JPH0893527A - Electronic fuel injection system - Google Patents

Abstract

PURPOSE: To improve fuel injection delay in starting of acceleration in an electronic fuel injection system for taking a gasoline engine as an object, and in which injectors are provided corresponding to respective cylinders. CONSTITUTION: In the intake air amount to a cylinder, the actual intake air amount is detected by an air flow sensor 3, and control estimated and calculated by a control unit 15 on the basis of the opening of a throttle valve is added, and the estimated air amount based on the opening of the throttle valve is used in order to correct the detection delay of the actual intake air amount, and of a throttle sensor 17 in acceleration-operating of an engine 7. The correction of the injection amount is taken as asynchronous injection in the low rotational range of the engine 7, and the injection correction amount is added to synchronous injection in the high rotational range, and fuel is injected.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improving fuel injection control in an engine using an electronically controlled fuel injection system.

[0002]

2. Description of the Related Art In an engine that uses gasoline as the main fuel, in order to maintain a good combustion state, the ratio of the amount of air to the supplied fuel, the so-called air-fuel ratio, is required to be around 14.7 in normal operating conditions and high output is required. In such a state, it is necessary to control so as to keep the weight ratio around 12.0 as the so-called power air-fuel ratio.

Therefore, it is required to measure the intake air amount correctly and inject the required amount of fuel correctly. As means for measuring the intake air amount, there are known means for directly measuring with an air flow meter or the like and means for indirectly measuring with intake pressure or the like. That is, in the former example, there are so-called vane type, hot wire type air flow meter and Karman vortex type type.

In the latter example, a method is known in which the intake air amount is calculated from the relationship between the opening amount of the intake pressure sensor or the throttle valve and the engine speed. From the measured intake air amount and the engine speed, the corrected fuel injection amount is calculated so that the predetermined air-fuel ratio is obtained, and the predetermined timing is set in the injector installed for each cylinder of the engine. That is, the injection is sequentially performed according to the intake stroke of the engine.

The present invention is intended for the above multipoint injection system (hereinafter referred to as MPI system),
Furthermore, the target is a so-called sequential injection system that sequentially injects each injector.

Here, the above-mentioned "corrected fuel injection amount" means, for example, an increase correction for insufficient vaporization state of gasoline at low water temperature, characteristic error of each component such as injector and air flow rate measurement, and It shows so-called learning corrections for changes over time.

When the engine is rotating or operating in a steady state, the above steady correction is sufficient and it is easy to control to a predetermined air-fuel ratio. That is, in the steady operation state, the fuel and gasoline injected from the injector are (1) the amount adhering to the wall inside the intake air pipe of the engine, and (2) the amount constantly evaporating and vaporizing from that.
(3) Since the three components that flow in the intake air and are directly sucked into the cylinder are balanced, steady correction is sufficient.

However, in a so-called unsteady state such as an acceleration state or a deceleration state of the engine, the target air-fuel ratio control value deviates from various values due to various factors, resulting in a so-called overrich state or lean state and proper air-fuel ratio control is not performed. Problems such as poor emission and engine misfire will occur.

This is because (1) the detection delay of the intake air amount measuring system and (2) the amount of the injected gasoline adhering to the wall inside the intake pipe fluctuates depending on the engine rotation and operating conditions.

[0010]

For the correction of the adhesion of the injected gasoline to the wall inside the intake pipe, there is, for example, "Actual No. 63-26739, Japanese Patent Laid-Open No. 63-26739, Air-Fuel Ratio Control Device for Internal Combustion Engine". . As for the detection delay of the intake air amount measuring system, there is, for example, "JP-A-63-57836".

In the latter example, for the detection delay, both the air amount indirectly calculated from the opening amount of the throttle valve and the air amount directly calculated from the detected value of the air flow meter are compared and the larger one is compared. The fuel injection amount is calculated based on the air amount, and the detection delay of the intake air amount measurement system during acceleration is attempted to be dealt with.

However, changes in the amount of gasoline adhering to the wall of the intake air pipe due to changes in the engine state are not taken into consideration, and therefore, there is an excess or deficiency in the amount of gasoline intake to the cylinder caused by this change in the amount of adhesion. The correction was not always sufficient for the problem phenomenon.

