JPH04101036A - Electronically controlled fuel supply system for internal combustion engines - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronically controlled fuel supply system for an internal combustion engine, and more particularly, to an improvement in fuel increase control during acceleration operation.

<Prior Art> Conventionally, electronically controlled fuel supply 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 rotational speed N, the basic fuel injection amount Tp = KXQ/N (K is the fuel injection valve 10a) corresponding to the intake air amount.
-10d characteristic constant), various correction coefficients C0EF mainly depending on the cooling water temperature, air-fuel ratio feedback correction coefficient α, and correction numerator s based on battery voltage are calculated, and the basic fuel injection amount Tp is adjusted based on these values. The final fuel injection amount T:='rpxcoE'F is corrected based on
Calculate xα+Ts.

Then, in synchronization with the engine rotation, an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti is outputted to the fuel injection valve to inject and supply fuel to the engine.

Furthermore, during engine acceleration, as shown in Figure 7, in order to prevent the indicated mean effective pressure from dropping due to lean misfire,
The fuel injection amount is increased by correcting the fuel injection amount Ti according to the acceleration driving conditions or by performing additional injection during normal injection, and the fuel injection amount is corrected during acceleration. This allows the indicated mean effective pressure to rise without any misfires, thereby preventing shocks and deterioration of exhaust properties due to misfires during acceleration.

<Problem to be solved by the invention> By the way, the increase in the amount of fuel injection at the time of acceleration described above ensures sufficient margin even if the wall flow increases when the engine is cold, and even if the fuel becomes heavier. In order to ensure a sufficient increased injection amount, it was necessary to perform matching in advance so that the increased amount was injected in a larger amount than the required amount.

For this reason, there is a problem that the air-fuel ratio during acceleration becomes over-rich due to fuel increase control to increase the indicated mean effective pressure during acceleration, and fuel efficiency and exhaust characteristics deteriorate.
It has been difficult to reliably avoid a drop in the indicated mean effective pressure due to misfire during acceleration, while also preventing deterioration of fuel efficiency and exhaust characteristics during acceleration due to increased correction.

The present invention has been made in view of the above problems, and an object of the present invention is to improve fuel consumption and exhaust characteristics during acceleration by making it possible to increase the indicated mean effective pressure during acceleration with a minimum amount of fuel increase correction. With the goal.

<Means for Solving the Problems> Therefore, an electronically controlled fuel supply system for an internal combustion engine according to the present invention is configured as shown in FIG.

In FIG. 1, the cylinder pressure detection means detects the cylinder pressure of the internal combustion engine, and the indicated mean effective pressure calculation means calculates the indicated mean effective pressure of the engine based on the cylinder pressure detected by the cylinder pressure detection means. .

The acceleration operation detection means detects the acceleration operation state of the engine, and the target indicated mean effective pressure storage means stores in advance the target indicated mean effective pressure in the acceleration operation state of the engine according to the acceleration operation conditions.

The acceleration increase correction amount correction means adjusts the indicated average effective pressure to the target indicated average effective pressure retrieved from the target indicated average effective pressure storage means when the accelerating operation state of the engine is detected by the acceleration operation detection means. The fuel increase correction amount during acceleration operation is increased or decreased so that the actual indicated mean effective pressure calculated by the pressure calculation means approaches.

The acceleration fuel increase correction means increases or corrects the fuel supply amount during engine acceleration operation based on the fuel increase correction amount corrected by the acceleration increase correction amount correction means.

<Function> According to this configuration, the amount of fuel is increased during engine acceleration so that the actual indicated mean effective pressure calculated during engine acceleration approaches the target indicated mean effective pressure stored in advance according to the acceleration operating conditions. Since the correction amount is increased or decreased, when the actual indicated mean effective pressure is larger than the target, the fuel increase is reduced to avoid excessive acceleration increase correction, and when it is below the target, the increase correction amount is increased. It is possible to avoid a drop in the indicated mean effective pressure during acceleration.

<Example> The present invention will be explained in detail below.

In FIG. 2 showing one embodiment, a 4-cycle, 4-cylinder internal combustion engine l includes an air cleaner 2. Throttle chamber 3.
Air is sucked in through the intake manifold 4. The combustion exhaust gas is then transferred to the exhaust manifold 5. Exhaust duct 6, three-way catalyst 7. It is discharged into the atmosphere via the muffler 8.

The throttle chamber 3 is provided with a throttle valve 9 that opens and closes in conjunction with an accelerator pedal (not shown), and the intake air amount of the engine 1 is controlled by the throttle valve 9.

Further, each branch portion of the intake manifold 4 is provided with an electromagnetic fuel injection valve 10a for injecting and supplying fuel to each cylinder.
~10d are installed, respectively, and are controlled to open independently according to injection pulse signals from a control unit 11 containing a microcomputer. The electromagnetic fuel injection valves 10a to 10d are supplied with fuel that is pressure-fed from a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator, and the fuel injection amount is controlled as the valve opening time. It's like coming.

Furthermore, cylinder pressure sensors 12a to 12d are provided as cylinder pressure detection means for detecting the cylinder pressure for each cylinder (#1 to #4).

Incidentally, the cylinder pressure sensors 12a to 12d mentioned above are
It may be of the type that is installed as a washer for the spark plug as disclosed in Publication No. 17432, or it may be of the type that detects the cylinder pressure as an absolute pressure by having the sensor part directly facing into the combustion chamber. Use or more desirable.

Further, a crank angle sensor 13 is provided on the camshaft (not shown) of the engine l, which detects the crank angle through the rotation of the camshaft, and every 180 degrees of crank angle corresponding to the stroke phase difference between cylinders (for example, A reference angle signal REF for each unit crank angle (BTDC 70') and a unit angle signal PoS for each unit crank angle are output, respectively.

Furthermore, a throttle sensor 14 is attached to the throttle valve 9 to detect the opening degree TVO of the throttle valve 9 using a potentiometer, and an air flow meter is provided upstream of the throttle valve 9 to detect the intake air flow rate Q of the engine l. There are 15.

The exhaust duct 6 is also provided with an oxygen sensor 16 that detects the oxygen concentration in the exhaust gas, which detects the oxygen concentration in the exhaust gas that varies depending on the air-fuel ratio, and determines the air-fuel ratio of the engine intake air-fuel mixture. It can now be detected indirectly.

The control unit 11 for the electronically controlled fuel supply system sets the fuel injection amount (fuel supply amount) Ti by the fuel injection valves 10a to 10d as shown in the flowcharts of FIGS. 3 and 4.

In this embodiment, the functions of the indicated mean effective pressure calculation means, the acceleration fuel increase correction amount correction means, and the acceleration fuel increase correction means are performed by the control unit 11 as shown in the flowcharts of FIGS. 3 and 4. Or is it prepared in terms of software? Further, in this embodiment, the acceleration operation detection means corresponds to the throttle sensor 14, and the target indicated mean effective pressure storage means corresponds to a memory (not shown) of the microcomputer built in the control unit 11.

The program shown in the flowchart of FIG. 3 is a learning program for the acceleration increase correction coefficient KACC for increasing the fuel injection amount Ti during acceleration operation of the engine 1.
In step 1 (indicated as Sl in the figure; the same applies hereinafter), the cylinder pressure P detected by the cylinder pressure sensors lOa to 10d is
is A/D converted and read for each unit crank angle detected by the crank angle sensor 11.

Then, in step 2, the indicated mean effective pressure Pi (=f
PdV; V=volume) is calculated.

In step 3, the rate of change ΔTVO of the opening degree TVO of the throttle valve 9 detected by the throttle sensor 14 is calculated;
By comparing this rate of change ΔTVO with a predetermined value, it is determined whether the opening degree TVO of the throttle valve 9 is changing in the opening direction at a rate greater than a predetermined rate.

When it is determined that the rate of change ΔTVO is greater than a predetermined value, it is assumed that the engine I is in an accelerated operating state, and the process proceeds to step 4. On the other hand, when the rate of change TVO is less than or equal to the predetermined value, it is assumed that steady operation or deceleration operation is in progress and the program is terminated.

In step 4, the current acceleration operating conditions are determined from a map in which the target indicated mean effective pressure Pi(s) is stored in advance using the basic fuel injection amount (basic fuel supply amount) Tp, the engine speed N, and the rate of change ΔTVO as parameters. Search and find the target indicated mean effective pressure Pi(s) commensurate with the above.

The basic fuel injection amount Tp is determined by the intake air flow rate Q detected by the air flow meter 15 and the engine rotational speed N calculated based on the detection signal from the crank angle sensor 13. Injection valve 10a-10
It is calculated as a characteristic constant of d) and is used as a value equivalent to the engine load.

In this embodiment, the target Pi(s) is set for each operating region divided into a plurality of regions based on the basic fuel injection amount Tp and the engine rotational speed N.
The stored map is calculated as the opening change rate △T of the throttle valve 9.
A plurality of maps are provided depending on the level of VO, and a map of target Pi(s) with basic fuel injection amount Tp and engine rotational speed N as parameters is selected based on the latest rate of change ΔTV○. Current basic fuel injection amount T of the selected map
Target Pi(s) in the area corresponding to p and engine rotational speed N
This is what you are looking for.

In the next step 5, the target indicated mean effective pressure Pi(s') corresponding to the current acceleration driving state obtained in step 4 is determined.
and the actual indicated mean effective pressure Pi calculated in step 2, and the result is expressed as ΔPi(←Pi(s)−P
i).

In step 6, the correction value ΔZ corresponding to the latest ΔP1 calculated in step 5 is calculated from the map storing the correction value ΔZ of the acceleration increase correction coefficient KACC according to the deviation ΔPi.
Find it by searching.

The correction value ΔZ is set as a positive value when the actual Pi is lower than the target P i (s) and the deviation ΔP1 is a positive value.
By adding Z to the acceleration increase correction coefficient KACC, the increase correction amount during acceleration is increased and the air-fuel ratio is made richer. When the air-fuel ratio becomes richer, the indicated mean effective pressure Pi increases as shown in FIG. 6, so as shown in FIG.
(s) by increasing the actual Pi that is lower than the target Pi (s/)
It is possible to come close to.

Conversely, when the deviation ΔPi is negative, the correction value ΔZ is set as a negative value, and this correction value ΔZ
As shown in Fig. 5, the acceleration increase correction coefficient KACC is decreased and the increase correction amount during acceleration is reduced. It is possible to reduce the actual Pi that exceeds Pi(s).

Therefore, over-riching of the air-fuel ratio that would result in an actual P1 exceeding the target Pi(s) is avoided, and fuel efficiency and exhaust characteristics during acceleration can be improved. This makes it possible to avoid slowing down the rise of the effective pressure Pi, and it is possible to perform fuel increase correction to the extent necessary for acceleration performance in line with the target P i (s). Here, by setting the target Pi (s) appropriately,
It becomes possible to control the acceleration characteristics of the engineer to a level that matches the characteristics of the vehicle.

In the next step 7, the acceleration increase correction coefficient KACC is updated for each region divided into a plurality of regions depending on the cooling water temperature Tw of the engine 1 and the throttle valve opening change rate ΔT V O.
The map value of the stored map is updated. That is, the acceleration increase correction coefficient KACC stored in correspondence with the current cooling water temperature Tw and the rate of change ΔTV○ is searched and obtained, and the correction value ΔZ obtained in step 6 is added to the correction coefficient KACC. The correction coefficient KACC memory value of the area is rewritten using the correction result as a new map memory value.

Acceleration increase correction coefficient KAC that is increased or decreased to bring the indicated average effective pressure P1 during acceleration closer to the target as described above.
C is used in the program shown in the flowchart of FIG.

In the program shown in the flowchart of FIG. 4, first, in step II, the intake air flow rate Q detected by the air flow meter 15 and the engine rotational speed N calculated based on the detection signal from the crank angle sensor 13 are calculated. input.

In the next step 12, the basic fuel injection amount Tp (←KXQ/N; K is the fuel injection valve 10a~ 10d characteristic constant).

In step 13, as described above, from the map storing the acceleration increase correction coefficient KACC (acceleration increase correction amount) according to the cooling water temperature Tw and the throttle valve opening change rate ΔTVO,
The acceleration increase correction coefficient KACC corresponding to the current cooling water temperature Tw and the rate of change ΔTVO is searched and determined.

Then, in the next step 14, various correction coefficients C0FF are set including the acceleration increase correction coefficient KACC. The various correction coefficients C0EF are the acceleration increase correction coefficients KA.
In addition to CC, a water temperature correction coefficient KTw and a post-start increase correction coefficient Kas, which are set based on the cooling water temperature Tw, are set as C0EF←1+KT, +KACC+KaS+, etc.

In step 15, the air-fuel ratio of the engine intake mixture detected by the oxygen sensor 16 is set to the target air-fuel ratio (theoretical air-fuel ratio).
The air-fuel ratio feedback correction coefficient α for feedback correction is set by, for example, a proportional product division unit.

Further, in step 16, a battery voltage correction numerator s is set for correcting a change in the effective valve opening time of the injector due to a voltage change in a battery (not shown) that is a driving power source for the fuel injection valves 10a to 1Od.

Then, in the next step 17, the basic fuel injection amount Tp calculated in step 2 is adjusted to the acceleration increase correction coefficient KACC.
The final fuel injection amount Ti (←2TpxCOEFxα+Ts
) is calculated.

At a predetermined fuel injection timing, the control unit 11 reads the latest value of the fuel injection amount Ti that is updated in step 17, and sends an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti to the fuel injection valve 10a. -10
d to cause the fuel injection valves 10a to 10d to inject fuel into the engine 1, or increase the indicated average effective pressure during acceleration so that it changes approximately in line with the target using the acceleration increase correction coefficient KACC during acceleration. It will be corrected.

In this embodiment, a device is described which increases the amount of fuel during acceleration by correcting the normal fuel injection amount Ti during acceleration, or an apparatus which performs interrupt injection during normal injection when the engine I accelerates. The device may be configured to increase the amount of fuel by using the interrupt injection, and if the injection amount by the interrupt injection is corrected to increase or decrease so that the actual indicated mean effective pressure Pi approaches the target, the same effect as in this embodiment can be obtained. can get.

In addition, in this embodiment, the electronically controlled fuel supply device is configured to set the basic fuel injection amount Tp based on the intake air flow rate Q detected by the air flow meter 15, or depending on the intake negative pressure and the engine rotation speed N. The basic fuel injection amount Tp may be set based on the throttle valve opening TVO and the engine rotational speed N. The device may be provided with a common fuel injection valve upstream of the throttle valve 9.

<Effects of the Invention> As explained above, according to the present invention, it is possible to avoid excessively increasing the amount of fuel supplied in order to ensure the rise characteristic of the indicated mean effective pressure during acceleration. This has the effect of preventing the deterioration of fuel efficiency and exhaust characteristics due to fuel increase correction.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a system schematic diagram showing an embodiment of the invention, and Figs. 3 and 4 respectively show details of fuel injection amount setting control in the above embodiment. Figure 5 is a time chart showing the characteristics of changes in indicated mean effective pressure during acceleration, Figure 6 is a line diagram showing the relationship between air-fuel ratio and indicated mean effective pressure, and Figure 7 is an interrupt during acceleration. 7 is a time chart showing an example of increase correction by injection. 1... Internal combustion engine 9... Throttle valve 10a
~10d... Fuel injection valve 11... Control unit 12a-12d... Cylinder pressure sensor 13.
... Crank angle sensor 14 ... Throat sensor 15 ... Air flow meter

Claims (1)

[Claims] A basic fuel supply amount commensurate with the intake air amount of the internal combustion engine is calculated, and fuel is supplied to the engine based on the basic fuel supply amount, while in addition to the basic fuel supply amount during engine acceleration operation. An electronically controlled fuel supply system for an internal combustion engine configured to supply a predetermined fuel increase correction amount to the engine, comprising a cylinder pressure detection means for detecting cylinder pressure of the internal combustion engine, and a cylinder pressure detection means for detecting the cylinder pressure detected by the cylinder pressure detection means. An indicated mean effective pressure calculation means for computing the indicated mean effective pressure of the engine based on the internal pressure; An accelerated running detection means for detecting the accelerated operating state of the engine; a target indicated average effective pressure storage means stored in advance according to the target indicated average effective pressure; Acceleration increase correction amount correction means for increasing or decreasing the fuel increase correction amount during acceleration operation so that the actual indicated average effective pressure calculated by the indicated average effective pressure calculation means approaches the effective pressure; An internal combustion engine characterized by comprising: fuel increase correction means during acceleration for increasing or correcting the amount of fuel supplied during engine acceleration operation based on the amount of fuel increase or decrease corrected by the amount correction means. Electronically controlled fuel supply system.