JPH0650078B2 - Electronically controlled fuel injection device - Google Patents

Description

The present invention relates to a synchronous injection means for injecting a predetermined fuel in synchronism with the intake timing of each cylinder, and an intake air of the cylinder when an acceleration state of the engine is detected. The present invention relates to an electronically controlled fuel injection device for an engine, which is provided with an asynchronous fuel injection means for increasing the amount of fuel in the initial stage of acceleration regardless of timing.

(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. Various corrections are added according to the operating state to determine the final fuel injection amount, and fuel injection is performed at the intake timing. In this case, when determining the basic fuel injection amount, the value of the intake air amount to be used is to grasp the accurate intake air amount by avoiding the influence of the intake fluctuation caused by the intake pulsation and the like inevitably occurring in the intake system. Therefore, a plurality of intake air amount values detected at fixed time intervals are taken into consideration for the calculation. This method accurately responds to the actual intake air amount in the operating state where the intake air amount change is relatively small, but when the intake air amount change occurs rapidly, 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, during acceleration from the lean control, the air-fuel mixture may be diluted at one time and a lean spike may occur. For this reason, conventionally, in addition to the synchronous fuel injection means for injecting fuel in synchronization with the intake timing of the cylinder for the purpose of improving responsiveness during acceleration, an asynchronous fuel injection for injecting fuel regardless of intake timing when acceleration is detected. There is known a fuel injection device including a means. For example, JP-A-60-
In Japanese Patent No. 3452, there are two types of fuel supply, a normal fuel supply and a fuel cut fuel supply, depending on the operating state of the synchronous fuel injection means.
There are two states.The asynchronous fuel injection means used during acceleration can be configured to change the acceleration increase amount by asynchronous injection depending on whether the asynchronous fuel injection means is from normal operation or from fuel cut. There is. Therefore, in this engine, good responsiveness can be obtained even in acceleration from the fuel cut state.

(Problems to be Solved by the Invention) In an electronic fuel injection engine, when acceleration occurs, fuel acceleration increase correction is performed according to a change in intake air amount based on acceleration. This acceleration increase correction is performed on the fuel in the synchronous fuel injection. However, since the intake air amount for determining the fuel injection amount is averaged (so-called smoothing process) based on a plurality of detection values sampled at constant time intervals, it is calculated after acceleration. Even if the injection amount is, the injection amount calculated based on the intake amount calculated including the intake amount detection value before acceleration is
This means that complete acceleration increase correction in synchronous injection will not be performed. Therefore, the asynchronous injection at the time of acceleration is made so as to compensate for the insufficient amount of increase in the synchronous injection acceleration increase correction only for the cylinder that has reached the intake stroke in the state where the above-described acceleration increase correction in the synchronous injection is not sufficiently performed. If you do
It is possible to ensure good responsiveness during acceleration. Then, in the multi-cylinder engine, after the acceleration state starts,
Before the complete acceleration increase in the synchronous fuel injection is performed, there are some cylinders in which the synchronous injection is performed and the cylinders in which the synchronous injection is performed after the complete acceleration increase correction is performed. However, in the device disclosed in Japanese Patent Laid-Open No. 60-3452, the cylinder that performs acceleration increase by asynchronous injection when acceleration is detected is not specified,
Therefore, at the time of acceleration, asynchronous injection as an acceleration increase is performed for all cylinders. Therefore,
In the above device, the problem of responsiveness at the time of acceleration can be solved, but asynchronous injection will be performed even for the cylinder for which complete synchronous fuel injection increase correction has been performed after acceleration, and fuel efficiency will be improved. There is a problem of getting worse.

(Means for Solving the Above Problems) The present invention is configured in view of the above circumstances, and provides an electronically controlled fuel injection device that has excellent acceleration response and can suppress deterioration of fuel efficiency as much as possible. The purpose is to provide.

