JPH0643820B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

The present invention relates to an electronically controlled fuel injection device for an internal combustion engine.

<Prior Art> Conventional examples of electronically controlled fuel injection devices for internal combustion engines include the following.

That is, based on the intake air flow rate Q detected by the air flow meter and the engine rotation speed N detected from the ignition signal and the like, the basic fuel injection amount Tp (= K × Q / N; K is a constant), and after calculating various correction coefficients COEF according to engine operating conditions such as engine cooling water temperature, air-fuel ratio feedback correction coefficient α, and correction amount Ts by battery voltage, fuel injection amount Ti ( = Tp × COEF × α + Ts) is calculated.

Then, an injection pulse signal having a pulse width corresponding to the calculated fuel injection amount Ti is output to the fuel injection valve to inject and supply a predetermined amount of fuel to the engine (JP-A-59-59).
203828, etc.).

By the way, according to such an electronically controlled fuel injection device, when the engine is accelerated, as shown in FIG. On the other hand, since the error becomes large, the fuel injection amount is set based on this erroneous detection value of the intake air flow rate, and over lean and over rich air-fuel ratios occur alternately, resulting in acceleration shock, breathing, and exhaust. There was a fear of causing deterioration of the property.

In order to solve such a problem, the electronic control is such that the fuel injection amount is set based on the detected values of the throttle valve opening degree and the engine rotation speed for a predetermined time from the acceleration detection (α-N control in FIG. 5). There is a controlled fuel injection device (Japanese Patent Application No. 61-10).
2165 (see JP-A-62-258143) and the like).

That is, data of the intake air flow rate Q corresponding to each operating region is stored in advance for each of a plurality of operating regions using the throttle valve opening α and the engine rotation speed N as parameters, and the throttle valve opening α and the engine rotation speed are stored. The data of the intake air flow rate Q in the corresponding operating region is searched from the data based on the detected value of the speed N.

When the acceleration of the engine is detected by the idle switch, the rate of change of the throttle valve opening, the rate of change of the basic fuel injection amount Tp, etc., the throttle valve opening α and the engine speed N are kept for a predetermined time from the detection of the acceleration. The basic fuel injection amount Tp is set from the intake air flow rate Q and the detected value of the engine rotation speed N which are searched based on the detected value, and the intake air flow rate Q detected by the air flow meter is set in the operating region other than the predetermined time. The basic fuel injection amount Tp is set based on the detected value of the engine rotation speed N.

<Problems to be Solved by the Invention> However, the data of the intake air flow rate Q retrieved based on the detected values of the throttle valve opening α and the engine rotation speed N is the air that is taken in by bypassing the throttle valve. Is not included, and even if there is a change in the air density, this cannot be dealt with. Therefore, the air-fuel ratio can be stably set to the desired value during acceleration when the fuel injection amount is set based on the search value of the intake air flow rate Q. There was a problem that it was difficult to control the value.

In other words, when the amount of air is increased by bypassing the throttle valve when the engine is cold (supplied by an air regulator or an auxiliary air passage for idle speed control), the non-acceleration condition is not limited to when the engine is idle. It is general that the bypass air amount is added even during idling. However, since the increased air amount is unrelated to the throttle valve opening α, the intake air used when calculating the fuel injection amount during acceleration. The air flow rate Q becomes smaller than the actual value. For this reason, the air-fuel ratio may become over lean (indicated by the one-dot chain line in FIG. 5 of the basic fuel injection amount Tp), and the acceleration performance may be impaired.

Further, when the engine is operated in a highland, the air density becomes lower than that in a flatland. Therefore, even if the throttle valve opening α and the engine rotation speed N are the same, the amount of air actually taken in is lower than that in a flatland. Also less. However, since the intake air flow rate Q based on the detected values of the throttle valve opening α and the engine rotation speed N is the data stored in the flatland, the intake air flowrate used when calculating the fuel injection amount in the highland. Q becomes larger than the actual value. For this reason,
The air-fuel ratio becomes overrich (basic fuel injection amount T in Fig. 5
There is a risk that breathing, spark plug wetting, and afterburn may occur as indicated by the solid line (p).

