JPS61178526A - Fuel injection control method of internal-combustion engine - Google Patents

Abstract

PURPOSE:To inject a defined quantity of fuel to an intake passage at all times by reducingly correcting a fuel injection time when the atmospheric pressure in higher than a reference atmospheric pressure while increasingly correcting said fuel injection time when it is lower than said reference pressure. CONSTITUTION:A correcting factor is obtained by a two-dimensional data map which is stored in an electric control unit 21, from an atmospheric pressure and an intake pipe pressure detected by an atmospheric pressure sensor 26 and an intake pipe pressure sensor 23. This correcting factor reducingly corrects fuel injection time when the atmospheric pressure is higher than a reference atmospheric pressure while increasingly corrects the fuel injection time when it is lower than the reference pressure. Therefore, by using an open-air type pressure regulator 11, a required quantity of fuel can be injectingly fed to an intake port 4 through a fuel injector 3 even if the flow rate of fuel at the injection port of the fuel injector 3 varies due to change in atmospheric pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a fuel injection control method for an internal combustion engine used in vehicles such as automobiles, and in particular to a method for controlling fuel injection by a fuel injector, which has been pressure regulated by an air-open pressure regulator. The present invention relates to a method of controlling fuel injection for an internal combustion engine, in which fuel is injected into an intake passage.

Conventional Technology A fuel injection control device for an internal combustion engine used in vehicles such as automobiles uses a pressure regulator to regulate the pressure of fuel pumped from a fuel tank by a fuel pump, and then sends the regulated fuel to an intake passage by a fuel injector. It is designed to be supplied by injection.

In the above-mentioned fuel injection control device, the amount of fuel injected from the fuel injector into the intake passage is determined by the fuel flow velocity at the fuel injector's nozzle and the valve opening time (fuel injection time) of the fuel injector. If the flow rate of fuel at the injector nozzle is kept constant, that is, if the differential pressure between the fuel pressure in the fuel injector and the intake pipe pressure is kept constant, the amount of fuel injected will be the same as that of the fuel injector. It is accurately defined in proportion to the valve opening time.

In conventional general fuel injection control devices, the fuel pressure inside the fuel injector is controlled so that the flow velocity of fuel at the fuel injector nozzle is kept constant regardless of changes in atmospheric pressure and intake pipe pressure. The intake pipe pressure is introduced into a back pressure chamber of a pressure regulator that determines the fuel pressure in the fuel injector so that the differential pressure between the fuel injector and the intake pipe pressure is kept constant. This will be clearly understood from the explanation using the following mathematical formula.

The fuel flow velocity at the fuel injector nozzle is -Cg
γ P - PIN)...(1) However, C: Area coefficient Q: Gravitational acceleration γ: Specific weight of fuel Pf: Fuel pressure in the fuel injector Pm: Intake pipe pressure (absolute pressure) When the intake pipe pressure is introduced into the back pressure chamber, the fuel pressure Pf in the fuel injector is pf −Pi +P, where the intake pipe pressure is pm and the set pressure of the pressure regulator is Ppr.
I)r, and the fuel flow velocity at the nozzle of the fuel injector is expressed by the following equation.

v=Cg γ pr (2) As a result, the fuel flow rate is kept constant without being affected by atmospheric pressure and intake pipe pressure.

Problems to be Solved by the Invention As mentioned above, when the intake pipe pressure is introduced into the back pressure chamber of the pressure regulator, the fuel flow velocity at the fuel injector nozzle is kept constant. In order to communicate and connect the intake passage and the back pressure chamber to guide the intake pipe pressure to the back pressure chamber of the regulator, a conduit and a pipe connecting member are required, and the intake pipe negative pressure outlet port is connected to a surge tank or other It is necessary to machine a screw for attaching the pipe connecting member to the intake passage component, which also restricts the placement position of the pressure regulator, reducing the degree of freedom in designing the fuel injection control device. .

