JPH01208540A - Device for feeding fuel of engine - Google Patents

Abstract

PURPOSE:To improve acceleration responsiveness by increasing a fuel injection quantity when a cylinder is in the latter period condition of a suction stroke at the time of carrying out an extra fuel injection which is asynchronous with an engine speed so as to be an accelerating condition, etc., in addition to an ordinary fuel injection synchronized with the engine speed. CONSTITUTION:At the time of an ordinary operation, a fuel injection valve A provided opposite to each cylinder of an engine is controlled being synchronized with the rotation of the engine by an ordinary injection control means C according to an ordinary fuel injection quantity which is set in accordance with the engine operating condition by an ordinary fuel injection quantity setting means B. Also, at the time of accelerating, etc., control is made so as to carry out fuel injection which is asynchronous with the rotation of the engine by an extra injection control means D. In this case, at the time of carrying out the asynchronous injection of fuel when a cylinder is in the latter period condition of a suction stroke, an extra fuel injection quantity with a relatively larger value is set by an extra fuel injection quantity setting means E.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention performs normal fuel injection in synchronization with the rotation of the engine, and also performs temporary fuel injection in addition to the normal fuel injection during acceleration etc. This invention relates to a fuel supply system for an engine.

(Prior Art) In an engine installed in an automobile, when the engine is shifted from a steady state to an accelerated state, or when it is shifted from a fuel supply stop state to a fuel return state where fuel supply is restarted, In order to obtain the required torque, the amount of fuel supplied is increased. In this case, for engines in which fuel is supplied by a fuel injection valve, the fuel is normally supplied intermittently in synchronization with the rotation of the engine, so the engine is forced to shift to an acceleration state, etc. At this time, there may be a delay in fuel supply, and in such a case, problems such as a decrease in acceleration response occur.

Therefore, in an engine in which fuel is supplied by a fuel injection valve, for example,
As shown in Publication No. 3, in addition to normal fuel injection that is performed in synchronization with engine rotation, temporary fuel injection that is immediately asynchronous to engine rotation when transitioning to an acceleration state or fuel return state, etc. It is known to perform injection.

(Problem to be Solved by the Invention) However, in an engine in which temporary fuel injection is performed immediately after transitioning to an acceleration state or a fuel return state as described above, for example, the engine is injected along the vertical axis. As shown in FIG. 5, where the vaporized amount U of fuel is plotted and the crank rotation angle θ is plotted on the horizontal axis, the intake stroke in the cylinder changes as the value of the crank rotation angle θ changes from θ1 to 02.
If the temporary fuel injection is performed when the cylinder is in the latter half of the intake stroke, the period from the time the temporary fuel injection is performed until the end of the intake stroke for that cylinder. Since the period is relatively short, the vaporized amount U of the fuel injected into the intake passage by the temporary fuel injection does not reach the required value U1, as shown by the solid line in FIG. As a result, the ignitability of the air-fuel mixture decreases, and there is a possibility that good acceleration response and the like may not be obtained.

To avoid such a situation where the amount of fuel vaporized U becomes insufficient (by increasing the temporary fuel injection amount,
As shown by the dashed line in FIG. 5, it is conceivable that even if the temporary fuel injection is performed in the latter half of the intake stroke, the vaporized amount U of the injected fuel will reach the required value U. However, with this arrangement, if temporary fuel injection is performed when the cylinder is in a state other than the latter half of the intake stroke, there is a risk that the amount of fuel supplied will be excessive, resulting in a decrease in fuel efficiency and combustibility. be.

In view of this, the present invention provides, in addition to normal fuel injection synchronized with engine rotation, to perform temporary fuel injection asynchronous to engine rotation immediately after transition to an acceleration state or fuel return state. Even if the temporary fuel injection is performed when the cylinder is in the latter half of the intake stroke, the injected fuel in the period from the time when the temporary fuel injection is performed until the end of the intake stroke in that cylinder is It is an object of the present invention to provide a fuel supply device for an engine in which a sufficient amount of fuel is vaporized, a reduction in ignitability of the air-fuel mixture can be avoided, and good acceleration response can be obtained. do.

