JPH0810673Y2 - Engine fuel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a fuel control device for an engine, and more particularly, to an improvement in calculation of an injection pulse width output to a fuel injection valve.

(Prior Art) Conventionally, as shown in FIG. 4, a fuel injection valve provided in a fuel injection type engine has a characteristic of increasing the injection amount in proportion to an input injection pulse width, but the injection pulse width is small. Then, there is a region where the injection amount is not proportional to this pulse width. Therefore, in a region where the fuel injection amount is less than the limit proportional to the injection pulse width, the desired fuel is not injected, and the air-fuel ratio of the air-fuel mixture varies.

Therefore, conventionally, the final injection pulse width output to the fuel injection valve, that is, the basic injection pulse width, and the correction amount for increasing or decreasing various fuels according to the engine operating state such as the engine cooling water temperature, and the vehicle battery The final injection pulse width calculated based on the three elements of the invalid injection pulse width according to the state of charge of the battery is used, and the minimum value of this pulse width is restricted to the lower limit value or disclosed in Japanese Patent Publication No. 62-56342. As described above, the minimum value of the basic injection pulse width is restricted to the lower limit value, and the fuel injection valve is used in the region where the injection amount is proportional to the pulse width.

(Problem to be solved by the invention) However, in the former case, since the entire vehicle including the invalid injection pulse width is regulated to the lower limit value, when the voltage of the vehicle battery is low and the invalid injection pulse width becomes long, Even in the region below the proportional limit of the injection amount, the final injection pulse width becomes larger than the lower limit value due to its long invalid pulse width, and the restriction to the lower limit value does not take effect, and as a result, There is a drawback that the fuel injection valve is controlled in a region less than the proportional limit of the injection amount and the air-fuel ratio varies. On the other hand, in the latter case, when the basic injection pulse width is restricted to the lower limit value because of the restriction of the basic injection pulse width to the lower limit value,
This regulated injection basic pulse width is further corrected by the various correction amounts to the increase side or the decrease side, and will be double adjusted, so even if the basic injection pulse width is regulated to the lower limit value, Conversely, when the correction amount on the decrease side is shortly corrected, it will be below the lower limit value, and when the correction amount on the increase side is corrected for a long time, the corrected pulse width will be the calculated basic injection pulse. There is also a drawback that the air-fuel ratio becomes too long compared with the width, which causes an overrich of the air-fuel ratio, which also causes variations in the air-fuel ratio.

The present invention has been made in view of such a point, and an object thereof is to appropriately use a fuel injection valve in a region within a proportional limit of an injection amount by appropriately controlling a lower limit value. The purpose of this is to inject an amount and suppress or prevent variations in the air-fuel ratio.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, the basic injection is performed so as not to be affected by various correction amounts according to the engine operating state such as the invalid injection pulse width and the cooling water temperature. The minimum value of the effective injection pulse width of the value obtained by correcting the pulse width with the correction amount is restricted to the lower limit value.

That is, the concrete solution means of the present invention is a basic width calculation means for calculating the basic injection pulse width based on the intake air amount detected by the air flow sensor, and a correction amount for the basic injection pulse width according to the engine operating state. And a correction amount calculation unit for calculating the effective injection pulse width based on the basic injection pulse width and the correction amount. When the effective injection pulse width calculated by the effective width calculation means is smaller than or equal to a preset lower limit value, a restriction means for restricting the effective injection pulse width to the lower limit value is provided, and the effective width calculation means or the restriction is set. The effective injection pulse width obtained by the means,
A final value calculating means for calculating the final injection pulse width output to the fuel injection valve based on the invalid injection pulse width according to the state of charge of the vehicle-mounted battery is provided.

(Operation) With the above configuration, in the present invention, after the minimum value of the effective injection pulse width is regulated to the lower limit value, the final injection pulse width is calculated with the invalid injection pulse width taken into consideration. Even if the value is low and the invalid injection pulse width is long, the effective injection pulse width can be restricted to the lower limit value, and the fuel injection valve can be used in a region within the proportional limit of the injection amount.

Even if the basic injection pulse width is corrected to the increase side or the decrease side by the correction amount, the effective injection pulse width that is the value after the correction is regulated to the lower limit value, so the injection amount It is possible to prevent variation in the air-fuel ratio without entering a region that is not proportional to the width or increasing the injection amount too much.

(Effect of the Invention) As described above, according to the fuel control device for an engine of the present invention, the minimum value of the effective injection pulse width excluding the invalid injection pulse width of the final injection pulse width is restricted to the lower limit value. The fuel injection valve can always be used in the region where the injection amount is proportional to the injection pulse width, and the variation in the air-fuel ratio of the air-fuel mixture can be effectively suppressed or prevented.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 1, 1 is an engine, 2 is a combustion chamber in which the volume is variable by a piston 4 slidably inserted in a cylinder 3 of the engine 1, one end of the combustion chamber 5 communicates with the atmosphere, and the other end is the above combustion. An intake passage 6 is opened to supply the intake air to the chamber 2. One end is an exhaust passage that communicates with the combustion chamber 2 and has the other end opened to the atmosphere to discharge the exhaust gas. A throttle valve 7 for adjusting an intake air amount;
A fuel injection valve 8 for injecting and supplying fuel is disposed downstream of the throttle valve 7, and a catalyst device 9 for purifying exhaust gas is disposed in the exhaust passage 6. Further, in the combustion chamber 2, an intake valve 10 is disposed at an opening of the intake passage 5, and an exhaust valve 11 is disposed at an opening of the exhaust passage 6. An ignition plug 12 for igniting is provided. In addition, 13 is an ignition coil that generates a high voltage, 14 is a distributor that distributes the high voltage of the ignition coil 13 to the ignition plug 12 of the cylinder that is in the combustion stroke, and detects the crank angle (engine speed). It also has a function as a rotation speed sensor.

In addition, 15 is a hot-wire type air flow sensor that detects the amount of intake air, 16 is an idle switch that is turned on when the throttle valve 7 is fully closed, and the detection signals of both are internally
It is input to the controller 20 having a CPU and the like. The controller 20 adjusts the fuel injection amount from the fuel injection valve 8 and adjusts the ignition timing of the air-fuel mixture in the combustion chamber 2 by the ignition plug 12 by adjusting the output timing of the ignition signal to the ignition coil 13. It works like this.

Next, the fuel injection amount control by the controller 20 will be described based on the control flow of FIG.

In the figure, after starting, the output signal U from the air flow sensor 15 is read in step S _A1 , the output signal Ne from the rotation speed sensor (power distributor 14) is read in step S _A2 , and then in step S _A3 Based on both detection signals, the basic injection pulse width Tps is calculated based on the equation Tps = 1000 × k / (Ne × U ² ) (k is a constant).

Thereafter, in step S _A4 , a process (gradient process) is performed to gradually change the injection pulse toward the target basic injection pulse width Tps obtained above, and the basic injection pulse width Tpx after the process is obtained, and then In step S _A5 , various correction coefficients for the basic injection pulse width Tpx according to the engine operating state are obtained. That is, the correction coefficient Ck of the constant k in the equation for obtaining the basic injection pulse Tps, the increase correction Cs immediately after the engine starts, the warm-up increase Cw for promoting the warm-up when the engine is cold, and the acceleration increase during the engine acceleration. Cacc, deceleration increase Cdec during engine deceleration operation, return reduction correction Crec for shock mitigation when fuel supply is restored after fuel cut during engine deceleration operation, high load increase during engine high load operation A correction Cer, a fuel feedback control correction coefficient Cfb, a basic injection pulse width learning correction coefficient Clrn, and an intake air temperature correction coefficient Cair are calculated.

Then, in step S _A6 , the final injection pulse width Ti, the invalid injection time Tv according to the state of charge of the in-vehicle battery, and the frequency division ratio correction coefficient Cd according to the number of injections per revolution of the engine are Cd.
iv is calculated by the formula Ti = Ck × Tpx × Cdiv × (Ctotal / 100) + Tv, and the final injection pulse width Ti is calculated in step S _A7.
Is output to the fuel injection valve 8 to return. Here above
Ctotal is a value calculated by the formula of Ctotal = (100% + Cs + Cw Cacc + Cdec−Crec + Cer + Cfb + Clrn) × Cair based on the above correction factors.

Next, the final injection pulse width determination flow will be described with reference to FIG. When the engine is started and the engine is in the overspeed region of the overspeed region flag Xzor = 1 in step S _B1 , the final injection pulse width Ti = 0 sec is set in step S _B2 in order to prevent the engine from overrotating. Make a cut.

In step S _B3 , the deceleration fuel cut area flag Xzcut
= 1 and the throttle valve fully closed flag Xidl = 1 in step S _B4 , the final injection pulse width Ti is determined in step S _2.
Set to = 0 to perform deceleration fuel cut.

Further, in step S _B5 , the engine start area flag Xzs is set.
Since t = 1, in step S _B6 the throttle valve fully open flag Xp
If ow = 1, normal water temperature flag Xwdchk = 1 at start in step S _B7 , water temperature sensor fail flag Xthwf = 0 in step S _B8 , and throttle valve fail flag Xtvof = 0 in step S _B9 , the engine is started. the final injection pulse width T in step S _B2 to prevent over-rotation of the engine when
Fuel is cut by setting i = 0. On the other hand, even when the engine is started, when the throttle valve 7 is not fully opened, when the engine cooling water temperature is low, when the water temperature sensor fails,
Alternatively, when the throttle valve fails, the injection pulse width tsta (i) at engine start is read from the engine cooling water temperature table in step S _B10 , and the invalid injection pulse having a value according to the charge state of the on-vehicle battery at this pulse width is read. Width Tv
(I) is added and the engine is started with the final injection pulse width Ti.

And during normal operation after starting, the effective injection pulse width
Tia, that is, Ck × Tpx × Cdiv × (Ctotal / 100) is compared with the preset lower limit value Timin of the pulse width in step S _B11 and with the upper limit value Timax in step S _B12 . If it is within the upper and lower limits, step S _B13
Then, in the effective injection pulse width Tia (i), an invalid injection pulse width Tv (i) having a value according to the state of charge of the vehicle-mounted battery at that time
Is added to obtain the final injection pulse width Ti. However, Tia ≤ T
If imin, the effective injection pulse width Tia in step S _B14
Instead of the lower limit value Timin, the invalid injection pulse width Tv at that time
(I) is added to obtain the final injection pulse width Ti and vice versa.
When a ≧ Timax, the effective injection pulse width is set in step S _B15.
Instead of Tia, the upper limit value Timax is set to the invalid injection pulse width Tv at that time.
(I) is added to obtain the final injection pulse width Ti.

Therefore, in the control flow of FIG.
The S _A3 constitutes the basic width calculating means 21 for calculating the basic injection pulse width Tps based on the intake air amount U detected by the air flow sensor 15, and the step S _A5 executes the basic injection according to the engine operating state. Correction amount calculation means for calculating various correction amounts Cs, Cw ... With respect to the pulse width Tps
Makes up 22. In addition, step S _{A6 of} the control flow
By receiving the outputs of both the calculation means 21 and 22, the effective injection pulse width Tia (= Ck × Tpx × Cdiv × Ctotal ÷ 100) is calculated based on the basic injection pulse width Tps and various correction amounts Cs, Cw ... The effective width calculating means 23 thus configured is configured.

Furthermore, in the control flow of FIG. 4, step S _B11
And S _B14 , when the effective injection pulse width Tia calculated by the effective width calculation means 23 is smaller than a preset lower limit value Timin, the effective injection pulse width Tia is set to the lower limit value Timin.
The restriction means 24 is configured to be restricted to. Further, in steps S _B13 and S _B14 , the effective width calculation means
23 or effective injection pulse width Tia obtained by regulating means 24
Alternatively, based on Timin and the invalid injection pulse width Tv (i) corresponding to the state of charge of the vehicle-mounted battery at that time, the fuel injection valve 8
The final value calculating means 25 is configured to calculate the final injection pulse width Ti to be output to.

Therefore, in the above embodiment, the target of which the minimum value is regulated by the regulation means 24 is the effective injection pulse width Tia.
Therefore, even if the in-vehicle battery voltage is low and the invalid injection pulse width Tv is long, the effective injection pulse width Ti
It is possible to regulate a to the lower limit value Timin. As a result, the fuel injection valve 8
As shown in FIG. 4, the region where is used is always in the region where the injection amount is proportional to the pulse width, so the fuel amount as controlled is injected and the air-fuel ratio of the air-fuel mixture is adjusted to the target air-fuel ratio. This prevents variations in the air-fuel ratio.

Further, for example, during deceleration operation of the engine, since the basic injection pulse width Tpx is set to be short, during the deceleration operation, the basic injection pulse width Tpx is corrected by, for example, the reduction correction amount Crec at the time of fuel recovery after fuel cut. Then, the corrected value (effective injection pulse width) Tia is regulated to the lower limit value Timin, but the fuel injection valve 8 can be used in a region proportional to the pulse width. On the other hand, when the basic injection pulse width Tpx is corrected by the deceleration increase correction amount Cdec for a long time, the corrected effective injection pulse width Tia is also corrected in the same manner as above.
Is regulated to the lower limit value Timin, so that the injection amount does not increase so much and the air-fuel ratio is not overriched as in the conventional case.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is an overall configuration diagram, FIGS. 2 and 3 are flow charts showing fuel injection amount control, and FIG. 4 is injection of a fuel injection valve. It is a figure which shows the injection amount characteristic with respect to a pulse width. 8 ... Fuel injection valve, 15 ... Air flow sensor, 21 ... Basic width calculating means, 22 ... Correction amount calculating means, 23 ... Effective width calculating means, 24 ... Restricting means, 25 ... Final value calculating means .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Katsuhiro Masui, 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture (56) References JP-A-61-190145 (JP, A) JP-A-63- 189656 (JP, A) JP 64-12048 (JP, A) JP 2-11853 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A basic width calculation means for calculating a basic injection pulse width based on an intake air amount detected by an air flow sensor, and a correction amount calculation means for calculating a correction amount for the basic injection pulse width according to an engine operating state. And an effective width calculation means for calculating the effective injection pulse width based on the basic injection pulse width and the correction amount, and the effective injection pulse width calculated by the effective width calculation means. When the value is smaller than the lower limit value, the effective injection pulse width is restricted to the lower limit value, and the effective injection pulse width obtained by the effective width calculation means or the restriction means, and invalid according to the charging state of the vehicle-mounted battery. A fuel control device for an engine, comprising: a final value calculating means for calculating a final injection pulse width output to the fuel injection valve based on the injection pulse width.