JPH03213637A - Fuel injection controller - Google Patents

Abstract

PURPOSE:To rapidly and smoothly perform acceleration from a low speed condition of an engine by additionally injecting a fuel injection quantity after synchronous injection under a timing same as that of intake stroke during which the injection fuel synchronous with engine speed is sucked in the engine. CONSTITUTION:In an engine (a), fuel is injected and supplied from an injector (b). In this case, fuel injection by the injector (b) is synchronized with the revolution of the engine (a) detected by an engine speed sensor (c), and controlled by a means (d). The synchronously injected fuel is controlled by a means (f) so that an increase in a required fuel quantity after the synchronous injection is additionally injected under the absorbing timing in an intake stroke same as the intake stroke absorbed in the cylinder of the engine (a), detected by an operation condition detection sensor (e). When the engine (a) is accelerated from a low speed rotational condition, want of the fuel is eliminated, and rapid/ smooth acceleration is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for means for supplying fuel to an engine. In particular, the present invention relates to a type of control device that calculates the amount of fuel required by the engine at a given time based on the operating state of the engine, and operates a fuel supply means based on this.

[Conventional technology]

The above-mentioned type of control device: ■ detects a parameter indicating the operating state of the engine, ■ calculates the required amount of fuel based on this, ■ operates the fuel supply means according to the calculated value, and ■ controls the supplied fuel. It is desirable to shorten the time required for suction into the cylinder as much as possible. This is because if the time period is shortened, even if the operating state of the engine changes from moment to moment, the exact amount of fuel required by the engine at that time can be sucked into the engine.

In response to this demand, the technology described in Japanese Patent Application Laid-Open No. 56-52'537 or Japanese Patent Publication No. 62-348 has been developed. This is in order to shorten the time mentioned in (■) above, by starting the operation of the fuel supply means before calculating the required amount of fuel, calculating the required amount of fuel in parallel with the fuel supply, and depending on the calculation result. This controls the timing at which the fuel supply means stops operating.

[Problem to be solved by the invention]

By the way, FIG. 1(B) is a timing chart showing the relationship between injection timing and suction timing. Due to the characteristics of the engine, after fuel is injected, the cylinder (intake valve)
The time it takes to reach the point is almost constant regardless of the engine speed. This is shown at T2 in the figure.

However, within these 12 hours, if the engine speed is high, the crank angle changes greatly, whereas if the engine speed is low, the angle of change in the crank angle is small.

Figure 1 (B) shows the crank angle on the horizontal axis.
The upper row shows the timing when the engine is rotating at maximum speed, and the lower row shows the timing when the engine is rotating at low speed.

When the engine is rotating at maximum speed, the amount of fuel required is large, and the fuel supply means is injecting for a long time. If this is expressed by the change angle of the crank, the crank angle changes greatly during injection. Furthermore, as described above, the time T2 until the injected fuel reaches the cylinder is not shortened even at high rotation speeds, so the crank angle changes significantly during these 12 hours. Since all of the injected fuel in this state must arrive at the cylinder during the intake stroke, it is understood that the fuel injection timing must start at time to at the latest.

A similar diagram is shown below. This indicates when the engine is running at low speed. At this time, if synchronous injection is started at time to in synchronization with the engine rotation, the crank angle will not change much during the time T2 until the fuel arrives at the cylinder, and the fuel will arrive before the start of the intake stroke. Sometimes. That is, it is understood that the injection timing for the injected fuel to arrive at the cylinder during the intake stroke is later than the time to. In this case, if the operating state of the engine is detected at the final timing when the injected fuel can reach the cylinder by the end of the intake stroke, the required amount of fuel is calculated, and fuel is supplied based on this, the operating state of the engine can be changed over time. The correct and correct amount of fuel will be drawn into the cylinder even if the temperature varies. In this way, even when the engine is accelerated from a low speed rotation state, an appropriate amount of fuel is supplied. However, as far as the applicant is aware, there is currently no technology that deals with this type of problem associated with synchronous injection.

Therefore, the present invention performs synchronous injection at a timing that does not cause the intake stroke of the injected fuel to be delayed by -cycle even when the engine is running at high speed, while at the same time, the fuel reaches the cylinder before the end of the intake stroke, which is particularly noticeable when the engine is running at low speed. This is to ensure that enough fuel is additionally supplied to compensate for the shortfall in the amount of intake fuel relative to the required amount of fuel that occurs due to the difference between the available injection timing and the synchronous injection timing.

In this way, even when the engine is accelerated from a low speed rotation state, the engine is quickly accelerated without running out of fuel.

[Means to solve the problem]

The above problem is to provide a fuel injection control device for an engine, the outline of which is shown in FIG. synchronous injection control means for operating the fuel injection means in synchronization with the rotation of the engine main body; and a timing at which the fuel injected by the synchronous injection is taken into the cylinder of the engine main body in the same intake stroke as the intake stroke. The problem is solved by a fuel injection control device having additional injection control means for additionally injecting the increased amount of fuel required after synchronous injection.

[For production]

Now, the operation of the above device will be explained with reference to FIGS. 1(B) and 1(C).

Now, let us consider a case where the engine is accelerating and the required amount of fuel increases over time as shown in FIG. 1(C). Here, to indicates the timing of synchronous injection, and the synchronous injection amount at that time is determined based on the operating state T1 hours earlier (here, TI is the time required to calculate the synchronous injection amount). If the engine is rotating at high speed, the synchronously injected fuel is drawn into the cylinder with a delay of T2 time. Therefore, to be more precise, the amount of fuel sucked into the cylinder is insufficient by the amount indicated by A in the figure.

However, this shortage amount A is smaller than the shortage amount B during low-speed rotation, which will be described later, and since the engine output is at a high level during high-speed rotation, it does not cause noticeable acceleration sluggishness.

On the other hand, when the engine is running at low speed, it is still not in the intake stroke even 12 hours after injection, and eventually T2 + T after injection.
After 3 hours, the fuel is sucked into the cylinder (here, T3 is the time from when the injected fuel arrives at the cylinder until the end of the suction stroke), and the amount sucked into the cylinder is less than the actually required amount by B in the diagram. ing. At this time, this shortfall B is larger than the shortfall A during high-speed rotation, and since the output level of the engine is originally low during low-speed rotation, this causes sluggish acceleration when the engine speed is increased from low-speed rotation.

However, according to the present invention, as shown in the lower column of FIG. 1(B), the shortfall B is compensated at the timing when the synchronously injected fuel is inhaled during the same intake stroke as the intake stroke when the synchronously injected fuel is inhaled. This solves the problem of fuel shortage that causes sluggish acceleration.

〔Example〕

Next, an embodiment embodying the present invention will be described.

FIG. 2 shows the entire engine system incorporating the fuel injection control device according to the present invention. Engine body 30
An intake pipe 32 is attached to the intake pipe 32, and a fuel injection means (injector) injects and supplies fuel into the intake pipe 32.
38 is installed. This engine system has a configuration controlled by an engine control unit 40, and the engine control unit 40 receives a signal from a pressure sensor 36 that detects the pressure in the intake pipe 32, and a crank of the engine body 30 rotates a predetermined angle. The output of a crank angle sensor 42 that outputs a pulse wave at each time is input. Further, an oxygen partial pressure sensor 44 is attached to the exhaust pipe 48, and its output is sent to the engine control unit 40.
is input.

Incidentally, numeral 34 in the figure is a throttle valve, which adjusts the amount of intake air. Further, the illustrated numeral 46 is a three-way catalyst that purifies exhaust gas.

This engine system uses a control method that determines the amount of intake air per revolution of the engine based on signals from the pressure sensor 36 and crank angle sensor 42, and supplies the required amount of fuel from the injector 38 at that time. At this time, depending on the case, the output of the oxygen sensor 44 may be referred to to perform feedback control of the amount of fuel to be supplied.

FIG. 3 shows the heart configuration of the signal processing system in the above system, which includes the intake pressure sensor 36 and the oxygen sensor 44.
The detected value is level-adjusted by the level correction circuit 50, and then converted to an analog-to-digital converter (A/D converter).
52, it is converted into a digital signal and sent to the central processing unit (C
PU) 54. The crank angle sensor 42 has a characteristic of outputting a pulse wave every time the crankshaft rotates by a predetermined angle, and this pulse wave is shaped by a waveform shaping circuit 58 and then taken into the CPU 54.

A ROM 60 and a RAM 62 are connected to the CPU 54, and the CPU 54 processes the signals according to a program stored in the ROM 60.

Note that in this process, the RAM 62 is used as necessary. The CPU 54 sends the processing results to the RAM 62 and the drive circuit 56. The signal sent to the drive circuit 56 here is a signal regarding the valve opening time and valve opening timing of the injector, and the valve opening time and valve opening timing of the injector 38 are controlled based on the signal. Next, the programs stored in the ROM 60 will be explained.

FIG. 4 shows the procedure processed by the synchronous injection amount calculation program.

Further, FIG. 5 shows a processing procedure for synchronous injection based on the calculation results shown in FIG. 4, and the synchronous injection is controlled by the processing shown in FIGS. 4 and 5. The processing timing shown in FIG. 5 is executed by interruption when the crank angle reaches a predetermined angle. Here, as shown in Figure 1 (B), this predetermined angle is such that all of the synchronously injected fuel arrives at the cylinder during the immediately following suction stroke when the engine is rotating at the maximum allowable rotation speed. It is set to the crank angle at which the engine is inhaled.

The process shown in FIG. 4 is set to be executed T1 hours earlier than that, and specifically, one cycle of the engine (from the intake stroke to the next intake stroke) is determined from the time interval of the output pulse of the crank angle sensor 42. Calculate the time required for (up to stroke), then subtract the time Tl required to calculate the synchronous injection amount to find the time (Ta), and when the time Ta has elapsed after the start of the execution in Figure 5, the process in Figure 4 interrupts. executed. Since it is set in this way, the process in FIG. 4 is started at time T1 before the start of the process in FIG. 5, and the process in FIG. 5 is executed based on the calculation result.

Now, in the process shown in FIG. 4, step 1 is a process for detecting the operating state of the engine, in which the intake pressure PM is read from the signal of the intake pressure sensor 36, and the engine rotational speed Ne is read from the pulse interval of the crank angle sensor 42.

In step 2, in order to calculate the increase in the required fuel amount after synchronous injection, the intake pressure PM read in step 1 is changed to PMO.
(O is old), and this PM
O is used in the processing shown in FIG. 6, which will be described later. Note that since the engine speed Ne does not vary significantly in a short period of time, it is not used in calculating the increase in the required amount of fuel.

Step 3 is a process to calculate the basic fuel injection amount TP from the intake pressure PM and engine speed Ne read in step 1. Basically, the intake air amount per engine revolution is calculated and multiplied by a constant. Calculated by the formula.

Step 4 is a process of calculating a correction amount, which calculates a coefficient that increases or decreases from the basic amount in order to increase the amount depending on the engine water temperature or increase the amount at startup. Step 5 multiplies the basic amount TP by the correction coefficient FT to obtain the synchronous injection amount. Here, the formula is set so that TE is calculated as the valve opening time of the injector 38 necessary to supply the calculated synchronous injection amount.

Step 6 is a step to obtain KTE by multiplying the correction coefficient FT by the constant Kl.
E is used when determining the increase in the required amount of fuel after synchronous injection. Step 7 is the time to calculate the invalid injection time TB from the battery voltage. Even when a voltage is applied to the injector 38, it is inevitable that the valve will not open instantaneously, but will open after a certain period of time. This delay time is dependent on the battery voltage B. Step 7 is this delay time TB
It is used to calculate.

Now, when the calculation is completed in this manner, the engine crank angle becomes the synchronous injection timing, and the process shown in FIG. 5 is executed. Step IO is a process of calculating the start timing of the additional injection program. Here, TX is calculated based on the following formula.

TX = TB - (TC + TD + T2) (Figure 1 (
(See B)) Here, TB is the time required for the engine to rotate from the crank angle of synchronous injection to the crank angle at the end of the intake stroke, and is determined from the engine rotation speed Ne.

Further, TC is the time required to calculate the additional injection amount, that is, the time required for the processing shown in FIG. 6, which will be described later, and is determined in advance. Also, TD is the additional injection time, which is determined precisely by the process shown in Figure 6, but the maximum value is determined based on the characteristics of the engine, and by using this maximum value, it is possible to calculate TX in advance. can. Furthermore, T2 is the time required for the injected fuel to arrive at the cylinder, and this is predetermined depending on the characteristics of the engine.

In this way, the time TX from the start of the synchronous injection until the start of the additional injection program is determined by the step 10.

Step 11 is a process of determining whether the thus obtained TX is less than or equal to TM, and when the engine is rotating at a predetermined number of revolutions or more, TX becomes less than or equal to TM. Here, TM is the time required to execute the process shown in FIG. 5, and TX <TM corresponds to the case where the intake stroke of synchronous injection is not inquired even if additional injection is performed. In this case, step 1
Skip step 2 and do not perform additional injection.

If TX is greater than or equal to TM, an interrupt timing timer is set according to the following equation so that the process shown in FIG. 6, which will be described later, is executed when TX time has elapsed after the start of synchronous injection in step 12.

Timer interrupt time = current time + TX -TN where TN
is the time required from the start of the process in FIG. 5 until the current time is detected in step 12, and is a predetermined time.

Step 13 is the T determined in steps 5 and 7 in Figure 4.
This process calculates the valve opening time TINJ for synchronous injection of the injector 38 from E and TB.
INJ time injector is activated. As mentioned above, T
Since the injector does not operate during the B time, fuel is eventually supplied from the injector 38 during the TE time. As a result, the required synchronous injection amount determined in the process shown in FIG. 4 is synchronously injected.

