JPS59201938A - Fuel injection control method - Google Patents

Abstract

PURPOSE:To improve the drivability by controlling a judgement level of the increased volume of power to regard a pressure of a suction pipe lasting for a fixed time based on the output of the suction pipe sensor with driving condition of an engine revolution number being below a fixed value and an opening degree of a throttle valve being above a fixed value as an atmospheric pressure. CONSTITUTION:A control circuit taking in output signals of a suction pipe pressure sensor has a signal processing circuit consisting of the first low pass filter LPF10, the second LPF12 having a delay of response by twice, a subtracter 14 to subtract signals V1 and V2 of each LPF10 and 12, and an adder 16 to output V4 showing 2V1-V2 gained by inputting the output signal V3 of the subtracter 14 and the V2. When a driving state with an engine revolution number being below a fixed value and an opening degree of a throttle valve being above a fixed value lasts for the time till the signal V4 is nearly damped, the signal V4 is read as an atmospheric pressure. If this value is below a fixed value, a decisive value to correct the fuel injection volume is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control method, and more particularly to a fuel injection control method for an internal combustion engine, in which the amount of fuel injection is set based on the pressure in the intake pipe and the engine rotation speed. It is.

In general, in automobile engines that use three-way catalysts and are equipped with exhaust gas purification measures, the exhaust gas is completely blown out, so it is necessary to control the air-fuel ratio, which indicates the combustion state of the engine, to be close to the stoichiometric air-fuel ratio. be.

For example, the air-fuel ratio is detected based on the residual oxygen concentration in the exhaust gas. Feedback control has conventionally been performed to adjust the air-fuel ratio to the stoichiometric air-fuel ratio depending on the output of the two sensors.

When the engine is operating under light load, the amount of nitrogen oxides emitted from the exhaust gas is small, so even if the air-fuel ratio is shifted to a leaner side than the stoichiometric air-fuel ratio, the exhaust emissions will not deteriorate much, and fuel efficiency can be improved. I can do it.

Based on these points, feedback control controls the air-fuel ratio so that the engine is operated at the stoichiometric air-fuel ratio,
Proposed an internal combustion engine for automobiles that switches between feed-forward control of the air-fuel ratio and lean control according to operating conditions so that the air-fuel ratio is operated leaner than the stoichiometric air-fuel ratio, thereby improving fuel efficiency. It's visible.

In such an internal combustion engine, for example, the engine cooling water temperature is 80℃ or higher, the intake pipe pressure is 550mlI-1g or lower, the intake throttle valve opening is 30 degrees or lower, and the vehicle speed is 15km/h with the intake throttle valve fully closed or not fully closed. above, and when the vehicle speed change within 2 seconds is 0.7 km/h or less.

Lean control is being executed. And one example.

Lean control is not in progress and the engine cooling water temperature is 40℃ or higher.
The feedback control is ridiculous when I am not cutting fuel but increasing power.

However, when driving at high altitudes, the atmospheric pressure itself decreases, and even in driving conditions where feedback control is possible on flat terrain, the intake pipe pressure decreases by the atmospheric pressure drop, so there is a risk that lean control will be executed. There is. In this case, the cutting edge decreases and drivability deteriorates.

On the other hand, in an internal combustion engine having a catalyst as described above, when the intake pipe pressure is at a predetermined level or higher and the load is high, power increase correction is performed to increase the fuel injection amount.

The aim is to increase output torque and reduce catalyst temperature.

However, for the same reasons as mentioned above.

Even in driving conditions where you can increase the power when driving on flat ground.

When driving at high altitudes, there is a driving range where power cannot be increased.

In such an operating range, it is impossible to increase the output torque and reduce the catalyst temperature, resulting in decreased drivability and problems with the durability of the catalyst. Such problems also occur in idle engines that selectively perform feedback control, open loop control, lean control, etc. as appropriate.

An object of the present invention is to propose a fuel injection control method that improves the drivability of a vehicle using various fuel injection control methods using intake pipe pressure by performing altitude compensation.

By the way, in an engine that determines the fuel injection amount based on intake pipe pressure and engine speed.

A signal processing circuit has been proposed that removes the pulsating component of the pressure signal detected by the intake pipe pressure sensor and at the same time improves the responsiveness during transients.