In the former example, the injected fuel of one or a plurality of injectors installed upstream of the throttle valve, which is a collection portion of the intake passage far from the engine cylinder, is distributed to a plurality of cylinders having a number larger than the number of injectors.
In an intake system, adhesion correction is taken into consideration for the detected intake air amount.

Also for the detection delay, the intake air amount is calculated for each predetermined cycle based on the opening amount of the throttle valve, and the fuel injection amount is calculated based on this calculation. The difference is injected every predetermined cycle in asynchronous injection in addition to the normal synchronous injection to correct the acceleration.

However, in this method, since the fuel injection is performed at the gathering place on the upstream side of the intake air pipe, the fuel injection amount cannot be precisely corrected for each of the plurality of cylinders downstream.

FIG. 4 will be described as another conventional example. In the figure, the throttle valve opening α is time st0
When it starts opening at, the actual intake air amount of the intake air Q, which is sucked into the cylinder, changes as shown by the solid line, but the value detected by the air flow meter rises with a delay as shown by the dotted line, and 6 (explained in FIG. 2) shows that overshoot occurs due to the filling amount.

The basic fuel injection amount TP is the intake air amount detection value Q.
The engine speed is calculated from the Q / N relationship, and rises from time st1 with a delay from the opening start time st0 of the throttle valve. For the overflow of the air flow meter detection value Q, a limiter is provided for the maximum detected air amount, or a limiter is provided for the maximum basic fuel injection amount calculated value.

Then, for the initial stage of acceleration, the corrected fuel injection amount TS1 set on the basis of the opening angle of the throttle valve per unit time and the engine speed is added to the synchronous injection of each cylinder as the adhesion correction amount. A method of injecting a predetermined number of times is performed. In the latter half of acceleration, the correction fuel injection amount is calculated in each predetermined cycle according to the intake air amount, its change amount, the engine speed, the engine cooling water temperature, etc., and the calculated values are sequentially added, and each time the engine synchronous injection is performed. There is a method in which another subtraction injection amount is calculated by each of the above inputs (intake air amount, its change amount, engine speed, water temperature, etc.) and is corrected by the corrected fuel injection amount TS2 that is the sum of the addition value and the subtraction value. Has been done.

However, even with this method, the corrected fuel injection amount TS1 at the initial stage of acceleration cannot follow the changing intake air amount, and therefore the correction is insufficient.

[0020]

In the present invention, in order to solve these problems, an injector for injecting fuel is installed in each cylinder of the engine, and it is preset based on each state input of the engine. In a fuel injection system equipped with a control unit that calculates and controls the fuel injection amount for each cylinder based on a constant and a calculation procedure, (1) The opening amount of the throttle valve provided in the intake pipe portion is detected, and from this opening amount Means for estimating and calculating the intake air amount, and (2)
Storage means for storing the intake air amount calculation value for each predetermined cycle;
(3) The latest intake air amount calculation value is compared with the stored estimated intake air amount before the fixed period of the predetermined period,
A means for calculating the fuel injection amount according to the difference value when the compared value is positive (latest intake air amount calculated value> intake air amount calculated value before a fixed period), and (4) this calculation A means for judging whether the injected fuel injection amount is to be injected synchronously or asynchronously based on the engine speed and the synchronous injection state; and (5) the calculated fuel injection amount is predetermined. And a means for determining whether or not the minimum limit value is exceeded,
(6) A means for storing and adding when the minimum limit value is exceeded is provided. In a region where the engine speed is higher than a predetermined number of revolutions determined by the determination means, the fuel injection amount calculated in (3) above is added to the normal synchronous injection amount to increase the fuel injection amount. In the predetermined low rotation region, the fuel injection amount calculated in (3) above is added to the synchronous injection amount for the cylinder during the synchronous injection, and
When the injection amount calculated in each predetermined cycle is equal to or exceeds the limit value determined in (5) above, the fuel injection amount calculated in (3) above is set during the intake stroke of the cylinder. Performs injection every predetermined calculation cycle, and when the injection amount determined in the above (5) falls below, the fuel injection amount calculated in the above (3) is added to the stored value and stored again. At the same time, the fuel injection amount calculated in the next predetermined calculation cycle is added, and the determination by the determination means in (5) is performed again, and when the limit value is exceeded, the fuel injection is performed during the intake stroke of the cylinder. To do. Further, when there is no corresponding cylinder in the synchronous injection, the injection amount calculated in each predetermined cycle is injected in each predetermined cycle by the method described above during the intake stroke of the cylinder that was synchronously injected immediately before. Electronically controlled fuel injection system is proposed.

