JPS62101857A - Electronically-controlled fuel injection device - Google Patents

Abstract

PURPOSE:To improve the acceleration responsibility of fuel injection by constituting a fuel injection device in such a manner that the acceleration correction to quantitative increase by way of asynchronous injection at the time of acceleration is made for, not all the cylinders, but only a specific cylinder for which the acceleration correction to quantitative increase by way of synchronous fuel injection is not made sufficiently. CONSTITUTION:When an engine 1 is in operation, in an ECU 27, first of all, the pulse width of the basic fuel injection is computed according to the intake air quantity per one cycle of engine, and said pulse width is corrected according to various correction factors which are obtained on the basis of signals from various sensors. Secondly, it is judged whether the engine 1 is in the accelerated state or not, and, when judged as being in the accelerated state, a cylinder, for which the acceleration correction to quantitative increase by way of asynchronous injection at the time of the initial acceleration is to be made, is selected; and, at the same time, an asynchronous injection quantity is also calculated. And further, the selection of such cylinders for the asynchronous injection is made in such a manner that the asynchronous injection is to be applied to any cylinders other than the cylinders for which, after the acceleration judgement, the acceleration correction to quantitative increase is made sufficiently, and the synchronous injection is to be made.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides synchronized injection means for injecting a predetermined amount of fuel in synchronization with the intake timing of each cylinder; The present invention relates to an electronically controlled fuel injection device for an engine, which is equipped with an asynchronous fuel injection means for injecting a predetermined amount of fuel regardless of timing to increase fuel at an early stage of acceleration.

(Prior art) Generally, in an engine equipped with an electronically controlled fuel injection device, an intake air amount is detected, and a basic fuel injection amount is set based on the detected intake air amount. The final fuel injection amount is determined by making various corrections depending on the operating condition, and fuel injection is performed in accordance with the intake timing. In this case, when determining the basic fuel injection amount, the value of the intake air amount to be used should be determined to avoid the influence of intake air fluctuations caused by intake pulsations that inevitably occur in the intake system, and to obtain an accurate intake air amount. Therefore, the calculation is performed by considering a plurality of intake air amount values detected at regular time intervals.

This method responds accurately to the actual intake air amount under operating conditions where the change in intake air amount is relatively small, but has the disadvantage that when a sudden change in intake air amount occurs, the response is delayed and proper fuel injection cannot be performed. There is. This phenomenon appears as deterioration of acceleration response during acceleration. In addition, when accelerating from lean control, there is a risk that the air-fuel mixture will be temporarily diluted and a lean spike may occur. For this reason, traditionally,
In addition to a synchronous fuel injection means that injects fuel in synchronization with the intake timing of a cylinder for the purpose of improving responsiveness during acceleration, a fuel that is equipped with an asynchronous fuel injection means that injects fuel regardless of the intake timing when acceleration is detected. Injection devices are known. For example, in Japanese Patent Application Laid-Open No. 60-3452, the synchronous fuel injection means can take two states depending on the operating condition: normal fuel supply and fuel cut-off fuel supply, The structure is such that the amount of acceleration increase due to asynchronous injection can be changed depending on whether the asynchronous fuel injection means used at the time is acceleration from normal operation or acceleration from fuel cut. Therefore, with this engine, good responsiveness can be obtained even when accelerating from a fuel cut state.

(Problems to be Solved by the Invention) In an electronic fuel injection type engine, when there is acceleration, an acceleration increase correction of fuel is performed in accordance with a change in intake air amount based on the acceleration. This acceleration increase correction is performed on fuel in synchronous fuel injection. However, the intake air amount used to determine the fuel injection amount is averaged (so-called smoothing) based on multiple detected values taken at regular time intervals, so it is not calculated after acceleration. Even if the injection amount is calculated based on the intake air amount calculated including the intake air amount detection value before acceleration, complete acceleration increase correction in synchronous injection will not be performed. Become. Therefore, only for those cylinders that enter the intake stroke before the acceleration increase correction in synchronous injection is sufficiently performed as described above, asynchronous injection during acceleration is performed to compensate for the lack of increase in the synchronous injection acceleration increase correction. By doing so, good responsiveness during acceleration can be ensured. and,
In a multi-cylinder engine, synchronous injection is performed in some cylinders after the acceleration state starts and before the above-mentioned complete acceleration increase in synchronous fuel injection is performed, but after the complete acceleration increase correction is performed. There are cylinders in which synchronous injection is performed. However, the device disclosed in JP-A No. 60-3452 does not specify the cylinder in which the acceleration amount is increased by asynchronous injection when acceleration is detected, and therefore, during acceleration, all cylinders are On the other hand, asynchronous injection will be performed as an acceleration increase. Therefore, with the above device, the problem of responsiveness during acceleration can be solved, but asynchronous injection will be performed even in the cylinders in which complete synchronous fuel injection increase correction has been performed after acceleration.
There is a problem that fuel efficiency deteriorates.