The present invention provides fuel injector valve opening time control regardless of changes in atmospheric pressure and intake pipe pressure even when intake pipe pressure is not introduced into the back pressure chamber of the pressure regulator, that is, even when an atmosphere-open pressure regulator is used. An object of the present invention is to provide an improved fuel injection control method for an internal combustion engine that can always inject a predetermined amount of fuel into an intake passage.

Means for Solving the Problems According to the present invention, the above-mentioned object is to inject fuel whose pressure is regulated by a pressure regulator open to the atmosphere into an intake passage by a fuel injector, and to inject fuel into an intake passage by a fuel injector according to the fuel injection time of the fuel injector. In a fuel injection control method for an internal combustion engine that controls the fuel injection amount, the fuel injection time is corrected to decrease when the atmospheric pressure is higher than the standard atmospheric pressure, and to increase when the atmospheric pressure is lower than the standard atmospheric pressure. This is also achieved by a fuel injection control method characterized in that the correction amount is decreased as the intake pipe pressure decreases.

Functions and Effects of the Invention When a pressure regulator that is open to the atmosphere is used, the fuel pressure Pf in the fuel injector in equation (1) is calculated as follows: Pf = (Atmospheric pressure Pat) + (Preset pressure Ppr of the pressure regulator) ), and the fuel flow rate V at the fuel injector nozzle is expressed by the following equation (3), which is influenced by atmospheric pressure Pat and intake pipe pressure Pm and changes according to these changes. is inevitable.

V=CQ 7 1)r+ (Pat7PIll
)...(3) On the other hand, in the fuel injection control method according to the present invention, as described above, the variation in the fuel flow velocity V at the fuel injector nozzle based on the change in atmospheric pressure and intake pipe pressure is The fluctuation in the fuel injection amount due to the above is compensated for by increasing or decreasing the fuel injection time, that is, by correcting the valve opening time of the fuel injector.

This correction may be performed by multiplying the basic fuel injection time determined according to the amount of intake air per stroke by a predetermined correction coefficient.

The basic fuel injection time may be determined in advance by experiment or calculation as a value under standard atmospheric pressure, taking into account changes in the fuel flow velocity at the fuel injector nozzle due to changes in intake pipe pressure. The fuel injection time correction may be performed when the atmospheric pressure is higher or lower than the standard atmospheric pressure, and the correction coefficient Ffp for this correction is expressed by the following equation (4).

However, pas is standard atmospheric pressure.

Correction coefficient Frp is fuel flow velocity at the fuel injector nozzle at standard atmospheric pressure VS)/(fuel flow velocity Vr at the fuel injector nozzle at current atmospheric pressure), where Vr is (3) It is the same as V in the formula, and Vs is the following formula (
5).

Vs -CQ 7 PI)r+ Pa5-PI
R))...(5) Equation (5) and equation (3) lead to the correction coefficient Ffp shown in equation (4), which is expressed as a function of atmospheric pressure pat and intake pipe pressure pm. Desired.

If the basic fuel injection time under standard atmospheric pressure is TAIJs, the actual fuel injection time TAIJr is TAUr - Ffp - TAUs - (6). Therefore, the data of the basic fuel injection time TAtJS is combined with the engine speed. It has a two-dimensional data map based on intake pipe pressure or engine speed and intake air flow rate, and further has correction coefficient Ffp data as a two-dimensional data map based on atmospheric pressure and intake pipe pressure, and injects fuel according to equation (6). Once the time is determined, fuel can be injected and supplied with a desired fuel injection amount without being affected by fluctuations in fuel pressure due to simplification of fuel pressure control.

The basic fuel injection time TAUs is determined by performing a bench test on an internal combustion engine in which the pressure regulator is opened to the atmosphere to adjust the fuel pressure under standard atmospheric pressure, for example - atmospheric pressure, under various operating conditions.

When implementing the fuel injection control method of the present invention using a computer with advanced calculation functions, for example, by using an atmospheric pressure sensor and an intake pipe pressure sensor, the atmospheric pressure detected at any time by an atmospheric pressure sensor and an intake pipe pressure sensor, and It is also possible to correct the fuel injection time by determining a correction coefficient Ffp based on the intake pipe pressure.

