Internal-combustion engines – Means to whirl fluid before – upon – or after entry into...
Reexamination Certificate
2001-08-24
2003-01-14
Mohanty, Bibhu (Department: 3747)
Internal-combustion engines
Means to whirl fluid before, upon, or after entry into...
C123S406110
Reexamination Certificate
active
06505604
ABSTRACT:
This application is based on Application No. 2001-48363, filed in Japan on Feb. 23, 2001, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ignition timing control apparatus for an internal combustion engine provided with a swirl control element for adjusting the magnitude or momentum of an intake air swirl according to engine operating conditions, and more particularly, it relates to such an ignition timing control apparatus for an internal combustion engine capable of preventing knocks from occurring immediately after an intake air control valve is driven to operate.
2. Description of the Related Art
In the past, it has been proposed that in an ignition timing control apparatus for an internal combustion engine, provision is made for a swirl control element for adjusting the magnitude or momentum of an intake air swirl in accordance with the operating conditions of the engine.
Such a kind of ignition timing control apparatus for an internal combustion engine is described in Japanese Patent Publication No.7-42916, for example. The apparatus disclosed therein sets ignition timing in accordance with the engine operating conditions including the operating state of an intake air control valve.
In addition, there has also been known another apparatus in which ignition timing data for an open state and a closed state, respectively, of an intake air control valve are set in advance so that they are switched over in accordance with the operating state of the intake air control valve.
In general, in an internal combustion engine equipped with a low-load intake air passage and a high-load intake air passage, the low-load intake air passage and the high-load intake air passage are switched from their open state to their closed state or vice versa in accordance with the engine operating conditions.
That is, when the engine is operating under a low load, the high-load intake air passage is closed to increase the magnitude or momentum of a swirl of intake air, thereby improving combustion efficiency and fuel economy, whereas when the engine is operating under a high load, the high-load intake air passage is opened to decrease intake air resistance, thus providing high power.
At this time, the burning rate of an air fuel mixture is higher when the momentum of the intake air swirl is strong than when the momentum of the intake air swirl is weak, and hence it is necessary to retard the ignition timing at a high burning rate. Accordingly, there has been proposed an apparatus which is capable of switching the settings of ignition timing corresponding to the opening and closing of an intake air control valve, as described above.
FIG. 5
is a block diagram illustrating a common ignition timing control apparatus for an internal combustion engine, which is applied to an automotive engine control apparatus for example. In
FIG. 5
, an intake pipe
3
with an air cleaner
2
attached at one end thereof is connected at the other end thereof with an internal combustion engine (hereinafter simply referred to as “engine”)
1
through a surge tank
4
and an intake manifold
5
, so that air is sucked into the engine
1
through the air cleaner
2
, the intake pipe
3
, the surge tank
4
and the intake manifold
5
.
Mounted on the intake pipe
3
is a throttle valve
6
which is associated with an unillustrated accelerator pedal or lever so that the throttle valve
6
is operated by or in synchronization with the accelerator pedal or lever.
An exhaust pipe
7
is connected at its one end with the engine
1
, and a catalytic converter
8
is inserted in the exhaust pipe
7
for purifying exhaust gases discharged from the engine
1
. Thus, the exhaust gases generated by combustion of an air fuel mixture in the engine
1
are purified by the catalytic converter
7
and discharged to the ambient atmosphere through the exhaust pipe
6
.
An electronic control unit (hereinafter simply referred to as “ECU”)
10
, which constitutes an engine controller proper for the engine control apparatus, is comprised of a microcomputer including a CPU
11
, a ROM
12
, a RAM
13
, etc., for controlling and driving a variety of actuators based on various sensor information representative of the operating conditions of the engine
1
.
An airflow sensor
17
and a throttle opening sensor
15
are mounted on the intake pipe
3
. The airflow sensor
14
measures the amount or flow rate of intake air flowing in the intake pipe
3
and generates a corresponding output signal to the ECU
10
. The throttle opening sensor
15
measures the opening of the throttle valve
15
and generates a corresponding output signal to the ECU
10
.
The engine
1
is provided with a crank angle sensor
16
and a water temperature sensor
17
. The crank angle sensor
16
detects the crank angle or rotational position of an unillustrated crankshaft of the engine
1
and hence the number of revolutions per unit time of the engine
1
, and generates a corresponding output signal to the ECU
10
. The water temperature sensor
17
detects the temperature of engine cooling water or coolant and generates a corresponding output signal to the ECU
10
.
Also, the engine
1
is further provided with an injector
21
for injecting fuel into each engine cylinder, and an ignition plug
22
for electrically igniting the fuel in each engine cylinder. In addition, an intake air control valve
23
is provided in the intake manifold
5
for adjusting the magnitude or momentum of a swirl of intake air sucked into the engine
1
.
The CPU
11
in the ECU
10
performs various calculations or operational processing based on the various signals input to the ECU
10
while using control programs stored in the ROM
13
, determines the operating conditions of the engine
1
, and calculates optimal control parameters for various actuators in accordance with the engine operating conditions thus determined.
That is, the ECU
10
controls the valve opening time of the injector
21
so that an optimal amount of fuel is supplied to the engine
1
in accordance with the engine operating conditions. At the same time, the ECU
10
also controls the energization time of an ignition coil so as to provide the ignition plug
22
with optimal ignition timing, and it additionally controls the opening and closing condition of the intake air control valve
23
so as to properly adjust the magnitude or momentum of an intake air swirl.
Next, reference will be made to a concrete processing operation according to the known ignition timing control apparatus for an internal combustion engine shown in
FIG. 5
while referring to a flow chart of FIG.
6
.
FIG. 6
illustrates a control sequence executed by the CPU
11
in the ECU
10
.
In
FIG. 6
, the ECU
10
first reads the number of revolutions per unit time of the engine based on the output signal from the crank angle sensor
16
(step S
100
), and reads the amount of intake air sucked into the engine
1
, based on the output signal from the airflow sensor
14
(step S
101
).
Also, the ECU
10
determines the operating conditions of the engine
1
based on the information output from other sensors (e.g., the water temperature sensor
17
, etc.) in addition to the above-mentioned information input thereto (step S
102
).
Further, the operating condition of the intake air control valve
23
is determined based on the operating conditions of the engine
1
(step S
103
), and when it is determined that the intake air control valve
23
is in a closed state, a valve closing flag SCV in the RAM
13
is set to “1” (step S
104
), whereas when it is determined that the intake air control valve
23
is in an open state, the valve closing flag SCV in the RAM
13
is set to “0” (step S
105
).
Subsequently, a determination is made as to whether the valve closing flag SCV is set to “1” (step S
106
), and when it is determined that SCV=1 (i.e., YES), a valve closing condition is established and hence the intake air control valve
23
is driven to close (step
Mitsubishi Denki & Kabushiki Kaisha
Mohanty Bibhu
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