U.S. patent application number 09/811696 was filed with the patent office on 2002-02-07 for engine control equipment.
This patent application is currently assigned to Hitachi Ltd.. Invention is credited to Nakagawa, Shinji, Ohsuga, Minoru, Yamaoka, Shiro.
Application Number | 20020014072 09/811696 |
Document ID | / |
Family ID | 18727030 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020014072 |
Kind Code |
A1 |
Nakagawa, Shinji ; et
al. |
February 7, 2002 |
Engine control equipment
Abstract
An engine control equipment capable of activating a catalyst and
preventing exhaust gas from deteriorating in order to early perform
combustion by compressive self-ignition. The engine control
equipment is an engine control equipment including a catalyst for
burning a mixed gas in a combustion chamber by compressive
self-ignition and purifying exhaust-gas components in the
combustion chamber and means for controlling the catalyst, in which
the means for controlling the catalyst is provided with means for
determining the activation of the catalyst and means for activating
the catalyst in accordance with a determination result by the means
for determining the activation of the catalyst.
Inventors: |
Nakagawa, Shinji;
(Hitachinaka, JP) ; Ohsuga, Minoru; (Hitachinaka,
JP) ; Yamaoka, Shiro; (Hitachi, JP) |
Correspondence
Address: |
Evenson, Mckeown, Edwards & Lenehan P.L.L.C.
Suite 700
1200 G St., N.W.
Washington
DC
20005
US
|
Assignee: |
Hitachi Ltd.
|
Family ID: |
18727030 |
Appl. No.: |
09/811696 |
Filed: |
March 20, 2001 |
Current U.S.
Class: |
60/285 ; 60/274;
60/284 |
Current CPC
Class: |
F02D 41/3035 20130101;
F02D 41/006 20130101; Y02T 10/18 20130101; Y02T 10/44 20130101;
Y02T 10/26 20130101; F02D 41/0057 20130101; F02D 37/02 20130101;
F02D 41/1456 20130101; F02D 41/187 20130101; Y02T 10/40 20130101;
F02D 41/405 20130101; F02D 41/3076 20130101; F02D 2200/0802
20130101; Y02T 10/22 20130101; F01N 3/2006 20130101; F02B 1/12
20130101; F02D 13/0253 20130101; F02D 41/024 20130101; F02P 5/045
20130101; F02D 2200/0804 20130101; Y02T 10/12 20130101; F02D
13/0261 20130101; F02D 41/0065 20130101; F02D 13/0219 20130101;
F01N 3/2033 20130101; F01N 3/2013 20130101; F02D 13/0207 20130101;
F02D 41/1441 20130101; Y02T 10/47 20130101; F02D 2041/001
20130101 |
Class at
Publication: |
60/285 ; 60/284;
60/274 |
International
Class: |
F01N 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 2, 2000 |
JP |
2000-234695 |
Claims
What is claimed is:
1. An engine control equipment having a catalyst for burning a
mixed gas in a combustion chamber by compressing self-ignition and
purifying exhaust gas components in the combustion chamber, wherein
the control equipment is provided with means for controlling the
catalyst and the means for controlling the catalyst is provided
with means for determining the activated state of the catalyst and
means for activating the catalyst in accordance with the
determination result by the means for determining the activated
state of the catalyst.
2. The engine control equipment according to claim 1, wherein the
means for determining the activated state of the catalyst is
provided with means for detecting or estimating the temperature of
the catalyst and means for determining the activation of the
catalyst.
3. The engine control equipment according to claim 1 or 2, wherein
the means for activating the catalyst controls the state of an
engine when the detected or estimated temperature of the catalyst
is equal to or lower than a predetermined value.
4. The engine control equipment according to any one of claims 1 to
3, wherein the means for activating the catalyst inhibits the
combustion by the compressive self-ignition and performs the
combustion by spark ignition when the detected or estimated
temperature of the catalyst is equal to or lower than a
predetermined value.
5. The engine control equipment according to any one of claims 1 to
3, wherein the means for activating the catalyst drives a heater
for the catalyst when the detected or estimated temperature of the
catalyst is equal to or lower than a predetermined value.
6. The engine control equipment according to any one of claims 1 to
3, wherein the means for activating the catalyst injects a fuel at
the timing other than normal fuel injection when the detected or
estimated temperature of the catalyst is equal to or lower than a
predetermined value.
7. The engine control equipment according to claim 6, wherein the
means for activating the catalyst injects the fuel in the explosion
or exhaust stroke of the engine in accordance with the temperature
of the catalyst.
8. The engine control equipment according to any one of claims 1 to
7, wherein the control equipment is controlled so as to early start
combustion by the compressive self-ignition when the temperature
detected by a temperature sensor provided to the upstream or
downstream side of the catalyst becomes a predetermined value or
more.
9. The engine control equipment according to any one of claims 1 to
8, wherein the catalyst the catalyst uses a three-way catalyst or
NOx catalyst provided for an exhaust pipe.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an engine control
equipment, particularly to a control equipment of a compressive
self-ignition engine for accelerating activation of a catalyst.
[0002] A car engine has such main problems as improvement of fuel
consumption and reduction of exhaust gas. A lean burn engine has
recently become a mainstream, which uses a combustion system
according spark ignition to improve the fuel consumption by
operating an air-fuel ratio at a lean in order to reduce a pump
loss.
[0003] However, though the spark-ignition-type lean burn engine can
reduce the pump loss by making an air-fuel ratio leaner, there is a
lean limit due to an ignition error according to the theory of the
engine because the engine uses combustion according to flame
spread.
[0004] However, there is a combustion-type engine according to the
compressive self-ignition of making a fuel-air mixture
spontaneously ignite in a combustion chamber instead of using the
spark ignition by a spark plug. The compressive-self-ignition
engine causes a combustion reaction everywhere in the combustion
chamber. Therefore, it is possible to improve the fuel consumption
and thereby reduce NOx because the engine has a lean limit higher
than that of the spark-ignition type and moreover, there is no
local high-temperature portion and the combustion temperature is
low.
[0005] Moreover, in the case of a usual engine, it is generally
performed to make an exhaust pipe of the engine oxidize hydrocarbon
(HC) and carbon monoxide (CO) contained in the exhaust gas
discharged from a combustion chamber and set a three-way catalyst
having a function for reducing an nitrogen oxide (NOx). In the case
of the three-way catalyst, the NOx reducing function of the
three-way catalyst hardly functions in a lean operation as shown by
the purifying performance of three components of a three-way
catalyst to the air-fuel ratio in FIG. 34. Therefore, an NOx
catalyst may be set which occludes or adsorbs NOx.
[0006] In the case of a compressive-self-ignition-combustion-type
engine, it is necessary to greatly increase the combustion chamber
in pressure and temperature. Therefore, various arts about an
engine control equipment for changing the spark ignition type and
the compressive self-ignition type in accordance with an engine
operating condition in which spark ignition using a spark plug is
performed when warming-up of the engine is not completed and the
compressive self-ignition combustion is performed in the cases
other than the above case or the compressive self-ignition
combustion is performed when the compressive self-ignition
combustion can be made and an ignition timing can be properly
obtained are disclosed (refer to official gazettes of Japanese
Patent Laid-Open Nos. 157220/1987, 6435/1999, 336600/1999,
62589/1999, 257108/1999, 166435/1999, and 294152/1999).
