Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-11-05
2001-08-21
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S478000
Reexamination Certificate
active
06276341
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a D-jetronic control system that calculates a fuel injection amount based on intake pressure of an internal-combustion engine, and more particularly, to correcting a fuel injection amount in response to a change in intake pressure caused by inertia charge.
2. Description of the Related Art
A typical conventional internal-combustion engine control system (hereinafter referred to as an engine control system or ECU) determines the amount of fuel injected according to the engine speed of the internal-combustion engine and intake pressure. The ECU generally determines the fuel injection amount by referring to a two-dimensional map stored and retained in an internal read-only memory (ROM). The two-dimensional map provides correction coefficients of fuel injection amounts that are determined based on the engine speed and differential pressure.
FIG. 10
schematically illustrates the configuration of a conventional internal-combustion engine control system disclosed in Japanese Unexamined Patent Application Laid-open No. 9-287496.
As shown in
FIG. 10
, the engine is provided with an air cleaner
1
, an intake manifold
2
, a throttle valve
3
, a throttle valve opening sensor
4
, an intake pressure sensor
5
, an injector
6
, a spark plug
7
, an exhaust manifold
8
, a catalyst
9
, an O
2
sensor
10
, a crankshaft
11
, a crank angle sensor
12
, a cam angle sensor
14
, an exhaust cam pulley
15
, an ECU
16
, and a variable valve timing device actuator
17
.
In the internal-combustion engine shown in
FIG. 10
, the ECU
16
determines the fuel injection amount based on engine speed, intake pressure, and amount of control of the variable valve timing device.
To be more specific, the ECU
16
determines the amount of fuel to be injected through the injector
6
according to the intake pressure detected by the intake pressure sensor
5
, the engine speed detected by the crank angle sensor
12
, a target value of valve timing advance (hereinafter referred to as “target advance”) detected by phase difference between output signals of the crank angle sensor
12
and the cam angle sensor
14
, and the control amount of the variable valve timing device
17
.
During an intake stroke of the internal-combustion engine, a spark produced by the spark plug ignites the fuel-air mixture taken into a cylinder. The explosive power pushes a piston
21
down, and the torque of the crankshaft
11
is taken out of the internal-combustion engine.
At this time, the ECU
16
carries out feedback control according to the amount of remaining oxygen in the exhaust gas detected by the O
2
sensor
10
so as to provide a stoichiometric ratio that permits the highest efficiency of exhaust gas purification in the catalyst
9
.
Moreover, the ECU
16
also controls the control amount of the variable valve timing device
17
so that the target advance stored in the ROM agrees with the actual advance in valve timing (hereinafter referred to as “actual advance”) detected by the crank angle sensor
12
and the cam angle sensor
14
.
Generally, in an internal-combustion engine, under a condition wherein acceleration or deceleration is being performed at a given opening of a throttle valve (hereinafter referred to as a “transitional operation mode”), there are cases wherein the effect of inertia charge is more conspicuous than in a steady operation mode.
The inertia charge refers to a state wherein inertia of the flow of an intake air introduced into an engine causes more intake air to be pushed into the engine than in the steady operation mode even if the opening of the throttle valve remains constant.
More specifically, even if the opening of the throttle valve
3
remains constant, more intake air is pushed into the engine in the inertia charge mode than in the steady operation mode. For this reason, the intake pressure in the inertia charge mode is seemingly lower.
Therefore, the intake pressure in the transitional operation mode is sometimes lower than that in the steady operation mode.
The conventional internal-combustion ECU determines basic fuel injection amount based on intake pressure actually detected by intake pressure sensor
5
. Therefore, the ECU decides that the amount of intaking air is decreased because the detected intake pressure is lowered under the transitional operation mode with the effect of inertia charge, and the fuel injection amount based on the detected intake pressure is decreased although the actual amount of intaking air is increased than that of steady state. As a result, sufficient amounts of fuel injection are not provided, and this has been posing problems such as air-fuel ratio (A/F ratio) fluctuations or feedback correction in the feedback control employing the O
2
sensor
10
significantly changes.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an internal-combustion engine control system that corrects amount of the fuel injection according to a differential pressure between an intake pressure in a steady operation mode and a current intake pressure in a transitional operation mode, wherein the effect of the inertia charge is enhanced, so as to suppress a change in an air-fuel ratio or a change in a feedback correction in feedback control using an O
2
sensor.
To this end, according to one aspect of the present invention, there is provided an internal-combustion engine control system provided with: intake pressure detecting means for detecting an intake pressure in the internal-combustion engine; operating state detecting means for detecting an operating state of the internal-combustion engine; and controlling means for controlling the operation of the internal-combustion engine according to the operating state of the internal-combustion engine, wherein the controlling means corrects the fuel injection amount according to a differential pressure between an intake pressure in a steady operation mode of the internal-combustion engine and an intake pressure detected by the intake pressure detecting means.
In a preferred form, the controlling means makes a correction to increase the fuel injection amount if the intake pressure detected by the intake pressure detecting means becomes lower than the intake pressure in the steady operation mode.
In another preferred form, the controlling means does not make a correction of the fuel injection amount based on the differential pressure if the differential pressure stays within a predetermined range.
In yet another preferred form, the internal-combustion engine is equipped with a variable valve timing device, and the controlling means corrects the fuel injection amount according to the control amount of the variable valve timing device and the differential pressure.
The controlling means is equipped with an acceleration and deceleration correcting function for correcting the fuel injection amount during acceleration or deceleration of a vehicle, and inhibits a correction of the fuel injection amount according to the differential pressure during acceleration or deceleration or for a predetermined period of time after the vehicle starts acceleration or deceleration.
In a further preferred form, the controlling means is equipped with an acceleration and deceleration correcting function for correcting the fuel injection amount during acceleration or deceleration of a vehicle, and inhibits a correction of the fuel injection amount according to the differential pressure during acceleration or deceleration or while an acceleration or deceleration correction is being made.
In yet another preferred form, the controlling means gradually increases the correction of the fuel injection amount calculated based on the differential pressure to a value at which making a correction is not inhibited, when the inhibition of making a correction of the fuel injection amount according to the differential pressure is removed.
REFERENCES:
patent: 4479186 (1984-10-01), Takao et al.
patent: 4967711 (1990-11-01), Morikawa
patent: 60823
Hashimoto Atsuko
Kawakami Takeshi
Takahashi Tatsuhiko
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
Wolfe Willis R.
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