JPH04128532A - Fuel supply controller of internal combustion engine - 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 (Field of Application of L-Rakudo) The present invention relates to a fuel supply control device for an internal combustion engine, and in particular, the present invention relates to a fuel supply control device for an internal combustion engine. 5. Related to the fuel supply control device for internal combustion engine There is a so-called speed density method.

As shown in Figure 5, this method takes advantage of the fact that when the engine speed is constant, there is a proportional relationship between the intake pipe pressure (negative pressure) P8 and the engine charging efficiency ηυ. , the basic amount of fuel corresponding to the intake pipe internal pressure and engine speed is retrieved from a map stored in advance in the storage means, and fuel is supplied to the engine accordingly.

The P8-ηυ characteristic in FIG. 5 is based on the normal type engine shown in FIG. This is a characteristic obtained in an engine provided with only one valve 56). In this conventional engine, the aperture 57
Absolute pressure P8 inside the intake pipe (collecting pipe) is detected by a pressure sensor 58 that communicates with the collecting part 55 via the intake pipe (collecting pipe).

The inside of the downstream collecting section of the throttle valve 56 forms a surge tank having a large volume chamber, and therefore the pulsating changes in the internal pressure PII are small. For this reason,
If the engine speed and air-fuel ratio are constant, the filling efficiency ηt
1 (σ basic fuel amount) is maintained in a state approximately proportional to the pressure pH in the collecting pipe. In addition, even when the atmospheric pressure PA changes (for example, when driving at high altitudes), the throttle valve is fully open (WOT).
The pressure I) decreases due to the decrease in atmospheric pressure PA (P,
#PA) alone, the proportional relationship between the charging efficiency +71+ and the intake pipe pressure Y)8 is maintained not only during WOT but also under other operating conditions. Therefore, a series of speed-density methods can be applied to such ordinary types of machinery, and even if there is a change in atmospheric pressure PA,
Changes in exhaust pressure due to this (for example, internal exhaust gas recirculation (EG)
If the influence of R) (change in amount) is ignored, there is no change in filling efficiency ηi) due to change in atmospheric pressure PA, and therefore there is no need to correct the basic fuel amount based on atmospheric pressure PA.

(Problems to be Solved by the Invention) However, when the fuel calculation method based on the speed density method is applied to, for example, a multiple throttle type engine as shown in FIG. 7, the following problems occur. In the case of such a method of detecting the pressure inside the intake pipe in one-scene multiple throttle type, the relationship between the charging efficiency ηυ and the pressure inside the intake pipe PB is not proportional as shown in FIG. 5 above, but is shown by the solid line in FIG. 8. As shown in the figure, it has been confirmed through experiments that η11 is lower for the same -Ps value than in the case of a normal type engine (dashed line)1. 71 to 74 intake pipe 71a~
Throttle valves 71b to 74b are provided upstream of 74a and downstream of gathering portion 75, respectively. Each intake pipe 71
The pressure in a to 7 and 4a is obtained by taking in the pressure in each intake pipe 71a to 74a through throttles 71c to 74c, respectively, collecting the taken pressure in a vibrator 76, and transmitting it to a pressure jumper 77. Determined by detection. In this way, the pressure sensor 77 detects the average value of the pressure inside each intake pipe,
This detected value is defined as the intake pipe absolute pressure P□.

By the way, when the above method is adopted for a multiple throttle engine, the pressure transmitted to the pressure jumper 77 becomes the composite negative pressure of the cylinder during the intake stroke and the cylinder other than the intake stroke, but the pressure of the cylinder other than the intake stroke Since j is close to atmospheric pressure, the combined pressure is a value that is shifted toward atmospheric pressure compared to normal types of pressure.

Therefore, as shown in Fig. 8, the air filling efficiency η for the same intake pipe internal pressure P is compared to a normal type engine.
υ becomes lower. However, when the throttle valve is fully open (WOT), air is not throttled and is supplied to the intake pipe at a sufficient flow rate, so the filling efficiency η1+ has the same value as a normal type engine.

In line with the characteristics shown in Figure 8 above, the intake pipe absolute pressure P, A and engine speed N are determined by the conventional speed density method.
If a map for calculating the basic fuel amount Ti is created based on e and applied to a multiple throttle engine, the following problems will occur.

For example, when creating a map of the intake pipe absolute pressure P and A versus the basic injection quantity, a large number of characteristics are required depending on the atmospheric pressure PA, as shown in FIG. Therefore, the amount of data stored increases, resulting in high costs.

However, in order to reduce costs, atmospheric pressure P
Assuming that A = 760 mm and 11 g, the absolute pressure in the intake pipe is P I
When calculating the basic injection amount based on IA, when the atmospheric pressure PA decreases, the proportional relationship between the intake pipe absolute pressures P and A and the required fuel amount does not hold in operating ranges other than the throttle valve fully open (WOT). , the relationship is complicated as shown in FIG. 9, making it impossible to calculate an accurate fuel injection amount.

The present invention has been made in view of the above circumstances, and it is noted that the air filling effect on the intake pipe internal pressure (72cm) output value is normally A fuel supply control device for an internal combustion engine that can more accurately and easily calculate the fuel supply amount regardless of changes in atmospheric pressure in an internal combustion engine that is much lower than the current internal combustion engine. The purpose is to provide and measure the

(Means for Solving Problem Y) In order to solve the above problems, the present invention provides an intake pipe absolute pressure detection means for detecting the absolute pressure in the intake pipe of an internal combustion engine, an atmospheric pressure detection means for detecting the intake pressure, An engine rotation speed detection means for detecting the engine rotation speed, a differential pressure calculation means for calculating the differential pressure between the inlet air pressure and the absolute pressure in the intake pipe, and a differential pressure calculated by the differential pressure calculation means and the following: Calculating the basic fuel amount according to the rotational speed and the basic fuel calculation means, and correcting the basic fuel amount according to the differential pressure and atmospheric pressure. k) a correction value calculation means for calculating the correction value of the second correction value, and a fuel supply amount calculation means for calculating the fuel supply amount by correcting the basic fuel amount by the second correction value; Example) Hereinafter, one embodiment of the present invention will be explained based on the drawings.

FIG. 1 is an overall configuration diagram of a fuel supply a1 device for an internal combustion engine according to an embodiment of the present invention.

In the figure, 1 is a multi-throttle internal combustion engine.In the intake pipe 20L of each cylinder, a throttle body 3 is installed, and a throttle valve 3' is installed inside it. The throttle valve 3' has the throttle valve opening (
θ Engineering 11) Palm +4 is connected, and outputs an electric signal according to the opening degree of the throttle valve 3' to control the electronic control unit (A), called "F rEC [1J"].
Supply to 5. .

The fuel injection valve 6 is provided for each cylinder between the engine] and the throttle valve 3' and a little on the J2 side of the intake valve (not shown) of the intake v2, and each injection valve is connected to a fuel pump (not shown). Each intake ￥f2σ) Sloso h JL # which is electrically connected to the ECL 15 and whose fuel injection valve opening time is controlled by a signal from the ECU 3.
Immediately downstream of 3'.

A v7 having a throttle 7a branches 5, and this pipe 7 is connected to a vibrator 14 which also connects to the pipe 7 of the other intake pipe 2, and an intake pipe absolute pressure (P, , A) sensor 8 is installed at one end of the vibrator 14.
are connected, and the absolute tap 1) in each intake pipe 2 is connected to the pipe 7.
The pressure is taken in through the sensor, collected by the vibrator 14, transmitted to the absolute pressure sensor 8, and converted into an electrical signal by the sensor. This converted absolute pressure (P, E) signal indicating the average absolute pressures P and A of each intake pipe 2 is supplied to the ECU 3.

On the other hand, an engine rotational speed (Ne) sensor 9 is attached around a crankshaft (not shown) of the engine 1.

