JPH03294635A - Fuel injection controller of engine - Google Patents

Abstract

PURPOSE:To remarkably improve the accuracy of air-fuel ratio by setting a compensation intake pipe pressure to be parameters by a value obtained through compensating an estimation intake pipe pressure by an intake pipe pressure compensation value which is set based on the deviation between the intake pipe pressure actually measured and the intake pipe pressure estimated. CONSTITUTION:In a pressure compensation set means M5, an intake pipe pressure compensation value is set based on the deviation between an estimated intake pipe pressure M3 and an average intake pipe pressure M4 at the time of normal operation. The intake pipe pressure compensation value is set to a preliminarily set value at the time of transient operation. In a compensation intake pipe pressure set means M6, an estimated intake pipe pressure M3 is compensated with the intake pipe pressure compensation value at the time of normal operation to set the compensation intake pipe pressure. In a basic fuel injection set means M7, a basic fuel injection quantity is set based on an cylinder intake air quantity M2 and the engine load. An intake air quantity to be supplied to the cylinder is accurately estimated so as to improve the accuracy of air-fuel ratio control.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is an engine that calculates the basic fuel injection amount from the cylinder intake air gap set based on the intake pipe pressure and the engine speed and the engine speed. Regarding the fuel injection control device.

[Prior Art and Problems to be Solved by the Invention] Conventionally, one of the means for setting the fuel injection suspension is the time [63-29039 publication or Japanese Patent Application Laid-open No. 63-1
There is so-called α-N control, as disclosed in Japanese Patent No. 83247, in which the basic fuel injection Hf1TP is set using the throttle opening α and the engine speed N as parameters.

This α-N control has a better response compared to the Subi-Densiddy method, which uses an intake pipe pressure sensor etc. to set the basic fuel injection DAM, and can simplify the structure, so it can be used in various ways. It is used in the engine of

In this α-N control, the detection accuracy of throttle opening is an important factor in determining the amount of fuel injection (I)J, but manufacturing errors of the throttle valve, assembly errors, and throttle opening If the zero point adjustment or idle position adjustment of the detection means is made too strict, manufacturing and assembly become complicated and costs increase.

In addition, the accuracy of detecting the throttle opening is significantly deteriorated due to deterioration of the throttle valve and the throttle opening detecting means over time, so adjustments must be made one after another, making maintenance and inspection complicated.

As a countermeasure against this problem, for example, in Japanese Patent Application Laid-Open No. 61-265340, intake pipe pressure data stored in an α-N map with throttle opening α and engine speed N as parameters is detected by an intake pipe pressure sensor. By sequentially updating the intake pipe pressure, the throttle opening detection Kl difference,
It is possible to set the fuel injection amount corresponding to the cylinder intake air level regardless of deterioration over time.

However, even during steady operation, the pressure inside the intake pipe fluctuates slightly due to intake air interference, and it is difficult to accurately determine the amount of intake air supplied into the cylinder from the intake pipe pressure. , easy to cause control hunting.

[Object of the Invention] The present invention has been made in view of the above circumstances, and is capable of accurately controlling the amount of intake air supplied to a cylinder without being affected by pressure fluctuations in the intake pipe in so-called α-N control. It is an object of the present invention to provide a fuel injection control device for an engine that can significantly improve air-fuel ratio control accuracy.

[Means for Solving the Problems] In order to achieve the F2 objective, the fuel injection control device for an engine according to the present invention, as shown in FIG. Throttle valve passing air amount setting means M1 sets the amount of air passing through the throttle valve based on the corrected suction pipe pressure set by the pressure setting means M6, and in-cylinder intake air is set based on the corrected suction pipe pressure and the engine speed. an estimated suction pipe pressure setting means M3 for estimating the suction pipe pressure based on the difference between the amount of air passing through the throttle valve and the cylinder intake air gap; suction pipe pressure averaging means M4 for setting an average suction pipe pressure by averaging the suction pipe pressures detected by the pressure detection means for each set cycle; and the estimated suction pipe pressure and the average suction pipe pressure during steady operation. In addition to setting the suction pipe pressure correction value based on the deviation from a pressure correction value setting means M5 for setting a suction pipe pressure correction value at a predetermined value during normal operation; and a pressure correction value setting means M5 for setting a corrected suction pipe pressure by correcting the estimated suction pipe pressure with the suction pipe pressure correction value during steady operation. It is provided with a corrected intake pipe pressure setting means M6 and a basic fuel injection amount setting means M7 for setting the basic fuel injection amount based on the above-mentioned cylinder intake air gap and engine rotational speed.

[Function] In the above configuration, first, the throttle valve passing air amount setting means M1 sets the throttle valve passing air amount based on the throttle valve opening and the corrected suction pipe pressure set by the corrected suction pipe pressure setting means M6. do.

Further, the cylinder intake air gap setting means M2 sets the cylinder intake air gap based on the above-mentioned corrected intake pipe pressure, engine speed, etc.

Then, the estimated suction pipe pressure setting means M3 estimates the suction pipe pressure based on the difference between the amount of air passing through the throttle valve and the intake air in the cylinder.

On the other hand, the suction pipe pressure averaging processing means M4 averages the suction pipe pressures detected by the suction pipe pressure detection means for each setting cycle to set an average suction pipe pressure.

Further, the pressure correction value setting means M5 sets a suction pipe pressure correction value based on the deviation between the estimated suction pipe pressure and the average suction pipe pressure during steady operation, and also adjusts the throttle opening and engine speed. The suction pipe pressure correction value is stored in the pressure correction value map M14PKP used as a parameter, and the suction pipe pressure correction value during transient operation is set to a predetermined value.

Furthermore, the corrected suction pipe pressure setting means M6 corrects the estimated suction pipe pressure using the suction pipe pressure correction value during steady operation to set a corrected suction pipe pressure.

Then, the basic fuel injection amount setting means M7 sets the basic fuel injection amount based on the cylinder intake air hl and the engine speed.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail based on the drawings.

Figure 2 and subsequent figures show one embodiment of the present invention, Figure 2 is an overall schematic diagram of the engine control system, Figure 3 is a flowchart showing the procedure for setting the pressure correction value, and Figure 4 is the setting of the fuel injection amount. A flowchart showing the procedure, and FIG. 5 is a conceptual diagram showing the intake state.

(Configuration) Reference numeral 1 in Fig. 2 is the engine body, and this engine body 1
A throttle valve 3 is interposed in the middle of the intake pipe 2 that communicates with the intake port 1a, and a chamber volume V is provided between the throttle valve 3 of the intake pipe 2 and the intake valve 4 inserted in the intake port 1a. It consists of

Further, an air cleaner 5 is installed upstream of the intake pipe 2, and an intake temperature sensor 6 is installed in an expansion chamber of the air cleaner 5. Further, a throttle sensor 7, which is an example of a throttle distance detection means, is installed in the throttle valve 3.
Further, a pressure sensor 8, which is an example of suction pipe pressure detection means, is connected to the chamber comb V. Further, the intake port 1a is provided downstream of the intake pipe 2.
The injector 9, which directs the nozzle to the side, is installed.

Furthermore, an 02 sensor 1 is placed facing an exhaust pipe 10 that communicates with the exhaust port 1b of the engine body 1. In addition, the code|symbol 12 is a catalytic converter.

On the other hand, a cooling water temperature sensor 13 faces the cooling water passage of the engine body 1, and a crank angle sensor 15, which is an example of engine rotation speed detection means, is connected to the crank rotor 14 which is pivotally mounted on the crankshaft 7l-1C. It is set up.

(Circuit configuration of control device) On the other hand, reference numeral 21 is a control device (FCU) consisting of a microcomputer, and this ECU 21 includes a CPU (central processing unit) 22, RC) M 23, RAM 24, and
I10 interfaces 25 are connected to each other via path lines 26.

Further, each of the above-mentioned sensors 6.7.11.13.15 is connected to the input port side of the above-mentioned I10 interface 25, and injector 9 is connected to the output port side of the above-mentioned I10 interface 25 via a drive circuit 27. It is connected.

