JPH0788803B2 - Fuel injection amount control system for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a system for controlling a fuel injection amount of an internal combustion engine.

BACKGROUND ART In a so-called electronically controlled fuel injection device for an internal combustion engine,
In the typical prior art as a method for obtaining the fuel injection amount,
It is determined by the number of revolutions of the internal combustion engine per unit time and the intake pressure. However, in this prior art, when the throttle valve opening suddenly changes, the intake pressure detected by the pressure detector provided in the intake passage causes a response delay from the opening / closing operation of the throttle valve. In order to accurately follow the opening / closing operation of the throttle valve to obtain the fuel injection amount, it is necessary to make a complicated correction during such a transition in which the throttle valve opening suddenly changes.

In order to solve this problem of the prior art, in the method previously proposed by the applicant of the present invention, the intake pressure under atmospheric pressure determined in advance by the throttle opening and the rotation speed of the internal combustion engine is used to obtain a table. The fuel injection amount is obtained from the intake pressure and the previous term rotational speed. With this method, there is no response delay, and the fuel injection amount can be obtained accurately following the opening / closing operation of the throttle valve. However, according to this method, errors due to manufacturing variations and matching of the valve opening detector that detects the opening of the throttle valve, or the slot valve opening stored as a table and the intake pressure data interpolation based on the number of revolutions are interpolated. There is a case where the read intake pressure has an error due to an error in time, and the fuel injection amount cannot be kept optimum.

Problems to be Solved by the Invention An object of the present invention is to provide a fuel injection amount control system for an internal combustion engine, which has good responsiveness and can always maintain an optimum fuel injection amount in response to opening / closing operation of a throttle valve. Is to provide.

Means for Solving the Problems The present invention is directed to an intake pressure under atmospheric pressure that is predetermined from the throttle valve opening θ and the number of revolutions Ne of the internal combustion engine per unit time.
Pmj is obtained in advance, and when the fuel injection amount Tp is obtained from the intake pressure Pmj and the rotational speed Ne, the throttle valve is adjusted so that the difference between the intake pressure Pmj and the actual intake pressure Pm becomes small. A fuel injection amount control system for an internal combustion engine, which is characterized by correcting the opening degree θ, the intake pressure Pmj or the fuel injection amount Tp.

In a preferred embodiment, the correction is performed at a steady state.

Also, in a preferred embodiment, the correction is performed in a transient manner.

In a further preferred embodiment, the intake pressure Pm or
It is characterized in that the correction terms θADJ1 to θADJ5 are selected according to the range of Pmj.

In a preferred embodiment, the correction terms θADJ1 to θADJ5 are selected according to the range of the throttle valve opening θ.

In a further preferred embodiment, said intake pressures Pmj and Pm
When the difference ΔP from and is less than a predetermined value P1, the correction is not performed, and when the difference is a predetermined value P1 or more, the correction is performed.

In a preferred embodiment, the intake pressure Pmj is directly corrected when the throttle valve opening θ or the intake pressures Pm, Pmj are large.

Operation According to the present invention, the intake pressure Pmj under a predetermined atmospheric pressure is determined in advance from the throttle valve opening θ and the rotation speed Ne of the internal combustion engine, and the intake pressure Pmj and the rotation speed Ne are determined.
The fuel injection amount Tp is calculated from Therefore, without causing a delay in response to the opening / closing operation of the throttle valve,
An accurate fuel injection amount Tp can be obtained.

Further, when there is a difference between the intake pressure Pmj and the actual intake pressure Pm, the throttle valve opening θ, the intake pressure Pmj or the fuel injection amount Tp is corrected so that the difference becomes small. Therefore, the fuel injection amount Tp is absorbed by absorbing the variation of the valve opening detector of the throttle valve and the error due to the matching.
Can always be kept at an optimum value.