[0007] Moreover, by considering that the purifying performance of
an exhaust gas by a three-way catalyst is lowered when an engine is
cooled, various arts of an engine control equipment for
accelerating activation of the catalyst are disclosed (refer to
official gazettes of Japanese Patent Laid-Open Nos. 4584/2000 and
336574/1999).
[0008] As shown in FIG. 35, the above three-way catalyst shows HC,
CO, and NOx purifying functions when an exhaust gas has a
predetermined temperature or higher. However, the catalyst has a
characteristic that it cannot completely purify the exhaust gas
when the exhaust gas has a temperature lower than the predetermined
temperature. Therefore, it is necessary to keep the exhaust gas at
a predetermined temperature or higher in order to maintain the
above activated state. That is, as shown in FIG. 36, in the case of
the three-way catalyst set to the exhaust pipe, the exhaust-gas
purifying performance of the catalyst is deteriorated in the period
from the time when an engine is started until the time when an
exhaust gas reaches a predetermined temperature or higher. This is
because the engine has the temperature equal to the then
outside-air temperature when it is started and the temperature of
its exhaust gas is also low, and the catalyst is activated after it
is heated by the exhaust gas.
[0009] Therefore, when setting a catalyst to the exhaust pipe, it
is necessary to shorten the time from start of an engine up to
activation of the catalyst, that is, any means for activating the
catalyst is necessary.
[0010] The above mentioned is particularly necessary for a
combustion-type engine according to compressive self-ignition. The
is because in the case of the combustion type according to
compressive self-ignition, the combustion temperature is lower than
the case of the spark ignition type and thereby, the effect of
raising the temperature of a catalyst by heating an exhaust gas is
small. Therefore, exhaust-gas deterioration becomes a large problem
at start of the engine.
[0011] That is, the present inventor obtains the new knowledge that
when setting a catalyst to the exhaust pipe of a combustion-type
engine according to compressive self-ignition, it is possible to
shorten the time from start of the engine up to activation of the
catalyst and therefore, it is possible to prevent exhaust-gas
deterioration also in the case of the combustion type according to
compressive self-ignition.
[0012] However, though the above prior art has means for changing
the spark-ignition type and the compressive self-ignition type, the
engine control equipments disclosed in the official gazettes of
Japanese Patent Laid-Open Nos. 157220/1987 and 6435/1999 notice
only a combustion state, determine directly or indirectly whether
the combustion state allows compressive self-ignition, and permit
the combustion by compressive self-ignition when the combustion
state allows the compressive self-ignition. Therefore, when
combustion by compressive self-ignition can be made even if a
catalyst is inactivated, compressive self-ignition combustion may
be performed. Moreover, other prior arts do not particularly
consider activating a catalyst in order to early perform the
combustion by compressive self-ignition though they respectively
control the opening/closing timing of an intake or exhaust valve in
accordance with the operation state or heat a catalyst in order to
reduce smoke and NOx at the same time.
[0013] The present invention is made to solve the above problems
and its object is to provide an engine control equipment capable of
preventing an exhaust gas from deteriorating b activating a
catalyst in order to early perform the combustion by compressive
self-ignition.
[0014] To achieve the above object, an engine control equipment of
the present invention is an engine control equipment basically
having a catalyst for burning a mixed gas in a combustion chamber
by compressive self-ignition and purifying exhaust-gas components
in the combustion chamber. The control equipment is provided with
means for controlling the catalyst and the means for controlling
the catalyst is provided with means for determining the activated
state of the catalyst and means for activating the catalyst in
accordance with a determination result of the means for determining
the activated state of the catalyst.
[0015] In the case of the engine control equipment of the present
invention constituted as described above, the means for activating
a catalyst accelerates the activation of the catalyst in accordance
with a determination result of a catalyst state. Therefore, it is
possible to shorten the time from start of an engine up to
activation of a catalyst, prevent an exhaust gas for activating the
catalyst from deteriorating, and improve the reliability of the
engine.
[0016] Moreover, in the case of a specific mode of an engine
control equipment of the present invention, the means for
determining the activated state of the catalyst is provided with
means for detecting or estimating the temperature of the catalyst
and means for determining the activation of the catalyst. The means
for activating the catalyst controls the operation state of an
engine when the detected or estimated temperature of the catalyst
is equal to or lower than a predetermined value.
[0017] In the case of another mode of the engine control equipment
of the present invention, the means for activating the catalyst
inhibits the combustion by the compressive self-ignition and
performs the combustion by spark ignition when the detected or
estimated temperature of the catalyst is equal to or lower than a
predetermined value.
[0018] In the case of still another mode of the engine control
equipment of the present invention, the means for activating the
catalyst drives a heater for the catalyst when the detected or
estimated temperature of the catalyst is equal to or lower than a
predetermined value.
[0019] In the case of still another mode of the engine control
equipment of the present invention, the means for activating the
catalyst injects a fuel at the timing other than usual fuel
injection when the detected or estimated temperature of the
catalyst is equal to or lower than the predetermined value and the
fuel injection timing coincides with the explosion or exhaust
stroke of the engine.
[0020] Moreover, an engine control equipment of the present
invention is controlled so as to early perform the combustion by
the compressive self-ignition when a temperature detected by a
temperature sensor provided for the upstream or downstream side of
the above catalyst shows a predetermined value or higher and the
catalyst uses a three-way catalyst or NOx catalyst set to an
exhaust pipe.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a general block diagram of an engine control
system provided with an engine control equipment of first
embodiment of the present invention;
[0022] FIG. 2 is an internal block diagram of the engine control
equipment in FIG. 1;
[0023] FIG. 3 is a control block diagram of catalyst control means
of the engine control equipment in FIG. 1;
[0024] FIG. 4 is a control block diagram of the engine control
equipment in FIG. 1;
[0025] FIG. 5 is a control block diagram of the catalyst control
means in FIG. 4;
[0026] FIG. 6 is an illustration of the
compressive-self-ignition-combusti- on permitting section in FIG.
4;
[0027] FIG. 7 is an illustration of the
basic-fuel-injection-quantity computing section in FIG. 4;
[0028] FIG. 8 is an illustration of the air-fuel-correction-term
computing section in FIG. 4;
[0029] FIG. 9 is an illustration of the target-opening computing
section in FIG. 4;
[0030] FIG. 10 is an illustration of the throttle-opening control
section in FIG. 4;
[0031] FIG. 11 is an illustration of the target-fresh-air-quantity
and EGR-quantity computing section in FIG. 4;
[0032] FIG. 12 is an illustration of the
target-exhaust-valve-opening-timi- ng computing section in FIG.
4;
[0033] FIG. 13 is an illustration of the
target-exhaust-valve-closing-timi- ng computing section in FIG.
4;
[0034] FIG. 14 is an illustration of the
target-intake-valve-opening-timin- g computing section in FIG.
4;
[0035] FIG. 15 is an illustration of the
target-intake-valve-closing-timin- g computing section in FIG.
4;
[0036] FIG. 16 is an illustration of the target-ignition-timing
computing section in FIG. 4;
[0037] FIG. 17 is a general block diagram of an engine control
system provided with an engine control equipment of second
embodiment of the present invention;
[0038] FIG. 18 is an internal block diagram of the engine control
equipment in FIG. 17;
[0039] FIG. 19 is a control block diagram of the engine control
equipment in FIG. 17;
[0040] FIG. 20 is a control block diagram of the catalyst control
means in FIG. 19; FIG. 21 is an illustration of the
heater-operation permitting section in FIG. 19;
[0041] FIG. 22 is an illustration of the target-opening computing
section in FIG. 19;
[0042] FIG. 23 is an illustration of the target-fresh-air-quantity
and EGR-quantity computing section in FIG. 19;
[0043] FIG. 24 is an illustration of the target-ignition-timing
computing section in FIG. 19;
[0044] FIG. 25 is an illustration of the catalyst-heater control
section in FIG. 19;
[0045] FIG. 26 is a general block diagram of an engine control
system provided with an engine control equipment of third
embodiment of the present invention;
[0046] FIG. 27 is a control block diagram of the engine control
equipment in FIG. 26;
[0047] FIG. 28 is a control block diagram of the catalyst control
means in FIG. 26;
[0048] FIG. 29 is an illustration showing the relation between
injection timing and exhaust-gas temperature in explosion and
exhaust strokes;
[0049] FIG. 30 is an illustration of the second injection
permitting section in FIG. 27;
[0050] FIG. 31 is an illustration of the second injection-timing
and injection-quantity computing section in FIG. 27;
[0051] FIG. 32 is a block diagram of the engine of another
embodiment;
[0052] FIG. 33 is a block diagram of the engine of still another
embodiment;
[0053] FIG. 34 is a characteristic diagram of a three-way catalyst
to an air-fuel ratio;
[0054] FIG. 35 is a characteristic diagram of a three-way catalyst
to temperature; and
[0055] FIG. 36 is an illustration showing the change of activation
temperature of a three-way catalyst and HC quantity passing through
the three-way catalyst.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0056] Embodiments of an engine control equipment of the present
invention are described below in detail by referring to the
accompanying drawings.
[0057] FIG. 1 shows a general configuration of an engine control
system provided with an engine control equipment of the first
embodiment of the present invention. An engine 50 is constituted of
a multiple cylinder 9 and an intake pipe 6 and an exhaust pipe 10
are connected to each cylinder 9.
[0058] An ignition plug 8 is set to each cylinder 9 and a fuel
injection valve 7 is set to the intake pipe 6 and moreover, an air
cleaner 1, an air-flow sensor 2, an electric-control throttle valve
3, and an ISC bypass 4 for bypassing the throttle valve 3 are set
to their proper positions at the upstream side of the intake pipe
6. Moreover, an exhaust-gas circulation path (EGR path) 18 is set
which bypasses the cylinder 9 and communicates the intake pipe 6
with the exhaust pipe 10 and an EGR valve 19 is set to the EGR path
18.
[0059] Moreover, a three-way catalyst 11 is set to the exhaust pipe
10, an A/F sensor 12 is set to the upstream side of the three-way
catalyst 11, and a temperature sensor 13 is set to the downstream
side of the three-way catalyst 11. Furthermore, a throttle-opening
sensor 17 is set to the portion where the throttle valve 3 is set,
a water-temperature sensor 14 is set to the lateral face of the
cylinder 9, and a crank-angle sensor 15 is set to the crank shaft
portion.
[0060] The air coming from the outside of the engine 50 is supplied
into a combustion chamber 16 after passing through the air cleaner
1, the intake pipe 6, and an intake valve 27 by lift-timing control
electromagnetic driving. The incoming airflow is mainly adjusted by
the throttle valve 3. However, the airflow is adjusted by an ISC
valve 5 set to the bypass 4 under idling and the engine speed is
controlled by the adjustment. Moreover, an incoming airflow is
detected by the airflow sensor 2, a signal is output from the
crank-angle sensor 15 every degree of rotation angle of the
crankshaft and the cooling-water temperature of the engine 50 is
detected by the water-temperature sensor 14.
[0061] An engine control equipment 100 (control unit) is set to the
engine 50, the control unit 100 receives a signal of each of the
above sensors and computes the signal and outputs a control signal
to each of the above operation units.
[0062] That is, signals of the air-flow sensor 2, throttle-opening
sensor 17, crank-angle sensor 15, water-temperature sensor 14, A/F
sensor 12, and temperature sensor 13, and a signal of an
accelerator pedal 32 are sent to the control unit 100, operation
states of the engine 50 are obtained from these sensor outputs, and
the basic injection quantity of a fuel and the main control input
of ignition timing are optimally computed. The fuel injection
quantity computed by the control unit 100 is converted to a
valve-opening pulse signal and the signal is sent to the fuel
injection valve 7.
[0063] Moreover, in the control unit 100, a predetermined ignition
timing is computed and a driving signal is output to the ignition
plug 8 from the control unit 100 so that ignition is performed at
the above ignition timing. Furthermore, an internal exhaust-gas
recirculation quantity and a fresh-air quantity are controlled by
using the intake valve 27 and exhaust valve 28 according to
lift-timing-control electromagnetic driving and the pressure and
temperature in the combustion chamber 16 are controlled so that
self-ignition is performed at a predetermined timing.
[0064] The fuel injected from the fuel injection valve 7 is mixed
with air supplied from the intake pipe 6 and enters the combustion
chamber 16 of each cylinder 9 to form a mixed gas. The mixed gas is
ignited and exploded by compressive self-ignition or a spark
generated by the spark plug 8 and the energy thus generated serves
as a motive-power source for the rotational driving force of the
engine 50.
[0065] The exhaust gas after explosion in the combustion chamber 16
is supplied to the three-way catalyst 11 through the exhaust valve
28 according to lift-timing-control electromagnetic driving and the
exhaust pipe 10. Exhaust-gas components of HC, CO, and NOx are
purified by the three-way catalyst 11 and then, the exhaust gas is
discharged to the outside of the engine 50. However, some of the
exhaust gas is recirculated to the intake pipe 6 through the EGR
path 18. Recirculation of the exhaust gas is controlled by the EGR
valve 19 in accordance with a signal sent from the control unit
100.
[0066] The A/F sensor 12 has a linear output characteristic to the
oxygen concentration in exhaust gas and the relation between oxygen
concentration in exhaust gas and air-fuel ratio becomes almost
linear. Therefore, it is possible to obtain the air-fuel ratio at
the upstream side of the three-way catalyst 11 by the A/F sensor
12. Moreover, the temperature sensor 13 makes it possible to detect
the exhaust-gas temperature at the downstream side of the three-way
catalyst 11.