The engine speed sensor 9 is located on the crankshaft of the engine 1.
At a predetermined crank angle position every 80 degree rotation, that is, at a predetermined crank angle position at the start of the intake stroke of each cylinder,
・Signal pulse (hereinafter referred to as rT) at the crank angle position before rT
It outputs a DC signal pulse (referred to as "DC signal pulse"). This TDC signal pulse is supplied to the ECU 3. Further, the ECU 3 is electrically connected to an atmospheric pressure (PA) sensor 10, and is supplied with a detected atmospheric pressure (PA) signal.

EC1J5 shapes the waveform of human input signals from various sensors,
! An input circuit 5a having functions such as adjusting the pressure bell to a predetermined level and converting an analog signal value into a digital signal value.
, central processing circuit (0 lower rcPLIJ, !=u”5
) 5b, a storage means 5c for storing various calculation programs and calculation results executed by the CPTJ 5b, an output circuit 5d for supplying a drive signal to the fuel injection valve 6, and the like. 2 due to various engine parameters from sensors not shown in the figure.
The fuel injection time T of the fuel injection valve 6 is determined according to various engine operating states and is synchronized with the DC signal based on the following equation (1) according to the engine operating state. Calculate the value. The calculation of this fuel injection time T C1kl T is as follows:
This is done based on the program described below.

TouT” Tix KrAX Kl+ K2
・ ・ (In here, Ti is the injection time T of the fuel injection valve 6. It is the basic injection amount of LIT, and the engine rotation speed Ne
, and T17:2 (not shown) set according to the differential pressure PA-P, A between the atmospheric pressure PA and the intake pipe absolute pressure P IIA.
read from the block. KPA is atmospheric pressure pA according to the present invention
This is a correction coefficient determined according to the differential pressure PA-P, and is read out from the FA map, as will be described later.

K, , and K are correction coefficients and correction variables that are calculated according to various engine parameter signals, respectively, and are set to predetermined values to optimize engine performance characteristics such as fuel consumption characteristics and engine acceleration characteristics according to engine operating conditions. The value has been determined.

The CPU 5b calculates the fuel injection time T obtained as described above.

A drive signal for opening the fuel injection valve 6 based on L and T is supplied to the fuel injection valve 6 via the output circuit 5d.

In this embodiment, the ECU 3 constitutes a differential pressure calculation means, a basic fuel amount calculation means, a correction value calculation means, and a fuel supply amount calculation means.

Next, a method for calculating the fuel supply amount according to the present invention will be explained.

Based on the relationship between the filling efficiency ηυ and the intake pipe absolute pressures P and A in FIG. 8, as shown in FIG.
Calculate the differential pressure between the intake pipe absolute pressure PIIA and the intake pipe absolute pressure PIIA.

Then, 6PA can have all the characteristics at the point where PA-P8A=0! ] BA'''O2, that is, when the throttle valve is fully open, the relationship between the absolute pressures P and A and the basic injection amount Ti is proportional as in a normal engine.

Therefore, as shown in Fig. 3, for example, P A = 650 + n
Basic injection amount T1 when the throttle valve is fully open when mHl (
．． In order to obtain , it is sufficient to obtain in advance the basic injection amount TIA when the throttle valve is fully open when PA = 760 miHg. That is, an accurate fuel injection amount when the throttle valve is fully open can be determined using the following equation (2) at any atmospheric pressure.

L-mu-T l h”T
lpX! “Tomoe---(2) TiA760
+60 This can be explained from the following.

When the throttle valve is fully open, the opening area A of the throttle part is constant, and if the engine speed is constant, the air flow rate t (is also constant. Therefore, the air flow rate Q = A
v also becomes constant.

Furthermore, air weight = QXρ (ρ is air density) (3)
Also, ρ−ρ. ×−P−5×−force−−・(4
)760 (273÷t) [ρ0 is the air density in the standard state, t is the intake air temperature 1 equation (4
), if the influence of the intake air temperature t is ignored, then (5) p#p0x76
0 Substituting equation (5) into equation (3) gives Mu ・(6) G ” Q x P ox760. Therefore, it can be seen that the air weight G is proportional to Mu. If so, the required fuel injection amount is also W
It can be understood from the second fact that equation (2) is correct.

In this way, as long as the throttle valve is fully open, even if the atmospheric pressure changes, the fuel injection amount Ti can be easily and accurately calculated using the above equation (2). However, at times other than when the throttle valve is fully open, the opening area A of the throttle section is not constant, so the above equation (2) cannot be applied, and therefore the fuel injection amount cannot be calculated accurately.

For example, considering the case of idling, when the atmospheric pressure PA decreases, pA "BA becomes smaller, so the basic fuel injection amount Ti is set to a larger value as shown in Fig. 3 for the same intake air amount. , so when atmospheric pressure decreases,
The air-fuel ratio tends to become richer than when the throttle valve is fully open.

Therefore, in the present invention, the differential pressures P, , -P, and A are calculated by dividing them into P, and one of the plurality of predetermined lines PGN of P6 is selected according to the differential pressure PG, and according to the detected atmospheric pressure PA. The correction value on the selected line P is set as the atmospheric pressure correction coefficient K1. This is what is sought as A.

That is, as shown in the map of FIG. 4, three lines Pco""Pc) corresponding to WOT, partial load, and idle are shown as examples for the above-mentioned line P, and these lines are selected when the differential pressure PG takes on each predetermined value. When the differential pressure P6 takes a value between these predetermined values, an appropriate line is determined by interpolation calculation. In the example map in Figure 4, the atmospheric pressure is up to 760 m) I
When it is between g~600rodl, each line PG0~
In PC2, the correction coefficient KPAO value decreases and is inclined in the direction of ). This means that the differential pressure P, (=PA-P,A) is the same value and t.

If the atmospheric pressure pA is low, the amount of intake air will be small, so
This is because the amount of fuel needs to be reduced accordingly.

Also, when the atmospheric pressure is less than 600 mmHg, line P
, o-P, , is the correction coefficient k PA value 0.8.0.7
．． Each is fixed at 0.6. In addition, the value of KPA is set to be smaller in the P and N lines where Pc is large, that is, in the L) line where the differential pressure between the atmospheric pressure PA and the intake pipe absolute pressure PIIA is applied. This is because the intake air amount tends to decrease as the differential pressure P increases, so the fuel amount also needs to be reduced accordingly. Detected atmospheric pressure))
The value of the P line to which A corresponds is read out as the correction coefficient krA.

The atmospheric pressure correction coefficient k l' A obtained in this way is
Based on the formula (1), as described later, the differential pressure r G
and the basic fuel injection 1k T i read from the T1 map according to the engine speed Ne.

Next, the procedure for calculating the fuel injection amount T, 11.1□ will be described based on the program flowchart shown in FIG.

Note that this program is executed in synchronization with each TDC signal pulse.

First, in step S], when the intake pipe absolute pressure PIIA, atmospheric pressure PA, and engine speed Ne are detected, in step S2, the differential pressure P between the atmospheric pressure PA and the intake pipe absolute pressure P is detected.
, :1(=PA-P,A) is calculated.

In step S3, this differential pressure P, the engine rotation #Ne
Based on this, the basic injection amount Ti is searched from the Ti map. 20T1 map is, for example, P in Fig. 3 mentioned above.
It is created based on the characteristics of A=760mm1G.

Next, in step S4, the differential pressure PI1. In order to obtain the correction value kPA based on the value of , the line PcN of P6 is set according to the map shown in FIG. In step S5,
Based on the set line PGN and the atmospheric pressure PA, the correction coefficient kPA is read out using the map shown in FIG.

In this way, the basic injection amount T1 of fuel and its correction coefficient,
After searching for A, in step S6.

11” According to formula (1), T1 is the atmospheric pressure correction coefficient KP.
3. A and other correction factors. The correction variable is corrected by the fuel injection amount T. Calculate LIT and end this program.

In this way, in this example, the atmospheric pressure PA is 76OnonJ
Based on the T1 map based on the time of atmospheric pressure PA
Search for the basic injection amount Ti according to the differential pressure P9 between the absolute pressure in the intake pipe and the absolute pressure pHA, and the engine speed Ne, and calculate the basic injection amount Ti according to the engine rotation speed Ne.
Since the value is corrected using the correction value KPA retrieved based on the differential pressure P6 and the atmospheric pressure PA, the fuel injection amount T (ILIa) can be calculated accurately with a small amount of memory.

