JPS6357835A - Electronic control fuel injection system for internal combustion engine - Google Patents

Abstract

PURPOSE:To aim at improvement in accelerability, by finding a deflection between a suction air flow to be retrieved out of a memory device on the basis of throttle valve opening and engine speed at the time of stationary driving and the detected value of the suction air flow, and renewing the stored value of the memory device according to the learning value of the deflection. CONSTITUTION:On the basis of each output of both throttle valve opening and engine speed detecting devices A and B, a suction air flow is retrieved out of a suction air flow memory device D by a retrieving device C. And, when engine accelerating time is detected by a detecting device E, an accelerating fuel injection quantity is set by a setting device F from the retrieved value of the suction air flow and the engine speed, and at the time of engine driving other than its accelerated state, a main fuel injection quantity is set by a setting device H from the engine speed and the detected value of a suction air flow detecting device G. In addition, at a renewing device I, a deflection between the detected value of the retrieved value of the suction air flow is learned at the time of engine stationary driving, and on the basis of this learning value, the suction air flow stored in the memory device D is made so as to be renewed.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine.

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

That is, from the intake air flow IQ detected by the air flow meter and the engine rotation speed N detected from the ignition signal, etc., the basic fuel injection amount Tp (=KXQ/N; constant), and
After calculating various correction coefficients C0EF according to engine operating conditions such as engine cooling water temperature, air-fuel ratio feedback correction coefficient α, and correction numerator s based on battery voltage, the fuel injection amount Ti is calculated.
(=TpXCOEFXα+Ts) is calculated.

Then, an injection pulse signal with a pulse width corresponding to the calculated fuel injection amount Ti was output to the fuel injection valve, thereby injecting and supplying a predetermined amount of fuel to the engine (Japanese Patent Application Laid-open No. 1983-1993-1).
(See Publication No. 203828, etc.).

By the way, according to such an electronically controlled fuel injection device, when the engine accelerates, the amount of air flowing into the cylinder is affected by a delay in the response of the intake air flow rate detected by the air flow meter, detection of intake manifold filling bones, etc., as shown in FIG. However, since the error becomes large, the fuel injection amount is set based on this incorrect detected value of intake air flow rate, and the air-fuel ratio becomes over-lean and over-rich alternately, resulting in acceleration shock, breathiness, and exhaust gas. There was habituation that caused deterioration of the product's properties.

In order to solve this problem, an electronic system is used that sets the fuel injection amount based on the detected values of the throttle valve opening and engine speed for a predetermined period of time after acceleration detection (α-NtlJ control in Figure 5). There is a controlled fuel injection device (patent application 1986-1)
02165 etc.).

That is, data on the intake air flow rate Q corresponding to each operating range is stored in advance for each of a plurality of operating ranges in which the throttle valve opening α and the engine speed N are parameters, and the data on the intake air flow rate Q corresponding to each operating range is stored in advance. Based on the detected value of the speed N, the intake air flow I in the corresponding operating region is determined from the above data.
The configuration is configured to search for data of Q.

Then, when engine acceleration is detected based on the idle switch ON-OFF, the rate of change of the basic fuel injection amount Tp, the rate of change of the throttle valve opening α, etc., the throttle valve opening α Intake air flow rate Q and engine rotation speed N searched based on the detected values of and engine rotation speed N
The basic fuel injection amount tTp is set based on the detected value of tTp, and in the operating range other than this predetermined time, the basic fuel injection amount 'rp is set based on the detected value of the intake air flow IQ detected by the air flow meter and the engine rotation speed N. I was trying to set it.

<Problems to be Solved by the Invention> However, the intake air flow IQ data retrieved based on the detected values of the throttle valve opening α and the engine rotational speed N is based on the data of the intake air flow IQ that is retrieved based on the detected values of the throttle valve opening α and the engine speed N. However, even if there is a change in air density, it cannot be accommodated, so the fuel injection amount is set based on the search value of the intake air flow rate Q. During acceleration, the air-fuel ratio is stabilized to the desired value. There was a problem that it was difficult to control the value.

In other words, when an increased amount of air is supplied by bypassing the throttle valve when the engine is cold (supplied by an air regulator or an auxiliary air passage for idle speed control), this increased amount of air increases the throttle valve opening α. Since this is unrelated to the actual value, the intake air flow rate Q used when calculating the fuel injection amount becomes smaller than the actual value. As a result, the air-fuel ratio becomes over-lean (as shown by the dashed line of the basic fuel injection ITp in FIG. 5), which tends to impair acceleration performance.

Also, when the engine is operated at high altitudes, the air density is thinner than when operating on flatlands, so the slow/torque valve opening α
Even if the engine speed N and engine speed N are the same, the intake air flow iQ actually taken in is smaller than that in the case of flat ground. However, since the intake air flow rate Q based on the detected values of the throttle valve opening degree α and the engine rotational speed N is stored data at level ground, the intake air flow rate Q used when calculating the fuel injection amount at high altitudes is Q becomes larger than the actual value. For this reason, there is a risk that the air-fuel ratio becomes overrich (as shown by the solid line of the basic fuel injection amount Tp in FIG. 5), resulting in wetting of the ignition plug, afterburn, etc.

Note that air flow meters such as hot wire flow meters can also detect air that is supplied by bypassing the throttle valve and can respond to changes in air density. In the fuel injection control region based on the above, the above problem does not occur.

The present invention has been made in view of the above problems, and by making the intake air flow rate, which is searched based on the detected values of the throttle valve opening degree and the engine rotation speed, gradually approach the actual value, The purpose is to prevent the air-fuel ratio from becoming over-lean or significantly over-rich.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. A means for detecting the opening degree of the installed throttle valve and the engine rotational speed, that is, an intake air flow rate detecting means.

Throttle valve opening detection means, engine rotational speed detection means, intake air flow rate storage means that stores intake air flow rates corresponding to each operating region for each operating region in which the throttle valve opening and engine rotational speed are parameters; an intake air flow rate search means for searching the intake air flow rate from the intake air flow rate storage means based on the detected values of the throttle valve opening degree and the engine rotational speed detected by the detection means; An acceleration fuel injection amount setting means for setting the fuel injection amount based on the detected values of the intake air flow rate and engine rotation speed searched by the search means, and a fuel injection amount setting operation range other than the fuel injection amount setting means by the acceleration fuel injection amount setting means. main fuel injection amount setting means for setting the fuel injection amount based on the detected values of the intake air flow rate and engine rotational speed detected by the detection means in the operating range of the engine; and detecting the intake air flow rate during steady engine operation. intake air flow rate updating means for learning the deviation between the intake air flow rate and the intake air flow rate retrieved by the intake air flow rate retrieval means and updating the intake air flow rate stored in the intake air flow rate storage means based on the learned value; A drive control means for driving and controlling the fuel injection valve according to the fuel injection amount set by the acceleration fuel injection amount setting means or the main fuel injection amount setting means.

<Operation> According to the electronically controlled fuel injection system having such a configuration, during steady engine operation, the intake air flow rate is searched based on the detected values of the throttle valve opening degree and the engine rotational speed, and the intake air flow rate detected by the intake air flow rate detection means is detected. The deviation between the calculated intake air flow rate and the intake air flow rate is determined, and the stored value of the intake air flow rate stored in the intake air flow rate storage means is updated based on the learned value of this deviation.

In other words, the intake air flow rate detection means has a large detection error when the engine is accelerating, but during steady operation it detects the intake air flow rate almost accurately. When there is a change in density, the intake air flow rate is detected in response to these changes, and the stored value of the intake air flow rate is rewritten based on this approximately accurate detected value. Therefore, during acceleration, the fuel injection amount is set based on the stored value of the intake air flow rate that has been updated to a substantially accurate value.

<Example> An embodiment of the present invention will be described below based on the drawings.

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

In this figure, the engine rotation speed N signal is the output of the rotation speed sensor 1 as the engine rotation speed detection means, the intake air flow rate Q signal is the output of the air flow meter 2 as the intake air flow rate detection means, and the throttle valve opening detection An opening α signal of a throttle valve (not shown) installed in the intake passage of the engine, which is the output of the throttle valve opening sensor 3 as a means, and an engine cooling water temperature Tw times signal, which is the output of the water temperature sensor 4; These signals are input to a control unit 5 containing a microcomputer constituted by an input/output device, a storage device, and a central processing unit, and the control unit 5 sends an injection pulse signal to the fuel injection valve, which is set as described below based on these signals. It outputs to the drive circuit 6 of 7.

That is, in this embodiment, the control unit 5:
The throttle valve opening sensor 3 constitutes an engine acceleration state detection means, and the drive circuit 6 constitutes a drive control means, while an intake air flow rate storage means, an intake air flow rate search means, an intake air flow rate update means, The fuel injection amount setting means for acceleration and the main fuel injection amount setting means are provided as software.

First, the fuel injection control routine will be explained based on the flowchart in FIG.

In step 1 (indicated as "S" in the figure, the same applies hereinafter), the engine rotation speed N detected by each sensor is
, intake air flow ff1Q, throttle valve opening α, and cooling water temperature Tw are input.

In step 2, it is determined whether the engine is in an accelerating state based on the opening change rate Δα obtained from the throttle valve opening α input in step 1 and the throttle valve opening α input last time. That is, when Δα shows a rate of change toward the open side of a predetermined rate or more, the engine is determined to be in an accelerating state, and the process proceeds to step 3.

In step 3, a map of the intake air flow iQs (hereinafter α-
N map), the intake air flow IQ in the relevant operating region
s is searched based on the throttle valve opening α and engine rotational speed N input in step 1.

Here, the intake air flow rate Qs stored in the α-N map has been determined in advance through experiments, etc., and is an actual value that does not include intake manifold filling bones, etc. (an actual value in a steady state, and the initial value is (It is similar to the one in which the engine is operated on flat ground but does not include an air bone that bypasses the throttle valve.) In addition, when obtaining the intake air flow 1lQs by searching as described above, the throttle valve opening α and the engine rotation speed N, which are the triggers for changing the intake air flow rate, are also used.
It can be said that there is almost no response delay in detection.

In step 4, the basic fuel injection amount Tp (=KXQs/
N; is a constant).

On the other hand, when it is determined in step 2 that the engine is not in an accelerating state, it is determined in step 5 whether or not the elapsed time from the first acceleration detection is within a predetermined time T (for example, 0.5 to 1 second). . Here, the predetermined time T1 is approximately equal to the time required for air filling into the intake manifold to be completed when the throttle valve is opened from an idle state (throttle valve fully closed state). Therefore, when the elapsed time is within the predetermined time T, it is estimated that the intake air flow rate Q detected by the air flow meter 2 has a large error. Therefore, when it is determined in step 5 that the elapsed time is within the predetermined time T, steps 3 and 4
Then, in the same way as when it is determined in step 2 that the engine is in an accelerating state, the basic fuel injection amount 'rp is calculated based on the retrieved intake air flow rate Qs.

Further, when it is determined in step 5 that the predetermined time 73 or more has elapsed, that is, when the engine is not in an acceleration state and the predetermined time 'r has elapsed since acceleration, the process proceeds to step 6 and the process proceeds to step 1. Entered air flow meter 2
The basic fuel injection amount Tp (=KxQ/N; K is a constant) is calculated based on the intake air flow rate Q, which is the detected value.

In this operating region, the intake air flow rate Q detected by the air flow meter 2 is approximately accurate, since the intake manifold filling bone is not detected as shown in FIG. 5 (shaded area).

When the basic fuel injection amount Tp is calculated and set in step 4 or step 6, the basic fuel injection amount 'rp is corrected and set in step 7 to obtain the final fuel injection amount T.
Find i.

That is, the cooling water temperature Tw detected by the water temperature sensor 4
Various correction coefficients C0EF, etc. are obtained by searching for correction coefficients based on each operating state stored and set in a storage device from various operating states such as engine speed and engine acceleration state, and calculating these correction coefficients with a central processing unit. The fuel injection amount Ti (=TpXC
OEF...).

When the fuel injection amount Ti is set in step 7, in step 8, 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 this way, during acceleration (in a state where acceleration is being detected or within a predetermined time T after acceleration detection) where the air flow meter 2 has a large detection error, the throttle valve opening α and the engine rotation speed, which have relatively small detection errors, The basic fuel injection amount 'rp is set by the intake air flow rate Qs retrieved based on N.

In addition, in the operating range where the detection error of the air flow meter 2 is small (other than during acceleration), the basic fuel injection amount 7'p is set based on the detected value of the air flow meter 2, so there may be changes in air density, etc. However, the actual intake air flow rate is detected, and fuel injection is performed in accordance with the engine's required value.

Next, updating of the intake air flow ff1Qs data stored in the control unit 5 will be explained based on the flowchart of FIG. Note that this routine is processed in parallel with the fuel injection control routine shown in FIG.

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

In step 11, it is determined whether the current engine operating state is steady operation by comparing the detected value input in step 10 with the previous value. Here, if it is determined that the operating state is steady, proceed to the next step 1.
Proceed to step 2, and if it is determined that the operation is not steady, return directly.

This is to update the memory value of the α-N map only during steady operation when the detection result by the air flow meter 2 is reliable, and there may be a delay in the detection response or the detected value may include intake manifold filling. No update processing is performed in the accelerated state.

In step 12, data on the intake air flow rate Qs stored in the storage device in the control unit 5 is retrieved based on the engine rotational speed N and throttle valve opening α input in step 10.

In step 13, a learning correction coefficient A is calculated based on the intake air flow IQs as the search result and the intake air flow rate Q as the detection result input in step 10. In this example, the ratio of the intake air flow iQ to the intake air flow 1iQs (Q/Qs)
This ratio is used as the learning correction coefficient A.

When the correction coefficient A is calculated and set in step 13, the intake air flow 11 stored in the α-N map is determined in step 14.
Qs is uniformly updated based on this correction coefficient A. Therefore, when the air density is thin due to operation at high altitudes, or when air is supplied by bypassing the throttle valve when the engine is cold, the intake air flow rate Qs stored in the α-N map and the actual value When a deviation occurs between the values of α and α, all the stored values of the α-N map are updated based on the detection results of the air flow meter 2, which almost accurately detects the actual value at this time.
This is to bring the stored values of the -N map closer to the actual values.

Thermal theory, updating of the intake air flow rate Qs is not limited to the above correction coefficient A; for example, a value obtained by multiplying the difference between the detected value Q and the search value Qs of the intake air flow rate by a certain correction coefficient k is added. It may be updated by (Qs+Qs+k(Q-Qs)). .

In this way, if the stored values in the α-N map are brought closer to the actual values one after another, the airflow will be reduced during engine acceleration when the fuel injection amount is set based on the intake air flow rate Qs retrieved from the α-N map. The fuel ratio does not become over-rich or over-lean, and engine operability in such an operating range can be improved.

In this embodiment, the stored values of the α-N map are uniformly updated based on the correction coefficient A calculated and set in step 13, but only the stored values of the relevant operating region are updated. Also good.

<Effects of the Invention> As explained above, according to the present invention, even if there is a change in air density or an air supply that bypasses the throttle valve, the search is performed based on the detected values of the throttle valve opening and the engine rotation speed. The stored value of the intake air flow rate can be brought closer to the actual value.

Therefore, in an engine acceleration state where the fuel injection amount is set based on the searched value of the intake air flow rate, the fuel injection amount is set in accordance with the actual intake air flow rate, and the air-fuel ratio can be controlled to the desired value. effective.

[Brief explanation 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 processing routine for updating the stored value of the intake air flow rate 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... Ice temperature sensor 5... Control unit 6... Drive circuit 7... Fuel injection valve patent application Person Japan Electronics Co., Ltd. Nissan Motor Co., Ltd. Agent Patent Attorney Fujio Sasashima Figure 3

Claims (1)

[Claims] an engine acceleration state detection means for detecting the acceleration state of the engine; a means for detecting the intake air flow rate of the engine; the opening degree and engine rotation speed of a throttle valve interposed in the intake passage of the engine; and the throttle valve opening degree. an intake air flow rate storage means that stores an intake air flow rate corresponding to each operating area for each operating area with parameters such as and engine rotational speed; An intake air flow rate retrieval means for retrieving an intake air flow rate from a storage means, and a fuel injection amount is set based on detected values of the intake air flow rate and engine rotational speed retrieved by the intake air flow rate retrieval means in an acceleration state of the engine. An acceleration fuel injection amount setting means, and a main unit that sets the fuel injection amount based on detected values of intake air flow rate and engine rotational speed in an operation region other than the fuel injection amount setting operation region by the acceleration fuel injection amount setting means. The fuel injection amount setting means learns the deviation between the detected value of the intake air flow rate during steady engine operation and the intake air flow rate retrieved by the intake air flow rate retrieval means, and stores the deviation in the intake air flow rate storage means based on this learned value. intake air flow rate updating means for updating the stored intake air flow rate; and drive control for driving and controlling the fuel injection valve according to the fuel injection amount set by the acceleration fuel injection amount setting means or the main fuel injection amount setting means. An electronically controlled fuel injection device for an internal combustion engine, comprising: means.