Since an air flow meter such as a hot wire type flow meter can detect air supplied by bypassing the throttle valve and can respond to changes in air density, fuel injection based on the detected value of the air flow meter can be performed. The above problem does not occur in the control area.

Therefore, it is possible to update the stored value of the intake air flow rate to a value close to the actual value based on the detection result of the air flow meter, but a throttle valve opening sensor that detects the opening of the throttle valve is generally Since the detection error increases in a region where the valve opening is small, the error in the intake air flow rate data searched based on this unreliable throttle valve opening becomes large, and the search intake air flow rate with this detection error is large. If the stored value of the intake air flow rate is updated by comparing the detected intake air flow rate with the detected intake air flow rate, incorrect learning may occur.

That is, even if the stored value of the intake air flow rate is substantially accurate, if there is an error in the throttle valve opening, it will not be possible to search for the intake air flow rate in the operating region, so there will be an error in the detected value of the throttle valve opening. Sometimes, even if the detected value of the intake air flow rate is compared with the search value, the error in the stored value cannot be accurately grasped.

The present invention has been made in view of the above problems, and by accurately comparing the detected value of the intake air flow rate with the stored value of the intake air flow rate in the operating region, the stored value of the intake air flow rate is set to the actual value. The purpose is to update the air fuel ratio to a close value and prevent the air-fuel ratio from becoming leaner or richer during acceleration.

<Means for Solving Problems> Therefore, according to the present invention, as shown in FIG. 1, the engine acceleration state detecting means for detecting the acceleration state of the engine and the suction for directly detecting the intake air flow rate of the engine. Air flow rate detection means,
Throttle valve opening detection means for detecting the opening of a throttle valve installed in the intake passage of the engine, engine rotation speed detection means for detecting the engine rotation speed, and throttle valve opening and engine rotation speed as parameters. Intake air flow rate storage means for storing the intake air flow rate corresponding to each operation area, and the intake air flow rate memory based on the detected values of the throttle valve opening and the engine speed detected by the detection means. Intake air flow rate searching means for searching the intake air flow rate from the means, and acceleration for setting the fuel injection amount based on the detected values of the intake air flow rate and the engine rotation speed searched by the intake air flow rate searching means in the engine acceleration state. Detected by the detecting means in an operating region other than the fuel injection amount setting means for acceleration and the fuel injection amount setting operating region by the fuel injection amount setting means for acceleration. The main fuel injection amount setting means for setting the fuel injection amount based on the detected values of the intake air flow rate and the engine rotation speed, and the detected value of the intake air flow rate during the engine normal operation and the intake air flow rate search means for searching. And a flow rate correction value setting means for setting a correction value for uniformly correcting the intake air flow rate stored in the intake air flow rate storage means based on the deviation from the intake air flow rate. Intake air flow rate updating means for uniformly correcting and updating and storing the intake air flow rate stored in the intake air flow rate storage means based on the set correction value, and the detected value of the throttle valve opening is below a predetermined opening. Correction inhibiting means for inhibiting the setting of the correction value by the flow rate correction value setting means at a certain time,
Drive control means for driving and controlling the fuel injection valve in accordance with the fuel injection quantity set by the acceleration fuel injection quantity setting means or the main fuel injection quantity setting means.

<Operation> According to the electronically controlled fuel injection device having such a configuration, the correction value setting by the flow rate correction value setting means is prohibited in the low opening region where the detection accuracy of the throttle valve opening is poor, and therefore it is used for learning the correction value setting. The retrieved value of the intake air flow rate that corresponds to the relevant operating range is corrected, and the stored value of the intake air flow rate in the operating range different from the actual one is compared with the detected value, and the stored data of the intake air flow rate is erroneously corrected. Never.

Therefore, learning can be performed by the detected value of the intake air flow rate that can cope with the air supply that bypasses the throttle valve and the change of the air density during the steady operation of the engine, and the stored value of the intake air flow rate in the operating region. Since it is possible to update the stored value of the intake air flow rate to a value close to the actual intake air flow rate, by searching this stored value, the fuel injection amount is set and the air-fuel ratio is desired during engine acceleration. It becomes possible to stably control the value of.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 2 shows the configuration of an embodiment of the electronically controlled fuel injection device according to the present invention.

In this figure, an engine rotation speed N signal which is an output of a rotation speed sensor 1 as an engine rotation speed detecting means, an intake air flow rate Q signal which is an output of an air flow meter 2 as an intake air flow rate detecting means, and a throttle valve opening degree detection. The output of the throttle valve opening sensor 3 as means is the opening α signal of the throttle valve (not shown) interposed in the intake passage of the engine, and the output of the water temperature sensor 4 is the engine cooling water temperature Tw signal. The control unit 5 is provided with a microcomputer including an input / output device, a storage device, and a central processing unit, and the control unit 5 outputs an injection pulse signal set based on these means as will be described later. 7 to the drive circuit 6.

That is, in this embodiment, the control unit 5 is
The throttle valve opening sensor 3 constitutes the engine acceleration state detecting means, and the drive circuit 6 constitutes the drive control means, while the intake air flow rate storage means, the intake air flow rate search means, the flow rate correction value setting means, The intake air flow rate updating means, the correction prohibiting means, the acceleration fuel injection amount setting means, and the main fuel injection amount setting means are provided by software.

First, the fuel injection control routine will be described based on the flowchart of FIG.

In step (indicated as "S" in the drawing, the same applies hereinafter) 1, the engine speed N, the intake air flow rate Q, the throttle valve opening α, and the cooling water temperature Tw detected by each sensor are input.

In step 2, it is determined whether or not the engine is in an accelerating state based on the opening rate change rate Δα obtained from the throttle valve opening α input in step 1 and the throttle valve opening previously input. That is, when Δα indicates a rate of change to the open side that is equal to or greater than a predetermined value, it is determined that the engine is in an accelerating state, and the routine proceeds to step 3.

In step 3, a map of the intake air flow rate Qs (hereinafter referred to as α-, which is stored in advance in association with a plurality of operating regions having the throttle valve opening α and the engine rotation speed N as parameters).
From the N map), the intake air flow rate Q of the operating region
s is searched based on the throttle valve opening α and the engine speed N input in step 1.

Here, the intake air flow rate Qs stored in the α-N map
Is obtained in advance by experiments, etc., and is an actual value that does not include the intake manifold filling, etc. (actual value in steady state, and the initial value does not include the air content that bypasses the throttle valve even in flatland operation. It is something that does not exist.) Further, when the intake air flow rate Qs is obtained by searching as described above, the throttle valve opening α and the engine rotation speed N that trigger the change of the intake air flow rate.
Therefore, it can be said that there is almost no response delay in detection.

In step 4, the basic fuel injection amount Tp (= K × Qs / is determined by the intake air flow rate Qs retrieved in step 3).
N; K is a constant).

On the other hand, when it is determined in step 2 that the engine is not in the accelerated state, it is determined in step 5 whether the elapsed time from the initial acceleration detection is within the predetermined time T ₁ (for example, 0.5 to 1 second). Here, the predetermined time T _1, when the throttle valve is opened from the idle state (fully closed state the throttle valve), the air charge into the intake manifold are time and substantially matched to the end. Therefore, when the elapsed time is within the predetermined time T ₁ , the air flow meter 2
It is estimated that the intake air flow rate Q detected by the error has a large error. Therefore, when it is determined in step 5 that the elapsed time is within the predetermined time T ₁ , the process proceeds to steps 3 and 4, and similarly to when it is determined in step 2 that the engine is in the accelerated state, the retrieved intake The basic fuel injection amount Tp is calculated based on the air flow rate Qs.

Further, when it is determined in step 5 that the predetermined time T ₁ or more has elapsed, that is, when the engine is not in the acceleration state and the predetermined time T ₁ has elapsed from the acceleration, the process proceeds to step 6 and step 1 A basic fuel injection amount Tp (= K × Q / N; K is a constant) is calculated based on the input intake air flow rate Q which is the detected value of the air flow meter 2. In such an operating region, the intake air flow rate Q detected by the air flow meter 2 is substantially accurate because it is an operating region in which the intake manifold filling portion is not detected as shown in FIG. 6 (hatched portion).

When the calculation setting of the basic fuel injection amount Tp is made in step 4 or step 6, the basic fuel injection amount Tp is corrected and calculated in step 7 to obtain the final fuel injection amount Ti.
Ask for.

That is, the cooling water temperature Tw detected by the water temperature sensor 4
Various correction factors COEF etc. obtained by retrieving correction factors based on the respective operating conditions stored and set in the storage device from various operating conditions such as engine and engine acceleration conditions and calculating these correction factors by the central processing unit. The fuel injection amount Ti (= Tp × COEF ·
・) Is set.

When the fuel injection amount Ti is set in step 7, an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti is output to the drive circuit 6 of the fuel injection valve 7 to perform fuel injection in step 8.

As described above, during acceleration with a large detection error by the air flow meter 2 (when acceleration is detected or within a predetermined time T ₁ from the acceleration detection), the throttle valve opening α having a relatively small detection error and good responsiveness. The basic fuel injection amount Tp is set by the intake air flow rate Qs retrieved based on the engine rotation speed N.

Further, in the operating region where the detection error of the air flow meter 2 is small (except during acceleration), the basic fuel injection amount Tp is set based on the detection value of the air flow meter 2, so that even if there is a change in the air density, etc. The actual intake air flow rate is detected, and fuel injection is performed according to the required value of the engine.

Next, updating of the data of the intake air flow rate Qs stored in the control unit 5 will be described based on the flowchart of FIG. Incidentally, this routine is processed in parallel with the fuel injection control routine shown in FIG.

In step 10, the engine speed N, the intake air flow rate Q, and the throttle valve opening α detected by each sensor are input.

In step 11, it is determined whether or not the current engine operating state is steady operation by comparing the detection value input in step 10 with the previous value. If it is determined that the vehicle is in the steady operation state, the process proceeds to the next step 12, and if it is determined that the vehicle is not in the steady operation, the process is returned as it is. This is for updating the data (memorized value) of the intake air flow rate Qs stored in the α-N map only during steady operation in which the detection result of the air flow meter 2 is reliable, and the response delay of the detection. In the acceleration state in which the detected value includes the intake manifold filling amount, the updating process is not performed.

In step 12, the throttle valve opening α input in step 10 is compared with the predetermined opening α ₁ retrieved from the two-dimensional map of the throttle valve opening α ₁ which is determined by the engine speed at which the intake air flow rate reaches a peak. If the throttle valve opening α is less than or equal to the predetermined opening α ₁ , the stored value Qs of the intake air flow rate is
When the throttle valve opening α exceeds the predetermined opening α ₁ without performing the update, the process proceeds to the next step 13.

This is to prevent learning from being performed in the low opening region of the throttle valve where the detection error of the throttle valve opening sensor 3 is large, whereby the detection accuracy of the throttle valve opening sensor 3 is improved. The stored value Qs of the intake air flow rate in the operating region corresponding to the actual engine operating region in the good region is searched.

In step 13, the intake air flow rate Qs is searched from the α-N map based on the throttle valve opening α and the engine speed N input in step 10. At this time, step 12
Since the area in which the detection accuracy of the throttle valve opening sensor 3 is good is determined in, the throttle valve opening α used for this search is the actual opening.

In step 14, the learning correction coefficient A is calculated based on the intake air flow rate Qs as the search result and the intake air flow rate Q as the detection result input in step 10. In the present embodiment, the ratio (Q / Qs) of the intake air flow rate Q to the intake air flow rate Qs is obtained, and this ratio is set as the learning correction coefficient A.

When the correction coefficient A is calculated and set in step 14, step
In step 15, the intake air flow rate Qs stored in the α-N map is uniformly updated based on the correction coefficient A. Therefore, when the air density is thin during operation in high altitude, or when there is air supplied by bypassing the throttle valve in the cold state, the intake air flow rate Qs and the actual value stored in the α-N map are stored. When a deviation occurs between and, all of the stored values of the α-N map are updated based on the detection result of the air flow meter 2 that almost accurately detects the actual value at this time, and the intake air flow rate of the α-N map is updated. This is to make Qs close to the actual value.

Of course, the update of the intake air flow rate Qs is not limited to the above-described correction coefficient A, and for example, a value obtained by multiplying the difference between the detected value Q of the intake air flow rate and the search value Qs by a constant correction coefficient k is added. It may be updated by {Qs ← Qs + k (Q−Qs)}.

If there is no determination of the throttle valve opening α in step 12, the updating process as described above will be performed even in the region where the detection accuracy of the throttle valve opening sensor 3 is poor.
There is a possibility that the intake air flow rate Qs stored in association with an operation area other than the operation area may be retrieved and erroneously learned.
As described above, since the learning is performed only in the region where the detection accuracy of the throttle valve opening sensor 3 is good, the learning is satisfactorily performed by comparing the detected value of the intake air flow rate with the search value of the intake air flow rate in the operation region. Can be done.

In this way, if the stored value of the α-N map is made to gradually approach the actual value, the empty value will be obtained during engine acceleration when the fuel injection amount is set based on the intake air flow rate Qs retrieved from the α-N map. It is possible to improve the engine drivability in such an operating region without causing the fuel ratio to become rich or over lean.

<Effects of the Invention> As described above, according to the present invention, the stored value of the intake air flow rate retrieved based on the detected values of the throttle valve opening degree and the engine rotation speed is the detection result by the intake air flow rate detection means. And the intake air flow rate retrieved based on the throttle valve opening detected with high accuracy, the intake air flow rate stored in the operating region and the detected value are accurately compared and updated. Even if there is an air supply that bypasses the throttle valve in the acceleration state where the air density changes or the stored value of the intake air flow rate is used, the stored value of the intake air flow rate should be close to the actual value. You can

Therefore, in the engine acceleration state in which the fuel injection amount is set based on the search value of the intake air flow rate, the fuel injection amount is set according to the actual intake air flow rate and the air-fuel ratio can be controlled to a desired value. effective.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is a system diagram showing an embodiment of an electronically controlled fuel injection device according to the present invention, and FIG. 3 is a flowchart showing a fuel injection amount setting control routine in the same embodiment, FIG. 4 is a flowchart showing a map value updating routine in the above embodiment, and FIG. 5 is a time chart for explaining problems in conventional control. 1 ... Rotation speed sensor, 2 ... Air flow meter, 3 ... Throttle valve opening sensor, 4 ... Water temperature sensor, 5 ... Control unit, 6 ... Drive circuit, 7 ... Fuel injection valve

Claims (1)

[Claims] 1. An engine acceleration state detecting means for detecting an acceleration state of an engine, an intake air flow rate detecting means for directly detecting an intake air flow rate of the engine, and an opening of a throttle valve interposed in an intake passage of the engine. Throttle valve opening detection means for detecting the degree, engine rotation speed detection means for detecting the engine rotation speed,
Based on the detected values of the throttle valve opening and the engine rotation speed, the intake air flow rate storage means that stores the intake air flow rate corresponding to each operation area with the throttle valve opening and the engine rotation speed as parameters. Intake air flow rate search means for searching the intake air flow rate from the intake air flow rate storage means,
An acceleration fuel injection amount setting means for setting a fuel injection amount based on a detected value of the intake air flow rate and the engine rotation speed searched by the intake air flow rate searching means in an engine acceleration state, and the acceleration fuel injection amount setting The fuel injection amount setting means for setting the fuel injection amount based on the detected values of the intake air flow rate and the engine speed in an operating region other than the fuel injection amount setting operating region, and the detection of the intake air flow amount during the engine steady operation. A flow rate correction value for setting a correction value for uniformly correcting the intake air flow rate stored in the intake air flow rate storage means based on the deviation between the value and the intake air flow rate searched by the intake air flow rate search means. The intake air flow rate stored in the intake air flow rate storage means is uniformly corrected and updated and stored based on the correction value set by the setting means and the flow rate correction value setting means. Intake air flow rate updating means, correction prohibiting means for prohibiting the setting of the correction value by the flow rate correction value setting means when the detected value of the throttle valve opening is less than or equal to a predetermined opening, and the acceleration fuel injection amount setting Means or a drive control means for driving and controlling the fuel injection valve according to the fuel injection amount set by the main fuel injection amount setting means, and an electronically controlled fuel injection device for an internal combustion engine.