(Means for solving the above problems) The present invention has been constructed in view of the above circumstances, and provides an electronically controlled fuel injection device that has good acceleration response and can suppress deterioration of fuel efficiency as much as possible. The purpose is to provide.

The device of the present invention is an electronically controlled fuel injection device for a multi-cylinder engine equipped with a synchronous fuel injection means for injecting fuel in accordance with the intake timing of each cylinder, and an acceleration determination means for determining the start of an acceleration state of the engine. , an asynchronous injection means for asynchronously injecting a predetermined fuel regardless of the intake timing of the cylinder when an acceleration state occurs due to the output from the acceleration determination means; and a synchronous fuel injection in which an acceleration increase correction is completely performed after the acceleration determination. The invention is characterized in that it further comprises a selection means for selecting cylinders so that the asynchronous injection is performed in cylinders other than the cylinder in which the asynchronous injection is performed.

Therefore, according to the present invention, when acceleration is detected, a predetermined amount of asynchronous injection is performed only in those cylinders for which acceleration increase correction in synchronous injection is not sufficiently performed.

(Effects of the Invention) According to the present invention, acceleration increase correction by asynchronous fuel injection during acceleration is performed not for all cylinders but only for specific cylinders in which acceleration increase correction by synchronous fuel injection is not sufficiently performed. I have to. Therefore, fuel consumption can be kept to the necessary minimum while ensuring good responsiveness during acceleration. Furthermore, the device of the present invention can be used in combination with a so-called lean control mechanism that performs feedback control of the air-fuel ratio to leaner than the stoichiometric air-fuel ratio in a predetermined operating region. Since the amount of fuel can be increased quickly, fluctuations in the air-fuel ratio can be suppressed as much as possible, and lean sensor failure can be effectively prevented.

(Description of Examples) Examples of the present invention will be described below with reference to the drawings. Referring to FIG. 1, the engine 1 of this example includes a cylinder block 2, and the cylinder block 2 is formed with a cylinder bore 4 in which a piston 3 reciprocates. A cylinder head 5 is connected to the cylinder block 2 from above, and a space is defined by a lower recess formed in the cylinder head 5 and an upper part of the cylinder bore 4 of the cylinder block 2. forms a combustion chamber 6. An intake port 7 and an exhaust port 8 are open to the combustion chamber 6, and the port 7.8 has an intake port 7 and an exhaust port 8.
An intake valve 9 and an exhaust valve 10 are respectively combined. The engine 1 includes an intake passage 11 and an exhaust passage 12 that communicate with the intake port 7 and the exhaust port 8, respectively. An air cleaner 13 is provided at the upstream end of the intake passage 11, and an intake temperature sensor 14 for detecting intake air temperature is attached to the air cleaner 13. An air flow meter 15 is provided downstream of the air cleaner 13 to detect the amount of intake air. Furthermore, a throttle valve 16 for adjusting the amount of intake air is arranged downstream of the air flow meter 15, and a surge tank 17 is arranged downstream of the throttle valve 16. Further, a throttle opening sensor 18 is attached to the throttle valve 16 to detect the opening of the throttle valve 16. Furthermore, an injector 19 is arranged near the intake port 8 of the intake passage 11 to form an intake system, which injects fuel into the intake air flowing through the passage. A catalytic converter 20 is provided within the exhaust passage 12 for purifying exhaust gas.