In this example, this method was applied to a multiple throttle internal combustion engine, but the invention is not limited to this, and even if the engine is a typical Eve type internal combustion engine with only one throttle valve, the intake pipe The present invention can also be applied to internal combustion engines with a small collecting part volume, and internal combustion engines with a large valve/L valve overlap between the intake valve and the exhaust valve.

(Effect for light) 4. As described above, according to the present invention, the intake pipe absolute pressure detection means for detecting the absolute pressure in the intake pipe of the internal combustion engine, the atmospheric pressure detection means for detecting the atmospheric pressure, and the engine an engine rotation speed detection means for detecting the rotation speed; a differential pressure calculation means for calculating a differential pressure between the atmospheric pressure and the absolute pressure in the intake pipe; and a differential pressure calculated by the differential pressure calculation means and the engine rotation speed. a basic fuel amount calculating means for calculating a basic fuel amount of fuel according to the differential pressure and the atmospheric pressure, a correction value calculating means for calculating a correction value for correcting the basic fuel amount according to the differential pressure and atmospheric pressure, and this correction value. and a fuel supply amount calculation means for calculating the fuel supply amount by correcting the basic fuel amount,
The basic fuel supply amount is searched according to the differential pressure such as atmospheric pressure and the absolute pressure in the intake pipe, and the engine speed, and the basic fuel supply amount is corrected by the correction value searched based on the differential pressure and atmospheric pressure. Therefore, the fuel supply amount T can be determined accurately with a small amount of memory and regardless of changes in atmospheric pressure. 1. Calculation of lT can be performed.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a reactor material supply control device according to an embodiment of the present invention, Fig. 2 is a flowchart showing a goragelum for calculating the fuel injection amount, and Fig. 3 is a flowchart showing a flowchart for a multi-throttle type internal combustion engine. Applicable atmospheric pressure PA, differential pressure P A-P
4th diagram showing the relationship between llAl and basic injection amount T1
The figure does not show a calculation map for the correction coefficient KPA based on the differential pressure P and the atmospheric pressure P6.
Figure 6 is a schematic diagram showing the configuration of a normal type internal combustion engine, Figure 7 is a diagram showing the configuration of a multiple flow/torque type internal combustion engine, and Figure 8 is a diagram showing the configuration of a multiple throttle type internal combustion engine. A diagram showing the relationship between intake pipe absolute pressure PHA and air filling efficiency ηt in an internal combustion engine. Figure 9 shows the basic injection jlT according to atmospheric pressure PA and intake pipe absolute pressure PhA in a multiple throttle internal combustion engine. In the calculation map, t
-) 4,] Internal combustion engine 22 Intake pipe, 3' Throttle valve, 5...EC11 (differential pressure calculation means, basic fuel amount calculation means, correction value calculation means, fuel supply jl calculation, f stage], 8 Intake pipe Absolute pressure palmist, 9 Nishijin concave rotation number 7shi strange, 10
Atmospheric pressure, PA Atmospheric pressure, )'RA Absolute pressure in the intake pipe, P3. Differential pressure, T1-basic injection amount, d(l L+
7 Fuel injection amount.

Claims (1)

[Claims] 1. Intake pipe absolute pressure detection means for detecting the absolute pressure in the intake pipe of an internal combustion engine; atmospheric pressure detection means for detecting atmospheric pressure; engine rotation speed detection means for detecting engine speed; A differential pressure calculating means for calculating a differential pressure with respect to an absolute pressure; a basic fuel amount calculating means for calculating a basic fuel amount of fuel according to the differential pressure calculated by the differential pressure calculating means and the engine rotation speed; a correction value calculation means for calculating a correction value for correcting the basic fuel amount according to the differential pressure and atmospheric pressure; and a fuel supply for calculating the fuel supply amount by correcting the basic fuel amount using the correction value. 1. A fuel supply control device for an internal combustion engine, comprising: quantity calculation means.