard Process When Returned From a Cylinder Deactivated
Operation)
[0162] Next, a retard process which is carried out when returned
from a cylinder deactivated operation state according to an
embodiment of the present invention will be explained in detail
with reference to FIG. 6.
[0163] The retard process is carried out to delay an ignition
timing to suppress the output of the engine thereby decreasing
generation of shock during reacceleration. The retard process is
performed after being returned to the all cylinder operation state
from the cylinder deactivated operation state. Note that this
process is repeated periodically.
[0164] In step S301, it is determined whether a MT/CVT
determination flag F_AT is "1" or not. If the determination result
is "YES" (AT vehicle, CVT vehicle), the process proceeds to step
S304, and if the determination result is "NO" (MT vehicle), then
the process proceeds to step S302.
[0165] In step S302, it is determined whether a neutral switch flag
F_NSW is "1" or not. If the determination result is "YES"
(neutral), the process proceeds to step S312, and if the
determination result is "NO" (in-gear), then the process proceeds
to step S303.
[0166] In step S303, it is determined whether a clutch switch flag
F_CLSW is "1" or not. If the determination result is "YES"
(disengaged clutch), the process proceeds to step S312, and if the
determination result is "NO" (engaged clutch), then the process
proceeds to step S305.
[0167] In step S304, it is determined whether a CVT in-gear flag
F_ATNP is "1" or not. If the determination result is "YES" (N, P
range), the process proceeds to step S312, and if the determination
result is "NO" (in-gear), then the process proceeds to step
S305.
[0168] In step S312, "0" is set for a retard amount IGACSR, and "0"
is set for an ignition timing control flag F_IGACSR in the
subsequent step S313, and the above process is repeated. Here, the
retard amount is a value expressed by an angle.
[0169] In step S305, it is determined whether the ignition timing
control flag F_IGACSR is "1" or not. If the determination result is
"YES", the process proceeds to step S314, and if the determination
result is "NO", then the process proceeds to step S306.
[0170] In step S306, it is determined whether a cylinder
deactivated operation flag F_DECCS is "1" or not. If the
determination result is "YES" (in the cylinder deactivated
operation), the process proceeds to step S307, and if the
determination result is "NO", then the process proceeds to step
S312.
[0171] In step S307, it is determined whether a previous fuel cut
flag F_FC is "1". or not. If the determination result is "YES" (in
the fuel cut), the process proceeds to step S308, and if the
determination result is "NO", then the process proceeds to step
S312.
[0172] In step S308, it is determined whether the fuel cut flag
F_FC is "1" or not. If the determination result is "YES", the
process proceeds to step S312, and if the determination result is
"NO", then the process proceeds to step S309.
[0173] In step S309, a predetermined value #CTIGACSR (for instance,
3) is set for a hold counter CIGACSR, and the process proceeds to
step S310. The predetermined value set by the counter is determined
so as to correspond to the time between reacceleration and matching
of the actual inlet pipe negative pressure PBGA with the estimated
inlet pipe negative pressure INFEPBG in the above-mentioned fuel
gradual addition coefficient calculation process.
[0174] In step S310, the retard amount IGACSR (predetermined amount
retard) is set by retrieving through the #IGACSRT table, and the
process proceeds to step S311. Note that the #IGACSRT table is a
value set in accordance with the throttle opening degree TH, and
becomes smaller as the throttle opening degree TH becomes larger
(high opening degree).
[0175] In step S311, "1" is set for the ignition timing control
flag F_IGACSR and the above process is repeated.
[0176] In step S314, the value of the hold counter CIGASCSR is
count down, and the process proceeds to step S315.
[0177] In step S315, it is determined whether the counter value of
the hold counter CIGACSR is equal to or smaller than "0". If the
determination result is "YES", the process proceeds to step S316.
If the determination result is "NO", then the above process is
repeated.
[0178] In step S316, a gradual subtraction value #DIGACSR is
subtracted from the retard amount IGACSR, and the process proceeds
to step S317. The gradual subtraction value #DIGACSR is set to be a
value which makes the retard amount IGACSR "0" in accordance with
the time (T0-T1) between the start of the fuel supply and the time
the amount of fuel reaches the ordinary amount.
[0179] In step S317, it is determined whether the retard amount
IGACSR is equal to or smaller than "0". If the determination result
is "YES", then the process proceeds to step S312. If the
determination result is "NO", then the above process is
repeated.
[0180] Accordingly, if the operation state is switched to the all
cylinder operation state by, for instance, reacceleration, from the
cylinder deactivated operation when the vehicle is in an in-gear
state, the determination made in step S305 becomes "NO" since the
ignition timing control flag F_IGACSR is initially "0", and the
determination result becomes "YES" since the value of cylinder
deactivated operation flag F_DECCS is "1" immediately after
reacceleration.
[0181] Then, in step S309, a predetermined value #CTIGACSR is set
in the counter CGASCR since the previous fuel cut flag F_FC is "1"
in step S307 and the current fuel cut flag F_FC is "0" in step
S309, and a retard amount IGACSR, which becomes an initial value of
the retard amount, is retrieved through the #IGACSR table in step
S310. In step S311, an ignition timing control flag F_IGACSR is
set.
[0182] Thereafter, the process proceeds to step S314 from step
S305, and its state (initial value of the retard amount) is
maintained (time T2) as shown in FIG. 8 until the hold counter
CIGACSR becomes "0", and the gradual subtraction value #DIGACSR is
subtracted from the retard amount IGACSR in step S316 when the hold
counter CIGACSR becomes "0" to decrease the delay of ignition
timing. By shifting the timing to start decreasing the retard
amount towards the time T1 by the hold counter, it becomes possible
to surely prevent the generation of shock.
[0183] Then, when the retard amount IGACSR gradually decreases and
becomes "0" (i.e., the point Q in FIG. 8) in step S317, "0" is set
for the retard amount IGACSR in step S312, and the ignition timing
control flag F_IGACSR is reset in step S313.
[0184] Accordingly, a return shock immediately after switching to
the all cylinder operation can be prevented by gradually increasing
the amount of fuel supplied and using the retard control of the
ignition timing after returning to the all cylinder operation state
from the cylinder deactivated operation state.
[0185] Next, a second embodiment according to the present invention
will be described with reference to the flowchart shown in FIG. 12.
In the first embodiment, when returning to the all cylinder
operation state from the cylinder deactivated state, the vehicle
cannot be accelerated if there is a fuel supply interval.
Accordingly, in the second embodiment, an amount of fuel smaller
than the ordinary amount is supplied between the period immediately
after returning to the all cylinder operation state and the time
the actual inlet pipe negative pressure PBGA becomes equal to the
estimated inlet pipe negative pressure INFEPBG so as to secure a
certain level of engine output.
[0186] The flowchart shown in FIG. 12 shows an estimated fuel
injection amount calculation process (F_TiYTH_CAL) after returning
to the all cylinder operation state. In this process, a basic fuel
injection amount TiM (corresponds to the actual inlet pipe negative
pressure PBGA), which is determined by the engine revolution number
NE and the current inlet pipe negative pressure HPB, is compared
with a fuel injection amount TiYTH (corresponds to the estimated
inlet pipe negative pressure PBGBYTH (same as the INFEPBG), which
is determined by the engine revolution number NE and the throttle
opening degree TH, and the smaller amount of fuel is supplied.
[0187] In step S401, the fuel injection amount TiYTHN is retrieved
through the fuel injection amount map, and the process proceeds to
step S402. Through the map, the fuel injection amount TiYTHN is
obtained based on the engine revolution number NE and the throttle
opening degree TH.
[0188] In step S402, a fuel injection amount correction value
DTiBYAC which flows through the secondary air passage 33 is
retrieved through the #DTiBYACM map, and the process proceeds to
step S403. This map is used to obtain the fuel injection amount
correction value DTiBYAC which flows through the secondary air
passage 33 using the engine revolution number NE and the throttle
opening degree TH.
[0189] In step S403, a correction conversion value KDTiBYAC, which
is obtained by a conversion using the fuel injection amount
correction value DTiBYAC obtained in step S402 as a coefficient, is
retrieved through the #KDTiBYAC table, and the process proceeds to
step S404. The correction conversion value KDTiBYAC is a value
which increases so as to correspond to a command value ICMD.
[0190] In step S404, a fuel injection amount TiYTH is obtained,
taking into account the fuel amount correction flows through the
secondary air passage 33, by subtracting the fuel injection amount
correction value DTiBYAC multiplied by the correction conversion
value KDTiBYAC from the fuel injection amount TiYTHN.
[0191] Then, in step S405, it is determined whether a fuel
injection amount estimation amount flag F_TiYTH, which is set as a
result of the process in this flowchart, is "1" or not. If the
determination result is "YES", then the process proceeds to step
S409, and if the determination result is "NO", the process proceeds
to step S406.
[0192] In step S406, it is determined whether the cylinder
deactivated operation flag F_DECCS is "1" or not. If the
determination result is "YES", the process proceeds to step S407,
and if the determination result is "NO", the process proceeds to
step S408.
[0193] In step S407, a predetermined value #TAFCSTi (predetermined
time) is set for the timer TAFCSTi, and the process proceeds to
step S410. Here, the predetermined value #TAFCSTi is, for instance,
2 seconds.
[0194] In step S408, it is determined whether the previous value of
the cylinder deactivated operation flag F_DECCS is "1" or not. If
the determination result is "YES", the process proceeds to step
S409, and if the determination result is "NO", the process proceeds
to step S410.
[0195] In step S409, it is determined whether the timer TAFCSTi is
"0" or not. If the determination result is "YES", the process
proceeds to step S410, and if the determination result is "NO", the
process proceeds to step S411.
[0196] In step S410, "0" is set for the fuel injection amount
estimation process flag F_TiYTH, and the process is terminated.
[0197] In step S411, it is determined whether the basic fuel
injection amount TiM is equal to or greater than the fuel injection
amount TiYTH. If the determination result is "YES" and the basic
fuel injection amount TiM is larger, the process proceeds to step
S410, and if the determination result is "NO" and the fuel
injection amount TiYTH is larger, the process proceeds to step
S412.
[0198] In step S412, the fuel injection amount TiYTH is set for the
basic fuel injection amount TiM by taking into account the fuel
flowing through the secondary air passage, and "1" is set for the
fuel injection amount estimation process flag F_TiYTH in step S415,
and the process is terminated.
[0199] That is, in this embodiment, immediately being returned to
the all cylinder operation state from the cylinder deactivated
operation state, an injection amount of fuel smaller than the
ordinary amount is set before a certain period of time has been
elapsed (step S409) counted by the timer set in step S407, when the
fuel injection amount TiYTH is larger than the basic fuel injection
amount TiM (i.e., TiM<TiYTH). On the other hand, if the basic
fuel injection amount TiM is equal to or larger than the fuel
injection amount TiYTH (TiM.gtoreq.TiYTH), "0" is set for the fuel
injection amount estimation process flag F_TiYTH to perform an
injection of fuel based on the basic fuel injection amount TiM.
[0200] Note that the fuel injection amount estimation flag F_TiYTH
becomes zero in step S410 when the above-mentioned timer TAFCSTi=0,
and hence no fuel injection amount estimation process is performed.
Accordingly, if the fuel injection amount estimation process is not
carried out for any reason, an ordinary fuel injection based on the
basic fuel injection amount TiM is performed.