[0021]

[Function] The intake air amount is detected at every predetermined cycle based on the opening amount of the throttle valve provided in the intake pipe portion, so that the intake air amount can be detected without the detection delay of the original air flow meter measurement system. When the difference between the calculated latest intake air amount calculated value and the estimated intake air amount calculated before the fixed period before the predetermined period is positive, that is, when the calculated air amount increases Injects a fuel injection amount corresponding to the value of this difference into a cylinder in the intake stroke of the engine.

This fuel injection is a normal injection (synchronous injection) which is in the intake stroke in a high rotation speed region higher than a predetermined rotation speed.
The fuel injection amount is increased by adding it to the synchronous injection amount of the cylinder to be performed. In the low rotation speed region, the fuel injection amount calculated above is injected (asynchronous injection) at every predetermined cycle of the injection amount calculation.

As a result, the correction injection amount is calculated at the same time as the acceleration is started, so that the intermittent injection is performed a plurality of times during the intake stroke period of the cylinder at a predetermined cycle at the time of low rotation, and the injection is performed early. The vaporization of fuel is promoted and contributes to the improvement of the combustion state. On the other hand, at the time of high rotation, since the correction injection amount is added to the normal synchronous injection and injection is performed, correction leakage can be prevented from occurring in the injection amount of each cylinder, and a stable acceleration state can be obtained.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2 and FIG. 3, air enters from the inlet 2 of the air cleaner 1 and is guided to the air flow sensor 3. This air enters a collector 6 through a connected duct 4, a throttle body 5 having a throttle valve controlling the air flow rate. Here, the air is distributed to each intake pipe 8 that is directly connected to the engine 7, and is sucked into the cylinder. On the other hand, fuel is sucked and pressurized by the fuel pump 10 from the fuel tank 9, the fuel damper 11, the fuel filter 12, and the injector 1.
3. The fuel pressure regulator 14 is supplied to the fuel system in which it is piped.

The fuel is regulated to a constant pressure by the regulator 14, and the injector 1 provided in the intake pipe 8 is controlled.
3 is injected into the intake pipe 8.

A signal for detecting the intake air amount is output from the air flow sensor 3, and this output is input to the control unit 15. A throttle sensor 17 for detecting the opening of the throttle valve is attached to the throttle body 5, and a signal from this sensor is also input to the control unit 15.

A water temperature sensor (not shown) for detecting the cooling water temperature is attached to the main body of the engine 7, and a signal from this sensor is also input to the control unit 15. The distort 16 has a built-in crank angle sensor, which outputs a signal corresponding to the rotation angle of the crankshaft and a signal indicating the specific crank angle position of each cylinder, and detects a reference signal for the injection timing and the ignition timing and the rotational speed. It becomes the reference signal. Then, these signals are input to the control unit 15.

The control unit 15 is an MP
U, ROM, A / D converter, an arithmetic unit including an input circuit, and performs a predetermined arithmetic processing by the output signal of the airflow sensor, the output signal of the crank angle sensor built in the distributor 16, and the like. The injector 13 is operated by a certain output signal, and a required amount of fuel is injected into each intake pipe 8.

Next, the control flow will be described with reference to FIG.

Depending on the operating condition of the engine, each sensor outputs signals such as throttle valve opening, rotational speed, intake air amount and engine cooling water temperature. Based on the map data set in the control unit based on the throttle valve opening and the engine speed, the intake air amount is searched every predetermined period (usually set to a value of 10 ms), and the intake air amount is calculated. Search value before a certain period in the air volume storage means,
For example, the value up to 50 ms before is stored every 10 ms cycle.

The latest retrieval value, the stored value 50 ms before, the signals of the engine speed and the engine cooling water temperature, and data are input to the corrected fuel injection amount calculation means. This corrected fuel injection amount calculation means controls the injection amount calculation at the start of acceleration, and calculates it at a predetermined cycle, that is, every 10 ms.