Embodiment FIG. 1 is a block diagram of an embodiment of the present invention. A plurality of combustion chambers E1 to Em are formed in the internal combustion engine 13, and combustion air is supplied to the combustion chambers E1 to Em from an intake pipe 15.
A throttle valve 16 is interposed in the intake pipe 15. Combustion air passing through the throttle valve 16 is guided from the surge tank 14 to intake pipes A1 to Am individually provided for the combustion chambers E1 to Em, respectively. The fuel injection valves B1 to Bm are connected to the intake pipes A1 to Am, respectively.
Is provided, and in each explosion stroke in each of the combustion chambers E1 to Em, the fuel amount Tp determined by the processing device 31 described later is injected. Each combustion chamber E1-Em has an intake valve
C1 to Cm and exhaust valves D1 to Dm are provided. The internal combustion engine 13
For example, a 4-cycle spark ignition internal combustion engine with spark plugs G1 to Gm.

The surge tank 14 is provided with a pressure detector 19 for detecting the intake pressure. The intake pipe 15 is provided with a temperature detector 27 that detects the intake air temperature. The internal combustion engine 13 is provided with a crank angle detector 28 for detecting a crank angle and a valve opening detector 30 for detecting an opening θ of the throttle valve 16. The temperature of the cooling water of the internal combustion engine 13 is detected by the temperature detector 24. An oxygen concentration detector 21 is provided in the middle of the exhaust pipe 20, and the exhaust gas is purified by the three-way catalyst 22 and discharged to the outside.

Processing device realized by a micro computer, etc.
Reference numeral 31 is an input interface 32 and an analog / digital converter for converting an input analog signal into a digital signal.
33, a processing circuit 34, an output interface 35, and a memory
Including 36 and. The memory 36 includes a read only memory and a random access memory. In the embodiment of the present invention, the fuel injection amount Tp for each stroke injected from the fuel injection valves B1 to Bm is controlled in response to the outputs from the detectors 19, 24, 28, 30 and the like.

On the other hand, in an automobile manufacturer, for example, at a predetermined atmospheric pressure of 760 mmHg, the rotation speed Ne of the internal combustion engine 13 per unit time is
And the intake pressure Pmj corresponding to the throttle valve opening θ are measured. The measurement result is as shown in FIG. 2, for example, and the intake pressure Pmj increases as the throttle valve opening θ increases and the rotation speed Ne of the internal combustion engine 13 decreases. The measurement results shown in FIG. 2 are stored in the memory 36 as a graph or a table as shown in FIG. Further, the fuel injection amount Tp corresponding to the intake pressure Pmj thus obtained and the rotation speed Ne of the internal combustion engine 13 is obtained, and this fuel injection amount Tp is also stored in the memory 36 as a map.

During the actual operation of the internal combustion engine 13, the rotation speed Ne detected by the crank angle detector 28 and the throttle valve opening θ detected by the valve opening detector 30 are stored as described above. The predetermined intake pressure Pmj stored in 36 is read, the fuel injection amount Tp corresponding to this intake pressure Pmj and the rotation speed Ne is read from the memory 36, and the fuel injection valves B1 to Bm are driven.

During steady-state operation of the internal combustion engine 13, the difference between the read intake pressure Pmj and the actual air pressure Pm corresponds to the above-mentioned manufacturing variation of the valve opening degree detector 30 and an error due to matching. Then, in this embodiment, the throttle valve opening θ is corrected so that this difference becomes small.

4 to 6 are flow charts for explaining the operation. FIG. 4 shows a process for obtaining the fuel injection amount Tp, which is performed, for example, at every one explosion stroke of the internal combustion engine 13. At step n1, the rotational speed Ne of the internal combustion engine 13 per unit time detected by the crank angle detector 28 is read, and at step n2, this rotational speed Ne and the intake pressure Pmj obtained as described later are calculated. The fuel injection amount Tp corresponding to is read from the memory 36. At step n3, the fuel injection portions B1 to Bm are driven corresponding to the fuel injection amount Tp, fuel is injected, and the process returns to step n1.