The function of executing the fuel injection control in the ECU 21 includes a throttle valve passing air amount setting means for setting the throttle valve passing air amount based on the throttle valve opening degree and the corrected suction pipe pressure set by the corrected suction pipe pressure setting means. and 1. In-cylinder intake air gap setting means for setting the in-cylinder intake air gap based on the above-mentioned corrected intake pipe pressure and engine speed; An estimated suction pipe pressure setting means for estimating the pipe pressure; a suction pipe pressure averaging means for setting the average suction pipe pressure by averaging the suction pipe pressure for each setting cycle detected by the suction pipe pressure detection means; The suction pipe pressure correction value is set based on the deviation between the above-mentioned H1 constant suction pipe pressure and the above-mentioned average suction pipe pressure at 00 correction suction pipe pressure setting means for correcting the estimated suction pipe pressure with the suction pipe pressure correction value to set a corrected suction pipe pressure; A basic fuel injection amount setting means for setting a basic fuel injection amount based on the internal intake air and the engine rotational speed is included.

(Operation) Next, the control procedure by the ECU 21 will be explained according to the flowcharts shown in FIGS. 3 and 4.

(Procedure for Setting Estimated Suction Pipe Pressure) As shown in FIG. Based on the output signal of the pressure sensor 8, the throttle opening α and the engine speed N1 are determined.
Calculate each suction pipe pressure PB.

Then, in 5102, the difference Δ between the throttle opening α and the throttle opening α(t-1) calculated in the previous routine
α (However, Δα−Iα−α(t−1) l ) is compared with a preset allowable variation value α0, and the above opening difference Δα
is less than the allowable variation value α0 (Δα〈α0), 31
If the opening degree difference Δα exceeds the allowable variation 1 value αO (7α≧αO), the process advances to 8105.

Proceeding to 5103, the difference between the engine speed N and the Ic engine speed N ft-1 calculated in the previous routine, dN (where ΔN= l If-N(t-1) l
) and the preset γ[capacity variation value NO, and if the rotational difference ΔN is less than the allowable variation value NO (ΔN<No),
It is determined that the operation is steady and proceeds to 5104, and the rotation difference ΔN
If exceeds the allowable variation value NO (ΔN≧NO), it is determined that the operating state is transient and the process proceeds to 5105.

Then, when proceeding to 5104, the pressure correction value setting flag FK
After setting p, proceed to 8106, and then proceed to 5105
When proceeding to , the pressure correction value setting flag FKp is set and the routine exits.

On the other hand, when proceeding to 5104, l
Find the average value PH of the numbered intake pipe pressure PB (
PH-Σ pB /n ), 5107 Te, the suction pipe pressure correction value Kl) is calculated from the following formula based on the estimated suction pipe pressure P (t) calculated in the previous routine and the above-mentioned average suction pipe pressure PH.

2 Kp = (P)l −P(t) ) /P(
t) ...(1) Then, in 8108, the suction pipe pressure correction value Kp is set in the corresponding area of the pressure correction value map MPKI), which is configured using the throttle opening degree α and the engine speed N as parameters. Store.

Next, in 5109, based on the estimated suction pipe pressure P (t) and the suction pipe pressure correction value Kp, a corrected suction pipe pressure PN is set from the following equation.

PN=P(t) (1+Kp) ...(
2) Then, in 5110, the throttle valve passing air m Q HAT is set from the throttle valve passing air amount map M p QHAT using the corrected suction pipe pressure PN and the throttle opening α as parameters. Also, 5
In step 111, a cylinder intake air gap map M P is created using the corrected suction pipe pressure PN and engine speed N as parameters.
Set the cylinder intake air PQMAP from QHAP.

The above throttle valve passing air amount map MPQHAT,
The above-mentioned cylinder intake air map M P QHAP is a three-dimensional map that takes the corrected intake pipe pressure PN, throttle opening α, corrected intake pipe 3 pressure PN, and engine speed N as parameters, and is specified by the above parameters. The area stores data on the amount of air passing through the throttle valve and data on the amount of intake air in the cylinder, which have been determined in advance through experiments and the like.

Then, at 5112, the throttle valve passing air Q
Based on the Q MAP between the HAT and the cylinder intake air, the estimated intake pipe pressure P(t) calculated in the previous routine, and the intake temperature T set based on the output signal of the intake temperature sensor 6, the next Estimated suction pipe pressure P (
t→1) is obtained from the following equation.

P (t+1) = K (QHAT -QH
AP') 10 P (t) (3) However, the coefficient is a function of the intake air temperature T (K=f(T)).

Then, at 8113, the estimated suction pipe pressure P(t+1)
is stored at a predetermined address in the RAM 24 (t+
1) ) , deviate from the routine.

By the way, Fig. 5 shows the intake system model, where the air ff1M in the bumper comb V is the current air 4 air aM(t), the inflowing air d (throttle valve passing air 1) QHAT, and the cylinder The amount of air supplied into the cylinder (between cylinder intake air) and the difference from QHAP, that is, M = M (t) + (QHAT - QHAP)
...It can be expressed as (4).

Also, the equation of state in the chamber volume V is P−V
= M-R-T ... (5) P: Chamber internal pressure R: Gas constant ■ = Intake air temperature, and from the above equations (4) and (5), the chamber internal pressure P can be determined by ■ .

When considering the time element, '-X-(M(t)) is.

■ Since the current pressure inside the chamber is P (t), the above (6
) If P on the left side of the equation is considered to be the chamber internal pressure P (t+i) in the following equation, the above equation (6) becomes 5 -T P(t+1)= (QHAT-QHAP
)+P(t)■...(7) It can be transformed as follows.

Furthermore, if we consider the gas constant R and chamber volume ■ to be constant at -T, then becomes a function of the intake air temperature T, and therefore, the above chamber internal pressure P(t+1) is
It can be determined if the amount of air passing through the throttle valve QHAT, the cylinder intake air lQNAP, and the intake air temperature T are set.

Therefore, the estimated chamber volume V above (3
) can be derived by the formula.

Further, the amount of air passing through the throttle valve QH^■ has a constant functional relationship between the throttle opening area (throttle valve opening) and the intake pipe pressure, regardless of the engine speed N. On the other hand, the above-mentioned cylinder intake air interval Q MAP
has a certain functional relationship between suction pipe pressure and engine speed. Therefore, using these as parameters,
APs can be mapped.

The suction pipe pressure PH, which is a parameter when setting the air amount Q HAT passing through the throttle valve and the cylinder intake air Q NAP, is set in step 5109, but 51
In 07, the average value PM of the actually measured suction pipe pressure PB
The deviation Kp between the estimated suction pipe pressure P (t) and the estimated suction pipe pressure P (t) is calculated, and in step 5109, the estimated suction pipe pressure P (t) is corrected by the deviation Kp. can set a substantial suction pipe pressure (corrected suction pipe pressure PN') corresponding to an error or deterioration over time.

Furthermore, since the actually measured suction pipe pressure PB is averaged, the influence of pressure fluctuations due to intake air interference is small.

(Fuel injection control procedure) As shown in FIG. 4, first, in 5201, the throttle opening α and the engine rotation speed N are calculated, and in 5202, it is determined whether the pressure correction value setting flag FKp is in the reset state, If FKp=O, it is determined that the operation is steady and the process proceeds to 5203; if FKp=1, it is determined that the operation is in a transient state and the process proceeds to 5204.

Proceeding to 5203, a pressure correction value map MPK is created using the throttle opening α and engine speed N as parameters.
A pressure correction value Kl) is set based on p.

Further, when proceeding to 5204, the pressure correction value Kp is uniformly set to 110.
Set to 1+.

Then, in 5205, based on the pressure correction value set in 5203 or 5204 plus 1 and the estimated suction pipe pressure P (t) stored in 8113 of the Ic control program, the corrected suction pipe pressure PN is set as the ) is obtained from the formula.

Next, in 8206, using the engine speed N and the corrected intake pipe pressure PN as parameters, the cylinder intake air is adjusted to the cylinder intake air interval QM based on the map MpQHAP.
Configure AP.

Then, at 5207, the cylinder intake air fi Q MA
Basic fuel injection ITEI based on P and engine speed N
is set from the following formula.

Tp =K-QHAP/N...(
8) K: Constant 8 Thereafter, in step 5208, the basic fuel injection amount Tp is calculated based on the output signal of the sensor 11. The fuel injection ITi should be set by correcting it using the set air-fuel ratio feedback correction coefficient KFB etc.T=Tp xcO[Fx
KFB), predetermined timing 'JT:, outputs a drive pulse corresponding to the above fuel injection amount Ti to the injector 9,
Falling out of routine.

In this way, during transient operation with many disturbance elements, the pressure correction value Kp is set by calculation (S105), and in fuel injection control, the pressure correction value Kp is set to the predetermined value 11011.
(3204), this not only simplifies the calculation process and reduces the burden on the ECU 21, but also
Malfunctions during transient operation can be prevented.

[Effects of the Invention] As described above, according to the present invention, the corrected suction pipe pressure, which is a parameter when setting the throttle valve passing air supply, J: and cylinder intake air distance, is calculated based on the estimated suction pipe pressure. Since the pressure was set at a value corrected by the suction pipe pressure correction value set based on the deviation between the actually measured suction pipe pressure and the estimated suction pipe pressure, in α-N control, the intake air pressure supplied to the cylinder can be accurately estimated without being affected by control errors such as throttle valves, assembly errors, and aging deterioration, making it possible to significantly improve air-fuel ratio control accuracy.

Furthermore, since the suction pipe pressure detected by the suction pipe pressure detection means is averaged for each set cycle, four measurements can be made accurately without being affected by pressure fluctuations due to intake air interference.

Furthermore, since the suction pipe pressure correction value during transient operation is set to a predetermined value, malfunctions during transient operation with many disturbance elements can be effectively prevented.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 and the following show an embodiment of the present invention, Fig. 2 is a general schematic diagram of the engine control system, and Fig. 3 shows the procedure for setting the pressure correction value. flower
4 is a 70-day diagram showing the procedure for setting the fuel injection amount l1FJ to 0, and FIG. 5 is a conceptual diagram showing the intake state. Kp... Suction pipe pressure correction value, Ml... Throttle valve passing air amount setting means, M2... Cylinder intake air gap setting means, M3... Estimated suction pipe pressure setting means, M4...
- Suction pipe pressure averaging processing means, M5...pressure correction value setting means, M6...correction suction pipe pressure setting means, M7...
・Basic fuel injection tAt setting means, M HPKP...pressure correction value map, N...engine speed, PB...suction pipe pressure, PM...average suction pipe pressure, PN...correction suction pipe Pressure, P (t)... Estimated suction pipe pressure, Q M
AP...Cylinder intake air gap, Q HAT...Amount of air passing through the throttle valve, Tp...Basic fuel injection amount, α.
・Throttle valve opening mark. 1 Procedural amendment (flag) August 1, 1990, Indication of the case 1990 Patent Application No. 98529 Name of the invention Engine fuel injection control device 3, Person making the amendment Relation to the case Address of patent publication Name Name Fuji Heavy Industries Co., Ltd., 7-2 Nishi-Shinjuku-chome (534), Shinjuku-ku, Tokyo Date of amendment order: July 31, 1990 (Shipping port) 6. Drawings subject to amendment

Claims (1)

[Claims] Throttle valve passing air amount setting means for setting the amount of air passing through the throttle valve based on the throttle valve opening and the corrected suction pipe pressure set by the corrected suction pipe pressure setting means; and an estimated suction pipe pressure setting means for estimating the suction pipe pressure based on the difference between the amount of air passing through the throttle valve and the amount of intake air in the cylinder. and suction pipe pressure averaging processing means for setting the average suction pipe pressure by averaging the suction pipe pressure detected by the suction pipe pressure detection means for each setting cycle, and the above estimated suction pipe pressure and the above average suction during steady operation. The suction pipe pressure correction value is set based on the deviation from the pipe pressure, and the above suction pipe pressure correction value is stored in a pressure correction value map that uses throttle opening and engine speed as parameters. a pressure correction value setting means for setting a suction pipe pressure correction value to a predetermined value; and a correction suction pipe for setting a corrected suction pipe pressure by correcting the estimated suction pipe pressure with the suction pipe pressure correction value during steady operation. A fuel injection control device for an engine, comprising a pressure setting means and a basic fuel injection amount setting means for setting a basic fuel injection amount based on the above-mentioned cylinder intake air amount and engine rotational speed.