It is also possible to easily correct the fuel injection time using an approximate formula.

That is, according to equation (5), the correction coefficient Ffp is, where tel (Pas - Pat) / (Ppr+ (Pa
Since t-Pm ) ) l <1, when this approximate correction coefficient is used, it is possible to easily eliminate these factors even if a computer with low arithmetic function is used.

Of course, this approximation correction coefficient may be stored in advance as a two-dimensional map of atmospheric pressure and intake pipe pressure.

To implement the fuel injection control method according to the present invention, it is necessary to detect atmospheric pressure and intake pipe pressure, and an atmospheric pressure sensor may be used to detect atmospheric pressure, but D-Jetronic's fuel injection control device Since it has an intake pipe pressure sensor, it is also possible to select a condition in which the intake pipe pressure is almost the same as the atmospheric pressure, and use the intake pipe pressure PIIl at that time as the current atmospheric pressure Pat.

The conditions for the intake pipe pressure to be almost the same as atmospheric pressure are during the period from when the engine key is turned on until cranking starts, or when the engine is operated with the throttle valve almost fully open or completely open. It is a time when The atmospheric pressure pat detected by the intake pipe pressure under the above-mentioned conditions may be maintained until the above-mentioned conditions are satisfied and the atmospheric pressure is newly detected.

When the fuel pressure is regulated by a pressure regulator that introduces intake pipe pressure into the back pressure air, the intake pipe pressure decreases.During idle operation, the fuel pressure decreases, which causes fuel vapor to build up in the fuel passage during idle operation. However, if a pressure regulator that is open to the atmosphere is used, as in the control method of the present invention, the fuel pressure will not drop during idling operation. The fuel pressure is always maintained at a relatively high pressure, suppressing the generation of fuel vapor in the fuel passage, and avoiding rough idle and vapor lock.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

FIG. 1 shows an example of a fuel injection control device for an internal combustion engine used to implement the fuel injection control method according to the present invention.

The fuel injection control device for an internal combustion engine shown in FIG. Fuel is injected and supplied toward the intake boat 4 of the internal combustion engine 1.

The intake manifold 2 is connected to a surge tank 5, and the surge tank 5 is connected to an air cleaner 7 via a throttle body 6.

Fuel pumped up from a fuel tank 9 by a fuel pump 8 is supplied to the fuel injector 3 via a delivery pipe 10. A pressure regulator 11 is attached to the delivery pipe 10, and the pressure regulator is connected to the fuel pump 8 from the fuel tank 9.
The pressure of the fuel pumped up and directed to the fuel injector 3 is adjusted.

The pressure regulator 11 is of the atmosphere open type, as shown in FIG.
It has a pressure regulating chamber 13 on one side of the diaphragm 12 and a back pressure chamber 14 opened to the atmosphere by an atmosphere release boat 15 on the other side of the diaphragm 12. The pressure of the fuel from the pump 8 is applied to the compression coil spring 1.
The valve closes when the pressure is lower than the set pressure determined by the spring force 7, and opens when the fuel pressure in the pressure regulating chamber 13 is higher than the set value. pressure regulator 11
When the valve is open, part of the fuel that has flowed into the pressure regulating chamber 13 from the boat 16 is returned to the fuel tank 9 from the return boat 18 via the return fuel conduit 19, thereby increasing the pressure of the fuel supplied to the fuel injector 3. is set to a pressure approximately equal to the set pressure of the pressure regulator 11.

However, since this pressure regulator 11 is of the atmospheric open type with the back pressure chamber 14 open to the atmosphere, the pressure regulating action of the fuel is influenced by atmospheric pressure, and as the atmospheric pressure decreases, the actual valve opening pressure decrease. Therefore, the pressure of the fuel supplied to the fuel injector 3 and the fuel pressure inside the fuel injector 3 decrease as the atmospheric pressure decreases.