FIG. 5 shows the intake pressure Pmj obtained by correcting the throttle valve opening θ.
Represents the process for determining
The throttle valve opening θ detected by
This is performed every time digital conversion is performed by the digital converter 33. At step n11, the throttle valve opening θ detected by the valve opening detector 30 is read. Step
At n12, the correction term θADJ is added to the throttle valve opening θ, and the throttle valve opening θ is updated. At step n13, the intake pressure Pmj under a predetermined atmospheric pressure corresponding to the rotational speed Ne and the updated throttle valve opening θ obtained at step n12 is read from the memory.

In step n14, it is judged whether or not the rate of change of the throttle valve opening θ is large, and when that is not the case, that is, in the steady state, the routine proceeds to step n15. At step n15, it is judged whether or not the read intake pressure Pmj is larger than the actual intake pressure Pm obtained as described later, and if so, the routine proceeds to step n16, where 1 is subtracted from the correction term θADJ and other Move to processing. When the intake pressure Pmj is equal to or lower than the intake pressure Pm in step n15, the process proceeds to step n17 and the correction term θA
1 is added to DJ and another process is started. At step n14, when the change rate of the throttle valve opening θ is large, that is, at the time of transition, the correction term θADJ of the throttle valve opening θ is not updated, and the process directly proceeds to another process.

FIG. 6 shows an operation for detecting the actual intake pressure Pm. In step n21, the intake pressure Pm detected by the pressure detector 19 is converted into a digital signal by the analog / digital converter 33 and processed. Read in 34. This operation is performed every time the conversion operation in the analog / digital converter 33 is performed.

As described above, in the present embodiment, the throttle valve opening θ is corrected so that the difference between the read intake pressure Pmj and the actual intake pressure Pm becomes small in the steady state where the rate of change of the throttle valve opening θ is small. As a result, the manufacturing variation of the valve opening detector 30, an error due to matching, or an intake pressure
The fuel injection amount Tp can always be kept at an optimum value by absorbing an error in Pmj interpolation. Further, since the fuel injection amount Tp is obtained using the intake pressure Pmj obtained from the throttle valve opening θ and the rotation speed Ne, compared to the method of obtaining the fuel injection amount Tp using the actual intake pressure Pm, The responsiveness at the time of transition can be improved.

FIG. 7 is a flow chart for explaining the correcting operation of the throttle valve opening θ according to another embodiment of the present invention. This embodiment is similar to the above-mentioned embodiment, and the corresponding parts are the same. Add a reference mark. In this embodiment, when the rate of change of the throttle valve opening .theta. In step n14 is large, that is, during transition, the process moves to steps n15a to n17a to perform the same operation as steps n15 to n17 shown in FIG. However, in this case, at step n16a, 1 is obtained from the correction term θADJ.
The smaller correction amount S1 is subtracted, and in step n17a, the correction amount S1 is added to the correction term θADJ.

By adding the steps n15a to n17a in this way, the same correction as in the steady state can be performed even during a transient state such as a rapid depression of the accelerator pedal.
Moreover, since the correction operation is performed more slowly than in the steady state, the fuel injection amount Tp can be held at an optimum value without causing so-called hunting. In this embodiment, the correction amount S1 in steps n16a and n17a is set to be smaller than 1 in order to gently perform the correction during the transition. However, as still another embodiment of the present invention, the correction amount S1 is set to 1
As a result, the processing of steps n15a to n17a may be performed with care.

Further, in the above-described two embodiments, the correction of the throttle valve opening θ is performed with a constant value. Therefore, intake pressure Pmj, Pm
There is a possibility that the corrected throttle valve opening θ has an error between the region close to the minimum and the region close to the maximum, and when the opening / closing operation of the throttle valve 16 is repeated, the correction term θADJ becomes Hunting may occur. For this reason, as shown in FIG. 8 as still another embodiment of the present invention, it is divided into several (5 in the example of FIG. 8) ranges corresponding to the throttle valve opening θ or the intake pressures Pm, Pmj. Then, by using the correction terms θADJ1 to θADJ5 set for each of the ranges, the correction term θADJ is obtained by performing interpolation calculation between the correction terms θADJ1 to θADJ5 as shown in FIG. You may In this case, the read intake pressure Pmj and the actual intake pressure Pm can be quickly matched. Further, even when an error occurs in the correction term θADJ due to, for example, a disturbance, it can be quickly returned to the normal value.