(Means for Solving the Problems) In order to achieve the above-mentioned object, an engine fuel supply device according to the present invention is provided corresponding to the cylinders of the engine, as the basic configuration is shown in FIG. A fuel injection means, a normal injection amount setting means for setting a normal fuel injection amount according to the operating state of the engine, and a normal injection control for causing the fuel injection means to perform fuel injection in synchronization with the rotation of the engine with the normal fuel injection amount. means, and temporary injection control means for causing the fuel injection means to perform fuel injection asynchronously with respect to engine rotation with a temporary fuel injection amount immediately after the operating state of the engine satisfies a predetermined condition. In addition, temporary injection amount setting means is provided, and the temporary injection amount setting means performs fuel injection asynchronously with respect to engine rotation by the fuel injection means when the cylinder is in the latter half of the intake stroke. When this is done, the temporary fuel injection amount is set to a larger value than when it is done when the cylinder is in the first half of the intake stroke, compression stroke, expansion stroke, and exhaust stroke.

(Function) In the engine fuel supply device according to the present invention having the configuration as described above, the fuel injection means provided corresponding to the engine cylinder is controlled by the normal injection control means depending on the operating state of the engine. Normal fuel injection is performed in synchronization with engine rotation using the normal fuel injection amount, and immediately after the engine operating state satisfies predetermined conditions, the temporary injection control means performs temporary fuel injection Temporary fuel injection is performed with the injection amount asynchronously to the rotation of the engine. In such a temporary fuel injection, if the temporary fuel injection amount is performed when the cylinder is in the latter half of the intake stroke, the temporary injection amount setting means determines whether the cylinder is in a state other than the latter half of the intake stroke. It is set to a larger value than when it is used.

By doing this, even when temporary fuel injection is performed while the cylinder is in the latter half of the intake stroke,
In a relatively short period of time from the start of the temporary fuel injection to the end of the intake stroke in the cylinder, the amount of vaporization of the injected fuel reaches the required amount, reducing the ignitability of the air-fuel mixture. is avoided, and good acceleration response etc. can be obtained.

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

FIG. 2 shows an example of an engine fuel supply system according to the present invention, together with a four-cycle four-cylinder engine to which the system is applied.

In FIG. 2, the engine body 10 is formed with four cylinders 1, 2, 3, and 4 into which pistons are inserted, and each of these four cylinders 1 to 4 has a The downstream ends of the four branch passages forming the upstream part of the exhaust passage 14 and the upstream ends of the four branch passage parts forming the upstream part of the exhaust passage 14 are respectively operated to open and close by known valve operating mechanisms. Connected through a valve. Spark plugs (not shown) facing the combustion chamber are installed at the top of cylinders 1 to 4, respectively.
Each of the spark plugs emits a spark to ignite the air-fuel mixture when supplied with an ignition signal from a distributor 16 that is rotationally driven by the engine. The ignition order of the air-fuel mixture by each of the spark plugs and the intake in each of cylinders 1 to 4.

The order in which the compression, expansion, and exhaust strokes are performed depends on the cylinder l.
→ cylinder 3 → cylinder 4 → cylinder 2.

A crank angle sensor 18 that detects the crank rotation angle and a rotation speed sensor 20 that detects the engine rotation speed are attached to the distributor 16.

In the upstream portion of the branch passage in the intake passage 12,
An air filter 22 that sequentially purifies the intake air from the upstream side. Air flow meter 24 for detecting the amount of intake air. Throttle valve 25 that opens and closes in conjunction with the accelerator pedal
, and a surge tank 26 are provided. Furthermore, fuel injection valves 31, 32, 33, and 34 are arranged in the four branch passage portions of the intake passage 12, respectively. The fuel injection valves 31 to 34 are each electronically controlled by injection drive pulse signals PJ, , PJ, , PJ, supplied from a control unit 100, which will be described later.
and PJ, are kept open for a period corresponding to the pulse width of
The pressure of the fuel is regulated and pressure-fed from the fuel supply system, and the fuel is injected toward the intake boat section relative to the combustion chamber.

Control of fuel injection in each of the fuel injection valves 31 to 34'
Ii: The control unit 100 receives a detection signal Sa corresponding to the amount of intake air obtained from the air flow meter 24 and a detection signal Sc corresponding to the crank rotation angle obtained from the crank angle sensor 18.

A detection signal Sn corresponding to the engine rotation speed obtained from the rotation speed sensor 20, a detection signal St1 corresponding to the throttle opening obtained from the throttle opening sensor 30 provided in relation to the throttle valve 25, and a detection signal St1 corresponding to the throttle opening obtained from the throttle opening sensor 30 provided in relation to the throttle valve 25. A detection signal Sw or the like corresponding to the engine cooling water temperature obtained from a relatedly provided water temperature sensor 29 is supplied.

The control unit 100 has detection signals Sa and Sn.
The basic fuel injection amount is set based on the intake air amount and engine rotational speed at which the detection signal Sw occurs, and a correction coefficient is set according to the engine operating state based on the cooling water temperature, etc. at which the detection signal Sw is caused, and the correction coefficient is set. is used to correct the basic fuel injection amount and set the normal fuel injection amount. Then, injection drive pulse signals PJ, -PJ, having a pulse width corresponding to the set normal fuel injection amount are formed, and are simultaneously applied to each of the fuel injection valves 31 to 34 in synchronization with the engine rotational speed. supply Thereby, normal fuel injection by the fuel injection valves 31 to 34 is performed intermittently, and fuel is supplied with a fuel injection amount according to the operating state of the engine.

The control unit 100 also detects that the engine has been shifted from a steady state to an accelerated state based on the detection signals Sa and Sn, and that the throttle valve 25 has been switched from a fully closed state to an open state based on a detection signal St. When this is detected, the engine will not synchronize with the rotation of the engine.
Temporary fuel injection will be performed immediately.

When such 'temporary fuel injection is performed, the temporary fuel injection quantities TR, TRI, TRx, and TR for each of the fuel injection valves 31 to 34 are determined in addition to the above-mentioned normal fuel injection quantity.
4 is calculated by the formula: %Formula%.

In the above equation, TB is the reference injection amount that is set based on the engine speed and engine load at that time, for example, the intake air amount or the basic fuel injection amount described above, and CTs is the throttle value at which the detection signal St is detected. CW is a correction coefficient that is set to a larger value as the opening increase rate is larger; CW is a correction coefficient that is set to a smaller value as the cooling water temperature of the engine at which the detection signal Sv is detected is higher; BF is a correction coefficient that is set to a smaller value as the engine cooling water temperature increases. Correction values for compensating for operational delays in the fuel injection valves 31 to 34 due to battery voltage fluctuations, and CvI to Cv4, are determined according to the conditions in each of cylinders 1 to 4, as shown in FIG. 3. This is a correction coefficient set by

As shown by the solid line in FIG. 3, the correction coefficient Cv, ~
Cv4 is each crank rotation angle θ in cylinders 1 to 4;
is the crank rotation angle range θY corresponding to the period from immediately after the start of each suction stroke to just before the end.

, θY2. θY and θY4, the value is set to increase as the crank rotation angle θ increases, and at other times, a fixed value that is smaller than the value that increases as the crank rotation angle θ increases; For example, 1
is set to

When the temporary fuel injection amounts TRt~TR4 are set as described above, the control unit lOO immediately starts the injection drive with the pulse width corresponding to the temporary fuel injection amounts TRt~TR, respectively. Pulse signal PJ, ~
PJ is formed and supplied to the fuel injection valves 31 to 34 at the same time.

As a result, temporary fuel injection is performed by the fuel injection valves 31 to 34 with the temporary fuel injection amounts TR, ~TRa. In that case, the temporary fuel injection amounts T Rr to TR4 injected from each of the fuel injection valves 31 to 34 are as follows: When carried out during the suction stroke, the injection amount is increased closer to the end of the suction stroke.

By doing this, the temporary fuel injection is performed in the cylinder 1.
Even if one of 4 to 4 is to be performed in the latter stage of the intake stroke, and the period from the time when the temporary fuel injection is performed to the time when the intake stroke ends is short,
The amount of vaporized fuel taken into the cylinder is sufficient, and a decrease in the ignitability of the air-fuel mixture is avoided, resulting in good acceleration response and the like.

Note that the correction coefficients CV + to Cv4 do not necessarily need to be set to increase as the intake strokes in cylinders 1 to 4 progress in the crank rotation angle range θYl to θY4; ,for example,
As shown by the dashed line in FIG. 3, it may be set to increase stepwise in the first half and the second half of the crank rotation angle range θY, to θY4.

The control unit 100 that performs the above-described control is configured using, for example, a microcomputer.
This will be explained with reference to the flowchart shown in the figure.

In the program shown in the flowchart of FIG. 4, after the start, in process 101, the detection signal Sa
, Sn, Sc, SL, Sw, etc., and in decision 102, it is determined whether or not the throttle valve 25 is in a fully closed state based on the detection signal St.
If it is determined that 5 is not fully closed, process 1
In step 03, the flag F is set to zero and the process proceeds to decision 106. If it is determined that the throttle valve 25 is fully closed, the flag F is set to 1 in process 105.
and proceed to decision 106.

In decision 106, it is determined whether the flag F has changed from 1 to 0. If it is determined that the flag F has not changed from 1 to 0, in process 107, the throttle is adjusted based on the detection signal St. Opening increase rate Δ
Th is calculated, and in the subsequent decision 108, it is determined whether the calculated increase rate ΔTh of the throttle opening is greater than or equal to a predetermined value α, and if it is determined that the increase rate ΔTh is less than the value α, returns to normal. Also, decision 1
If it is determined in 0B that the increase rate ΔTh is greater than or equal to the value α, and in decision 106, the flag F is
If it is determined that the value has changed from 1 to 0, the process proceeds to process 110.

Then processes 110, 111, 112, 113 and 1
14, the reference injection amount TB is sequentially determined.

correction coefficient CTs, correction coefficient CW, and correction coefficient cv,
-cv is set as described above, and in process 115, the reference injection amount TB is set.

correction coefficient CTs, correction coefficient CW, and correction coefficient cv,
-cv, to set the temporary fuel injection amount T Rr~TR, and in process 116, the temporary fuel injection amount ff1T
Form injection drive pulse signals PJ+ to PJ4 having pulse widths corresponding to R and -TR, respectively, and immediately apply these injection drive pulse signals PJt to PJ4 to the fuel injection valve without synchronizing with the engine speed. 31 to 34 and returns.

(Effects of the Invention) As is clear from the above description, according to the engine fuel supply device according to the present invention, the fuel injection means provided corresponding to the cylinder performs normal fuel injection synchronized with the engine rotation speed. In addition, temporary fuel injection is performed asynchronously to engine rotation immediately after the transition to the acceleration state or fuel return state, and temporary fuel injection is performed when the cylinder is in the latter half of the intake stroke. If the temporary fuel injection is performed, the amount of fuel injection is increased compared to when the cylinder is in another state, so the intake stroke ends from the moment the temporary fuel injection is performed. In the relatively short period up to this point, the amount of vaporized fuel injected by the fuel injection means is sufficient, it is possible to avoid a decrease in the ignitability of the air-fuel mixture, and it is possible to obtain good acceleration response etc. It becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram showing the present invention in accordance with the claims, and Fig. 2 shows an example of an engine fuel supply system according to the present invention, and a 4-cycle, 4-cylinder engine to which it is applied. FIG. 3 is a characteristic diagram for explaining the operation of the example shown in FIG. 2, and FIG. FIG. 5 is a flowchart showing an example of a program executed by such a microcomputer, and is a diagram used to explain the relationship between the timing of temporary fuel injection and the amount of fuel vaporized when the cylinder is in the intake stroke. given name. In the figure, 1 to 4 are cylinders, 12 is an intake passage, 18 is a crank angle sensor, 20 is a rotation speed sensor, 24 is an air flow meter, 30 is a throttle opening sensor, 31 to 34 are fuel injection valves, and 100 is a control unit. It is. Figure 1 Figure 5 (0)

Claims (1)

[Scope of Claims] A fuel injection means provided corresponding to a cylinder of the engine; a normal injection amount setting means for setting a normal fuel injection amount according to the operating state of the engine; normal injection control means for performing fuel injection in synchronization with engine rotation with the normal fuel injection amount; and immediately after the operating state of the engine satisfies a predetermined condition, the fuel injection means controls temporary injection control means for performing fuel injection asynchronous to rotation with a temporary fuel injection amount; and a temporary injection control means for performing fuel injection asynchronous to rotation of the engine by the fuel injection means, and When the temporary fuel injection amount is performed when the cylinder is in the latter stage of the intake stroke, the temporary fuel injection amount takes a larger value than when it is performed when the cylinder is in the first stage of the intake stroke, compression stroke, expansion stroke, and exhaust stroke. An engine fuel supply device comprising: temporary injection amount setting means for setting;