Now, Figure 6 shows the additional injection program, and this is the 5th
It is executed only when TX is greater than TM in step 11 of the figure. This operation timing is executed when the time set in step 12 of FIG. 5 arrives. This timing is the final timing when the additional fuel amount is calculated after that, and when the additional injected fuel arrives at the cylinder, the additional fuel is sucked in the same intake stroke as the synchronously injected fuel. be.

In step 21, the intake pipe pressure PM at that time is read, and the difference (62M) between the intake pipe pressure and the intake pipe pressure during synchronous injection is determined. Then, in step 23, the effective valve opening time TADD for additional injection is determined (step 23). TA here
DD is calculated using the following concept. Now, since the injector opening time T is the relationship between the intake pipe pressure PM and the engine speed Ne, it is as follows. Here, since ΔNe does not vary significantly during the suction stroke, it can be calculated as θ PM. Since the constant 1 is set so that KTE (KI Instead of this method, the required amount of fuel may be calculated again and the shortage calculated from there.The above formula simplifies the calculation and allows the additional amount to be calculated in a short time.

Now, if the TADD obtained in this way is negative, no additional injection is necessary, and therefore no additional injection is performed (route F). If TADD is positive, the process proceeds to step 25, where it is determined whether synchronous injection is still in progress. If it is a synchronous injection, step 26 is executed and further TAD is performed following the synchronous injection.
D time is extended so that the injector 38 can be opened. If simultaneous injection is not in progress, additional injection is performed separately from the synchronous injection (step 28). At this time as well, the invalid injection time is taken into consideration (step 27).

The additional fuel injected in this way is inhaled during the same intake stroke as the synchronously injected fuel, and the total amount of intake fuel becomes equal to the amount required by the engine at the end of the intake stroke. This prevents fuel shortage even when the engine is accelerated from a low speed state.

FIG. 7 shows a second embodiment of the additional injection control means, in which additional injection is performed only when the engine speed is 2,000 revolutions or less. This means that when accelerating from 2°000 rpm or higher, the fuel shortage is so large (
This is because there is no problem with sluggish acceleration. In this way, the amount of calculations when the engine speed is 2,000 revolutions or more is reduced, and the workload of the engine control unit 40 can be reduced.

Note that the above 1. In the second embodiment, whether or not to perform additional injection is controlled based on the engine speed, but this may be performed all the time. In this way, when the engine rotates at high speed, a part of the additional injection amount may not be inhaled in the same intake stroke as synchronous injection, but it will be inhaled in the next intake stroke, causing special problems for engine control. It will not occur.

As yet another embodiment, the arithmetic expression in step 23 of FIG. 6 may be used. Here, TG is the time from the start time of additional injection amount calculation to the end of the intake stroke, and as mentioned above, T
I is the time required to calculate the synchronous injection amount, and TX is the time required to start calculating the additional amount after synchronous injection (see Figure 1).
See C). In this way, the required amount of fuel at the end of the intake stroke can be estimated, the difference between this amount and the synchronous injection amount can be determined, and this can be additionally supplied. Therefore, if this formula is used, the shortage can be additionally supplied more accurately.

〔Effect of the invention〕

By using this method, even when the engine is accelerated from a low rotation speed, fuel shortage can be prevented and the engine can be smoothly accelerated. Therefore, the drivability of the vehicle is improved and safety is enhanced.

[Brief explanation of drawings]

FIG. 1(A) is a schematic diagram showing the concept of the present invention; FIG. 1(B) is a schematic diagram showing the concept of the present invention;
) and FIG. 1(C) are timing charts and graphs explaining the present invention in detail, FIG. 2 is a diagram showing an engine system incorporating the present invention, and FIG. 3 is a system block of the engine control unit and its peripheral equipment. 4 is a diagram showing the synchronous injection amount calculation process, FIG. 5 is a diagram showing the synchronous injection control procedure, FIG. 6 is a diagram showing the additional injection control procedure, and FIG. 7 is a diagram showing another embodiment of the additional injection. It is a figure showing a control procedure.

Claims (1)

[Scope of Claims] A fuel injection control device for an engine, comprising an engine body and a means for injecting and supplying fuel to the engine body, the fuel injection means controlling the fuel injection means in synchronization with the rotation of the engine body. a synchronous injection control means to be activated; and a synchronous injection control means for controlling an increase in the required amount of fuel after the synchronous injection at a timing when the fuel injected by the synchronous injection is taken into the cylinder of the engine body in the same intake stroke. A fuel injection control device having additional injection control means for performing additional injection.