JP2551378Y2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly to a technique for improving engine stability immediately after starting.

<Prior Art> In an electronically controlled fuel injection device for an internal combustion engine, in order to improve the startability, the fuel injection amount is increased from the normal fuel injection amount at the start (cranking) to improve the ignitability. (See Japanese Utility Model Application Laid-Open No. 61-183437).

That is, normally, the fuel injection amount corresponding to the intake air amount per unit rotation of the engine is basically set, but when the starter switch is ON and the starter motor is driven in the cranking state, the engine temperature is set in advance. The starting basic injection amount T _ST stored in association with the representative cooling water temperature Tw
The a rotational speed correction coefficient K _NST starting time injection amount T ₁ obtained by correcting the like, a normal and constant coefficient of fuel injection amount Ti which is set to correspond to the intake air amount per Similarly engine unit rotation comparing the fuel injection quantity T ₂ obtained by increasing by multiplying, by selecting something towards the greater fuel injection amount is a fuel injection amount in the cranking state.

Immediately after the transition from the cranking state in which the increased fuel is supplied to the state in which the normal fuel injection control is performed, the stability of the engine deteriorates. A correction coefficient _KAS is provided to increase and correct the injection amount Ti immediately after and at the start of the engine.

The startup correction coefficient K _AS is in the cranking state, the fuel injection quantity T ₂ and increasing correction according to the decrease of the coolant temperature Tw, is reduced to gradually reference value immediately after the cranking completion The normal fuel injection amount Ti is increased until the reference value is reached.

<Problems to be solved by the invention> By the way, the time from the start of cranking to the complete explosion (cranking time) varies greatly depending on engine conditions (battery voltage, engine oil, etc.). Then, the engine stability immediately after the start was greatly affected.

That is, as shown in FIG. 5, the cranking time T is A,
B, if they occur a variation in C, for example, when B is a standard cranking time T ₁ is the injection amount of the sum in the cranking when cranking time T is longer C than B Since the excess fuel injection becomes larger than the standard B and remains in the intake port and the cylinder, the air-fuel ratio immediately after the start tends to be enriched, while the cranking time T is larger than the standard B. In the case of A, the sum of the injection amounts during cranking is smaller than the standard B, and the amount of fuel remaining in the intake port and the cylinder is smaller than the standard B. Indicates a lean tendency.

However, conventionally, after the fuel injection amount in accordance with the coolant temperature Tw at the time the correction coefficient K _AS by cranking start has been increasing correction, in the after-start returning gradually reference value from the values in the cranking Irrespective of the length of the cranking time, the amount is increased in a predetermined period immediately after the start based on the amount of increase determined by the cooling water temperature at the time of cranking. When the cranking time T becomes longer or shorter, the air-fuel ratio immediately after starting cannot be corrected for the change in the air-fuel ratio due to the residual fuel amount, and the air-fuel ratio immediately after the start greatly deviates from the target air-fuel ratio. Sometimes it disappeared.

The present invention has been made in view of the above-described problem, and the water-temperature-dependent increase correction value for a predetermined period immediately after the start is changed according to the cranking time, so that the air-fuel ratio immediately after the start is affected by the cranking time. It is an object of the present invention to enable correction corresponding to a state.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, the fuel injection amount is set based on the engine operating state, and the drive of the fuel injection means is controlled based on the set fuel injection amount. In the electronically controlled fuel injection device for the internal combustion engine, the cranking state detecting means for detecting the cranking state of the engine, the engine temperature detecting means for detecting the engine temperature, and the cranking state detecting means In the cranking state, the fuel injection amount is increased and corrected in accordance with the engine temperature detected by the engine temperature detecting means, and the starting and starting are performed such that the increased amount is gradually reduced from the end of cranking to zero. Cranking time required from the start to the end of cranking based on the detection result of the post-increase amount correction means and the cranking state detection means The cranking time measuring means to be measured and the increasing correction amount at the end of cranking by the starting and post-start increasing correction means are corrected based on the cranking relaxation measured by the cranking time measuring means, and the correction is performed. When the cranking time is shorter, the decreasing rate when the increasing correction amount is gradually decreased with the increased increasing correction amount as the initial value is set to be larger, and the increasing correction amount is set to be greater as the cranking time is shorter. And a post-start increase correction means for correcting so as to reduce the amount.

<Operation> According to this configuration, the fuel injection amount is increased and corrected in accordance with the engine temperature in the cranking state, and the increased correction amount is gradually reduced from the end of cranking to zero to change to zero. A configuration in which the increase correction amount at the end of ranking is corrected based on the cranking time, and the decrease rate when the increase correction amount is gradually reduced from the corrected initial value is also corrected based on the cranking time, Further, the decreasing rate is set to be larger as the cranking time is shorter, and the increasing correction amount is decreased at a larger decreasing rate as the cranking time is shorter.

That is, the fuel condition in the intake system and the cylinder at the end of the cranking differs depending on the cranking time, and accordingly, the increase correction amount at the end of the cranking and the subsequent decrease rate are corrected, and the increase correction that meets the request is made. Is executed.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, air is sucked into the engine 1 through an air cleaner 2, a throttle body 3, and an intake manifold 4.

A throttle valve 5 is provided in the throttle body 3 in conjunction with an accelerator pedal (not shown), and a fuel injection valve 6 as fuel injection means is provided upstream of the throttle valve 5. The fuel injection valve 6 is an electromagnetic fuel injection valve which is energized by a solenoid to open, is de-energized, and is closed. The fuel injection valve 6 is energized by a drive pulse signal from a control unit 14 to be described later and is opened. Fuel which is pressure-fed from a fuel pump and adjusted to a predetermined pressure by a pressure regulator is injected and supplied. Although this example is a single point injection system, a multipoint injection system in which a fuel injection valve is provided for each cylinder at a branch portion of the intake manifold 4 or an intake port of the engine may be used.

An ignition plug 7 is provided in a combustion chamber of the engine 1. A high voltage generated in an ignition coil 8 is applied to the ignition plug 7 through a distributor 9 based on an ignition signal from a control unit 14, whereby spark ignition is performed to ignite and burn the mixture.

Exhaust gas is exhausted from the engine 1 through an exhaust manifold 10, an exhaust duct 11, a three-way catalyst 12, and a muffler 13.

The control unit 14 includes a microcomputer including a CPU, a ROM, a RAM, an A / D converter, and an input / output interface, receives input / output signals from various sensors, performs arithmetic processing as described below, The operation of the combustion injector 6 and the ignition coil 8 is controlled.

As the various sensors, a potentiometer type throttle sensor 15 is provided in the throttle valve 5,
A voltage signal corresponding to the opening θ of the throttle valve 5 is output.
An idle switch 16 that is turned on when the throttle valve 5 is fully closed (idle position) is provided in the throttle sensor 15.

A crank angle sensor 17 is provided in the distributor 9 and outputs a position signal for every 2 ° crank angle and a reference signal for every 180 ° crank angle (in the case of four cylinders). Here, the engine speed N can be calculated by measuring the number of pulses of the position signal per unit time or the period of the reference signal.

Further, a water temperature sensor 18 as an engine temperature detecting means for detecting an engine cooling water temperature Tw representing the engine temperature, a vehicle speed sensor 19 for detecting a vehicle speed VSP, and the like are provided.

Further, the exhaust manifold 10 is provided with an O ₂ sensor 20. The O ₂ sensor 20 is a known sensor in which the electromotive force changes abruptly when the air-fuel mixture is burned near the stoichiometric air-fuel ratio which is the target air-fuel ratio.

Further, a battery 21 is connected to the control unit 14 via an ignition key switch 22 as an operating power supply and for detecting a power supply voltage, and an ON / OFF of a starter switch 23 as a cranking state detecting means.
OFF signal is input. In addition, as an operating power supply for the RAM in the control unit 14, the battery 21 is connected via an appropriate stabilized power supply without passing through the ignition key switch 22 in order to retain the stored contents even after the ignition key switch 22 is turned off. .

Here, the CPU of the microcomputer built in the control unit 14 performs arithmetic processing according to a program on a ROM shown as a flowchart in FIG. 3 to control fuel injection.

The functions of the cranking time measuring means, the post-start increase correction means, the start and the post-start increase correction means are achieved by the program.

The routine shown in the flowchart of FIG. 3 is executed at predetermined small time intervals (for example, 10 ms), and in step ("S" in the figure; the same applies hereinafter) 1, a signal from the throttle sensor 15 is output. The throttle valve opening θ detected on the basis of the detected value and the engine speed N calculated based on a signal from the crank angle sensor 17 are read.

In step 2, the intake air flow rate Q corresponding to the throttle valve opening degree θ and the engine speed N is determined in advance by experiments or the like, and a map on a ROM stored is referred to, and the intake air flow rate corresponding to the actual θ, N The flow rate Q is searched and found. In this embodiment, since the engine is not provided with an air flow meter,
Although the intake air flow rate Q is obtained based on θ and N as described above, an engine equipped with an air flow meter may be used. In this case, the intake air flow rate Q is directly obtained from the output of the air flow meter. Can be detected.

In step 3, a basic fuel injection amount Tp (= K × Q / N; K is a constant) corresponding to the intake air flow rate per unit rotation is calculated from the intake air flow rate Q and the engine speed N.

In step 4, ON / OFF of the starter switch 23 is determined. When the starter switch 23 is ON and the cranking state in which the starter motor is driven (engine starting state), the process proceeds to step 5.

In step 5, it is determined whether or not the ON determination of the starter switch 23 is the first time.
Then, the timer for measuring the cranking time T (the time required from the start of cranking to the end of cranking) is zero-started, and then the process proceeds to step 7. If not during the first time but during cranking, step 6 is jumped. To step 7.

In step 7, the current coolant temperature detected by the coolant temperature sensor 18 is obtained from a map of a start-up / post-start increase correction coefficient K _AS (start and post-start increase correction means) previously set according to the coolant temperature Tw. Based on Tw, a corresponding start-up / start-up increase correction coefficient _KAS is searched for and obtained.

In step 8, the start-up
Various correction coefficients COEF (= 1 + K _AS + K) including the water temperature correction amount K _TW and the mixture ratio correction coefficient K _MR in addition to the increase correction coefficient K _AS after starting.
_MR + ……)).

In step 9, the basic fuel injection amount Tp calculated in step 3 is multiplied by the various correction coefficients COEF to obtain an effective injection amount Te.
(= Tp × COEF).

Then, in the next step 10, the effective injection amount Te is multiplied by a constant (1.3 in this embodiment), the battery voltage correction amount Ts is added to a value obtained by increasing the amount more than usual, and the starting based on the intake air flow rate Q is started. setting the fuel injection amount T ₁ time. The battery voltage correction Ts is for correcting a change in the injection flow rate of the fuel injection valve 6 due to the battery voltage fluctuation.

Further, in the next step 11, the basic injection amount of fuel injection during startup amount T ₂ that is set to the cooling water temperature Tw as the main condition T _ST
From a preset map based on the cooling water temperature Tw detected by the water temperature sensor 18. Then, in the next step 12, the search to the determined startup basic injection amount T _ST to the rotational speed correction coefficient K _NST start timing fuel injection amount by multiplying the like _{T 2 (= T ST × T} NST × Step 11 ……).

In step 13, by comparing the start time fuel injection quantity T ₂ calculated in start timing fuel injection amount T ₁ and the step 12 obtained in the step 10, finally proceeds to a step 14 when a T ₁ ≧ T ₂ such a set in the output register start time fuel injection amount T ₁ as the fuel injection amount, set in the output register the start timing fuel injection amount T ₂ as the final fuel injection amount when a T ₁ <T ₂ I do. Thus, at a predetermined engine rotation-synchronous fuel injection timing, the set T ₁ or
Drive pulse signal having a pulse width corresponding to T ₂ is performed is given to the fuel injection valve 6 fuel injection.

Thus, in the cranking state starter switch 23 is ON, the one in which to perform the fuel injection by selecting the larger the start timing fuel injection amount T ₁ and the starting time fuel injection quantity T _2.

On the other hand, when it is determined in step 4 that the starter switch 23 is not ON, the process first proceeds to the switch 16 to determine whether or not it is the first time after the starter switch 23 has been turned OFF from ON.

Here, when the first determination is made, the process proceeds to step 17,
The time (cranking time) T required from the start of cranking to the end of cranking, which is measured based on the timer that has been zero-started in step 6, is read.

Then, in the next step 18, the cranking time T is set.
Setting the α correction factor to increase or decrease correcting the enrichment coefficient K _AS after start-start based on. The K _AS correction coefficient α is set to 1 in the predetermined standard cranking time T ₁ in the reference value, the cranking time T is set to a value larger than 1 according shorter than the standard T _1, Conversely, the value is set to a value smaller than ₁ as the cranking time T becomes longer than the standard T1. That is, the cranking time T is shorter and after the start and the start enrichment coefficient K _AS than the standard T ₁ is the increased corrected, cranking time T is set to be long, the decrease correction than the standard T _1.

In the next step 19, it sets the correction coefficient β to also correct the reduction ratio K _D cranking time T after the start-start enrichment coefficient K _AS based on the read in step 17.
Those after start-start enrichment coefficient K _AS is to return to zero is gradually reference value when cranking is finished, in the present embodiment for varying in accordance with the reduction ratio K _D cranking time T It is. In this case, as with the correction coefficient alpha, although the standard cranking at time T ₁ the correction factor β is set to 1 the reference value, greater than 1 according to the cranking time T is shorter than the standard T ₁ It is set to a value smaller than ₁ as the cranking time T becomes longer than the standard T ₁ . That is, although such is alleviated reduced rate as cranking time T becomes shorter return slowly to zero than in the standard T _1, when the standard T ₁ to rapidly decrease ratio that the cranking time T becomes longer Try to return to zero faster.

In step 20, the correction coefficient α obtained in step 18 is corrected by multiplying the start-up / start-up increase correction coefficient K _AS used in the cranking state (starter switch 23 ON) by a new coefficient K _AS Set as Thus, as shown in Figure 4, variable according to the initial value of the correction coefficient K _AS back from the cranking is finished (after complete explosion) to zero cranking time T.

In the next step 21, when the value is “1”, a flag is set to 1 indicating that the start / post-start increase correction coefficient _{KAS is} to be gradually returned to zero.

In step 22, as in step 8,
In addition to the start-up and post-startup increase correction coefficient K _AS obtained in step 20, various correction coefficients CO including the water temperature correction amount K _TW and the mixture ratio correction coefficient K _MR
Set EF (= 1 + K _AS + K _MR + ...), and then go to step 23
Then, the fuel injection amount Ti (= Tp × COEF + Ts) is calculated.

In step 24, the fuel injection amount calculated in step 23
Set Ti in the output register.

On the other hand, if it is determined in step 16 that the OFF determination of the starter switch 23 is not the first time, the process proceeds to step 25.

In step 25, a determination flag is set to "1", when the flag is in a state to be subjected to reduction setting of "1" was in after starting, the start enrichment coefficient K _AS in step 21, step 26 Proceed to.

In step 26, the increase correction coefficient K
_AS is multiplied by the reduction coefficient K _D corresponding to the standard cranking time T ₁ , and the correction coefficient K _AS is multiplied by the reduction rate correction coefficient β set in step 19 at a rate corresponding to the cranking time T. Decrease. That is, since when cranking time T has been the standard T ₁ is β is 1, but the correction coefficient K _AS a decrease rate determined by the reduction factor K _D decreases, when cranking time T is short β 1 When the cranking time T is long, the value β becomes less than 1 and the reduction rate increases (see FIG. 4).

If the correction coefficient _KAS is set to decrease in step 26, it is determined in next step 27 whether the correction coefficient _KAS has returned to near zero or not.
After returning the flag to zero in step 28, the process proceeds to step 22, but if the correction coefficient _KAS has not returned to near zero, the flag is kept at 1 to set the correction coefficient _KAS to decrease again in the next time, and step 22 is performed. Proceed to.

Step 22 and subsequent steps are the same as when the process proceeds from step 16 to step 17.

Thus, in this embodiment, when the cranking is ended, as well as correcting the enrichment coefficient K _AS after start-start on the basis of the time required for cranking back the correction coefficient K _AS after the correction to zero The speed is also corrected according to the cranking time T.

That is, when cranking time T is shorter than the standard T _1, to the air-fuel ratio immediately after starting (immediately after cranking completion) indicates lean tendency, as shown in FIG. 4, after the start and the start than Time in order to increase the bulking immediately after cranking termination by enrichment coefficient K _aS, to return slowly to zero after increase correction of K _aS. Further, when the cranking time T is longer than the standard T _1, to the air-fuel ratio immediately after starting indicates enrichment tendency, as shown in FIG. 4, according to the after-start-start enrichment coefficient K _AS than Time in order to reduce the increase, so quickly returned to zero after corrected by decreasing the K _aS.

<Effects of the invention> As described above, according to the present invention, the initial value and the decrease rate of the post-start increase correction value are corrected according to the length of the cranking time. It is possible to perform the increase correction of the fuel injection amount according to the air-fuel ratio immediately after, and it is possible to improve the stability of the engine operation immediately after the start.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a schematic diagram of a system showing one embodiment of the present invention, FIG. 3 is a flowchart showing control contents in the above embodiment, and FIG. A time chart showing the increase correction characteristic in,
FIG. 5 is a time chart for explaining the problem of the conventional increase correction. 1 ... engine, 6 ... fuel injection valve, 14 ... control unit, 15 ... throttle sensor, 17 ... crank angle sensor, 18 ... water temperature sensor, 23 ... starter switch

Claims (1)

(57) [Scope of request for utility model registration] An electronically controlled fuel injection device for an internal combustion engine configured to set a fuel injection amount based on an engine operating state and to drive and control fuel injection means based on the set fuel injection amount. A cranking state detecting means for detecting a cranking state; an engine temperature detecting means for detecting an engine temperature; and an engine temperature detected by the engine temperature detecting means in a cranking state detected by the cranking state detecting means. The fuel injection amount is increased according to the amount of the fuel, and the starting and post-start increasing amount correcting means for gradually decreasing the increasing correction amount to zero from the end of cranking and changing the amount to zero, based on the detection result of the cranking state detecting means. A cranking time measuring means for measuring a cranking time required from the start to the end of the cranking; The increasing correction amount at the end of cranking by the increasing correcting means is corrected based on the cranking time measured by the cranking time measuring means, and the corrected increasing correction amount is gradually set with the corrected increased correction amount as an initial value. A decreasing rate when decreasing the cranking time is set larger as the cranking time is shorter, and a post-start increasing correction means for correcting the increasing correction amount so as to decrease at a larger rate as the cranking time is shorter; An electronically controlled fuel injection device for an internal combustion engine, comprising: