JPS5988623A - Flow rate signal smoothing apparatus for engine - Google Patents

Abstract

PURPOSE:To stabilize the control at a high accuracy based on a signal free from the effect of intake pulsation without impairing response by switching the smoothing of an intake air flow rate signal or a control signal based thereon over to the level appropriate for the full operation of the engine delayed by a specified time detecting the vicinity of the full operation of the engine. CONSTITUTION:When a full operation detector 2 detects the vicinity of the full operation of the engine based on an intake air flow rate signal provided from an air flow rate sensor, the level of smoothing with a smoothing switch gear 1 is changed over through a switching delay adjustor 3 to performing a smoothing adapted to the intake pulsation in the vicinity of the full operation of the engine. After the intake air flow rate Q is smoothed to a certain extent S1, a basic injection pulse width Tp is calculated by Q/NXK (where, N is engine revolutions and K constant) S2 and stored into a memory S3. Then, it is determined whether the Tp determined previously, namely, the Tp 10msec before is above 5msec or not S4 and when it is below 5msec, the new Tp is read out of the memory S5. A fuel injection level is computed with Tp= new Tp as basic injection level subsequently subject to due correction thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for smoothing an engine intake air flow rate signal or a control signal based on the intake air flow rate.

Fuel injection control of an engine equipped with an electronically controlled fuel injection device uses an air flow sensor to measure the intake air flow rate in order to determine the fuel injection time according to the intake air flow rate flowing through the intake passage. There are various types of air flow sensors, but when divided by response speed, there are slow response types such as flapper type air flow meters, and fast response types such as Karman vortex flow rate sensors and pot wire type flow rate sensors. .

Among these, the former has poor responsiveness (sensitivity) and is therefore less susceptible to the influence of intake pulsation, but is inferior in injection control transient characteristics during acceleration and deceleration. On the other hand, the latter has excellent responsiveness and good injection control transient characteristics, but because it detects intake pulsation with high sensitivity, the detection signal is smoothed and used for fuel injection control.

However, the conventional signal smoothing processing device described above only performs the same level of smoothing processing even when the engine is operating at full throttle (at or near full load), where intake pulsation is large, as during partial load operation where intake pulsation is small. Because of this, when the engine is near full throttle, the fuel injection amount is reduced to 1
The variation from run to run becomes large, which can adversely affect driveability and exhaust performance.

For this reason, some devices use the opening signal of the throttle valve to switch to proceed with smoothing when the engine is close to full throttle. No. 32047). However, as shown in Fig. 5, in this case, the constant opening curve of the throttle valve moves away from the engine fully open state as the speed range changes from the low speed range to the high speed range.
In the low-speed range, the area that overlaps with the area with large output fluctuations near full throttle becomes large, making it impossible to perform sufficient smoothing.On the other hand, in the high-speed range, the area where smoothing progresses becomes too wide, leaving a large area with poor responsiveness. However, the above-mentioned difficulties could not be sufficiently solved.

The present invention has been made in view of these conventional problems, and includes a means for accurately detecting the vicinity of full engine opening based on the amount of intake air per rotation, for example, and detecting the degree of smoothing in the vicinity of full opening. In addition to increasing the degree of smoothing by delaying it for a predetermined period of time when entering near full throttle, it is possible to improve the transient response and not be affected by intake pulsation while controlling the intake air flow rate or the control signal based on this. It is an object of the present invention to provide an engine flow rate signal smoothing device that smoothes and improves the control accuracy of the engine based on the Wm signal.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which a full-open detection device 2 is activated based on an intake air flow rate signal given from an air flow rate sensor installed in the intake system of an engine (not shown). When the engine is detected to be in the vicinity of full throttle, the degree of smoothing of the smoothing switching device 1 is switched via the switching delay adjustment device 3 to perform smoothing appropriate to the intake pulsation when the engine is in the vicinity of full throttle. When the engine is no longer near full throttle, the degree of smoothing is immediately lowered to match partial load operation.

FIG. 2 is a flowchart 1 showing the detailed operation of the embodiment shown in FIG.
Determine the basic fuel injection pulse width 1゛p based on the signal,
The value of this pulse width is smoothed.

This calculation, which is not shown in Flowchart 1, is performed every 10 milliseconds. First, the intake air flow rate Q is smoothed to some extent (step S +), and then Q/NxK (however, N
The basic injection pulse width Tp is calculated (steer knob S2) and stored in the memory (step S3). Next, the previously determined Tp, that is, the T 10 milliseconds ago, (hereinafter referred to as "r p")
Step S4) determines whether or not is longer than 5 milliseconds, and if it is shorter than 5 milliseconds, new 'rp is continuously outputted from the memory. Correction has been made; the amount of fuel injection is calculated. On the other hand, if the old Tp is longer than 5 milliseconds, the new r'p is read out from the memory (step S6), and it is determined whether the new Tp is longer than 5 milliseconds (step S7).
If it is less than 5 milliseconds, it is used in subsequent calculations as <Tp=new Tp as described above (step 39). And the new Tp also starts smoothing of ζ1゛p when it is longer than 5 milliseconds.
- New "T"pxl/84-11" TpX7/8 is calculated (step So).

As a result, even if the new Tp has a large variation, the variation in Tp becomes small. In this way, both old and new Tp are 5
Smoothing is performed only when the value is large, such as milliseconds or more. In other words, when entering near full-throttle operation for 5 milliseconds or more, there is a smoothing switching delay of at least 10 milliseconds or more. Conversely, when escaping from near full-open, Tp
Stop the smoothing process.

Therefore, normally (during partial load operation), only the intake air flow rate Q is smoothed, and in the vicinity of full opening, smoothing is also performed using the basic injection pulse width Tp.

FIG. 3 shows the relationship between the pulse width fluctuation rate of Tp that has undergone the smoothing process by the above-mentioned switching and the engine intake negative pressure. The solid line is the result obtained by implementing the present invention, and the broken line is the result not obtained by the present invention.As shown by the broken line, the pulse width fluctuation rate, which should increase rapidly as the engine is fully opened, is slightly reduced according to the present invention. Moreover, the maximum region of the pulse width fluctuation rate is not at the time when the engine is fully opened, but near it, and it is clear that smoothing is performed quickly.

Figure 4 shows how the fuel injection pulse width Tp changes during acceleration and deceleration.The solid lines of the three step-like waveforms showing pulse width changes are the ones according to the present invention, and the broken lines are smooth lines for when the engine is near full throttle. When switching is not performed, the dashed-dotted lines are each waveform when the switching delay according to the present invention is not performed. In other words, if the switching delay is not performed, the response will deteriorate due to smoothing, making it impossible to follow acceleration operations (dotted chain line), and if smoothing is not performed when the engine is near full throttle, pulsation will occur (dashed line). . In this regard, the present invention has excellent responsiveness during acceleration, and can also avoid the influence of intake pulsation near full engine opening after acceleration.

Furthermore, as shown in Fig. 5, the constant injection pulse width (basic injection pulse Tp) and the engine full throttle change in good correspondence over almost the entire rotational speed range, and the difference between them is small, so the constant injection pulse width (basic injection pulse Tp) and the engine full throttle change in a good manner. The transition will be smooth. Therefore, by comparing the basic injection pulse width Tp with the set value, the
It is possible to detect the full range of the engine (・Y) well, and by controlling smoothing switching based on this detection, the intake air flow rate signal and the injection amount based on this can be controlled with high precision in the entire operating range. is clear.

In the second embodiment, the basic injection pulse width Tp was the target of smoothing, but it is of course possible to target the intake air flow iQ at the previous stage.
Although the delay was set at 20 milliseconds or more, the delay may be longer than that. However, it is better to avoid a time longer than 1 second because the fluctuation in the injection pulse width becomes large.

Furthermore, in the above embodiment, the basic injection amount is used to detect when the engine is near full throttle, and the injection amount signal is thereby smoothed directly or through smoothing of the intake air flow rate signal. Any device that detects the vicinity of full engine opening based on the amount of intake air per revolution and smoothes the intake air flow rate signal or the control signal based on this is sufficient, for example, the ignition timing control signal based on the intake air flow rate signal. It can also be applied to smoothing. In this case as well, variations in ignition timing can be suppressed.

As explained above, according to the present invention, the vicinity of the fully open engine is detected by, for example, the value of Q/H, and upon detection, smoothing of the intake air flow rate signal or the control signal based on the signal is performed with a predetermined time delay when the engine is fully open. Therefore, the control based on the signal can be made highly accurate and stable without impairing the responsiveness of the engine and without being affected by intake pulsation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a flowchart showing the detailed operation of the embodiment of FIG. 1 of the present invention, and FIG. 3 is a fuel injection pulse according to the present invention. Figure 4 is a diagram showing the transient characteristics of the fuel injection pulse width according to the present invention, and Figure 5 is a diagram showing the width fluctuation characteristics compared with the conventional one. It is a characteristic diagram shown in comparison with the throttle valve opening degree switching method. ■... Smoothing switching device 2... Fully open detection device 3.
...Switching delay adjustment device patent applicant Fujio Sasashima Patent attorney, Nissan Motor Co., Ltd. Figure 2 Figure 4

Claims (1)

[Claims] engine full-open detection means for detecting an operating state near full load of the engine; delay means for delaying and outputting the detection signal of the engine full-open detection means by a predetermined time; When a signal is input from the means, it is smoothed to an extent corresponding to engine operation at near full load, and when no signal is input, it is smoothed to an extent corresponding to engine partial load operation. An engine flow signal smoothing device characterized by: