JPS6131635A - Fuel feed control in cranking of internal-combustion engine - Google Patents

Abstract

PURPOSE:To permit the superior start even when the fuel property varies or the battery voltage lowers by counting the frequency of fuel injection and correcting the fuel injection amount according to said counted value, when an engine is in cranking state. CONSTITUTION:When an engine starts, an ECU5 judges if the water temperature Tw detected by a water-temperature sensor 9 is over a prescribed value (e.g., 0 deg.C) or not, and if the judgement is NO, the existence of cranking state is judged. In other words, it is judged if the number Ne of revolution which is detected by a revolution speed sensor 10 is below the number NCR of cranking revolution (e.g., 400rpm), and if the judgement is YES, the TDC counted value nCR corresponding to the frequency of fuel injection is added by 1 to form a new nCR value. When the nCR value is below a prescribed upper limit value, the valve opening standard-time correction coefficient value of a fuel injection valve 6 is set to 1, and when the nCR value is over the prescribed upper limit value, the correction coefficient value is set to a prescribed value smaller than 1 according to the counted value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a fuel supply control method during cranking that improves the starting characteristics of an internal combustion engine.

(Technical background of the invention and its problems) The opening time of a fuel injection valve during cranking of an internal combustion engine, particularly a gasoline engine, is adjusted according to the engine temperature, and the amount of fuel supplied is reduced as the engine temperature increases. A fuel supply control method that sets a reference valve opening time at This method has been proposed by the present applicant (Japanese Patent Laid-Open No. 57-206736).

In such a fuel supply control method, the reference valve opening time during cranking is set according to the engine temperature because a part of the injected fuel adheres to the inner wall of the intake pipe or the cylinder, and the fuel evaporates. This is because the amount of fuel changes depending on the engine temperature, and in particular when the engine temperature is low such as during a cold start, a large amount of fuel is supplied to the engine to obtain good starting characteristics. However, due to changes in the volatile content of the fuel due to engine neglect, the amount of fuel supplied to the engine during cranking may not necessarily be the optimal value for ignition, and due to such changes in fuel properties, Due to changes in ignition performance due to a drop in battery voltage, for example when the device is cold,
If the cranking state continues for a long period of time without igniting after one or several spark discharges and without reaching a state where the engine can operate independently due to complete ignition (this is defined as a "complete explosion state"), The air-fuel ratio of the air-fuel mixture in the combustion chamber gradually becomes richer, and as a result, a so-called fogging or smoldering phenomenon occurs in the ignition plug, making ignition increasingly difficult.

(Summary of the Invention) The present invention has been made to solve the above problems, and provides a fuel supply control method that enables starting even when starting is difficult due to changes in fuel properties or a drop in battery voltage. The purpose is to provide. In order to achieve such an object, the present invention provides a fuel supply control method for injecting and supplying an amount of fuel according to an engine temperature value to an internal combustion engine when the internal combustion engine is cranking. There is provided a fuel supply control method during cranking of an internal combustion engine, characterized in that the number of fuel injections in a certain state is counted, and the fuel amount is corrected according to the counted value.

(Example of the invention) Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is an overall configuration diagram of a fuel supply control system to which the method of the present invention is applied. Reference numeral 1 indicates, for example, a four-cylinder internal combustion engine, and an intake pipe 2 is connected to the engine 1. A throttle body 3 is provided in the middle of the intake pipe 2, and a throttle valve 3' (not shown) is provided inside. A throttle valve opening sensor 4 is connected to the throttle valve 3', which converts the valve opening of the throttle valve 3' into an electrical signal and controls an electronic control unit (hereinafter referred to as rEC1) 5.
It is supposed to be sent to

A fuel injection valve 6 is provided in the intake pipe 2 between the engine 1 and the throttle body 3. The fuel injection valve 6 is connected to a fuel pump (not shown) and electrically connected to the ECU 3, and the opening time of the fuel injection valve 6' is controlled by a signal from the ECU 3.

On the other hand, an absolute pressure sensor 8 is provided downstream of the throttle valve 3' of the throttle body 3 via a pipe 7.
The absolute pressure signal converted into an electrical signal by the absolute pressure sensor 8 is sent to the ECU 3.

An engine water temperature sensor 9 is provided on the engine 1 body,
This sensor 9 is composed of a thermistor or the like, and is installed in the peripheral wall of the engine cylinder filled with cooling water, and supplies a detected water temperature signal to the ECU 3.

Engine speed sensor (hereinafter referred to as rNe sensor) 1
The Ne sensor 10 outputs a TDC signal, that is, one pulse at a predetermined crank angle position every 180° rotation of the engine crankshaft. , this pulse is sent to the ECU3.

Further, a starter 11 is attached to the engine 1 to drive the engine 1 during cranking.
is connected to a battery 13 via a starter switch 12. The starter switch 12 is also connected to the ECU 3 and supplies an on/off state signal to the ECU 3.

The engine ignition switch 14 is connected to the ECU 3, and the ECU 3 is connected to the ignition switch 1.
4 on/off state signals are supplied. Furthermore, other parameter sensors 15 such as an intake air temperature sensor, an atmospheric pressure sensor, and an 02 sensor are connected to the ECU 3, and the ECJJ
'5 is supplied with a detection signal from another parameter sensor 15.

Next, the operation of the fuel supply control device configured as described above will be explained.

Operating parameter signals from the throttle valve opening sensor 4, absolute pressure sensor 8, engine water temperature sensor 9, Ne sensor 10, etc. are supplied to the ECU 3, and the ECU 3 receives these operating parameter signals from the starter switch 12 and the ignition switch 14. The engine operating state, such as cranking, is determined based on the on/off state signal, and the fuel supply amount to the engine 1, that is, the opening time Tout of the fuel injection valve 6, is calculated according to the determined state.

Valve opening time TOu during cranking of the fuel injection valve 6
T is given by the following formula.

Tout:kCRXTi cgXKNe +Tv-(1
) Here, Ticg is the valve opening reference time of the fuel injection valve 6 during cranking, which is set according to the engine water temperature value Tw, and the valve reference time Ticg value during this period is, for example, T in FIG.
It can be found from the ic art T, w table. Ticg-T
w table is a calibration variable for the valve opening reference time Ticg value and the engine water temperature value Tw, and is set to a predetermined value Tc2. -5. Twc*□-s is set, and the actual water temperature detection value Tw is each value TwcRz-
If it is in the middle of s, the valve opening reference time TicR is calculated by interpolation calculation.

kce is a valve opening reference time correction coefficient that is set according to the number of fuel injections by a control program shown in FIG. 1, which will be described later.

KNe and Tv are a correction coefficient and a correction variable, respectively, which are set according to, for example, an engine rotational value, a battery voltage value, etc.

FIG. 4 is a diagram showing the circuit configuration inside the ECU 3 of FIG.
The engine rotation speed signal from the Ne sensor 10 in FIG. Me.
The counter 502 counts the time interval from when the previous predetermined position signal was input from the Ne sensor 10 to when the current predetermined position signal was input, and the counted value Me is proportional to the reciprocal of the engine rotation speed Ne. Me counter 502 supplies this counted value Me to CPU 503 via data bus 510.

Throttle valve opening sensor 4, absolute pressure sensor 8 in Fig. 2,
The respective output signals from various sensors such as the engine water temperature sensor 10 are corrected to a predetermined voltage level by a level correction circuit 504, and then sequentially supplied to an A/D converter 506 by a multiplexer 505. The A/D converter 506 sequentially converts the output signals from each sensor described above into digital signals and sends the digital signals to the CP via the data bus 510.
Supply to U503.

The on/off state signals from the starter switch 12 and ignition switch 14 in FIG.
After the signal is corrected to a predetermined voltage level in step 12, it is converted into a predetermined signal in a data input circuit 513 and supplied to the CPU 503 via a data bus 510.

The CPU 503 is further connected to a read-only memory (hereinafter referred to as FROMJ) 507, a random access memory (RAM) 508, a nonvolatile memory 511, and a drive circuit 509 via a data bus 5.10.
508 temporarily stores the calculation results etc. in the CPU 503, and the ROM 507 stores the aforementioned Tie large table and the CPU 50.
The non-volatile memory 511 is a RAM connected so as to continue to be supplied with power regardless of whether the ignition switch 14 is turned on or off, and stores the control program, etc., which will be described later and is executed in step 3. Store the TDC count value ncg. Then, the CPU 503 calculates the fuel injection time Tout of the fuel injection valve 6 according to the various engine parameter signals described above according to the control program stored in the ROM 507, and sends this calculated value to the drive circuit 50 via the data bus 510.
Supply to 9. The drive circuit 509 supplies a drive signal to the fuel injection valve 6 to open the fuel injection valve 6 according to the calculated value.

FIG. 1 is a flowchart showing the procedure for setting the valve-opening reference time correction coefficient value kce (hereinafter simply referred to as "coefficient value +4J") executed in the CPU 503 of FIG. 4, according to the present invention.

First, when the engine ignition switch 14 is turned on, the CPU 503 in the ECU 3 initializes (step 1), and at the same time reads the TDC count nil stored in the nonvolatile memory 511 (step 2). In step 3, the new T
Let the DC count value be ncR. The reason why the predetermined value Nc2g is added here is to quickly make the air-fuel mixture supplied to the engine lean through steps 4 to 13, which will be described later, and to prevent plug fogging.

Thereafter, the processing from step 4 to step 13 is performed using the above-mentioned TD.
The engine is started due to an interrupt by the C signal, and in step 4, the engine water temperature value Tw is set to a predetermined value Twcek (for example, 0°C).
Determine whether or not the above is true, and the determination result is affirmative (Yes)
If so, reset the TDC count value nQg to zero (step 5) and set the coefficient value kcyB to the value 1.0 (
Step 6). If the determination result in step 4 is negative (NO), the process proceeds to step 7.

In step 7, it is determined whether the engine is in a cranking state. This determination can be made, for example, by the engine speed value Ne.
is a predetermined cranking rotation value Nc (for example, 400p)
pm) or less and determine whether the engine rotation value Ne
If it is less than the cranking rotational value NC, R, it is determined that the engine is in the cranking state. If the determination result in step 7 is negative (NO), that is, if the engine leaves the cranking state and enters the complete explosion state, the process proceeds to step 5 described above and the ncyH value is reset to zero. If the determination result in step 7 is affirmative (Yes), the value 1 is added to the TDC count value ncR to obtain a new ncg value (step 8). This TDC count value nQR represents the number of fuel injections when cranking continues without the engine reaching a complete explosion state, and TDC
DC count value nQg is stored in nonvolatile memory 511. The nQi value stored in the nonvolatile memory 511 is retained even when the ignition switch 14 is turned off, and as described above, when the ignition switch 14 is turned on again, this stored ncg value is read into the CPU 503 (step 2).

Next, in steps 9 to 11, the TDC count value nQl is determined. That is, in step 9, TD
If the C count value ncg is a predetermined upper limit value n14LM (for example, 50
0) or less, in step 10 it is determined whether or not it is less than a predetermined value ncgl (for example, 250), and in step 11 it is determined whether or not it is less than or equal to a predetermined value nQ*o (for example, 100). Determine. Now, if the TDC count value nCR is less than or equal to the predetermined value n c Ro (100), that is, if the determination results in steps 9 to 11 are all affirmative (Yes), the coefficient value keg is set to the value 1.0 (step 6)
. The TDC count value ncR is nap, and the complete explosion state of the engine cannot be obtained when the value is below the value, and the TDC count value nol is the predetermined value nc,
! .

(IQO) or more and less than or equal to the predetermined value nQR-(250), the coefficient value kce is set to a predetermined value Kc2o' (for example, 0.85) (step 12). Coefficient value keg
By setting KcRo to a predetermined value, the air-fuel mixture in the engine combustion chamber becomes slightly leaner.

In addition, if the engine cannot be fully detonated.

That is, when the TDC count value nc4 is greater than or equal to the predetermined value nc*□ (250) and less than or equal to the upper limit value nCRLM (500), the coefficient value kc4 is set to the predetermined value KQR□ (for example, 0.7). Makes the mixture more concentrated. Also, the determination result in step 9 is negative (No), that is, TD
C count value ncR is the predetermined upper limit n cgLM (500)
When the TDC count value ncR is reset to zero (step 5), the coefficient value kcg is set to 1.0 (step 6), and the air-fuel mixture is returned to a state in which no correction is made by the coefficient value keg. In this way, the air-fuel mixture is repeatedly leaned by the coefficient value keg corresponding to the TDC count value nQH until the engine reaches a complete explosion state.

The coefficient value kcyH set as described above is calculated using both equations (1
), and the valve opening time ToutT during cranking of the fuel injection valve 6 is set.

(Effects of the Invention) As detailed above, according to the present invention, the number of fuel injections when the internal combustion engine is in a cranking state is counted, and the amount of fuel supplied to the engine is corrected according to this counted value. As a result, optimal ignition conditions can be obtained regardless of changes in fuel properties, and this increases the possibility that the engine will reach a complete explosion quickly even if it is difficult to start, improving engine starting characteristics. .

Also, since the TDC count value nQl is stored in non-volatile memory, the stored TDC count value n (4) is retained even if the ignition switch is turned off, and even if the ignition switch is turned off during cranking. When the engine is turned on again, it is possible to continue counting the number of fuel injections from the stored n0g value, and optimal ignition conditions can be quickly obtained.

Furthermore, since the predetermined value Ncgg is added to the nc4 value when the ignition switch is turned on, the optimum ignition conditions can be quickly obtained.

[Brief explanation of drawings]

FIG. 1 is a flowchart illustrating the procedure for setting the fuel injection valve opening reference time correction coefficient kcg during cranking according to the present invention, and FIG. 2 is a fuel supply control of an internal combustion engine to which the method of the present invention is applied. The overall configuration of the device, Figure 3 is a diagram explaining the fuel injection valve opening reference time TicR table during cranking, and Figure 4 shows the internal configuration of the electronic control unit (F, CU) 5 in Figure 2. It is a block diagram. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 5... Electronic control unit (ECU), 6... Fuel injection valve, 9... Engine water temperature sensor, 10... Engine rotation speed sensor (N
e sensor), 12...Starter switch, 503...
- Central processing unit (CPU), 507... Read only memory (ROM), 508... Random access memory (RAM), 511... Nonvolatile memory. Volume 1 illustration

Claims (1)

[Scope of Claims] 1. In a fuel supply control method for injecting and supplying an amount of fuel according to an engine temperature value to an internal combustion engine when the internal combustion engine is cranking, the number of fuel injections when the internal combustion engine is in a cranking state. 1. A fuel supply control method during cranking of an internal combustion engine, characterized in that the amount of fuel is corrected according to the counted value. 2. The fuel supply control method during cranking of an internal combustion engine according to claim 1, wherein the fuel amount is corrected to decrease as the count value of the number of fuel injections increases. 3. The fuel supply control method during cranking of an internal combustion engine according to claim 1, wherein the fuel amount is corrected when the engine temperature value is below a predetermined value. 4. The count value of the number of fuel injections is reset to zero when the internal combustion engine leaves the cranking state and reaches a complete explosion state. A fuel supply control method during cranking of an internal combustion engine. 5. When the internal combustion engine leaves the cranking state and stops without reaching a complete explosion state during the previous cranking of the internal combustion engine, storing a count value of the number of fuel injections at the time of stopping, The fuel supply control method during cranking of an internal combustion engine according to claim 1, characterized in that counting of the number of fuel injections is started using the stored count value as an initial value during cranking this time. . 6. The fuel supply control method during cranking of an internal combustion engine according to claim 5, characterized in that the stored value of the number of fuel injections is stored in a non-volatile storage means. 7. The internal combustion engine according to claim 4 or 5, wherein counting of the number of fuel injections is started using a value obtained by adding a predetermined value to the stored count value as an initial value. Fuel supply control method during cranking. 8. Fuel supply during cranking of an internal combustion engine according to claim 1, wherein the counted value of the number of fuel injections is reset to zero every time the counted value reaches a predetermined value. Control method.