As shown in FIG. 1, this signal processing circuit includes a first low-pass filter IO connected to the pressure sensor, a second low-pass filter 12 following the first low-pass filter 0, and a first low-pass filter IO. Signal from Ronokusu filter 10■
, and the signal ■ from the second low/cus filter 12,
a subtracter 14 that calculates (V, -V21) with the input awn;
The signal V from the subtractor 14 and the first low-pass filter J
Signal V1 from O is input and added, +2V, -V2
and an adder 16 which outputs a signal V4ffi indicating 1.

The second low-pass filter 12 is selected to have a response delay approximately twice that of the first low-pass filter 10.

The intake pipe pressure is a pulsating component of about 20 to 30 Hg when the throttle valve is relatively closed, but when the engine speed is relatively low and the throttle valve is open for a predetermined period or more, When the intake pipe pressure is close to atmospheric pressure, the peak-to-peak value is 100 rm Hg,
The signal processing circuit configured in this manner can improve the rise characteristics of the intake pipe pressure, and is also effective in removing pulsating components when the intake pipe pressure is close to atmospheric pressure.

cn et al. each signal V, ~V4u, 4th u, A), (B
) It has the characteristics shown in K. In C, the point at which the signal 4 substantially converges is shown as the decay time T1.

Incidentally, a specific example of the circuit shown in FIG. 1 is shown in FIG. In this example, three operational amplifiers OP1 to OP3 are used. It is composed of resistors R, 1 to R5 (!:,), and performs the same signal processing as explained in the block diagram above.

In the first to fourth inventions, the operating state in which the engine speed is below a predetermined value and the intake throttle valve opening is above a predetermined value is:
The intake pipe pressure read after continuing for at least the decay time of the output signal from the signal processing circuit of the intake pipe pressure sensor is considered to be atmospheric pressure.

In the first invention, when the atmospheric pressure data is below a predetermined value, the determination level for determining whether or not to increase the power is set to small σ, and in the second invention, the smaller the atmospheric pressure data is, the larger the value is set in the intake pipe. In the third invention, the basic fuel injection time reduced in lean control is prevented from becoming less than a predetermined value, and the fourth invention
In the invention of.

The smaller the atmospheric pressure data is, the greater the pressure is added to the intake pipe pressure to determine whether lean control is necessary or not.

According to the present invention, it is possible to prevent a decrease in output torque during high-altitude driving, and to improve the durability of the catalyst.

The present invention will be explained based on the following five drawings.

FIG. 4 shows a configuration example of an internal combustion engine for an automobile including an electronic fuel injection control device to which the present invention is applied. The air filter 1 is connected to a throttle body 5 via an inlet vibe 3. The throttle body 5 is provided with a fuel injection valve 7 on its upstream side, and an intake throttle valve 9 that adjusts the amount of intake air in conjunction with an accelerator pedal (not shown) is provided downstream of the fuel injection valve 7. An intake pipe absolute pressure sensor 11 is provided downstream of the intake throttle valve 9 to measure the absolute pressure at that location. Further, there is a valve opening position sensor 2 that measures the opening position of the intake throttle valve 9, an idle switch 4 that is turned on only when the intake throttle valve 9 is fully open, and a valve opening position sensor 2 that measures the opening position of the intake throttle valve 9, and an idle switch 4 that is turned on only when the intake throttle valve 9 is fully open. There is a power switch 6 that turns on only when the temperature exceeds the temperature.

Several phrases are mentioned in relation to the intake throttle valve 9.

The throttle body 5 is connected to the intake manifold 13, which has a branch pipe connected to each cylinder of the engine.
The intake manifold 13 is provided with an intake temperature sensor 15 that measures the intake air temperature within the intake manifold 13. [Intake manifold] The bottom wall 13a before the branch of intake manifold 3 has a riser section 1 for circulating engine cooling water and heating the air-fuel mixture.
7 is provided.

Reference numeral 19 designates a well-known engine body, which includes a piston 21, a cylinder 23, and a cylinder head 25, and a combustion chamber 27.
The air-fuel mixture drawn into the combustion chamber 27 through the intake valve 29 is ignited by the spark plug 31. A water jacket 33 is formed around the cylinder 23, and engine cooling water is circulated through the 700 water jacket 33 to cool the parts including the cylinder 23. and.

A water jacket 3 is provided on the outer wall of the cylinder block 35.
An engine coolant temperature sensor 37 is provided to measure the temperature of the engine coolant in the engine.

An exhaust manifold 39 is connected to an exhaust boat (not shown) of the cylinder head 250, and an oxygen sensor 41 for measuring the residual oxygen concentration in the exhaust gas is provided downstream of the exhaust manifold 39. The exhaust manifold 39 is connected to an exhaust pipe 45 via a three-way catalyst 43.

47 is a transmission connected to the engine body 19;
There are several vehicle speed sensors 49 that measure the speed of the vehicle based on the number of revolutions of its final output shaft.

Further, 51 is a key switch, and 53 is an igniter.

55 is a distributor, and the distributor 55 is provided with a Ne sensor 57 that outputs an on/off signal at every predetermined crank angle θl.

The G sensor 59 can determine the engine speed and a predetermined crank angle position from the output signal, and also outputs an on/off signal at every angle θ2 larger than the angle θ1.
is provided, and its output signal is used to determine the cylinder and to detect the dead center position. I cut it. 60 indicates a battery.

The control circuit 6J includes a valve opening position sensor 2, an idle switch 4, a power switch 6, an intake pressure sensor]1. Intake temperature sensor 15. Engine coolant temperature sensor 37.0□Sensor 4
1. Vehicle speed sensor 49. Key switch 51. Ne sensor 5
7. They are connected to the G sensor 59 and the battery 60, respectively, and receive a valve opening signal Sl, an idle signal S2, a power signal S3, an intake pressure signal S4 . Intake temperature signal S5. Water temperature signal S6° Air fuel ratio signal S7. Vehicle speed signal S8. Start signal S
9. Engine speed signal S10. A cylinder discrimination signal S11 and a battery voltage signal S14 are input from each sensor. The control circuit 61 also includes the fuel injection valve 7 and the igniter 5.
3, and outputs a fuel injection signal S12 and an ignition signal 813 based on predetermined calculations.

As shown in FIG. 5, the control circuit 61 includes a central processing unit (CPU) 61a that controls all of the various devices.

One-drive only memory (ROM) 6 lb in which various numerical values and programs are written in advance, random access memory (RAM) 61 c in which numerical values and flags for calculation processes are written in predetermined areas, A/D converter (ADC) to convert 61 d,
An input/output interface (Ilo) 61e through which various digital signals are manually input and output, a puncture-up memory (BU-RAM) 61f that retains memory when powered from an auxiliary power source when the engine is stopped, and these. Pass line 61g that each device can be connected to
It consists of The program described below is in ROM61.
b is written in advance.

In the engine described above, fuel is injected according to the flowchart shown in FIG. Referring to Figure 6, 5
In step P1, the engine speed Ne is read based on the engine speed signal S1, which is a reference position signal, and the intake pipe pressure PMi is read based on the intake pipe pressure signal S4. In step P2, 5 revolutions 1'Je and intake pipe pressure P
Based on M.

Determine the basic injection time TP from the map shown in Figure 7. 5 Steps P3
In this step, a corrected injection time τ is determined by executing a correction calculation process according to the operating conditions of the engine.

Here, the corrected injection time τ by the correction calculation process of step P3
The operation of is explained in detail.

The injection time τ is generally determined by the following equation.

r=TPXFWLXFAFXFTHAX (FTC+F
PO+PSE+FLEAN)...(1)
Where: TP - Basic fuel injection time FWL - Warm-up increase coefficient FA A, F - Air-fuel ratio feedback correction coefficient FTC -
Transient air-fuel ratio correction coefficient I! ” T I-IA - Intake temperature correction coefficient FSE - Post-start increase coefficient FPO = Power increase coefficient FLEAN - Lean correction coefficient Then, each coefficient is calculated based on the τ calculation routine shown in Fig. 8, and the injection time τ is determined. Desired.

That is, the warm-up increase coefficient FWL is calculated at step pH, and the air-fuel ratio feedback correction coefficient F is calculated at step P12.
The AF calculation process is executed, the transient air-fuel ratio correction coefficient FTC is completely calculated in the second step P13, the power increase coefficient FPO is calculated in the fifth step P14, and the post-start increase coefficient PSE is calculated in the first step P15. Execute the calculation process of the lean correction coefficient FLEAN in step P]6, and execute the calculation process of the lean correction coefficient FLEAN in step P3.
7 to find the intake temperature correction coefficient F T HA, ? ', and in step P18, calculate the above equation (]) and execute step P in Figure 6.
Return to 4.

In step P4, the final injection time Fτ is determined by correcting the corrected injection time τ according to the battery voltage, and the injection timing is determined in step P5.Then, the final injection time Fτ is determined from the fuel injection valve 7 at the timing of step P6. Fuel is injected with the injection valve 7 fully open for a time corresponding to .

Next, each step from pH to P17 in FIG. 8 will be explained.

The procedure pH warm-up increase coefficient FWL in FIG. 8 is.

For example, engine cooling water temperature THW and engine speed Ne
Based on this, the lower the water temperature THW and the unreasonable engine speed Ne, the larger the value obtained.

This is to increase the basic fuel injection time TP.

In addition, the air-fuel ratio feedback correction coefficient FA of step P12
F is 1, for example, a value smaller than 1.0 when the air-fuel ratio signal S7 from the sensor 41 is larger than the reference value, and a value larger than 1.0 when it is smaller than the reference value.

In addition, the transient air-fuel ratio correction coefficient FTC in step P13 is calculated by calculating the total amount of change in intake pipe pressure based on the intake pressure signal S4 from the intake pipe pressure sensor 11, and based on the amount of change, the amount of change is large. The larger the value is obtained, the more the basic fuel injection time TPi is increased.

Further, the power increase coefficient FPO of one step P14 is calculated as follows.

Referring to FIG. 9, when this program is started at a predetermined timing, it is determined in the fifth hand Il@P 51 whether or not the engine rotation speed Ne is greater than 400 Orpm. Then, it is determined whether the data PMA read as atmospheric pressure is smaller than 700tTBHg. If the atmospheric pressure PMA is less than 700 smHg, in other words, if it is determined that the area is at a high altitude, the process proceeds to step P53. In step P53, it is determined whether the latest data on the intake pipe pressure PM is greater than 4501 Hg. Pressure I) If M is thicker than 450mmHg, 2 steps P55
In order to increase the power, the power increase coefficient FPOk1
．． 15. On the other hand, the pressure PM is 450 am I-I
If it is worse than g, in step P56, the power increase coefficient FPO is set to 0 to prevent the power increase.

In step P52, atmospheric pressure PMA is 700■I-1g
If the pressure PM is greater than 500, proceed to step P54.
Determine whether it is greater than arm Hg. If an affirmative determination is made, in step P55, the power increase coefficient FPO'
i=1.15, and if a negative determination is made, the power increase coefficient FPO is set to zero in step P56.

In addition, even when the rotational speed Ne is 400 Orpm or less.

The coefficient FPOtd becomes zero.

Next, referring to No. 10, the procedure for determining the lean correction coefficients FLEA, N in step P16 of FIG. 8 will be explained.

When the program shown in FIG. 10 is started, first step P
In step 21, a full judgment is made as to whether the mode condition XMODE is satisfied. This condition is satisfied when the engine is not in the starting state, when the engine is not in the initial state after starting, and when the output is not increasing.The starting state is determined based on the start signal S9 and the engine speed signal S10, Whether the output is being increased or not is determined based on the post-start increase coefficient PSE stored in a predetermined storage area, and whether or not the output is being increased is determined based on the power increase coefficient stored in the predetermined storage area. Judgment based on FPO is disgusting. If this condition is satisfied, step P22
In step P23, it is determined whether the lean control execution conditions are satisfied or not, and if they are satisfied, the process proceeds to step P23. The execution conditions for lean control are 1. For example, the water temperature THW is 80℃ or higher, the intake pipe pressure PM is 550m) (g or higher, the intake throttle valve opening is 50 degrees or lower, and the amount of change in vehicle speed SPD and engine rotation speed Ne Satisfied when the amount of change in is less than a predetermined value.

These conditions are determined by the water temperature signal S6. Intake pipe pressure signal 84. Power signal S3. This determination is made based on the vehicle speed signal S8 and the engine speed signal SIO.

1l-1 in step P23: RA is set in advance as described later.
Data PMA as atmospheric pressure stored in M61C
700nnHg or less.
If it is below, it is determined that the area is at a high altitude and the process proceeds to step P24.
Lean correction coefficient FLEA stored in RAM61C
Determine whether N is smaller than 0.8.