A cold start injector 20 is installed in the surge tank 5.
is attached to the injector, and fuel whose pressure is regulated by a pressure regulator 11 is supplied to the injector.

Fuel injector 3 and cold start injector 2
0 and the fuel pump 8 are operated by an electric control device 21 including a microcomputer.

The electric control device 21 receives information regarding the rotational speed of the internal combustion engine 1 from the engine ignition system distributor 22, information regarding the intake pipe pressure from the intake pipe pressure sensor 23, and information regarding the engine cooling water moisture from the water temperature sensor 24. The starter switch 25 provides information regarding opening and closing of the starter switch, and according to this information, the fuel pump 8, fuel injector 3, and cold start injector 2
It is designed to control the operation of 0.

The electric control device 21 stores in a storage means such as a ROM, the fuel injector 3 based on changes in intake pipe pressure due to changes in engine load as the basic fuel injection time under standard atmospheric pressure.
It has data on the fuel injection time TAUS determined in anticipation of changes in the fuel flow rate at the nozzle as a two-dimensional data map based on the engine speed and intake pipe pressure, and the engine speed detected by the signal from the distributor 22. The two-dimensional data map of the basic fuel injection time is searched based on the engine speed and the intake pipe pressure detected by the signal from the intake pipe pressure sensor 23, and from this, the basic fuel according to the engine speed and intake air amount at this time is searched. The fuel injection time TAUr to be actually performed is determined by determining the injection time TAUS and multiplying this basic fuel injection time TAUS by a correction coefficient Ffp. In addition, the correction term when calculating the fuel injection time ALIr that should actually be performed includes not only the correction term of Ftp, which is a multiplication correction coefficient, but also the addition/subtraction or multiplication correction term determined according to the water temperature or other conditions. It's okay to stay.

The correction coefficient Ffp is stored in advance in a storage means such as a ROM of the electric control I device 21 as a two-dimensional data map as shown in FIG. 3 based on the atmospheric pressure and the intake pipe pressure. It is determined by reading from the two-dimensional data map according to the pipe pressure Ptn. Atmospheric pressure can be detected by a signal from the intake pipe pressure sensor 23 under the above-mentioned conditions where the intake pipe pressure is approximately atmospheric pressure, or by a newly installed atmospheric pressure sensor 26. good.

As clearly shown in Fig. 3, the correction coefficient Ffp is 1 when the standard atmospheric pressure pas is applied, regardless of the value of the intake pipe pressure Pra, and when the atmospheric pressure pat is the standard atmospheric pressure pa.
When the atmospheric pressure pat is larger than s, the value becomes 1 or less, and when the atmospheric pressure pat is lower than the standard atmospheric pressure Pas, the value becomes 1 or more.
When it is not as, the deviation value from 1, that is, the correction amount is decreased as the intake pipe pressure P- decreases. This correction coefficient Ffp
The two-dimensional data map may be created according to the above-mentioned equation (4).

Since the correction coefficient Ffp is determined as described above, when the atmospheric pressure pat is higher than the standard atmospheric pressure pas, the fuel injection time is corrected to decrease, so that the atmospheric pressure Pat becomes the standard atmospheric pressure p.
When it is lower than as, the fuel injection time is corrected to increase, and in either case, the correction amount decreases as the intake pipe pressure decreases. By correcting the fuel injection time in this way, the pressure regulator 11 that is open to the atmosphere is used, and even if the fuel flow rate at the nozzle of the fuel injector 3 changes due to a change in atmospheric pressure, the required amount of fuel can be maintained. The air is injected and supplied from the injector 3 to the intake boat 4.

Note that the correction coefficient Ffp may be calculated at any time based on the atmospheric pressure and the intake pipe pressure using a calculation function included in the microcomputer of the electric control device 21. In this case, the correction coefficient F' may be calculated according to equation (4) or equation (7), which is an approximate calculation equation.

Further, the fuel injection control method according to the present invention is also applied to the L-Jetronic method, and in this case, it is sufficient to newly provide an intake pipe pressure sensor.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto.
It will be apparent to those skilled in the art that various embodiments are possible within the scope of the invention.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing one embodiment of a fuel injection control device for an internal combustion engine used to carry out the fuel injection control method according to the present invention, and Fig. 2 is an embodiment of an atmosphere-opening pressure regulator. FIG. 3 is a three-dimensional graph showing an example of a two-dimensional data map of correction coefficients used in the fuel injection control method according to the present invention. 1... Internal combustion engine, 2... Intake manifold, 3...
・Fuel injector, 4... Intake port, 5... Surge tank, 6... Throttle body, 7... Air cleaner. 8...Fuel pump, 9...Fuel tank, 10...
Delivery vibe, 11...pressure regulator,
12...Diaphragm, 13...Pressure control chamber, 14...
・Back pressure air. 15...Atmosphere open boat, 16...Boat, 17.
...Compression coil spring, 18...Return boat, 19
...Return fuel conduit, 20...Cold start injector, 21...Electric control device, 22...
Distributor, 23...Intake pipe pressure sensor, 2
4...Water temperature sensor, 25...Starter switch, 2
6... Atmospheric pressure sensor patent applicant: Toyota Motor Corporation representative
Patent Attorney Masatake Akashi Figure 1 Figure 2 Figure 3 (Voluntary) Procedural Amendment March 13, 1985 Commissioner of the Patent Office Manabu Shiga! R letter 1, case description 1985 patent application No. 020729 2
, Name of the invention, Fuel injection control method for internal combustion engines 3, Relationship with the case of the person making the amendment Patent applicant address: 1, Toyota-cho, Toyotafu, Aichi Prefecture Name (3)
20) Toyota Motor Corporation 4, Agent Address: 6-19-19 Shinkawa 1-chome, Chuo-ku, Tokyo 104 Number of inventions increased by amendment +1 (1) The scope of claims is amended as follows. (1) A fuel injection control method for an internal combustion engine in which fuel whose pressure is regulated by a pressure regulator open to the atmosphere is injected into the intake passage by a fuel injector, and the amount of fuel injection is controlled by the fuel injection time by the fuel injector. ,
1. A fuel injection control method for an internal combustion engine, comprising decreasing the fuel injection time when the atmospheric pressure is higher than the standard atmospheric pressure, and increasing the fuel injection time when the atmospheric pressure is lower than the standard atmospheric pressure. (2) In a fuel injection control method for an internal combustion engine, in which fuel whose pressure is regulated by an atmospheric pressure regulator is injected into an intake passage by a fuel injector, and the amount of fuel injection is controlled by the fuel injection time by the fuel injector, Decrease the fuel injection time when the atmospheric pressure is higher than the standard atmospheric pressure, increase it when the atmospheric pressure is lower than the standard atmospheric pressure, and in both cases reduce the amount of correction as the intake pipe pressure decreases. A fuel injection control method for an internal combustion engine, characterized by: j (2) “Increase correction,” on page 5, lines 16-17 of the specification
Correct ``to force'' to ``to correct the bottle.'' (3) On page 5, lines 18 and 19 of the same specification, it says, ``If more accurate correction is required, the fuel injection time should be corrected by decreasing it when the pressure is higher than atmospheric pressure. When the pressure is lower than the standard atmospheric pressure, the correction amount should be increased, and in both cases, the amount of correction should be reduced as the intake pipe pressure decreases.''

Claims (1)

[Claims] In a fuel injection control method for an internal combustion engine, in which fuel whose pressure is regulated by a pressure regulator that is open to the atmosphere is injected into an intake passage by a fuel injector, and the fuel injection amount is controlled by the fuel injection time of the fuel injector, the fuel When the atmospheric pressure is higher than the standard atmospheric pressure, the injection time is corrected to decrease, and when the atmospheric pressure is lower than the standard atmospheric pressure, the injection time is corrected to increase, and in both cases, the amount of correction is decreased as the intake pipe pressure decreases. A fuel injection control method for an internal combustion engine featuring features.