[0067] The control unit 100 calculates the air-fuel ratio at the
upstream side of the three-way catalyst 11 in accordance with a
signal of the A/F sensor 12 and performs the feedback (F/B) control
for sequentially correcting the above basic injection quantity so
that the air-fuel ratio of the mixed gas in the combustion chamber
16 becomes equal to a target air-fuel ratio. Moreover, the throttle
valve 3, intake valve 27, and exhaust valve 28 are controlled so
that they respectively have their target opening, the ignition
timing of the spark plug 8 is controlled so as to coincide with a
target ignition timing, and activation of the three-way catalyst 11
is accelerated by catalyst control means 150 to be mentioned layer
in accordance with a signal of the temperature sensor 13 and the
like.
[0068] FIG. 2 shows the inside of the control unit 100.
[0069] Output values of the A/F sensor 12, temperature sensor 13,
throttle-opening sensor 17, air-flow sensor 2, crank-angle sensor
15, and water-temperature sensor 14 are input to the control unit
100, signal processing such as noise removal is applied to the
output values by an input circuit 23, and then the output values
are sent to an input/output port 24. The value of the input/output
port 24 is stored in a RAM 22 and computed by a CPU 20. A control
program in which the content of arithmetic processing is described
is previously written in a ROM 21.
[0070] A value showing each actuator working value computed in
accordance with the control program is stored in the RAM 22 and
then, sent to the input/output port 24. Then, as a working signal
of the spark plug 8, an on/off signal is set which is turned on
when the primary coil of an ignition output circuit 25 is
electrified and turned off when the coil is not electrified. The
ignition timing is the time when the on/off signal changes from on-
to off-states. The signal for the spark plug 8 set to the
input/output port 24 is amplified so as to have a sufficient energy
necessary for combustion by the ignition output circuit 25 and
supplied to the spark plug 8. Moreover, as a driving signal of the
fuel injection valve 7, an on/off signal is set which is turned on
when a valve opens and turned off when the valve closes, amplified
so as to have the energy enough to open the fuel injection valve 7
by a fuel-injection-valve driving circuit 26 and sent to the fuel
injection valve 7. Furthermore, driving signals of
electromagnetic-driving intake and exhaust valves 27 and 28 are
sent to the intake and exhaust valves 27 and 28 through driving
circuits 29 and 30 to open/close the valves at optional timing.
Furthermore, a driving signal for realizing the target opening of
the electric-control throttle valve 3 is sent to the
electric-control throttle valve 3 through an electronically
controlled throttle driving circuit 31.
[0071] Moreover, as shown in FIG. 3, the control unit 100 is
provided with control means 150 for the three-way catalyst 11. The
catalyst control means 150 is constituted of means 200 for
determining the state of the three-way catalyst 11 in accordance
with an output signal of the temperature sensor 13 or the like and
means 201 for activating the three-way catalyst 11 in accordance
with the determination result. The catalyst-state determining means
200 is constituted of catalyst-temperature detecting means 101A for
detecting the temperature of the three-way catalyst 11 and
catalyst-activation determining means 101B for determining the
activation of the three-way catalyst 11 to activate the catalyst 11
in accordance with the activated state of the three-way catalyst
11, achieve early compressive self-ignition, and further prevent
exhaust gas from deteriorating.
[0072] The control program written in the ROM 21 is described
below.
[0073] FIG. 4 shows a control block diagram of the control unit
100. The catalyst control means 150 of the control unit 100
inhibits the combustion by compressive self-ignition and performs
combustion by changing the above combustion to the combustion by
spark ignition to activate the catalyst 11 by the exhaust heat of
the combustion by the spark ignition. Moreover, the control unit
100 is constituted of a compressive-self-ignition-combustion
permitting section 101 which is one mode of the catalyst-state
determining means 200, a basic-fuel injection-quantity computing
section 102, an air-fuel-ratio correction-term computing section
103, a target-opening computing section 104, a throttle-opening
control section 105, a target-fresh-air-quantity and EGR-quantity
computing section 106, a target-exhaust-valve-opening-ti- ming
computing section 107, a target-exhaust-valve-closing-timing
computing section 108, a target-intake-valve-opening-timing
computing section 109, a target-intake-valve-closing-timing
computing section 110, and a target-ignition-timing computing
section 111 which is one mode of the catalyst activating means 201.
Each control block is described below in detail.
[0074] FIG. 5 is a control block diagram of the catalyst control
means 150 in the control unit 100.
[0075] The catalyst control means 150 conceptually includes the
compressive self-ignition-combustion permitting section 101 and the
target-ignition-timing computing section 111 for computing a target
ignition timing by performing the spark ignition, which is
constituted of the catalyst-temperature detecting means 101A and
catalyst-activation determining means 101B, detects the temperature
of the three-way catalyst 11 by the catalyst-temperature detecting
means 101A, determines the activation of the three-way catalyst 11
by the catalyst-temperature detecting means 101B, and outputs a
signal for executing the combustion not by compressive
self-ignition but by spark ignition by the
compressive-self-ignition inhibiting means 111 to the
target-opening computing section 104, target-fresh-air-quantity and
EGR-quantity computing section 106, and target-ignition-timing
computing section 111.
[0076] FIG. 6 is an illustration for permission of the compressive
self-ignition by the compressive-self-ignition-combustion
permitting section 101, in which the compressive-self-combustion
permitting section 101 determines whether to permit compressive
self-ignition in accordance with a downstream temperature Cat of
the catalyst 11, an accelerator opening Apo, and an engine speed
Ne. Specifically, when all of the following conditions (1) to (3)
are effectuated, the section 101 sets a compressive-self-ignition
permit flag fpauto to 1 to perform compressive-self-ignition
combustion. However, when not all of the conditions (1) to (3) are
effectuated, the section 101 inhibits compressive self-ignition and
sets the compressive-self-ignition permit flag fpauto to 0 to
change the compressive self-ignition to spark ignition.
TmpCat.gtoreq.TmpCatAuto (1)
Apo.ltoreq.ApoAuto (2)
Ne.ltoreq.NeAuto (3)
[0077] In the above expressions, TmpCatAuto denotes a set value of
downstream temperature, ApoAuto denotes a set value of accelerator
opening, and NeAuto denotes a set value of engine speed which are
stored in the ROM 21. Then, the expression (1) shows the activated
state of a catalyst, in which a catalyst becomes the inactivated
state when the catalyst temperature TmpCat is lower than
TmpCatAuto.
[0078] FIG. 7 is an illustration of the calculation of a basic
fuel-injection quantity by the basic-fuel-injection-quantity
computing section 102. The basic-fuel-injection-quantity computing
section 102 computes a fuel injection quantity for simultaneously
realizing a target torque and a target air-fuel ratio under an
optional condition in accordance with signals of an incoming air
quantity Qa by the air-flow sensor 2, an engine speed Ne, and an
accelerator pedal 32. Specifically, the section 102 computes a
basic fuel-injection quantity Tp as shown by the following
expression (4).
Tp=K.times.Qa/(Ne.times.Cyl) (4)
[0079] In the above expression, k denotes a constant value for
adjusting the incoming air quantity Qa so as to always realize a
theoretical air-fuel ratio and Cyl denotes the number of cylinders
9.
[0080] FIG. 8 is an illustration of the calculation of an
air-fuel-ratio correction term by the air-fuel
ratio-correction-term computing section 103. The air-fuel-ratio
correction-term computing section 103 performs F/B control so that
an air-fuel ratio becomes equal to a theoretical air-fuel ratio
under an optional operating condition in accordance with the
deviation Dltabf between an actual air-fuel ratio detected by the
A/F sensor 12 and a target air-fuel ratio Tabf. Specifically, an
air-fuel-ratio correction term Lalpha is computed through PI
control. Then, the air-fuel-ratio correction term Lalpha is
multiplied by the basic-fuel-injection quantity Tp, held so that
the air-fuel ratio of an engine always becomes equal to a
theoretical air-fuel ratio, and output to the fuel injection valve
7.
[0081] In general, to cause compressive self-ignition, it is
necessary to control the pressure and temperature in the cylinder 9
to predetermined values at a predetermined crank angle and
simultaneously realize a torque intended by a driver. Therefore,
this embodiment controls fresh-air quantity and internal EGR
quantity by using the electric-control throttle valve 3,
electromagnetic-driving-type intake valve 27, and
electromagnetic-driving-type exhaust valve 28 and performs the
following coordination control so that the pressure and temperature
in the cylinder 9 become predetermined high values.
[0082] First, because a combustion air-fuel ratio is made equal to
a theoretical air-fuel ratio, the above fresh-air quantity and
torque are proportional to each other, that is, it is possible to
control the torque by the fresh-air quantity. Therefore, the
fresh-air quantity is controlled by the electric-control throttle
valve 3 and electromagnetic-driving-type intake valve 27 and the
pressure and temperature in the cylinder 9 are controlled by the
remaining gas in the cylinder 9, that is, the internal EGR quantity
is controlled by the electromagnetic-driving-type exhaust valve
28.
[0083] Moreover, because compressive-self-ignition combustion is
different from spark-ignition combustion in requested EGR quantity,
a target internal EGR quantity is changed by the value of the
compressive-self-ignition permit flag fpauto and thereby, the
opening/closing timing of the intake valve 27 for taking a
requested fresh-air quantity into the cylinder 9 in accordance with
an internal EGR quantity is changed.
[0084] That is, a fresh-air quantity and an internal EGR quantity
are controlled so that the following expressions (5) and (6) are
effectuated under an optional operating condition.
.eta.a,a=.eta.,s (ma,a=ma,s) (5)
.eta.e,a=.eta.,s (me,a=me,s) (6)
[0085] In the above expressions, .eta.a,a denotes the filling
efficiency of fresh-air quantity under compressive-self-ignition
combustion, .eta.a,s denotes the filling efficiency of fresh-air
quantity under spark-ignition combustion, .eta.e,a denotes the
filling efficiency of internal EGR quantity under
compressive-self-ignition combustion, ma,a denotes fresh-air
quantity under compressive-self-ignition combustion, ma,s denotes a
fresh-air mass under spark-ignition combustion, me,a denotes an
internal EGR mass under compressive-self-ignition combustion, and
me,s denotes internal EGR mass under spark-ignition combustion.
[0086] Moreover, in general, because internal EGR quantity
requested for compressive self-ignition is more than that under
spark-ignition combustion, the following expressions (7) to (9) are
effectuated.
.eta.g,a>.eta.g,s (mg,a>mg,s) (7)
mg,a=ma,a+me,a (8)
mg,s =ma,s+me,s (9)
[0087] In the above expressions, .eta.g,a denotes the gas filling
efficiency in the cylinder 9 under compressive-self-ignition
combustion, .eta.g,s denotes the gas filling efficiency in the
cylinder 9 under spark-ignition combustion, mg,a denotes the gas
mass in the cylinder 9 under compressive-self-ignition combustion,
and mg,s denotes the gas mass in the cylinder 9 under
spark-ignition combustion. Moreover, the control unit 100 of this
embodiment first decides a target internal EGR quantity and then,
decides a fresh-air quantity for realizing a target torque.
[0088] FIG. 9 is an illustration for calculation of a target
opening of the electric-control throttle valve 3 by the
target-opening computing section 104. The target-opening computing
section 104 computes a throttle opening for realizing a target
boost under an optional operating condition in accordance with
signals of the air-flow sensor 2, crank-angle sensor 15, and
accelerator pedal 32 and the compressive-self-ignition permit flag
fpauto. Specifically, a target boost TgBoosta for compressive
self-ignition or a target boost TgBoosts for spark ignition is
decided in accordance with the accelerator opening Apo and engine
speed Ne by referring to a map, a target boost TgBoost is set by
changing the boost TgBoosta or TgBoosts by the
compressive-self-ignition permit flag fpauto, a target opening
TgTvo is decided in accordance with the target boost TgBoost and
engine speed Ne by referring to a map, and they are output to the
throttle-opening control section 105, target-fresh-air-quantity and
EGR-quantity computing section 106.
[0089] FIG. 10 is an illustration of the throttle-opening control
section 105. The throttle-opening control section 105 performs F/B
control in accordance with the actual throttle opening Tvo by the
throttle-opening sensor 17 so that the opening of the
electric-control throttle valve 3 becomes equal to the target
opening TgTvo and the control result is output to the
electric-control throttle valve 3. Though the control algorithm of
this embodiment uses PI control, other position-control algorithm
can be also used.
[0090] FIG. 11 is an illustration for calculation of a target
fresh-air quantity and a filling rate by the
target-fresh-air-quantity and EGR-quantity computing section 106.
The target-fresh-air-quantity and EGR-quantity computing section
106 computes a target fresh-air quantity and a target EGR quantity
for realizing a target torque, a target in-cylinder-9 temperature,
and a target in-cylinder-9 pressure under an optional condition in
accordance with the accelerator pedal 32, target boost TgBoost, and
compressive-self-ignition permit flag fpauto. Specifically, a
target fresh-air quantity TgAir is decided in accordance with the
accelerator opening Aoi and engine speed Ne by referring to a map
and output to the target-intake-valve-opening-timing computing
section 109 and target-intake-valve-closing-timing computing
section 110.
[0091] Moreover, a target EGR quantity under compressive
self-ignition or a target EGR quantity under spark ignition is
decided in accordance with the accelerator opening Apo and engine
speed Ne by referring to a map and changed by he value of the
compressive-self-ignition permit flag fpauto to set a target EGR
quantity TgEgr. Moreover, the differential pressure DeltaP between
an in-intake-valve-6 pressure and an in-cylinder-9 pressure is
decided in accordance with the target EGR quantity TgEgr and engine
speed Ne by referring to a map and output to the
target-intake-valve-opening-timing computing section 109 and
target-intake-valve-closing-timing computing section 110. The above
target EGR quantity is changed in accordance with the value of the
compressive-self-ignition permit flag fpauto because requested EGR
quantities are different from each other under
compressive-self-ignition combustion and spark-ignition
combustion.
[0092] Furthermore, a target gas quantity TgGas is obtained in
accordance with the target EGR quantity TgEgr and target fresh-air
quantity TgAir, a filling efficiency ItaGas is decided in
accordance with the maximum gas quantity MaxGas and a target gas
quantity TgGas obtained from the engine speed Ne and output to the
target-exhaust-valve-opening-timing computing section 107 and
target-exhaust-valve-closing-timing computing section 108.
[0093] FIG. 12 is an illustration for calculation of an opening
timing by the target-exhaust-valve-opening-timing computing section
107. The target-exhaust-valve-opening-timing computing section 107
computes the opening timing of an exhaust valve for realizing the
target EGR quantity TgEgr in accordance with the filling efficiency
ItaGas and engine speed Ne. Specifically, a target-exhaust-valve
opening timing TgEvo is decided in accordance with the filling
efficiency ItaGas and engine speed Ne by referring to a map and
output to the electromagnetic-driving-type exhaust valve 28.
[0094] FIG. 13 is an illustration for calculation of a closing
timing by the target-exhaust-vale-closing-timing computing section
108. The target-exhaust-vale-closing-timing computing section 108
computes the closing timing of an exhaust valve for realizing the
target EGR quantity TgEgr in accordance with the filling efficiency
ItaGas and engine speed Ne. Specifically, a target exhaust-valve
closing timing TgEvc is decided in accordance with the filling
efficiency ItaGas and engine speed Ne by referring to a map and
output to the electromagnetic-driving-type exhaust valve 28.
[0095] FIG. 14 is an illustration for calculation of an opening
timing by the target-intake-valve-opening-timing computing section
109. The target-intake-valve-opening-timing computing section 109
computes the opening timing of an intake valve for realizing the
target fresh-air quantity TgAir in accordance with the target
fresh-air quantity TgAir and differential pressure DeltaP.
Specifically, a target-intake-valve opening timing TgIvc is decided
in accordance with the target fresh-air quantity TgAir and
differential pressure DeltaP by referring to a map and output to
the electromagnetic-driving-type intake valve 27.
[0096] FIG. 15 is an illustration for calculation of a closing
timing by the target-intake-valve-closing-timing computing section
110. The target-intake-valve-closing-timing computing section 110
computes the closing timing of an intake valve for realizing the
target fresh-air quantity TgAir in accordance with the target
fresh-air quantity TgAir and differential pressure DeltaP.
Specifically, a target-intake-valve closing timing TgIvc is decided
in accordance with the target fresh-air quantity TgAir and
differential pressure DeltaP by referring to a map and output to
the electromagnetic-driving-type intake valve 27.
[0097] FIG. 16 is an illustration for calculation of a target
ignition timing by the target-ignition-timing computing section
111. The target-ignition-timing computing section 111 computes an
optimum ignition timing under an optional operating condition in
accordance with signals of the air-flow sensor 2, crank-angle
sensor 15, and accelerator pedal 32 and the
compressive-self-ignition permit flag fpauto. Specifically, the
target boost TgBoosta under compressive self-ignition or TgBoosts
under spark ignition is decided in accordance with the accelerator
opening Apo and engine speed Ne by referring to a map and changed
by the compressive-self-ignition permit flag fpauto to set a target
ignition timing Adv and the timing Adv is output to the spark plug
8. Moreover, ignition can be performed preparing for a misfire even
under compressive self-ignition combustion. In this case, a target
ignition timing is selected at more retard side than a
self-ignition timing.
[0098] FIGS. 17 to 25 show an engine control equipment of second
embodiment which is the same as the engine control equipment of the
first embodiment except the configuration based on the catalyst
control means 150. Therefore, the above point is described below in
detail.
[0099] FIG. 17 shows the general configuration of an engine control
system provided with the engine control equipment of the second
embodiment of the present invention, in which a three-way catalyst
11 is set to an exhaust pipe 10 of an engine 50A, an A/F sensor 12
is set to the upstream side of the three-way catalyst 11, and a
temperature sensor 13 is set to the downstream side of the
three-way catalyst 11. Moreover, a catalyst heater 35 is set to a
proper position of the three-way catalyst 11. The catalyst heater
35 is operated in accordance with an output signal of an engine
control equipment (control unit) 100A when the temperature of the
catalyst 11 is equal to or lower than a predetermined value to
activate the catalyst. In FIG. 18, a catalyst-heater driving
circuit 33 is provided as shown by an internal block diagram of the
control unit 100A.
[0100] FIG. 19 shows a control block diagram of the control unit
100A in which the catalyst control means 150 drives the catalyst
heater 35 when the temperature of the catalyst 11 is equal to or
lower than a predetermined value to activate the catalyst 11 by the
heat of the heater 35. Moreover, the control unit 100A is
constituted of a heater-operation permitting section 121 which is
one mode of the catalyst-state determining means 200, a
basic-fuel-injection-quantity computing section 102, an
air-fuel-ratio-correction-term computing section 103, a
target-opening computing section 104A, a throttle-opening control
section 105, a target-fresh-air-quantity and EGR-quantity computing
section 106A, a target-exhaust-valve-opening-timing computing
section 107, a target-exhaust-valve-closing-timing computing
section 108, a target-intake-valve-opening-timing computing section
109, a target-intake-valve-closing-timing computing section 110, a
target-ignition-timing computing section 11A, and a catalyst-heater
control section 122 which is one mode of the catalyst activating
means 201. Each control block is described below in detail.
[0101] FIG. 20 is a control block diagram of the catalyst control
means 150 in the control unit 100A.
[0102] The catalyst control means 150 conceptually includes the
heater-operation permitting section 121 and the
catalyst-temperature raising means 122 for driving-controlling the
catalyst heater 35, which is constituted of the
catalyst-temperature detecting means 101A and catalyst-activation
determining means 101B and which detects the temperature of the
three-way catalyst 11 by the catalyst-temperature detecting means
101A in accordance with an output signal of the temperature sensor
13, determines the activation of the three-way catalyst 11 by the
catalyst-activation determining means 101B in accordance with the
detected temperature, and outputs a signal for executing heater
operations to the catalyst-heater control section 122 in accordance
with the above determination result.
[0103] FIG. 21 is an illustration for permission of a heater
operation by the heater-operation permitting section 121, in which
the heater-operation permitting section 121 determines permission
of compressive self-ignition in accordance with the downstream
temperature TmCat of the catalyst 11. Specifically, when the
following expression (10) is effectuated, the section 121 sets a
catalyst-heater-operation flag fpheat to 1 to perform heater
operations. However, when the expression (10) is not effectuated,
the section 121 stops heater operations and sets the
catalyst-heater-operation flag fpheat to 0.
TmpCat.gtoreq.TmCatAuto (10)
[0104] In this case, the expression (10) shows a catalyst
activation state and a catalyst becomes an inactive state when the
catalyst temperature TmpCat is lower than TmpCatAuto.
[0105] The basic-fuel-injection-quantity computing section 102 and
air-fuel-correction-term computing section 103 are the same as
those of the first embodiment.
[0106] FIG. 22 is an illustration for calculation of a target
opening of the electric-control throttle valve 3 by the
target-opening computing section 104A. The target-opening computing
section 104A computes a throttle opening for realizing a target
boost under an optional operating condition in accordance with
signals of the air-flow sensor 2, crank-angle sensor 15, and
accelerator pedal 32. Specifically, the target boost TgBoost is set
in accordance with the accelerator opening Apo and engine speed Ne
by referring to a map, and the target opening TgTvo is decided in
accordance with the target boost TgBoost and engine speed Ne by
referring to a map and they are output to the throttle-opening
control section 105 and target-fresh-air-quantity and EGR-quantity
computing section 106A.
[0107] The throttle-opening control section 105 is the same as that
of the first embodiment.
[0108] FIG. 23 is an illustration for calculation of target
fresh-air quantity and filling efficiency by the
target-fresh-air-quantity and EGR-quantity computing section 106A.
The target-fresh-air-quantity and EGR-quantity computing section
106A computes a target torque and a target fresh-air quantity and a
target EGR quantity for realizing the temperature and pressure in
the target cylinder 9 under an optional operating condition in
accordance with the accelerator pedal 32 and the target boost
TgBoost. Specifically, the target fresh-air quantity TgAir is
decided in accordance with the accelerator opening Apo and engine
speed Ne by referring to a map and output to the
target-intake-valve-open- ing-timing computing section 109 and
target-intake-valve-opening-timing computing section 110.
[0109] Moreover, the target EGR quantity TgEgr under compressive
self-ignition is set in accordance with the accelerator opening Apo
and engine speed Ne by referring to a map, and the differential
pressure DeltaP between the internal pressures of the intake pipe 6
and cylinder 9 is decided in accordance with the target EGR
quantity TgEgr and engine speed Ne by referring to a map and they
are output to the target-intake-valve-opening-timing computing
section 109 and target-intake-valve-closing-timing computing
section 110.
[0110] Furthermore, the target gas quantity TgGas is obtained from
the target EGR quantity TgEgr and target fresh-air quantity TgAir,
and the filling efficiency ItaGas is decided in accordance with the
maximum gas quantity MaxGas obtained from the engine speed Ne and
the target gas quantity TgGas and they are output to the
target-exhaust-valve-opening-ti- ming computing section 107 and
target-exhaust-valve-closing-timing computing section 108.
[0111] The target-exhaust-valve-opening-timing computing section
107, target-exhaust-valve-closing-timing computing section 108,
target-intake-valve-opening-timing computing section 109, and
target-intake-valve-closing-timing computing section 110 are the
same as those of the first embodiment.
[0112] FIG. 24 is an illustration for calculation of a target
ignition timing by the target-ignition-timing computing section
11A. The target-ignition-timing computing section 111A computes a
target ignition timing when a misfire also occurs under
compressive-self-ignition combustion in accordance with signals of
the air-flow sensor 2, crank-angle sensor 15, and accelerator pedal
32. Specifically, the target ignition timing Adv is set in
accordance with the accelerator opening Apo and engine speed Ne by
referring to a map and output to the ignition plug 8. The target
ignition timing is selected at more retard side than a
compressive-self-ignition timing.
[0113] FIG. 25 is an illustration for a heater operation by the
catalyst heater control section 122. The catalyst heater control
section 122 is changed by the catalyst-heater-operation flag fpheat
to operate the catalyst heater 35 when the
catalyst-heater-operation flag fpheat is set to 1 and stop the
operation of the catalyst heater 35 when the flag is not set to
1.
[0114] FIGS. 26 to 31 show the engine control equipment of the
third embodiment, which is the same as the engine control
equipments 100 and 100A of the first and second embodiments except
the configuration of the catalyst control means 150. Therefore, the
above point is described below in detail.
[0115] FIG. 26 shows the general configuration of an engine control
system provided with the engine control equipment of the third
embodiment of the present invention, in which a fuel injection
valve 34 is set to a cylinder 9 of an engine 50B. The fuel
injection valve 34 injects fuel in the cylinder 9 when the
temperature of a catalyst 11 is a predetermined value or lower in
accordance with an output signal of an engine control equipment
(control unit) 100B to activate the catalyst.
[0116] FIG. 27 shows a control block diagram of the control unit
100B. The catalyst control means 150 of the control unit 100B
injects surplus fuel in the explosion and exhaust strokes of an
engine when the temperature of the catalyst 11 is equal to or lower
than a predetermined value, causes oxidation in the cylinder 9,
exhaust pipe 10, and catalyst 11, and activates the catalyst 11 by
the heat due to the oxidation. Moreover, the control unit 100B is
constituted of a second injection permitting section 131 which is
one mode of the catalyst-state determining means 200, a
basic-fuel-injection-quantity computing section 102, an
air-fuel-ratio-correction-term computing section 103, a
target-opening computing section 104A, a throttle-opening control
section 105, a target-fresh-air-quantity and EGR-quantity computing
section 106A, a target-exhaust-valve-opening-timing computing
section 107, a target-exhaust-valve-closing-timing computing
section 108, a target-intake-valve-opening-timing computing section
109, a target-intake-valve-closing-timing computing section 110, a
target-ignition-timing computing section 111A, and a second
injection-timing and injection-quantity computing section 132 which
is one mode of the catalyst activating means 201. Each control
block is described below in detail.
[0117] FIG. 28 is a control block diagram of the catalyst control
means 150 in the control unit 100B.
[0118] The catalyst control means 150 conceptually includes the
second injection permitting section 131 and explosion-stroke and
exhaust-stoke injection means 132. The second injection permitting
section 131 is constituted of catalyst-temperature detecting means
101A and catalyst activating means 101B and outputs a signal for
detecting the temperature of the three-way catalyst 11 by the
catalyst-temperature detecting means 101A in accordance with an
output signal of a temperature sensor 13, determining the
activation of the three-way catalyst 11 by the catalyst-activation
determining means 101B in accordance with the detected temperature,
and computing the injection timing and quantity of surplus fuel in
explosion and exhaust strokes in accordance with the above
determination result to a second injection-timing and
injection-quantity computing section 132.
[0119] FIGS. 29 and 30 are illustrations for permission of
injection of second fuel by the second injection permitting section
131, in which FIG. 29 shows the relation between the injection
timing and the exhaust-gas temperature in the explosion and exhaust
strokes. From FIG. 29, it is found that the peak of an exhaust-gas
temperature is present in the explosion stroke when surplus fuel is
injected in the explosion (expansion) and exhaust strokes (shown by
a continuous line) compared to the case in which no surplus fuel is
injected (shown by a broken line) and the exhaust-gas temperature
rises until the exhaust stroke. This is because the fuel injected
in the above strokes is oxidized in the exhaust pipe 10 or catalyst
11 and the exhaust-gas temperature is raised by the heat of the
oxidation. Moreover, the second injection permitting section 131
for permitting the injection of the surplus fuel determines the
permission of compressive self-injection in accordance with the
downstream temperature TmpCat of the catalyst 11 as shown in FIG.
30. Specifically, when the condition of the following expression
(11) is effectuated, the section 131 sets a second injection permit
flag fpti2 to 0 but it does not second injection in the expansion
and exhaust strokes. However, when the condition is not
effectuated, the section 131 sets the second injection permit flag
ftpi2 to 1 and performs second injection.
[0120] TmpCat.gtoreq.TmpCatAuto (11)
[0121] In this case, the expression (11) shows a catalyst
activation state and the catalyst becomes inactive when the
catalyst temperature TmpCat is lower than TmCatAuto.