An apparatus according to the present invention comprises an intake air amount detecting means for detecting an intake air amount sucked into an engine, and an averaging means for time-averaging the intake air amount detection values detected a plurality of times by the intake air amount detecting means. And a fuel injection amount setting means for setting the fuel injection amount according to the output of the average processing means, and the fuel injection amount set by the fuel injection amount setting means for injecting fuel in accordance with the intake timing of each cylinder. In an electronically controlled fuel injection device for a multi-cylinder engine having a synchronous fuel injection means, an acceleration determination means for determining the start of an acceleration state of the engine,
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 an intake air amount detection value detected after the acceleration determination and after all the acceleration determination And selecting means for selecting the cylinders so that the asynchronous injection is performed with respect to the cylinders other than the cylinders in which the injection of the fuel injection amount corresponding to the average intake air amount is performed by the synchronous fuel injection means. It is further characterized by being equipped.

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

(Effect of the Invention) According to the present invention, the acceleration increase correction by the asynchronous injection at the time of acceleration is performed not for all the cylinders but only for a specific cylinder for which the acceleration increase correction by the synchronous fuel injection is not sufficiently performed. I have to. Therefore, fuel consumption can be minimized while ensuring good responsiveness during acceleration. Further, the device of the present invention can be used in combination with a so-called lean control mechanism that feedback-controls the air-fuel ratio to the lean side of the stoichiometric air-fuel ratio in a predetermined operation region, and accelerates at the time of acceleration from the lean control state. Since it is possible to rapidly increase the fuel amount, it is possible to suppress fluctuations in the air-fuel ratio as much as possible, and it is possible to effectively prevent the occurrence of lean spikes and the like.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, an engine 1 of the present example includes a cylinder block 2, and a cylinder bore 4 in which a piston 3 reciprocates is formed in the cylinder block 2. A cylinder head 5 is coupled to the cylinder block 2 from above, and a space defined by a lower recess formed in the cylinder head 5 and an upper portion of a cylinder bore 4 of the cylinder block 2 is formed. ,
The fuel chamber 6 is formed. An intake port and an exhaust port 8 are opened in the fuel chamber 6, and an intake valve 9 and an exhaust valve 10 are combined with the ports 7 and 8, respectively. 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 air temperature sensor 14 that detects the intake air temperature is attached to the air cleaner 13. An air flow meter 1 for detecting the amount of intake air is provided downstream of the air cleaner 13.
5 are provided. Further, a throttle valve 16 for adjusting the intake air amount is arranged downstream of the air flow meter 15, and the surge tank 1 is provided downstream of the throttle valve 16.
7 is provided. Further, the throttle valve 16 has a throttle opening sensor 1 for detecting the opening of the throttle valve 16.
8 is attached. Further, an injector 19 for injecting fuel into the intake air flowing in the passage is arranged near the intake port 8 of the intake passage 11 to form an intake system. A catalytic converter 20 for purifying exhaust gas is provided in the exhaust passage 12. Further, a lean sensor 21 is installed in the exhaust passage on the upstream side of the catalytic converter 20 in response to the oxygen concentration in the exhaust gas to generate an output that is substantially proportional to the oxygen concentration. Further, a cooling water passage 22 for cooling the engine is formed inside and around the engine 1, and a water temperature sensor 23 for detecting the cooling water temperature is attached to the cooling water passage 22. Further, the engine 1 of the present example is provided with a distributor 25 that outputs an ignition signal to the igniter 24 and a battery 26 as a power source of various electric devices at a predetermined timing according to a change in the engine speed. ing. Further, the engine 1 of this example preferably includes an electronic control unit 27 configured by incorporating a microcomputer. The control unit 27 includes a signal indicating the intake air temperature from the intake air temperature sensor 14, an air flow meter 15
Signal indicating the intake air amount from the throttle opening sensor 1
8, a signal indicating the oxygen concentration in the exhaust gas from the exhaust sensor 21, a signal indicating the engine cooling water temperature from the water temperature sensor 23, and a distributor 25.
A signal corresponding to the engine speed from is input. Further, the control unit 27 includes an output from an atmospheric pressure sensor 28 that detects the intake pressure and an idle switch 2 that detects whether the engine is in an idle state.
The control unit 27 to which the outputs from the cylinder 9 and the cylinder discrimination sensor 30 are also input determines the fuel injection amount according to the operating state based on these signals, and outputs an appropriate fuel injection pulse signal corresponding to this.

