JP3152024B2 - Fuel injection control device for starting internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for starting an internal combustion engine, and more particularly to a technique for suppressing a variation in the total amount of fuel injected and supplied at the time of starting.

[0002]

2. Description of the Related Art As a fuel injection control device at the time of starting, there is a device disclosed in Japanese Patent Laid-Open No. 61-212640. This is configured to calculate an initial injection amount at the time of start according to the engine temperature, and to gradually attenuate the initial injection amount with a constant characteristic according to an on-time (cranking time) of a starter. I have.

[0003] The above-described damping correction makes it possible to suppress the air-fuel mixture in the cylinder from being over-rich even if the cranking time becomes long.

[0004]

However, in the above-described conventional injection control at the start, the injection pulse width is reduced at a fixed rate after a certain time has elapsed from the start of the start. There is a problem that a large variation occurs in the total amount of injection during cranking due to variations in engine temperature (cooling water temperature) that determines oil pressure, variations in cranking speed due to changes in friction, changes in battery voltage, and the like. .

That is, if it is assumed that the injection amount per injection is constant in the injection control synchronized with rotation, the injection amount is attenuated at a certain time after the start of the engine. When the ranking rotation speed is high, the total number of injections in the certain time increases because the number of injections increases, but conversely, the total number of injections in the certain time decreases because the number of injections decreases when the cranking rotation speed is low, The total injection amount during cranking greatly varies depending on the cranking speed. For example, if the damping characteristic is adapted to a relatively low rotation speed so as to secure the minimum injection amount, when the cranking rotation speed is high, the total injection amount becomes excessive and the exhaust property deteriorates (HC , CO increase). On the other hand, if the crankshaft rotation is adjusted to a high rotation side, the required fuel amount cannot be secured when the cranking rotation is low.

Further, even if the cranking rotational speed is the same, the injection amount per injection (basic injection amount) greatly varies due to variations in the engine temperature. Will vary greatly. The present invention has been made in view of the above problems, and provides a starting fuel injection control device that can avoid a large variation in the total injection amount during cranking. The aim is to improve.

[0007]

According to the present invention, there is provided a method for manufacturing a semiconductor device comprising:
The internal combustion engine start-time fuel injection control device is configured as shown in FIG. In FIG. 1, an engine temperature detecting means and an engine speed detecting means detect an engine temperature and an engine speed, respectively.

Further, startup basic injection amount calculating means calculates a basic injection amount at engine start-up based on the engine temperature detected by at least the engine temperature detecting means, the engine temperature is low
The larger the basic injection amount, the larger the time . Further, the injection amount attenuating means obtains the starting injection amount by gradually attenuating and correcting the basic injection amount calculated by the starting basic injection amount calculating means at a predetermined timing. On the other hand, the damping characteristic varying means hastens the timing of the damping correction by the injection amount attenuating means as the engine speed detected by the engine speed detecting means increases .

The start-time injection control means controls the driving of the fuel injection valve when the engine is started, based on the start-time injection amount obtained by the injection amount attenuation means. Claim 2
In the starting-time fuel injection control apparatus for an internal combustion engine, the injection
The timing of the attenuation correction by the quantity attenuation means
The higher the engine speed detected in the stage, the earlier the speed, and
The lower the engine temperature detected by the engine temperature detection means, the lower
A configuration is provided in which the attenuation characteristic variable means is hastened.

[0010]

According to the start-up fuel injection control device having such a configuration, the timing for attenuating and correcting the basic injection amount at the time of start-up is set as follows.
Early Luke smaller the higher the engine speed, or early enough at higher institutional rotational speed and the engine temperature detected by the engine temperature detecting means to expedite smaller the lower. That is,
Since the number of injections changes due to the variation in the engine speed, and the injection amount per injection varies due to the variation in the engine temperature, the timing of the damping correction is changed based on these parameters, so that during the cranking, The variation in the total injection amount is suppressed.

[0011]

Embodiments of the present invention will be described below. In FIG. 2 showing a system configuration of an embodiment, an internal combustion engine 1 includes:
Air is sucked in through the air cleaner 2, the intake duct 3, the throttle chamber 4, and the intake manifold 5.

The intake duct 3 is provided with an air flow meter 6 for detecting an intake air flow rate Q of the engine.
The throttle chamber 4 is provided with a butterfly type throttle valve 7 for adjusting the intake air amount, and the throttle valve 7 is provided with a potentiometer type throttle sensor 8 for detecting the opening TVO. I have.

In order to control the amount of auxiliary air supplied to the engine by bypassing the throttle valve 7, an idle control valve 9 whose opening is controlled, a fast opening / closing on / off in response to an air conditioner signal. An idle control valve (FICD) 10 and an air regulator 11 for adjusting the amount of auxiliary air in response to the cooling water temperature are provided.

On the other hand, electromagnetic fuel for intermittently injecting and supplying fuel to the engine 1 from the fuel tank (not shown) and adjusted to a predetermined pressure by a pressure regulator is supplied to each branch of the intake manifold 5. An injection valve 12 is provided, and the fuel injection amount, and thus the air-fuel ratio of the engine intake air-fuel mixture, can be controlled via the opening time of the fuel injection valve 12.

Further, the spark plug 13 faces the combustion chamber of each cylinder.
A high voltage generated by an ignition coil 14 in response to an ignition timing control signal is distributed and supplied to the ignition plug 13 via a distributor 15. The distributor 15 has a built-in crank angle sensor 16 (revolution detecting means), and the crank angle sensor 16 outputs a detection signal at every predetermined crank angle. The engine speed N is calculated based on the detection signal from the crank angle sensor 16.

The exhaust from the engine 1 is exhaust manifold 1
7. The exhaust gas is exhausted to the atmosphere via an exhaust duct 18, a catalytic converter 19, and a muffler 20. The exhaust duct 18 is provided with an oxygen sensor 21 for detecting the oxygen concentration in the exhaust gas, which is closely related to the air-fuel ratio of the engine intake air-fuel mixture. The catalytic converter 19 has an exhaust gas temperature sensor for detecting the exhaust gas temperature.
22 are provided.

In FIG. 2, reference numeral 26 denotes a canister, which adsorbs and collects the evaporated fuel in a fuel tank (not shown), and desorbs and supplies the adsorbed and collected evaporated fuel to an engine intake system. A control unit 23 having a built-in microcomputer is provided with a water temperature sensor 24 for detecting an engine cooling water temperature Tw representing an engine temperature, in addition to the various sensors.
(Engine temperature detecting means), a detection signal from a knock sensor 25 or the like for detecting knocking vibration of the engine, etc., is inputted, and a fuel injection amount by the fuel injection valve 12, an ignition timing by the spark plug 13,
Further, it has a function of controlling the amount of auxiliary air adjusted by the idle control valve 9 and the like.

In the control of the fuel injection amount, specifically, a basic fuel injection amount Tp (basic injection pulse width) is calculated based on the intake air flow rate Q detected by the air flow meter 6 and the engine speed N. On the other hand, the basic fuel injection amount Tp is set based on the correction coefficient COEF according to the operating conditions such as the invalid injection time Ts by the fuel injection valve 12 and the cooling water temperature Tw, and further, the detection result of the oxygen sensor 21. The final fuel injection amount Ti is determined by correcting with the air-fuel ratio feedback correction coefficient α or the like, and an injection pulse signal corresponding to the fuel injection amount Ti is synchronized with the fuel injection valve 12 in accordance with engine rotation. This is done by outputting.

In order to improve the startability, the control unit 23 adjusts the starting injection amount so that the starting injection amount is slightly larger than the normal injection amount at the time of starting (during cranking). The control unit 23 determines whether the starter switch 27 is ON or OFF to detect the starting state.
A signal is input.

In this embodiment, the starting fuel injection amount TIST (hereinafter simply referred to as the starting injection amount) is calculated according to the following equation. TIST = TCST × TCSN × TKCS Here, TCST is a starting basic injection amount (starting basic pulse width). As shown in FIG. 3, TCST is larger as the engine is colder based on a cooling water temperature Tw representing the engine temperature. It is to be calculated.

Further, TCSN is a rotating speed correction coefficient corresponding to the cranking rotation speed (engine speed during cranking), as shown in FIG. 4, at cranking speed is below a predetermined rotational speed N ₁ is 1.0, and is calculated to gradually decrease as the rotation increases, and the predetermined rotation N
_If it is ₂ or more, it will change to a constant value. Furthermore,
TKCS is the duration of the starting state, that is, if the starter is O
A time correction coefficient corresponding to the elapsed time (cranking time) from being N, as shown in FIG. 5, from the beginning of startup until the predetermined time T ₁ is calculated to 1.0, the predetermined time T ₁
After the lapse of time, it decreases at a fixed rate and converges to 0 in a predetermined time T ₂ (> T ₁ ).

That is, the starting basic injection amount TCST set based on the cooling water temperature Tw is corrected according to the cranking speed and the cranking time. In the present embodiment, the time correction coefficient TK
CS is not always determined to be a constant value with respect to the cranking time, but the predetermined times T ₁ and T ₂ for determining the attenuation correction timing are determined by the cranking rotation speed,
Alternatively, the change is made based on the cranking speed and the cooling water temperature Tw.

Here, a first embodiment in which the attenuation correction timing based on the time correction coefficient TKCS is changed according to the cranking speed will be described with reference to the flowchart of FIG. In this embodiment, the basic injection amount calculating means at the start, the injection amount attenuating means, the damping characteristic varying means by the rotation speed ,
The function as the start-time injection control means is provided by the control unit 23 as software as shown in the flowchart of FIG.

In the flowchart of FIG. 6, in S1, it is determined whether the starter switch 27 is ON or OFF. When it is detected that the starter switch 27 is ON and the engine is in the starting state, the process proceeds to S2 and the water temperature sensor
The cooling water temperature Tw detected at 24 is read. And S
In step 3, the basic injection amount at start TCST is calculated based on the coolant temperature Tw read in step S2 (see FIG. 3).

Next, at S4, the engine speed N calculated based on the detection signal from the crank angle sensor 16 is read. In S5, the engine speed correction coefficient TCSN is calculated based on the engine speed N (cranking engine speed) read in S4 (see FIG. 4). Next S6 and S
In step 7, the predetermined times T ₁ and T ₂ for determining the damping correction timing based on the time correction coefficient TKCS are variably set based on the cranking speed read in S4.

The setting of the predetermined times T ₁ and T ₂ stipulates a required value of the total amount of fuel injected during cranking, as shown in FIG. 7. The time is set in correlation with the time. That is, when the cranking rotation speed is high, the injection interval is short and the number of injections per unit time increases, so that the predetermined time T ₁ ,
T ₂ are set shorter, so that early attenuation correction based on the time correction coefficient TKCS is made from the beginning of startup.

Conversely, when the cranking rotation speed is low, the injection interval becomes longer and the number of injections per unit time decreases, so that the predetermined times T ₁ and T ₂ are set longer, and a relatively long time from the start of starting is set. Time correction coefficient TK after elapse
The attenuation correction based on CS is performed so that the total fuel amount is secured. As described above, the variable settings of the predetermined times T ₁ and T ₂ based on the cranking rotation speed are configured such that the lower the cranking rotation speed is, the more the timing of the attenuation correction based on the time correction coefficient TKCS is delayed. Thus, it is possible to avoid a large variation in the total injection amount during cranking due to the influence of the cranking rotation speed.

The predetermined times T ₁ and T ₂ based on the cranking speed may be set such that only _one of the predetermined times T ₁ and T ₂ is variable. A configuration in which changes are made at the same time may be adopted. However, in any case, the lower the cranking rotation, the longer the predetermined time T
_1, T ₂ is set to be longer. As described above, the characteristics of the attenuation correction based on the time correction coefficient TKCS are variably set for the times T ₁ and T ₂ according to the cranking rotation speed. Is set to be delayed,
In the next S8, a cranking time (elapsed time since the starter is turned on) t is read.

[0029] Then, in the next S9, the predetermined time T ₁ that defines the start timing for attenuating shifts the time correction coefficient TKCS from 1.0 which is the initial value, and compares the actual cranking time t. Here, when the cranking time t is determined to be ₁ less than the predetermined time T, the process proceeds to S10, sets an initial value of 1.0 to the time correction coefficient TKCS.

On the other hand, cranking time t when it is determined that exceeds the predetermined time T _1, the process proceeds to S11, in fact that the predetermined time T ₂ that defines the timing for converging the time correction coefficient TKCS to 0 in S9 Compare with the cranking time t. Here, the cranking time t is a predetermined time T
If it does not reach ₂ , it indicates a period in which the time correction coefficient TKCS is gradually attenuated from the initial value 1.0 to 0. In this case, the process proceeds to S12, where the time correction coefficient TKCS is set according to the following equation. I do.

[0031] _{TKCS = 1.0 -t / (T 2} -T 1) Further, in S11, when the cranking time t is determined to have exceeded the predetermined time T ₂ are, the process proceeds to S13, the time correction coefficient TKCS Set 0. In S14, the basic injection amount T set as described above is set.
CST, rotation speed correction coefficient TCSN, time correction coefficient TKC
S, the final start-up injection amount TIST (= TCS
T × TCSN × TKCS).

When the starter switch 27 is turned on, the control unit 23 outputs an injection pulse signal having a pulse width corresponding to the injection amount TIST at the start to the fuel injection valve 12 at a predetermined timing synchronized with the engine rotation. The fuel injection amount at the time is controlled. By the way, in the above embodiment, the predetermined times T ₁ and T ₂ for determining the damping correction timing by the time correction coefficient TKCS are variably set in accordance with the cranking rotation speed. It is good if there is no large variation in the amount, but if there is a large variation in the injection amount per injection due to the cooling water temperature Tw, the intended purpose of suppressing the variation in the total injection amount cannot be sufficiently achieved. There is fear.

Therefore, it is preferable to determine the predetermined times T ₁ and T ₂ by using the cooling water temperature Tw as a parameter together with the cranking speed. The second embodiment will be described with reference to the flowchart of FIG. In the flowchart of FIG. 8, a step (S24) of setting a table for determining the predetermined times T ₁ and T ₂ according to the cooling water temperature Tw is added to the flowchart of FIG. The processing contents of the steps (S27, S28) for calculating the predetermined times T ₁ , T ₂ differ accordingly, but the calculation processing in the other steps is performed in the same way, so only the different step parts will be described and the same Processing part (S21 ~
The description of S23, S25 to S26, and S29 to S35) is omitted.

In the flowchart of FIG. 8, in S24, a table for variably setting predetermined times T1 and T2 for determining the attenuation correction timing by the time correction coefficient TKCS based on the cooling water temperature Tw read in S22 is set. I do. Specifically, as shown in FIG. 9, similarly to the first embodiment, a table of characteristics in which the predetermined times T1 and T2 are set to be longer as the cranking rotation speed is lower is stored in the cooling water temperature at that time. The predetermined times T1 and T2 are shifted in such a manner as to be shorter as Tw is lower .

That is, the injection time is determined by the cranking speed.
When the number changes and the injection amount per injection is considered to be constant
The lower the cranking speed, the longer the time
T₁, T _TwoTo increase the number of injections (total injection amount)
In practice, the basic injection amount TCST is
As the recirculating water temperature Tw is lower, it is set higher,
If the recirculating water temperature Tw is low, the same cranking speed condition
, The total injection amount tends to increase.

Therefore, at a low water temperature where the injection amount per injection is large, the predetermined times T1 and T2 are shortened so as to suppress the variation of the total injection amount due to the variation of the cooling water temperature Tw. The table set in S24 is referred to in the calculation of the predetermined times T1 and T2 in S27 and S28, and the cranking speed and the cooling water temperature T are referred to.
The attenuation correction timing is changed based on w.
(Means for varying damping characteristics depending on the number of revolutions and engine temperature) .

In the above embodiment, the characteristics of the damping correction (timing of the damping correction) according to the elapsed time from the start of the cranking are determined by the cranking speed and the cooling water temperature T.
However, if the damping correction timing is determined based on the number of injections without using the parameter of the cranking time, the basic injection is performed based on the fixed number of injections regardless of the cranking speed. Attenuation correction of the amount can be executed, and the same effect as in the first embodiment can be obtained.

Further, the reference number of injections for determining the damping correction timing is determined by the cooling water temperature Tw representing the engine temperature.
, The variation in the total injection amount can be suppressed in accordance with the variation in the basic injection amount due to the change in the cooling water temperature Tw.

[0039]

As described above, according to the present invention,
It is possible to avoid a large variation in the total amount of fuel injection during cranking due to variations in the engine temperature and the cranking speed, thereby improving the exhaust properties at the start and immediately after the start.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a schematic diagram showing a system configuration of an embodiment.

FIG. 3 is a diagram showing characteristics of a basic injection amount in the embodiment.

FIG. 4 is a diagram showing characteristics of a rotation speed correction coefficient in the embodiment.

FIG. 5 is a diagram showing characteristics of a time correction coefficient in the embodiment.

FIG. 6 is a flowchart showing start injection control according to the first embodiment.

FIG. 7 is a diagram showing a change characteristic of attenuation correction timing in the first embodiment.

FIG. 8 is a flowchart illustrating start injection control according to a second embodiment.

FIG. 9 is a diagram showing characteristics of changing the attenuation correction timing in the second embodiment.

[Explanation of symbols]

 1 Internal combustion engine 6 Air flow meter 12 Fuel injection valve 16 Crank angle sensor 23 Control unit 24 Water temperature sensor 27 Starter switch

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/06 330 F02D 45/00 312 F02D 45/00 370

Claims (2)

(57) [Claims] An engine temperature detecting means for detecting an engine temperature; a rotational speed detecting means for detecting an engine speed; and a basic injection amount at the time of engine start based on at least the engine temperature detected by the engine temperature detecting means. And a basic injection amount calculating means for starting which sets the basic injection amount larger as the engine temperature is lower, and gradually attenuating the basic injection amount calculated by the basic injection amount calculating means at predetermined timing. Injection amount attenuating means for determining the injection amount at start-up, damping characteristic variable means for advancing the timing of the attenuation correction by the injection amount attenuating means as the engine speed detected by the rotation speed detecting means is higher, and the injection amount. Starting injection control means for controlling the driving of the fuel injection valve at the time of starting the engine, based on the starting injection amount obtained by the damping means; and Fazed fuel injection control device. 2. An engine temperature detecting means for detecting an engine temperature; a rotational speed detecting means for detecting an engine rotational speed; and a basic injection amount at the time of engine start based on at least the engine temperature detected by the engine temperature detecting means. And a basic injection amount calculating means for starting which sets the basic injection amount larger as the engine temperature is lower, and gradually attenuating the basic injection amount calculated by the basic injection amount calculating means at predetermined timing. and injection amount attenuating means for determining the starting time injection amount Te, the timing of the attenuation correction by the injection amount attenuating means
The higher the engine speed detected by the speed detector, the higher the engine speed.
A damping characteristic variable means that is advanced earlier and when the engine temperature detected by the engine temperature detecting means is lower, and a fuel injection valve at the time of starting the engine based on the starting injection amount obtained by the injection amount attenuating means. A start-time fuel injection control device for an internal combustion engine, comprising: a start-time injection control means for controlling the driving of the engine.