[0122] The basic-fuel-injection-quantity computing section 102,
air-fuel-ratio-correction-term computing section 103,
throttle-opening control section 105,
target-exhaust-valve-opening-timing computing section 107,
target-exhaust-valve-closing-timing computing section 108,
target-intake-valve-opening-timing computing section 109, and
target-intake-valve-closing-timing computing section 110 are the
same as those of the first embodiment and the catalyst-temperature
detecting means 101A, target-fresh-air-quantity and EGR-quantity
computing section 106A, and target-ignition-timing computing
section 111A are the same as those of the second embodiment.
[0123] FIG. 31 is an illustration for calculation of the second
fuel-injection quantity and fuel-injection timing by the second
injection-timing and injection-quantity computing section 132. The
second injection-timing and injection-quantity computing section
132 computes the second fuel-injection quantity and fuel-injection
timing in accordance with signals of the crank-angle sensor 15 and
accelerator pedal 32. Specifically, the second injection quantity
is set in accordance with the accelerator opening Apo and engine
speed Ne by referring to a map and changed in accordance with the
value of the second injection permit flag fpti2 to decide a second
injection quantity TI2 and moreover, a second injection timing IT2
is decided in accordance with the accelerator opening Apo and
engine speed Ne by referring to a map and they are output to the
fuel injection valve 34 by which the second injection is performed.
A technique is used which experientially decides the value of a map
in accordance with the performance of an engine.
[0124] As described above, embodiments of the present invention
have the following functions by using the above configuration.
[0125] That is, the engine control equipment of this embodiment has
the catalyst control means 150 for accelerating the activation of
the three-way catalyst 11 in accordance with output signals of the
temperature sensor 13 at the downstream side of the three-way
catalyst 11 and the like, the catalyst control means 150 of the
engine control equipment 100 of the first embodiment has the
compressive-self-ignition-c- ombustion permitting section 101 for
inhibiting the combustion according to compressive self-ignition,
changes the combustion to the combustion according to spark
ignition to perform the combustion when the temperature of the
catalyst 11 is equal to or lower than a predetermined value and the
compressive-self-ignition inhibiting means 111, and the
compressive-self-ignition-combustion permitting section 101 is
constituted of the catalyst-temperature detecting means 101A for
detecting the temperature of the three-way catalyst 11 and the
catalyst-activation determining means 101B for determining the
activation of the three-way catalyst 11 in accordance with the
temperature to change the combustion to the combustion according to
spark ignition whose exhaust-gas temperature is higher than that of
the compressive-self-ignition combustion and activate the three-way
catalyst 11 by the exhaust-gas temperature. Therefore, it is
possible to shorten the time from start of an engine up to
activation of a catalyst by always activating the three-way
catalyst 11, prevent exhaust gas from deteriorating even for a
combustion system by a compressive-self-ignition engine whose
combustion temperature is low because compressive self-ignition is
not performed when the three-way catalyst 11 is inactive, and
improve the reliability of the engine.
[0126] Moreover, the catalyst control means 150 of the engine
control equipment 100A of the second embodiment has the
heater-operation permitting section 121 for driving the catalyst
heater 35 when the temperature of the catalyst 11 is equal to or
lower than a predetermined value and the catalyst-temperature
raising means 122. The heater-operation permitting section 121 is
constituted of the catalyst-temperature detecting means 101a for
detecting the temperature of the three-way catalyst 11 and the
catalyst-activation determining means 101B for determining the
activation of the three-way catalyst 11 in accordance with the
detected temperature, which changes to the driving of the catalyst
heater 35 in accordance with an output signal of the temperature
sensor 13 to activate the catalyst 11. Therefore, it is possible to
shorten the time from start of an engine up to activation of a
catalyst and prevent exhaust gas from deteriorating even for a
combustion system by a compressive-self-ignition engine.
[0127] Furthermore, the catalyst control means 150 of the engine
control equipment 100B of the third embodiment has the second
injection permitting section 131 for injecting surplus fuel in the
explosion and exhaust stroke of an engine when the temperature of
the catalyst 11 is equal to or lower than a predetermined value and
the explosion-and-exhaust-stroke injecting means 132. The second
injection permitting section 131 is constituted of the
catalyst-temperature detecting means 101A for detecting the
temperature of the three-way catalyst 11 and the
catalyst-activation determining means 101B for determining the
activation of the three-way catalyst 11 in accordance with the
detected temperature, which causes oxidation in the cylinder 9,
exhaust pipe 10, and catalyst 11 in accordance with an output
signal of the temperature sensor 13 and activate the catalyst 11 by
the heat of the oxidation. Therefore, also in this case, it is
possible to shorten the time from start of an engine up to
activation of a catalyst and prevent exhaust gas from deteriorating
even for a combustion system by a compressive-self-ignition
engine.
[0128] Three embodiments of the present invention are described
above. However, the present invention is not restricted to the
embodiments. Various modifications are permitted through design as
long as they are not deviated from the gist of the present
invention described in claims.
[0129] For example, the catalyst-temperature detecting means 101A
detects the temperature of the three-way catalyst 11 from the
temperature sensor 13 set to the downstream side of the catalyst
11. However, it is also permitted to use means for estimating the
temperature of the three-way catalyst 11 in accordance with various
operation parameters of the airflow sensor 2 and crank-angle sensor
15. Also in this case, the same advantage can be obtained.
[0130] Moreover, the engine control equipment of each of the above
embodiments accelerates the activation of the catalyst 11 in
accordance with output signals of the A/F sensor 2 set to the
upstream side of the three-way catalyst 11 and the temperature
sensor 13 set to the downstream side of the catalyst 11. As shown
in FIG. 32, however, it is also possible to accelerate the
activation of the catalyst 11 in accordance with output signals of
the temperature sensors 13A and 13B set to the upstream side and
downstream side of the three-way catalyst 11. In this case, it is
possible to more-accurately detect the temperature of the catalyst
11.
[0131] Furthermore, as shown in FIG. 33, it is permitted to use a
configuration having the three-way catalyst 11 or NOx catalyst 36
at the downstream side of the three-way catalyst 11, that is, a
configuration having a plurality of three-way catalysts or a
configuration obtained by combining a three-way catalyst with an
NOx catalyst. Furthermore, it is permitted to use a configuration
obtained by combining a three-way catalyst with an HC adsorption
catalyst. Also in this case, the same advantage can be
obtained.
[0132] Furthermore, in the case of the above embodiments, though
the intake and exhaust valves 27 and 28 respectively use a
lift-timing-control electromagnetic driving valve, it is also
permitted to apply the valves to a phase-control-type driving valve
or it is permitted to use an engine control system not using the
electric-control throttle valve 3. For example, control by only the
intake valve 27 and exhaust valve 28 can be executed.
[0133] As understood from the above explanation, an engine control
equipment of the present invention determines whether a catalyst is
active in a compressive-self-ignition engine and when the catalyst
is inactive, quickly activates the catalyst. Therefore, it is
possible to shorten the time from start of an engine up to
activation of a catalyst and control deterioration of exhaust
gas.
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