2 and 3 show flowcharts of the control of 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 amount Tp is given as an average value of four detection values detected for each fixed crank rotation angle. Then, the engine speed Ne is calculated based on the signal from the distributor 26. Next, the basic fuel injection pulse width T _BASE is calculated based on the intake air amount Tp. Further, the control unit 27 of the engine of this example uses the basic fuel injection pulse width T based on the signals from various sensors.
Calculate various correction factors to correct _BASE . The correction coefficient includes an enrichment correction coefficient C _{E for} increasing the fuel amount during high load operation, acceleration and deceleration correction factors C _ACC , C _DEC for correcting the fuel injection amount during acceleration / deceleration, and the battery voltage of the injector 19 according to the battery voltage. An invalid injection time correction coefficient T _V for pulse width correction based on the invalid injection time is included. Then, when the operating condition satisfies the feedback control condition, the feedback correction for correcting the injection pulse width according to the deviation of the target air-fuel ratio from the actual air-fuel ratio based on the output from the lean sensor 21. Calculate the coefficient C _FB . Further, the control unit 27 calculates in accordance with the correction coefficient C _AF of the air-fuel ratio to the operating state.

Next, the control unit 27 makes an acceleration determination as to whether or not an engine acceleration state has occurred. When it is determined that the vehicle is not in the acceleration state, the control unit 27 calculates the final fuel injection pulse width Ti. This final fuel injection pulse width Ti corresponds to the fuel amount of the synchronous fuel injection performed at the intake timing. When it is determined that the vehicle is in the accelerated state, the cylinder for performing the acceleration increase correction by the asynchronous injection at the initial stage of acceleration is selected and the asynchronous injection amount is calculated. In this case, the selection of the acceleration determination asynchronous injection cylinder 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 determines whether or not the idle switch 30 is ON, and when it is not ON, that is, in the non-idle state, further determines whether or not the idle switch was ON at the time of the previous program execution. If the idle switch was turned 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 constant acceleration state has occurred, and the cylinder for which the acceleration increase correction by the asynchronous injection is performed is selected. In this case, referring to FIG. 4 together, two types of cylinder discrimination signals G ₁ and G ₂ are input to the control unit 27 at every crank rotation of 360 °. The engine of this example has four cylinders, the signal G ₁ corresponds to the first cylinder and the third cylinder, and the signal G ₂ corresponds to the second cylinder and the fourth cylinder. The ignition order of the engine of this example is 1-3-4-2. Therefore, each cylinder performs the intake stroke with a constant deviation of the crank rotation angle with respect to the cylinder discrimination signals G ₁ and G ₂ , so that the cylinder is specified by associating the discrimination signal with the crank angle signal. be able to. Further, the asynchronous fuel injection amount TAU _{1 in} this case is preset, and when the acceleration is determined, the fuel TAU ₁ is asynchronously injected into the selected cylinder. Further, in this example, even when the throttle opening change exceeds a predetermined value, even in the non-idle state, it is determined that the acceleration state has occurred, the cylinder is identified, and the cylinder Inject. In this case, the control unit 27
Has a table of the asynchronous injection amount TAU ₂ set for each magnitude of the throttle opening change, reads the value of the asynchronous fuel injection amount TAU ₂ corresponding to the throttle opening change caused by acceleration from the table, This amount TAU
₂ asynchronous fuel injection. Control unit 27
When the acceleration is determined, the process for the asynchronous injection is performed in the above procedure, and then the final injection pulse width Ti for the synchronous injection is calculated as shown in FIG.