On the other hand, the detected value of the intake air amount from the air flow sensor 3, the detected value of the rotation speed and the engine cooling water temperature, and the signal value are input to the basic fuel injection amount calculation means. In this basic fuel injection amount calculation means, the fuel injection amount is calculated based on the actual detected air amount and the engine speed, and the steady fuel injection amount calculation for performing correction in the steady state, that is, water temperature correction and learning correction, is performed. The calculation cycle is set to every 10 ms like the above-mentioned corrected fuel injection amount calculation means.

The calculated values of the basic fuel injection amount calculation means and the corrected fuel injection amount calculation means are input to the cylinder-specific (cylinder-specific) fuel injection amount setting means. At this stage, the final fuel injection amount is set and output to the injector provided in each cylinder. Here, general characteristics of the injector will be described with reference to FIG. The horizontal axis of the figure represents the injection pulse width, which means the time during which the injector is energized, and is generally expressed in units of msec. The vertical axis in the figure shows the injection amount. The injection amount increases linearly with the increase of the injection pulse width, but conversely, when the injection pulse width becomes smaller, the characteristics enter the non-linear operation range due to friction inside the injector and other factors, and the injection quantity characteristic is disturbed. Therefore, in engine control, a minimum limit value is set so that the injection pulse width command value does not enter the non-linear region. In the present invention, this limit value is used as Tmin in the following description.

Next, the flow of control will be described with reference to the drawings. FIG. 6 is a diagram for explaining the flow of control corresponding to the corrected fuel injection amount calculation means shown in FIG. 1. In step 11, the engine rotation speed N, the throttle valve opening α from the throttle sensor 17, and the engine cooling from the water temperature sensor. The water temperature TW is input.

Next, at step 12, in the control unit 15, the throttle valve opening α and the engine speed N
An intake air amount estimation value Qα is searched from an α-N map with the and axes as grid axes. In step 13, the latest Qα search value and the search value Qαold before a certain period (for example, 5
The difference dQα from the search value before 0 ms) is calculated.

In step 14, the fuel injection amount calculation correction coefficient Kα is retrieved from a map having the engine speed N and the engine cooling water temperature TW as lattice axes. Step 15
Then, the corrected fuel injection pulse width TSA is calculated by the following equation 1.

[0037]

[Equation 1]

Where K: calculated air amount, injector 1
A constant determined by characteristics such as 3.

DQA: Difference value of Qα search value.

N: Engine speed.

Kα: Fuel injection amount calculation correction coefficient.

The flow from step 11 to step 15 is performed at a predetermined cycle, for example, every 10 ms, and the value before 50 ms before the fixed cycle in step 13 is used.

Next, FIG. 7 will be described. FIG. 7 is a diagram for explaining the control flow corresponding to the basic fuel injection amount calculation means shown in FIG. 1. In step 21, the engine rotation speed N, the detected intake air amount Q from the air flow sensor 3, and the engine cooling from the water temperature sensor. The water temperature TW is input. Next, at step 22, the engine rotation speed N and the engine cooling water temperature T
From the map where W is the axis of the grid, the maximum air amount setting value Qmax
To search.

In step 23, the detected intake air amount Q is compared with the above-mentioned maximum air amount set value Qmax, and if Q> Qmax
If so, the value of the detected intake air amount Q is set to Qmax in step 24.
Replace with. This operation is performed to cut the amount of overshoot of the intake air amount described with reference to FIG.

In step 25, the basic fuel injection pulse width TP is calculated by the equation 2.

[0046]

[Equation 2]

Here, K: calculated air amount, injector 1
A constant determined by characteristics such as 3.

Q: intake air amount or maximum air amount set value.

N: Engine rotation speed.

Next, at step 25, based on the basic fuel injection pulse width TP, the corrected fuel injection pulse width Ti which has been subjected to steady correction is calculated. Steady-state correction here means increase correction for insufficient vaporization of gasoline at low water temperature, so-called learning correction for characteristic error of each component such as injector and air flow rate measurement, and secular change, and high correction. When the output is required, the power air-fuel ratio is 1
The correction is included in the corrected fuel injection amount TS2 described with reference to FIG. 4, that is, the intake air amount detection value (the intake air amount changes depending on the opening amount of the throttle valve). Therefore, the correction that is performed in the latter half of acceleration is included for the intake air amount detection value that rises with a delay.