[0201] According to this embodiment, since a small amount of fuel
can be supplied immediately after being returned to the all
cylinder operation state from the cylinder deactivated operation
state, an acceleration performance can be maintained while
minimizing the deterioration in fuel consumption efficiency as
compared to the case where no fuel is supplied until the estimated
inlet pipe negative pressure matches the actual inlet pipe negative
pressure. Also, as compared with the case where a normal injection
amount of fuel is supplied when returned to the all cylinder
operation state, it becomes possible to prevent the generation of
shock and to improve the fuel consumption efficiency. Note that
although the above explanation on the second embodiment has been
made with the treatments in the first embodiment as prerequisites,
it is possible to apply the second embodiment without the
treatments in the first embodiment.
[0202] Next, the third embodiment according to the present
invention will be explained with reference to the flowchart shown
in FIG. 13. This embodiment is to prevent deterioration in the
acceleration performance using a motor assisting the driving of
engine when returned to the all cylinder operation state from the
cylinder deactivated operation state, and utilizes the treatments
in the first embodiment, which are carried out thereafter, as the
prerequisites. That is, the, acceleration performance is secured by
the driving assist of the motor immediately after returning to the
all cylinder operation state until the actual inlet pipe negative
pressure PBGA matches the estimated inlet pipe negative pressure
INFEPBG. Note that since the time in which the motor assists the
drive is short, the influence of the motor on the remaining charge
of the battery 3 is small. The motor assist treatment will be
explained with reference to the flowchart shown in FIG. 13.
[0203] In step S501, a motor output calculation treatment is
carried out, and the process proceeds to step S502. The treatment
is to set a motor output final command value PMOTF, which is
defined in accordance with the engine revolution number NE, and the
throttle opening degree TH.
[0204] In step S502, it is determined whether the cylinder
deactivated operation flag F_DECCS is "1" or not. If the
determination result is "YES", then the process proceeds to step
S507, and if the determination result is "NO", the process proceeds
to step S503.
[0205] In step S507, "0" is set for the motor output final command
value PMOTF, and the motor output final command value PMOTF, i.e.,
"0", is set for an assist command value ASTPWRF in step S508, and
the process is terminated. That is no driving assist by the motor
is performed in this case.
[0206] In step S503, it is determined whether the previous value of
the cylinder deactivated operation flag F_DECCS is "1" or not. If
the determination result is "YES", then the process proceeds to
step S504, and if the determination result is "NO", the process
proceeds to step S506.
[0207] In step S506, the motor output final command value PMOTF is
set for the assist command value ASTPWRF, and the process is
terminated.
[0208] In step S504, the motor output final command value PMOF is
multiplied by a correction coefficient KMOTAS (smaller than 1) for
when returned to the all cylinder operation state, and the
resultant value is set for the motor output final command value
PMOTF. By using the motor output final command value PMOF
multiplied by the correction coefficient KMOTAS, the driving assist
is carried out by the motor with a small output until the supply of
fuel is restarted so that the acceleration performance is not
deteriorated.
[0209] Then, in step S505, the motor output final command value
PMOTF is set for the assist command value ASTPWRF, and the process
is terminated.
[0210] Accordingly, in this embodiment also, the salability can be
maintained by preventing the deterioration in acceleration
performance immediately after returning to the all cylinder
operation state from the cylinder deactivated state, and by
minimizing the deterioration in acceleration performance between a
time interval that the actual inlet pipe negative pressure matches
the estimated inlet pipe negative pressure and the fuel is supplied
in the first embodiment.
[0211] Having thus described an exemplary embodiment of the
invention, it will be apparent that various alterations,
modifications, and improvements will readily occur to those skilled
in the art. Such alterations, modifications, and improvements,
though not expressly described above, are nonetheless intended and
implied to be within the spirit and scope of the invention.
Accordingly, the foregoing discussion is intended to be
illustrative only: the invention is limited and defined only by the
following claims and equivalents thereto.
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