If it is less than 08, in step P25, the lean correction coefficient FLE
AN Total 0.8 and this arithmetic routine is completely terminated.

That is, in lean control during high-altitude driving, the minimum value of the lean correction coefficient FLEAN is limited to 0.8.

In step P23, if it is determined that the atmospheric pressure PMA is not less than 700 fiHg, the process proceeds to step P26.

In step P26, it is determined whether the intake throttle valve 9 has a fully closing force or not based on the idle signal S2, and if an affirmative determination is made, step P is performed.
Proceed to step P27, and if the determination is negative, proceed to step P28, and press R.
The lean correction coefficient FLEAN stored in a predetermined area of AM61C is set to i0.92, and this l''LEAN calculation process is completely completed. In this case.

Lean control is implemented. In step P27, a lean correction coefficient FLEAN is determined based on the intake pipe pressure PM from a map of the intake pipe pressure PM and the lean correction coefficient FLEAN having the relationship shown in FIG. 11, and is temporarily stored in the A register.

Next, proceed to step P29, and the engine speed Ne is 250.
Orpm or less is judged, and if the judgment is affirmative, in step P30, the value of the A register is multiplied by Ne/2500, and in step P31, the result is judged to be greater than 1.0. Let fi i be 1.0, and 1.
If it is determined to be unscrupulous than 0, step P32 is skipped and the process proceeds to step P33. In step P33, the lean correction coefficient FLEAN stored in a predetermined area of %RAM61C is 1.
．． 0, i.e.

It is determined whether or not feedback control based on the air-fuel ratio signal S7 is being performed, and if the determination is affirmative, a full determination is made in step P34 as to whether the vehicle speed SPD is 10 Km/h or more. If an affirmative judgment is made, in step P35, RA, M61Ct7)
Store the contents of the AV register in the predetermined area FLEAN and end this process. When the vehicle speed SPD is 10 Km/'h or less and the number of rotations Ne is 250 Orpm or more, and when the condition
1.0 is stored in the storage area FL EAN, and this arithmetic routine ends.

In addition, the intake temperature correction coefficient FTHA of 5 steps P l '7 is:
This is done to compensate for the density of the intake air, which varies depending on the temperature, and a predetermined value k is set in the digital pupil of the intake air temperature THA.
It can be found by adding.

Next, the atmospheric pressure data PM described above with reference to FIG.
Reading of A will be explained.

The program shown in FIG. 12 is started every 4 Q m s, and in one step P41 it is determined whether the power signal S3 is on (high level) or not. In other words, it is determined based on the total power signal S3 whether the intake throttle valve 9 is opened by 50 degrees or more. If the intake throttle valve opening is 50 degrees or less, proceed to step P4.
Proceed to step 2 and reset the counter COU to zero. If the power signal S3 is on, the process advances to step P43, where it is determined whether the engine rotational speed Ne is 200 Orpm or less. If the determination is negative, all counters COU are reset in step P42.

If the intake throttle valve 9 is open 50 degrees or more and the engine speed Ne is 2000 rpm or less, proceed to step P4.
4K advance. In step P44, the counter COU is incremented by +1. Then, in step P45, counter C
It is determined whether the value of OU is equal to 250 or not, and if an affirmative judgment is made (6), in step P46, the latest intake pipe pressure data is stored in a predetermined area HMA of RAM61C to be regarded as atmospheric pressure. End the calculation routine.

In this way, the first. Second Invention In this embodiment, when the engine operating state in which the intake throttle valve opening degree is 50 degrees or more and the engine speed Ne is 200 Orpm or less is maintained for 1 second, the latest intake air When calculating the pressure increase coefficient FPO and lean correction coefficient FLEAN by multiplying the pipe pressure data by 1 no. from the atmospheric pressure PMA, the atmospheric pressure PMA is 7.
' If it is smaller than OOmyx Hg, it is determined that the altitude is high, and the judgment level f is used to determine whether or not to increase the amount of water.
From 500 +o+Hg to 450mI-Ig, and
The minimum deviation of the lean correction coefficient FLEAN was limited to 0.8.

Therefore, there is no possibility that the output will decrease during high-altitude driving or that the catalyst will become overheated and its durability will be affected.

3 with reference to FIGS. 13 and 14. An embodiment including the fourth invention will be described.

