JPH0610441B2 - Electronically controlled fuel injection device - Google Patents

Description

The present invention relates to a fuel injection device for an electronically controlled engine having a plurality of intake valve types, that is, a combustion chamber of each cylinder having a plurality of intake valves, and more particularly to a fuel injection device with improved fuel injection timing. Regarding

The two-intake-valve internal-fuel engine has (a) a large total area of the intake valve opening, and (b) the intake valve is closed at a time later than the bottom dead center of the intake stroke in order to achieve high output. In the latter half, the blowback of intake air from the combustion chamber to the intake passage is increasing. Synchronous fuel injection is performed in synchronism with the engine rotation, that is, the crank angle or the ignition signal, but the synchronous fuel injection from the fuel injection valve is performed once per revolution in all cylinders as in the conventional electronically controlled fuel injection device. When this is done, the fuel injection timing in any of the cylinders becomes the blowback period of the intake air, and the phenomenon occurs in which the fuel is blown back and does not enter the fuel chamber. Further, due to the high intake efficiency of the dual intake valve type electronically controlled engine, the change in the intake air flow rate with respect to the change in the throttle opening becomes large, and the delay in following the fuel injection amount becomes noticeable during acceleration. Due to such blow-back and follow-up delay, the air-fuel mixture in the combustion chamber becomes lean at the time of acceleration, and the problem that acceleration performance is likely to deteriorate easily occurs.

An object of the present invention is to provide a fuel injection device for a multiple intake valve type electronically controlled engine that can avoid backflow of fuel and improve followability of the fuel injection amount during acceleration.

In order to achieve this object, the present invention is an internal combustion engine having a plurality of intake valves in each cylinder, an electronically controlled fuel injection device in which synchronous fuel injection is performed at an injection timing other than the intake blowback timing, Detection means for detecting a throttle opening change amount per unit time at equal time intervals shorter than the synchronous injection timing; a maximum value of the fuel injection amount allowed at the time of detecting the throttle opening change amount; Correction for obtaining a difference from the synchronous injection amount by the synchronous injection immediately before the detection time of the throttle opening change amount, and reducing the amount of fuel corresponding to the difference as the throttle opening change amount detected by the detection means is smaller. Calculating means for calculating the asynchronous fuel injection amount, and the calculating means when the throttle opening change amount detected by the detecting means is a throttle opening change amount of a predetermined value or more. And a control means for performing an asynchronous fuel injection based on the asynchronous fuel injection amount calculated by the step.

By setting the synchronous fuel injection timing in this way, the blowback of the fuel is avoided, the fuel is smoothly introduced into the combustion chamber, and during the acceleration, the asynchronous fuel injection is performed due to the shortage of the injection amount of the synchronous fuel injection. Therefore, the followability of the fuel injection amount during acceleration is improved.

Embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, the intake passage 1 of the electronic control engine is provided with an air cleaner 2, an intake air temperature sensor 3, an air flow meter 4, an intake hose 5, a throttle valve 6, a surge tank 7 and an intake pipe 8 in order from the upstream side. The passage 9 is provided in parallel with the throttle valve 6. The combustion chamber 10 is provided in the engine body 11 and is defined by the cylinder head 12, the cylinder block 13, and the piston 14. Fuel is injected from a fuel injection valve 15 installed near the intake port, enters the combustion chamber 10 through two intake valves 16a and 16b (Fig. 2), and after combustion, becomes exhaust gas and two exhaust valves. 17
It is discharged to the exhaust passage 18 via a and 17b (Fig. 2). The exhaust passage 18 is provided with an exhaust branch pipe 19, an exhaust pipe 20, and a catalytic converter 21 in order from the upstream. The water temperature sensor 25 is attached to the cylinder block 13 to detect the temperature of the cooling water for a certain period, the throttle sensor 26 detects the opening degree of the throttle valve 6, and the O ₂ sensor 27 is provided at the collecting portion of the exhaust branch pipe 19. The crank angle sensor 30 detects the oxygen concentration in the exhaust gas and detects the crank angle from the rotation of the shaft of the distributor 31. The electronic control unit 32 receives power and voltage signals from the storage battery 33, receives inputs from the sensors 3, 4, 25, 26, 27, 30 and, based on these input data, injects fuel injected from the fuel injection valve 15. Calculate the amount.

FIG. 2 shows the vicinity of the intake port. The combustion chamber 10 has two intake valves 16a, 16b and two exhaust valves 17a, 17b,
It also has a spark plug 36 on the top. The intake pipe 8 and the inside of the intake port correspond to the intake valves 16a, 16b by a partition wall 37,
It is partitioned by 38, and the fuel injected from the fuel injection valve 15 is distributed to the intake valves 16a and 16b.

FIG. 3 shows the electronic control unit 32 in detail. CPU4
1, A / D (analog / digital) converter 42, output interface circuit 43, ROM 44, and RAM 45 are bus 46
Are connected to each other via. The crank angle sensor 30
A 180 ° crank angle signal 46 that generates a pulse for each 180 ° CA (CA: crank angle) change and a 720 ° crank angle signal 47 that generates a pulse for each 720 ° crank angle are generated.
The 80 ° crank angle signal 46 is sent to the CPU 41 via the waveform shaping circuit 48.
To the analog input circuit 49 for T _p 1 pulse shaping, and the 720 ° crank angle signal 47 is sent to the interrupt input terminal of the CPU 41 via the waveform shaping circuit 48. T _p 1
The pulse shaping analog calculation circuit 49 utilizes the charge and discharge of the capacitor to extract the pulse width T _p from the data of the intake air flow rate Q from the air flow meter 4 and the data of the engine speed N of the 180 ° crank angle signal. 1 (T _p 1 is one half of the basic fuel injection time T _p 2) is proportional to Q / N and generates a T _p 1 pulse signal 50 having a cycle of 360 ° in crank angle. A
The / D converter 42 receives input signals from the intake air temperature sensor 3, the water temperature sensor 25, the throttle sensor 26, the O ₂ sensor 27, and the storage battery 38, and selectively A / D converts these input signals. The output interface 43 sends a variable injection pulse for each group of fuel injectors 15. In the embodiment, the electronically controlled engine is a 4-cylinder engine, and the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder are defined in order from one end of the engine body 11, and the ignition order is the first cylinder, the first cylinder, and the second cylinder. There are three cylinders, a fourth cylinder, and a second cylinder. The first cylinder and the second cylinder are classified into a group A, and the third cylinder and the fourth cylinder are classified into a group B.

FIG. 4 is a flow chart of the synchronous fuel injection routine. The final fuel injection time T _au is calculated, and the fuel injection valve 15 of the A group and the fuel injection valve 15 of the B group are selected and driven depending on the presence or absence of the 720 ° CA signal. In step 54, the pulse width T _p 1 is detected from the T _p 1 pulse signal 50. In the T _p 1 pulse shaping analog circuit 49, synchronous fuel injection is performed twice per cycle of the engine. That is, it is designed for one intake valve type (each combustion chamber has only one intake valve) electronically controlled engine in which synchronous fuel injection is performed once for each crank angle change of 360 °, and T _p 1 is once Is 1/2 of the basic fuel injection time T _p 2 of the synchronous fuel injection.
Reasons for not calculating the direct basic fuel injection time T _p 2 is to reduce the time required for detection of the basic fuel injection time T _p 2. In step 56, it is judged whether or not the fuel cut condition is satisfied, and if the fuel cut condition is satisfied, the execution of the following steps is omitted, and if not satisfied, step 58 is executed.
Go to. The fuel cut condition is, for example, a deceleration period in which the engine speed is equal to or higher than a predetermined value. At step 58, 2 · T _p 1 · K1 is substituted for the fuel injection time T _au 1.
T _au 1 is the final fuel injection time when the synchronous fuel injection from each fuel injection valve is performed twice per engine cycle. By multiplying T _p 1 by 2, the basic fuel injection time T _p
2 is obtained, and the basic fuel injection time is corrected by further multiplying 2 · T _p 1 by K1. K1 is a correction coefficient determined by the intake air temperature, engine cooling water temperature, etc. In step 60, it is determined whether or not the group-by-group injection execution condition is satisfied. If the condition is satisfied, the process proceeds to step 64, and if not, the process proceeds to step 62. Satisfying the injection conditions for each group means that the period rotation speed fluctuates and the 180 ° crank angle signal fluctuates, for example, during a low engine rotation speed period such as a starting period. In this case, if the group-by-group synchronous fuel injection is performed, the intervals of the synchronous fuel injection are disturbed, which is not preferable for the period operation.
In step 62, synchronous fuel injection is performed simultaneously for all cylinders. At step 64, the final fuel injection time T _au 2 · T _au 1 is substituted. The reason why T _au 1 is multiplied by 2 is that in the fuel injection by group, the synchronous fuel injection from each fuel injection valve 15 is once instead of twice per cycle. Step 66
Then, it is determined whether or not there is a 720 ° crank angle signal, and if there is, the process proceeds to step 68, and if there is not, the process proceeds to step 70. 720
The ° crank angle signal occurs at the top dead center of the first cylinder's power stroke. In step 68, the group A fuel injection valve 15 is driven, and in step 70, the group B fuel injection valve 15 is driven. Therefore, synchronous fuel injection from each fuel injection valve
The latter half of the intake stroke and the first half of the compression stroke of the corresponding cylinder of the fuel injection valve, that is, the blowback period of the intake air is avoided.

FIG. 5 is a flow chart of the asynchronous fuel injection routine. This routine is a time interrupt routine executed every 16 msec. The change amount ΔTh of the throttle opening Th is equal to or larger than a predetermined value, and therefore the required degree of acceleration is large, and the maximum fuel injection time T _pmax and T _p 1 corresponding to the last synchronous fuel injection are set. If the difference ΔT _p of ΔT _p is positive, asynchronous fuel injection is performed for the fuel injection time related to ΔT _h and ΔT _p . At step 76, the throttle opening
Detect Th. At step 78, Th-Th 'is substituted for the change amount ΔTh of the throttle opening. Th ′ was the last time, ie 16
It is the throttle opening detected msec before. In step 80, the upper limit ΔTha and the lower limit ΔThb of the change amount ΔTh are limited.
In step 82, it is judged whether or not ΔThΔTh1, and ΔThTh1
If so, the process proceeds to step 84, and if ΔTh <ΔTh1, the execution of the following steps is omitted. Thus the throttle opening
The asynchronous fuel injection is performed only when the change amount ΔTh of Th is larger than ΔTh1. In step 84, the correction coefficient K2 as its function is calculated from ΔTh. Figure 6 shows ΔTh and K
The relationship with 2 is shown. K2 increases in a rapid acceleration state. At step 86, the maximum value Tpmax defined as the basic fuel injection time when the throttle valve is fully opened at the present engine speed is taken in. Tpmax is determined in relation to the engine speed. In step 88, T _pmax -T _p 1 is changed to ΔT _p
To. T _p 1 in the step 88 is T _p 1 becomes such basic injection quantity of the last performed synchronization fuel injection. At step 90, it is determined whether or not ΔT _p > 0, and ΔT _p >
If it is 0, the process proceeds to step 92, and if ΔT _p 0, the execution of the following steps is ended. Thus, the asynchronous fuel injection is performed only when the final synchronous fuel injection amount is insufficient with respect to the required fuel injection amount. At step 92, K2 · ΔT _p is substituted for the asynchronous fuel injection time T _as . At step 94, asynchronous fuel injection is performed. Asynchronous fuel injection is performed simultaneously for all cylinders.

Figure 7 shows the throttle opening T at an engine speed of 1000 rpm.
3 is _a timing chart of the synchronous fuel injection I _s and the asynchronous fuel injection I _a when h is suddenly opened from 0 ° to full opening. FIG. 7 shows the intake stroke of each cylinder. The synchronous fuel injection I _s is performed for each group of fuel injection valves 15,
The operation is performed outside the predetermined crank angle range including the bottom dead center of the intake stroke at which the intake air is blown back. The 180 ° crank angle signal occurs 10 ° before the top dead center of each cylinder. The asynchronous fuel injection I _a is performed each time the time interrupt routine of FIG. 5 is executed when the required fuel injection time is longer than the last synchronous fuel injection time.

FIG. 8 is a functional block diagram of the present invention. The synchronous fuel injection calculation means 100 calculates the injection amount and injection timing of the synchronous fuel injection based on the input signals from the crank angle sensor 30 and the T _p 1 pulse shaping analog calculation circuit 49. The required fuel injection amount calculation means 101 calculates the basic fuel injection amount T _pmax when the throttle valve is fully opened at the present engine speed.
Asynchronous fuel injection calculation means 102 T _p 1 from T _p 1 pulse shaping analog arithmetic circuit 49, the required fuel injection amount calculating means 101
And the injection amount and injection timing of the asynchronous fuel injection are calculated based on the data of P _pmax from the throttle sensor 26 and the data of the throttle opening Th from the throttle sensor 26. The drive means 103 sends the output of the synchronous fuel injection calculation means 100 to the group A fuel injection valve 15 or the group B fuel injection valve 15 based on the 720 ° crank angle signal of the crank angle sensor 30, and the output of the asynchronous fuel injection calculation means 102. Group A and Group B fuel injection valve 1
Send to 5.

[Brief description of drawings]

FIG. 1 is a schematic view of an electronic control engine to which the present invention is applied, FIG. 2 is a detailed view of the two intake valves in the vicinity of an intake port of the electronic control engine, and FIG. 3 is a detailed view of the electronic control device of FIG. Block diagram, Fig. 4 shows the flow chart of the synchronous fuel injection routine,
FIG. 5 is a flow chart of the asynchronous fuel injection routine, FIG. 6 is a graph showing the relationship between the change amount of the throttle opening and the asynchronous fuel injection correction coefficient, and FIG. 7 is the throttle opening 0.
FIG. 8 is a functional block diagram of the present invention, which is a timing chart for synchronous fuel injection, asynchronous fuel injection, and the like when the angle changes from .degree. 10 ... Combustion chamber, 15 ... Fuel injection valve, 16a, 16b ... Intake valve, 30 ...
Crank angle sensor, 100 ... Synchronous fuel injection calculation means, 101 ...
Fuel injection amount calculation means 102 ... Asynchronous fuel injection calculation means.

Front Page Continuation (72) Inventor Mamoru Yoshioka 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP-A-56-54929 (JP, A) JP-A-56-124637 (JP, A) JP-A-56-148633 (JP, A) JP-A-55-131541 (JP, A) JP-A-58-28541 (JP, A) JP-B-47-41288 (JP, B1)

Claims (1)

[Claims] 1. An electronically controlled fuel injection device, comprising: an internal combustion engine having a plurality of intake valves in each cylinder, wherein synchronous fuel injection is performed at an injection timing that deviates from a timing of intake blowback, and is shorter than the synchronous injection timing. Detection means for detecting the throttle opening change amount per unit time at equal time intervals, the maximum value of the fuel injection amount allowed at the time of detecting the throttle opening change amount, and the throttle opening change amount Asynchronous fuel injection in which a difference from the synchronous injection amount by the synchronous injection immediately before the detection time point is obtained, and the amount of fuel corresponding to the difference is reduced as the throttle opening change amount detected by the detection means is smaller. Calculation means for calculating the amount, and a non-calculated value calculated by the calculation means when the throttle opening change amount detected by the detection means is equal to or larger than a predetermined value. Electronically controlled fuel injection apparatus characterized by a control means for performing an asynchronous fuel injection on the basis of the period the fuel injection amount.