Further, a lean sensor 21 is installed in the intake passage on the upstream side of the catalytic converter 20, which is sensitive to the oxygen concentration in the exhaust gas and generates an output substantially proportional to the oxygen concentration. Furthermore, a cooling water passage 22 for cooling the engine is formed inside and around the engine 1, and
A water temperature sensor 23 is attached to the cooling water passage 22 to detect the temperature of the cooling water. The engine 1 of this example also includes a distributor 25 that outputs an ignition signal to the igniter 24 at a predetermined timing according to a change in the engine speed, and a battery 2 that serves as a power source for various electrical devices.
It is equipped with 6. Furthermore, the engine 1 of this example preferably includes an electronic control unit (27) incorporating a microcomputer. The control unit 27 receives a signal representing the intake air temperature from the intake temperature sensor 14, a signal representing the intake air amount from the air flow meter 15, a signal from the throttle opening sensor 18, and an oxygen concentration in the exhaust gas from the exhaust sensor 21. A signal representing the engine cooling water temperature, a signal representing the engine cooling water temperature from the water temperature sensor 23, and a signal corresponding to the engine rotation speed from the distributor 25 are inputted. Furthermore, the control unit 27 also receives outputs from an atmospheric pressure sensor 28 that detects intake pressure, an idle switch 29 that detects whether the engine is in an idle state, and outputs from a cylinder discrimination sensor 30.
Based on these signals, the fuel injection amount is determined according to the operating state, and a corresponding appropriate fuel injection pulse signal is output.

FIGS. 2 and 3 show flowcharts of control in this example.

Referring to FIG. 2, the control unit 27 first initializes the system and reads signals from various sensors. Next, the signal from the air flow meter 15 is subjected to temperature correction based on the signal from the intake air temperature sensor 14, and the intake air amount Tp per cycle of the engine is calculated. In this case, in order to eliminate adverse effects such as intake pulsation, the intake air m T p is given as an average value of four detection values detected at each constant crank rotation angle.

Then, based on the signal from the distributor 26, the engine rotation speed Ne is calculated. Next, the basic fuel injection pulse width TBASε is calculated based on the intake air collapse Tp. Furthermore, the control unit 27 of the engine of this example calculates various correction coefficients for correcting the basic fuel injection pulse width TBASE based on signals from various sensors. This correction coefficient includes an enrich correction coefficient CE that increases the amount of fuel during high-load operation, and an acceleration and deceleration correction coefficient CACC% C that corrects the fuel injection amount during acceleration and deceleration.
Injector 1 depending on oi+c and buffer voltage
The invalid injection time correction coefficient T9 for correcting the pulse width based on the invalid injection time of 9 is included. When the operating state satisfies the feedback control conditions, feedback correction is performed to correct the injection pulse width according to the deviation between the target air-fuel ratio and the actual air-fuel ratio based on the output from the lean sensor 21. Calculate the coefficient Cp a. Furthermore, the control unit 27 calculates an air-fuel ratio correction coefficient CAF according to the operating state.

Next, the control unit 27 performs an acceleration determination to determine whether an acceleration state of the engine has occurred. If it is determined that the vehicle is not in an acceleration state, the control unit 27 calculates the final fuel injection pulse width T1. This final fuel injection pulse width T1 corresponds to the fuel amount of synchronous fuel injection performed in accordance with the intake timing. If it is determined that the engine is in an accelerating state, a cylinder for acceleration increase correction by asynchronous injection in the early stage of acceleration is selected, and an asynchronous injection amount is calculated. In this case, the acceleration determination asynchronous injection cylinder selection and the asynchronous injection amount are performed according to the procedure shown in the flowchart of FIG. Referring to FIG. 3, the control unit 27 includes an idle switch 3
It is determined whether or not 0 is ON, and if it is not ON, that is, in a non-idle state, it is further determined whether the idle switch was ON when the program was executed last time. If the idle switch was ON last time, it means that the idle state has just been switched to the non-idle state. In this case, in this example, it is determined that a certain acceleration state has occurred, and a cylinder is selected to perform acceleration increase correction by asynchronous injection. In this case, referring to FIG. 4, the control unit 27 has two
The type of cylinder discrimination signal G,,G2 is 360 degrees of crank rotation.
It is becoming more and more human-powered. Further, the engine in this example has four cylinders, and the signal G1 corresponds to the first cylinder and the third cylinder, and the signal G2 corresponds to the second cylinder and the fourth cylinder. The ignition order of the engine in this example is 1-3-
The score is now 4-2. Therefore, each cylinder performs an intake stroke with a certain crank rotation angle deviation with respect to the cylinder discrimination signal c, G2, so the cylinder can be identified by associating the discrimination signal with the crank angle signal. I can do it. Also, in this case, the asynchronous fuel injection amount TAUI
is set in advance, and when there is an acceleration determination, fuel TAU is asynchronously injected to the selected cylinder. Furthermore, in this example, even in a non-idling state, if a certain condition is satisfied, such as when the change in throttle opening exceeds a predetermined value, it is determined that an acceleration state has occurred,
Specify the cylinder and perform asynchronous injection. In this case, the control unit 27 is equipped with a table of asynchronous fuel injection amounts T A U 2 set for each magnitude of throttle opening change, and the asynchronous fuel injection amount T corresponding to the throttle opening change caused by acceleration. The value of A U2 is read from the table, and this amount TALh is asynchronously injected.

When the acceleration determination is made, the control unit 27 processes the asynchronous injection according to the above procedure, and then calculates the final fuel injection pulse width T1 during the synchronous injection, as shown in FIG. 3.

In FIG. 4, when the acceleration determination is made at time Ti, the control unit 27 immediately instructs the asynchronous injection of the fuel T A 02 calculated in the above procedure. At the same time, a synchronous injection pulse Ti is calculated. In this example, the crank rotation angle is 36o.

The synchronous injection pulse Ti is calculated at a rate of approximately 4 times per cycle, but the intake air amount Tp, which is the reference for calculating the injection pulse Ti, is calculated at least 3 times at a crank rotation angle immediately after acceleration.
If the angle is within 60 degrees, the calculation will include the detected value before the acceleration determination, and will be a smaller value than the actual intake air amount. Therefore, after acceleration is determined, synchronously injected fuel T! Acceleration correction will not be performed sufficiently. Therefore, in this example, asynchronous injection is performed for the third and fourth cylinders where such a situation occurs, and asynchronous injection is also performed for the first cylinder that performed synchronous injection immediately before the acceleration determination. ing. In addition, after the acceleration judgment, the crank rotation angle is 3.
For the second cylinder that performs synchronous injection after 60 degrees,
The injection pulse width Ti is calculated based on the intake air amount Tp calculated from the intake air amount detection value after all acceleration judgments,
Therefore, since complete acceleration increase correction is performed in synchronous injection, asynchronous injection is not performed in the second cylinder. In this example, the reason why asynchronous injection is performed even in the first cylinder where synchronous injection was performed immediately before the acceleration determination is that acceleration increase correction, including correction by synchronous injection, is performed for a very limited period of time. Especially when the acceleration state ends in a short time,
Depending on the timing of acceleration, after the acceleration increase correction is completed,
This is because there is a possibility that synchronous injection will be performed, and in this case, acceleration correction will be insufficient for that cylinder.

According to the above control, the acceleration increase correction by asynchronous injection is performed only for specific cylinders where the overall acceleration increase correction including synchronous injection is insufficient, so that the acceleration increase correction is performed only for the intended purpose of the acceleration increase. Good acceleration response can be ensured, and fuel consumption can be suppressed as much as possible. Note that the present invention can be applied to other multi-cylinder engines as well. For example, in a 6 cylinder engine,
The intake air amount detection value, which is the basis for calculating the intake air amount Tp, is all updated every 240 degrees of crank rotation angle, so after acceleration judgment, for cylinders where synchronous injection is performed after approximately 240 degrees of crank rotation angle, In this case, asynchronous injection will not be performed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an engine according to an embodiment of the present invention;
2 and 3 are flowcharts of control according to an embodiment of the present invention, and FIG. 4 is a graph showing changes in injection pulse width in control of the embodiment of the present invention. 1... Engine, 2... Cylinder lock, 3... Piston, 4... Cylinder bore, 5... Cylinder head, 6・・・・・・
...Combustion chamber, 7°...Intake port, 8...
...Exhaust port, 9...Intake valve, 10...
・・Exhaust valve, 11・・Intake passage, 12・・River・
Exhaust passage, 13...Air cleaner, 14. Old.
・Intake temperature sensor, 15... Air flow meter, 1
6. Old... Throttle valve, 18... Throttle opening sensor, 19... Injector, 21. Old... Lean sensor, 22... Cooling water passage, 23
...Water temperature sensor, 24...Igniter, 25...Distributor, 26...
-Battery, 27...Electronic control unit. 1j: Air cleaner

Claims (1)

[Claims] Acceleration determining means for determining the start of an acceleration state of the engine in an electronically controlled fuel injection device for a multi-cylinder engine equipped with a synchronous fuel injection means for injecting fuel in accordance with the intake timing of each cylinder; Asynchronous injection means for asynchronously injecting a predetermined fuel regardless of the intake timing of the cylinder when an acceleration state occurs, and cylinders other than cylinders in which synchronous fuel injection is performed with complete acceleration increase correction after the acceleration determination. an electronically controlled fuel injection device, further comprising a selection means for selecting a cylinder so that the asynchronous injection is performed.