When the FPO operation program shown in Fig. 13 is started, 1
In step P6], it is determined whether the engine speed Ne is 400 rpm or more, and in step P62, it is determined whether the data PMA read as atmospheric pressure is 700 mnHg or less. When these steps are answered in the affirmative and the process proceeds to step P63, the process proceeds to step P63.

1 straight 76-. Showing atmospheric pressure on flat ground. Subtract data 1) M A from 0τHg and use the result as intake pipe pressure P
It is added to M to obtain a new intake pipe pressure PM. Next.

In step P64, the intake pipe pressure PM is 500+o.
It is determined whether or not it is greater than +Hg, and if an affirmative determination is made, the power increase coefficient FPOi is set to 1.15. Steps P61, P
If a negative judgment is made in 62 or P64.

In step P66, the power increase coefficient F P O”(r
Set to zero.

When the FLEAN calculation program shown in FIG. 14 is started, it is determined in step P71 whether or not the XMODE condition is satisfied, and if an affirmative determination is made, the process proceeds to step P72, in which it is determined whether the atmospheric pressure PMA is greater than 700 mHg. to judge.

If the PMA is more than 700 mHg, proceed to step P73. In step P73, the data PMA is subtracted from the value 760Hg indicating the atmospheric pressure on flat ground, and the result is added to the intake pipe pressure PM to create a new intake pipe pressure PM.
shall be.

In step P74, similarly to step P22 shown in FIG. 10, it is determined whether the lean control conditions are satisfied or not. If the judgment is affirmative, step P75 is proceeded to, and the idle switch 4 is turned off. ) power 1 no car f judgment i1
-ru. For the subsequent steps, see step 110 in Figure 1O.
Since it is the same as P.27 to P.36, it will be omitted.

Power increase coefficient FPO, 'J-on correction coefficient I'LEAN
The rest is the same as the first embodiment described above.

In this way, in the embodiments including the third and fourth inventions, the pressure PMA force (7oof) I read as atmospheric pressure is
If it is lighter than g, subtract atmospheric pressure data PMA' from 760 m Hg, which indicates the popular IEli on flat ground,
Altitude compensation is performed by adding the result to the intake pipe pressure PM. Note that the value (760w+Hg) indicating the atmospheric pressure on flat ground varies depending on the specifications of the engine, and may be, for example, 740mmHg.

By the way, in step P45 of FIG. 12, ti and engine rotational speed Ne are 200 Orpm or less, and.

A full judgment is made as to whether the intake throttle valve opening is 50 degrees or more or has remained open for more than 1 second.
This value is larger than the decay time TI of the output signal 4 in the signal processing circuit explained in FIG.

[Brief explanation of drawings]

Figure 1 is a block diagram showing an example of a circuit that processes signals from an intake pipe pressure sensor, Figures 2 (A) and (B) are time charts showing signal waveforms of each part of the processing circuit, and Figure 3 is a 1 is a circuit diagram showing a specific example, FIG. 4 is a configuration diagram showing an example of an automobile internal combustion engine to which the present invention is fully applied, FIG. 5 is a detailed block diagram showing an example of its control circuit, and FIG. 6 is a fuel A flowchart showing an example of the injection procedure, Fig. 7 is a diagram showing an example of a map for reading out the basic fuel injection time TP from the engine speed Ne and the intake pipe pressure 1) M, and Fig. 8 is a diagram showing an example of the correction injection. A flowchart showing an example of the procedure for calculating the time τ, FIG. 9 is a flowchart showing an example of the calculation process for the power increase coefficient FPO, and FIG. 10 is a flowchart showing an example of the calculation process for the power increase coefficient FPO.
Flowchart showing an example of EAN calculation processing, No. 11
The figure is a graph showing the relationship between intake pipe pressure PM and lean correction coefficient FLEAN, Figure 12 is a flowchart showing an example of a procedure for reading data as atmospheric pressure, and Figure 13 is another example of the calculation process of power correction coefficient FPO. FIG. 14 is a flowchart showing another example of the calculation process of the lean correction coefficient FLEAN. 7...Injection valve, 9...Intake throttle valve, 11...Intake pipe pressure sensor, 13...Intake manifold% 1
5-゛. Intake temperature sensor, 17... Riser part, 19... Engine body h 27... Combustion chamber, 33... Water jacket. 37...Engine coolant temperature sensor, 41...02 sensor, 49...Vehicle speed sensor, 51...Key switch. 53...Igniter, 55...Distributor. 57...Ne sesen% 59...G sensor, 61...
control circuit. Agent: Tatsuyuki Unuma (and 1 other person) Figure 1 (A) (B) Nissaimont
-■脣h1 ↑- Figure 3○P3 Figure 6 Figure 8 Figure 9 Figure 11

Claims (4)

[Claims] (1) The output signal from the pressure sensor provided in the intake passage is supplied to a first filter to filter out the pulsation component to obtain a first signal, and this first signal is transmitted to the first filter. , and subtracts the value of the second signal from the value obtained by approximately doubling the first signal to obtain a third signal. The intake pipe pressure is read based on the third signal, the basic fuel injection time is calculated based on the read intake pipe pressure and the engine speed, and at least when the intake pipe pressure is equal to or higher than the first judgment value, In the fuel injection control method that performs power correction to increase the basic fuel injection time, an operating state in which the engine rotation speed is below a predetermined value and the opening degree of the intake throttle valve is above a predetermined value is determined by at least the third signal. The third signal is read as atmospheric pressure when it continues for a period of time until it almost attenuates. A fuel injection control method characterized in that the first determination value is decreased when the blood level is below a predetermined level. (2) The output signal from the pressure sensor provided in the intake passage is supplied to the first filter, the pulsation component is filtered to obtain the first signal, and this first signal is transmitted to the first filter. and a third signal is obtained by subtracting the value of the second signal from the value obtained by approximately doubling the first signal. The intake pipe pressure is read based on the third signal, the basic fuel injection time is calculated based on the read intake pipe pressure and the engine speed, and at least when the intake pipe pressure is equal to or higher than the first judgment value, In the fuel injection control method in which power is corrected to increase the basic fuel injection time, at least the third signal is detected in an operating state in which the engine rotation speed is below a predetermined value and the opening degree of the intake throttle valve is above a predetermined value. When the third signal continues for a period of time until it almost attenuates, the third signal is read as atmospheric pressure. A fuel injection control method characterized in that when the value is less than a predetermined value, the value (vL) read as the atmospheric pressure is added to the intake pipe pressure as the value is unreasonably large. (3) Supply the output signal from the pressure sensor provided in the intake passage to the first filter to filter out the pulsation component to obtain the first signal, and send this il signal to the first filter. The second signal is supplied to a second filter having a response delay approximately twice that of the first signal, and a third signal is obtained by subtracting the value of the second signal from the value obtained by approximately doubling the first signal. The intake pipe pressure is read based on the signal in step 3, the basic fuel injection time is calculated based on the read intake pipe pressure and engine speed, and the air-fuel ratio is leaner than the stoichiometric air-fuel ratio under predetermined operating conditions. In the fuel injection control method that performs lean correction in which the basic fuel injection time is completely reduced according to the intake pipe pressure, when the engine speed is below a predetermined value and the opening degree of the intake throttle valve is above a predetermined value, The operating state is at least the third
When the signal continues for a period of time until it almost attenuates,
The fuel injection control is characterized in that the third signal is read as atmospheric pressure, and when the atmospheric pressure is below a predetermined value, the basic fuel injection time that is reduced in the lean correction is prevented from becoming less than a predetermined value. Method. (4) The output signal from the pressure sensor provided in the intake passage is supplied to the first filter to filter out the pulsation component to obtain a first signal, and this first signal is transmitted to the first filter. , and a third signal is obtained by subtracting ([ of the second signal from a value that is approximately twice the first signal. The intake pipe pressure is read based on this third signal, and the basic fuel injection time is calculated based on the read intake pipe pressure and engine speed, and the air-fuel ratio is determined to be stoichiometric under predetermined operating conditions. In a fuel injection control method in which the basic fuel injection time is reduced or compensated for depending on the intake pipe pressure so that the fuel ratio is leaner than the fuel ratio, the engine rotation speed is below the t'Ir constant, and the intake air When the operating state in which the opening degree of the throttle valve is below a predetermined value continues for at least the time at which the third signal is almost attenuated, the third signal is read as atmospheric pressure, and the Oli is determined to be below the predetermined value. A fuel injection control method characterized in that, in some cases, the more unfavorable the value read as the atmospheric pressure, the larger a value is added to the intake pipe pressure.