10 and 11 are waveform charts for explaining the operation of another embodiment of the present invention. In the above embodiment, when the actual intake pressure Pm changes as shown in FIG. 10 (1), the read intake pressure Pmj changes as shown by the broken line in FIG. 10 (1). . Therefore, the correction term θ
ADJ changes as shown in Fig. 10 (2),
Hunting may occur in the intake pressure Pmj. Therefore, in this embodiment, the intake pressure Pm shown in FIG. 11 (1) and the intake pressure Pm shown in broken line in FIG. 11 (1).
When the difference ΔP from j is less than the predetermined value P1 indicated by the slanted line in FIG. 11 (1), the correction term θADJ should not be updated as shown in FIG. 11 (2). A so-called dead zone is provided. Therefore, the intake pressure Pmj
Is within this dead zone, the correction term θADJ is not updated, and thus hunting as described above can be prevented.

FIG. 12 is a flow chart for explaining the operation shown in FIG. In step s11, the valve opening detector 30
The throttle valve opening θ detected by is read.
At step s12, the correction term θADJ is added to the throttle valve opening θ to update the throttle valve opening θ. In step s13, the intake pressure Pmj under a predetermined atmospheric pressure corresponding to the rotation speed Ne and the updated throttle valve opening θ obtained in step s12 is read from the memory 36.

At step s14, it is judged whether or not the difference ΔP between the intake pressure Pmj read at step s13 and the actual intake pressure Pm obtained as described above is equal to or more than a predetermined value P1. Sometimes it goes to step s15.

At step s15, the read intake pressure Pmj is the actual intake pressure.
It is determined whether or not it is larger than Pm, and if so, the process proceeds to step s16, 1 is subtracted from the correction term θADJ, and another process is performed. The intake pressure Pmj is the intake pressure at step s15.
When it is equal to or more than Pm, the process proceeds to step s17, and the correction term θADJ
Is incremented by 1 and the process moves to another process. If the difference ΔP between the intake pressure Pmj and the intake pressure Pm is less than the value P1 in step s14, that is, if the difference ΔP is within the dead zone, the process directly proceeds to another process.

FIG. 13 is a flow chart for explaining the operation of still another embodiment of the present invention. When the rotation speed Ne of the internal combustion engine 13 is constant, when the throttle valve opening θ becomes large,
The intake pressures Pm and Pmj are, for example, 600 m as shown in FIG.
It becomes almost constant at about mHg. Therefore, using this, when the throttle valve opening θ is large, the intake pressures Pm, P
The responsiveness can be further improved by directly correcting mj.

That is, the throttle valve opening θ is read in step u1, it is determined in step u2 whether the intake pressure Pm exceeds, for example, 600 mmHg, and if so, the process proceeds to step u3.

At step u3, the intake pressure Pmj corresponding to the throttle valve opening θ and the rotational speed Ne is read, and at step u4 this intake pressure Pmj is read.
The correction term PmjADJ is added to and the intake pressure Pmj is updated. At step u5, it is judged whether or not the updated intake pressure Pmj exceeds the actual intake pressure Pm, and if so, 1 is subtracted from the correction term PmjADJ at step u6, and the processing shifts to another processing. When the intake pressure Pmj corrected in step u6 is equal to or lower than the actual intake pressure Pm, 1 is added to the correction term PmjADJ in step u7 and the process proceeds to another process.

At step u2, when the actual intake pressure Pm is 600 mmHg or less, the routine proceeds to step u8, and proceeds to the operation shown at steps n12 to n17 in FIG. 5 described above to correct the throttle valve opening θ.

In this embodiment, when the throttle valve opening θ is large and the actual intake pressure Pm exceeds 600 mmHg, the intake pressure Pmj is corrected.However, as another embodiment of the present invention, the throttle valve opening θ The intake pressure Pmj may be directly corrected regardless of the magnitude of θ. Furthermore, as another embodiment of the present invention, the fuel injection amount Tp obtained by using the intake pressure Pmj may be directly corrected.

As described above, according to the present invention, the fuel injection amount Tp is obtained from the intake pressure Pmj obtained from the throttle valve opening θ and the rotation speed Ne of the internal combustion engine per unit time, and the rotation speed Ne. Therefore, an accurate fuel injection amount Tp can be obtained without causing a response delay with respect to the opening / closing operation of the throttle valve. When there is a difference between the intake pressure Pmj and the actual intake pressure Pm, the throttle valve opening θ, the intake pressure Pmj or the fuel injection amount T is set so that the difference becomes small.
Since p is corrected, the fuel injection amount Tp can always be kept at an optimum value by absorbing variations in the valve opening detector of the throttle valve and errors due to matching.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between the rotational speed Ne of the internal combustion engine 13 and the intake pressure Pmj at each throttle valve opening θ, and FIG. FIG. 4 is a flow chart for explaining the operation for obtaining the fuel injection amount Tp, and FIG. 5 is a flow for explaining the correction operation of the throttle valve opening θ according to the embodiment of the present invention. FIG. 6 is a flow chart for explaining the actual detection operation of the intake pressure Pm, and FIG. 7 is a flow chart for explaining the correction operation of the throttle valve opening θ according to another embodiment of the present invention. 8 and 9 are graphs for explaining the correction operation of the throttle valve opening θ according to still another embodiment of the present invention, FIG. 10 is a graph for explaining the hunting operation, and FIG. FIG. 12 is a graph for explaining the operation of another embodiment of the invention. 11 is a flow chart for explaining the correction operation of the throttle valve opening θ of the embodiment shown in FIG. 11, FIG. 13 is a flow chart for explaining the operation of yet another embodiment of the present invention, and FIG. 6 is a graph for explaining the operation of the embodiment shown in FIG. 13 …… Internal combustion engine, 14 …… Surge tank, 15 …… Intake pipe,
16 …… Slottle valve, 19 …… Pressure detector, 20 …… Exhaust pipe, 24,27 …… Temperature detector, 28 …… Crank angle detector, 3
0 …… valve opening detector, 31 …… processing device, B1 to Bm …… fuel injection valve, E1 to Em …… combustion chamber, G1 to Gm …… spark plug

Claims (7)

[Claims] 1. An intake pressure Pmj under a predetermined atmospheric pressure is obtained from a throttle valve opening θ and a rotation speed Ne of an internal combustion engine, and a fuel is calculated from the intake pressure Pmj and the rotation speed Ne. In determining the injection amount Tp, the throttle valve opening θ, the intake pressure Pmj or the fuel injection amount Tp is corrected so that the difference between the intake pressure Pmj and the actual intake pressure Pm becomes small. Fuel injection amount control method for internal combustion engine. 2. The fuel injection amount control system for an internal combustion engine according to claim 1, wherein the correction is performed in a steady state. 3. The fuel injection amount control system for an internal combustion engine according to claim 1, wherein the correction is performed in a transient manner. 4. According to the range of the intake pressure Pm or Pmj,
The fuel injection amount control system for an internal combustion engine according to claim 1, wherein the correction terms θADJ1 to θADJ5 are selected. 5. According to the range of the throttle valve opening θ,
The fuel injection amount control system for an internal combustion engine according to claim 1, wherein the correction terms θADJ1 to θADJ5 are selected. 6. A correction is not performed when a difference ΔP between the intake pressures Pmj and Pm is less than a predetermined value P1, and a correction is performed when the difference is a predetermined value P1 or more. A fuel injection amount control system for an internal combustion engine according to claim 1. 7. The throttle valve opening θ or intake pressure Pm, P
The fuel injection amount control system for an internal combustion engine according to claim 1, wherein the intake pressure Pmj is directly corrected when mj is large.