The calculation is performed by the equation 3.

[0052]

[Equation 3] Ti = K2 × TP × (1 + ALPHA + GAKSH) + K3 + K4 (Equation 3) where K2 is a constant for correcting the air-fuel ratio according to the water temperature and the load state of the engine.

K3: correction characteristic for compensating the operating characteristics of the injector 13, mainly the operation delay.

ALPHA: A control value as a result of performing feedback control by the signal of the air-fuel ratio sensor. When the air-fuel ratio is larger than the control target value (usually set to 14.7) with 0 as the center value (mixture mixture) Is a positive value, and in the opposite case, that is, when the air-fuel mixture is rich, takes a negative value.

GAKSH: A so-called learning correction value for characteristic error of each constituent device such as injector and air flow rate measurement and aging.

K4: A correction value performed in the latter half of acceleration with respect to the intake air amount detection value that rises with a delay after the intake air amount changes depending on the opening amount of the throttle valve.

The flow from step 21 to step 26 generally has the same cycle as the flow of control of the corrected fuel injection amount shown in FIG. 6, and is performed, for example, every 10 ms.

Next, FIG. 8 will be described. FIG. 8 is a diagram for explaining the control flow corresponding to the fuel injection amount setting means for each cylinder shown in FIG. 1. In step 31, the engine speed N and the judgment speed NLT are compared in magnitude.

When the engine speed N exceeds the judgment speed NLT in step 31, that is, when it is in the high speed region, and when it is judged in step 32 that it is in the low speed region and the synchronous injection is being performed, the step is performed. 33
Leading to. In step 33, the additional injection amount TE is calculated.
In step 34, the fuel injection amount TE is synchronously injected to the corresponding cylinder at each timing of synchronous injection of each cylinder.

When the rotation speed is equal to or lower than the determination rotation speed in step 31, that is, when it is in the low rotation speed region, step 32
Proceed to. In step 32, it is determined whether the injector 13 is performing synchronous injection. Here, the synchronous injection is steadily determined so that the injection is performed at a specific crank rotation angle for each cylinder, and the corrected fuel injection pulse width Ti obtained by the steady correction shown in FIG. This means that fuel injection is being performed.

The specific crank rotation angle for injection is set within the range from the latter half of the exhaust stroke to the intake stroke of each cylinder.

In step 35, the magnitude of the corrected fuel injection pulse width TSA and the limit value Tmin determined from the injector operating characteristics is judged.

In step 36, the fuel injection having the corrected fuel injection pulse width TSA calculated in FIG. 6 is performed on the cylinder to which the synchronous injection was performed immediately before, at each calculation cycle when the cylinder is in the intake stroke. To jet.

This injection ends when the intake stroke ends and when the next cylinder in the injection target cylinder reaches the synchronous injection stroke.

When the determination in step 35 is negative, that is, when the corrected fuel injection pulse width TSA falls below the minimum value Tmin, the fuel injection characteristic is in the non-linear operation range as described with reference to FIG. Since the fuel injection amount is not accurately performed, the fuel amount correction which is the object of the present invention is not performed.

Therefore, in this state, the fuel injection command to the injector 13 is not output and the routine proceeds to step 37. Here, the corrected fuel injection pulse width TSA is added to the stored TSAold (that was not injected in the determination up to the previous time) and stored as (new) TSA.

In step 38, it is judged again that the value is the minimum limit value, fuel injection is performed, or the process stands by until the next predetermined calculation cycle.

The flow from step 31 to step 38 generally has the same cycle as the flow of control of the corrected fuel injection amount shown in FIG. 6, and is performed, for example, every 10 ms, so it is shown in step 36 in the low rotation region. The fuel injection with the corrected fuel injection pulse width TSA is performed every calculation cycle (following the synchronous addition injection shown in step 32).

Although the control flow has been described with reference to FIGS. 6 to 8, the actual injection situation will be described with reference to FIG.

In FIG. 9, the intake air amount Qα is obtained by the opening change of the throttle valve opening α, and the intake air amount difference dQα is calculated from this. This intake air amount difference
The process of calculating the corrected fuel injection pulse width TSA based on dQα is as described above.

Next, in the low rotation speed region, for example, it is assumed that the fourth cylinder (cylinder) has finished the synchronous injection, and the first cylinder to be injected in the next order has not reached the synchronous injection timing. . In this state, the corrected fuel injection pulse width TSA is calculated every predetermined period (time t in the example of FIG. 9), and when the calculation is within the intake stroke range of the fourth cylinder, asynchronous correction injection (interruption injection) is performed. It In the example of the figure, the first cylinder to be injected next reaches the timing of synchronous injection after a total of three asynchronous injections, and therefore the synchronous addition injection amount TE is injected at this point.

Asynchronous injection is continuously performed in the first cylinder until the next second cylinder to be synchronously injected reaches a predetermined timing and when the first cylinder is within the intake stroke range.

In the explanation example of the second cylinder, the portion A circled in the figure shows that the asynchronous injection is once waited by the flow of steps 35 and 37 in FIG. ing. Stable fuel injection is performed when the corrected fuel injection amount TSA added by waiting once enters the linear operating range of the injector characteristics.

In the high engine speed region, the corrected fuel injection pulse width TS calculated at the timing a shown in the figure.
It is shown that A is synchronously added and injected into the first cylinder (cylinder). At the time when the second cylinder in the next injection sequence reaches the synchronous injection timing, the corrected fuel injection pulse width T
Since SA is calculated at the timing of b, the latest calculated value is synchronously added and injected. In the third cylinder, since the synchronous injection is performed before the timing c, the value calculated at the timing b is used as the latest calculated value of the corrected fuel injection pulse width. The correction value calculated at the timing c is the fourth cylinder and the first cylinder.
Synchronous additive injection is performed in the cylinder. Similarly, it is shown that the latest correction value calculated up to that timing is used for each timing of the synchronous injection of each cylinder.

Although related to FIG. 8 as well, the determination rotational speed NLT for distinguishing between the high rotation region and the low rotation region in the control is provided.
This section describes the concept of setting.

As described above, the corrected fuel injection pulse width TSA
The calculation of is performed at a predetermined cycle and is set to a value of 10 ms, for example, as described above. Where 10
ms is 4 cycles 4 engines, 30 minutes per minute
It corresponds to the explosion stroke interval (= suction stroke interval) of each cylinder at 00 revolutions. Therefore, when the cycle of the correction fuel injection pulse width calculation is 10 ms, even if the asynchronous injection is performed each time the correction amount calculation is performed, cylinders in which the asynchronous injection is not performed occur in the region where the rotational speed exceeds 3000 rpm. Since a problem that is not corrected occurs, the control is switched to add to the synchronous injection of each cylinder in the high rotation region to prevent this.

[0077]

According to the present invention, the intake air amount to the engine is estimated and calculated corresponding to the opening of the throttle valve, and the corrected fuel injection amount is immediately injected corresponding to the increase in the calculated air amount. It is possible to correct the fuel injection delay at the start of acceleration due to the delay in the actual intake air amount detected value by the air flow sensor, etc., and because the divided injection is performed at every predetermined cycle, the evaporation and vaporization of gasoline for the early injection can be prevented. Since it is sufficiently performed, the combustion state of the engine is improved, and it is possible to reduce the amount of carbon monoxide HC generated due to defective combustion that tends to occur during acceleration. This effect is remarkable especially in a low water temperature state.

Further, by improving the combustion state, the fuel consumption rate during acceleration is also improved. Further, in the high rotation speed region, the correction fuel injection is performed by adding to the synchronous injection instead of the asynchronous injection correction at the low rotation speed. Therefore, it is possible to prevent cylinders that are not corrected from being injected depending on the timing of calculation of the correction injection amount. As a result, it is possible to prevent fluctuations in rotation due to non-uniformity and variations in fuel injection amount between cylinders during acceleration. Further, according to the present invention, when the corrected injection amount calculation value enters the non-linear region of the injector characteristic, the asynchronous injection is not performed, and the portions are sequentially added,
When the total calculated value falls within the linear range of the injector characteristic, injection is controlled so that good fuel correction is possible.

In the present invention, an example in which the fuel injection is corrected according to the intake air amount difference dQα as long as the value exists in FIG. 9 is explained. It is possible to limit the number of times, and this also does not impair the effects obtained by the present invention. In setting the specific number of times, it is natural that it should be determined in consideration of the engine rotation speed at the start of acceleration (that is, the opening start of the throttle valve), the engine cooling water temperature, the opening speed of the throttle valve, and the fluctuation amount thereof. is there.

[Brief description of drawings]

FIG. 1 is a control flowchart showing an embodiment of the present invention.

FIG. 2 is a system configuration diagram showing an embodiment of the present invention.

FIG. 3 is a system configuration diagram showing a relationship between the device of FIG. 2 and a computer according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an example of conventional correction control.

FIG. 5 is an explanatory diagram showing characteristics of the injector.

FIG. 6 is a control flow chart (No. 1) showing an embodiment of the present invention, corresponding to the basic fuel injection amount calculation means of FIG. 1.

FIG. 7 is a control flowchart (No. 2) showing an embodiment of the present invention, corresponding to the cylinder-by-cylinder fuel injection amount calculation means of FIG. 1;

FIG. 8 is a control flow chart (No. 3) showing an embodiment of the present invention, corresponding to the cylinder-by-cylinder fuel injection amount calculation means of FIG. 1;

FIG. 9 is an explanatory diagram showing a situation of correction injection.

[Explanation of symbols]

3 ... Air flow sensor, 5 ... Throttle body, 13 ...
Injector, 15 ... Control unit, 17 ... Throttle sensor.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Midori Miyazaki 68 Nitto Software Engineering Co., Ltd., 1822 Hirasu-cho, Mito City, Ibaraki Prefecture (72) Seiji Asano Seiji Asano 2520 Takata, Katsuta-shi, Ibaraki Hitachi, Ltd. (72) Inventor Haruhiko Kobayashi 2520, Takaba, Katsuta-shi, Ibaraki Hitachi Ltd., Automotive Equipment Division, Hitachi Ltd.

Claims (1)

[Claims] 1. An injector for injecting fuel is installed in each cylinder of an engine, and a fuel injection amount is calculated for each cylinder based on a predetermined constant and a calculation procedure based on each state input of the engine. In a fuel injection system including a control unit for controlling, (1) a means for detecting an opening amount of a throttle valve provided in an intake pipe portion and estimating and calculating an intake air amount from the opening amount; and (2) every predetermined cycle. Storage means for storing the calculated intake air amount of (3)
The latest intake air amount calculated value is compared with the stored estimated intake air amount before the fixed period of the predetermined period, and the compared value is positive (latest intake air amount calculated value> constant period before Means for calculating the fuel injection amount according to the difference value when the intake air amount calculation value), and (4) determination of whether the calculated fuel injection amount is injected synchronously or asynchronously. Means for determining the engine speed and the synchronous injection state, (5) means for determining whether or not the calculated fuel injection amount exceeds a predetermined determination value, and (6) this determination value. And (7) means for storing and adding, and (7) the fuel injection amount calculated in (3) above in the normal rotation speed range higher than the rotation speed predetermined by this determination means. To increase the fuel injection amount by adding it to the synchronous injection amount, At the low rotation region defined fuel injection amount calculated in the above (3), with respect to the cylinder in the sequential injection to injection by adding the synchronous injection amount,
When the injection amount calculated in each predetermined cycle is equal to or exceeds the limit value determined in (5) above,
During the intake stroke of the cylinder, the fuel injection amount calculated in (3) is injected at a predetermined calculation cycle, and the fuel injection amount is calculated in (5) above.
When it falls below the injection amount determined in, the fuel injection amount calculated in (3) above is added to the stored value and stored again, and the fuel injection amount calculated in the next predetermined calculation cycle is added. Then, when the judgment is made again by the judgment means of the above (5) and the judgment value is exceeded, fuel injection is performed if the cylinder is in the intake stroke, and if there is no corresponding cylinder in the synchronous injection, synchronization is performed immediately before. An electronically controlled fuel injection system, characterized in that, during the intake stroke of an injected cylinder, the injection amount calculated in each predetermined cycle is injected in every predetermined cycle by the method described above.