In FIG. 4, when the acceleration judgment is made at time Ti,
The control unit 27 immediately commands the fuel TAU ₁ or TAU ₂ calculated by the above procedure to be asynchronously injected. At the same time, the synchronous injection pulse Ti is calculated.
In this example, the synchronous injection pulse Ti is calculated almost every four times at the crank rotation angle of 360 °, but the intake air amount Tp that is the reference for calculating the injection pulse Ti is
At least within the crank rotation angle of 360 °, it is calculated including the detection value before the acceleration determination, and becomes a value smaller than the actual intake air amount. Therefore, the acceleration correction of the synchronous injection fuel Ti is not sufficiently performed for the cylinder that has reached the intake stroke within the crank rotation angle of 360 ° after the acceleration determination. Therefore, in this example, the asynchronous injection is performed for the third cylinder and the fourth cylinder in which such a state occurs, and the asynchronous injection is also performed for the first cylinder that has performed the synchronous injection immediately before the acceleration determination. ing. In addition, for the second cylinder that performs synchronous injection after the crank rotation angle of 360 ° has elapsed after the acceleration determination, the injection pulse width is calculated based on the intake air amount Tp calculated from the intake air amount detection value after the acceleration determination for all the second cylinders.
Since Ti is required and therefore the complete acceleration increase correction is performed in the synchronous injection, the asynchronous injection is not performed in the second cylinder. In the present example, the asynchronous injection is performed even for the first cylinder that has performed the synchronous injection immediately before the acceleration determination, because the acceleration increase correction includes the correction by the synchronous injection and is extremely limited time. In particular, when the acceleration state ends in a short time, there is a possibility that synchronous injection may be performed after completion of the acceleration increase correction depending on the timing of acceleration. This is because the acceleration correction is insufficient for the cylinder.

According to the above control, since the acceleration increase correction by the asynchronous injection is performed only for the specific cylinder for which the overall acceleration increase correction including the synchronous injection is insufficient, it is the initial purpose of the acceleration increase. It is possible to ensure high acceleration response and to suppress fuel consumption as much as possible. The present invention can be similarly applied to other multi-cylinder engines. 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 at almost every crank rotation angle of 240 °. Asynchronous injection is not performed for the cylinder in which is performed.

[Brief description of drawings]

FIG. 1 is a schematic view of an engine according to one embodiment of the present invention,
2 and 3 are flowcharts of control according to one embodiment of the present invention, and FIG. 4 is a graph showing changes in the injection pulse width in the control of the embodiment of the present invention. 1 ... Engine, 2 ... Cylinder block, 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 ... Exhaust passage, 13 ... Air cleaner, 14 ... Intake temperature sensor, 15 ... Air flow meter, 16 ... Throttle valve, 18 ... Throttle opening sensor , 19 ... injector, 21 ... lean sensor, 22 ... cooling water passage, 23 ... water temperature sensor, 24 ... igniter, 25 ... distributor, 26 ... battery, 27 ... electronic control unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-60-56141 (JP, A) JP-A-59-51137 (JP, A) JP-A-59-203840 (JP, A) JP-A-58- 48730 (JP, A) JP 59-206630 (JP, A) JP 59-188045 (JP, A)

Claims (1)

[Claims] 1. An intake air amount detecting means for detecting an intake air amount sucked into an engine, and an averaging means for time-averaging a plurality of intake air amount detection values detected by the intake air amount detecting means. A fuel injection amount setting means for setting the fuel injection amount according to the output of the average processing means, and a synchronization for injecting fuel in accordance with the intake timing of each cylinder based on the fuel injection amount set by the fuel injection amount setting means. In an electronically controlled fuel injection device for a multi-cylinder engine having a fuel injection means, an acceleration determination means for determining the start of the acceleration state of the engine
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 an intake air amount detection value detected after the acceleration determination and after all the acceleration determination And selecting means for selecting the cylinders so that the asynchronous injection is performed with respect to the cylinders other than the cylinders in which the injection of the fuel injection amount corresponding to the average intake air amount is performed by the synchronous fuel injection means. An electronically controlled fuel injection device, further comprising: