JPS5996443A - Fuel injection device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To have stable air-to-fuel ratio characteristic, in an arrangement in which the intaken air amount sensed is fed into a fuel injection control device through an annealing circuit, by enlarging the time constant of this circuit during deceleration. CONSTITUTION:The intaken air amount Vs sensed by an air amount sensor 2 is fed into an annealing circuit 68. The output therefrom is fed into an operator circuit 63. The annealing circuit 68 is to judge the operating condition of the car on the basis of the changing voltage value Vs given by said air amount sensor 2, and if judgement reveals that it is under deceleration, the sensed voltage Vs shall be output through a considerably larger filtration than during normal operation. Thereby a stable air-to-fuel characteristic is obtained.

Description

[Detailed description of the invention] The present invention relates to improvements in fuel injection devices for internal combustion engines.

Conventionally, in this type of device, an air amount detector 2, which is located downstream of an air filter 1 and measures the intake air amount of the engine, is connected to a dam plate 4 disposed in an intake pipe 3 of the engine, as shown in FIG.
An electric signal (1) Vs is generated in accordance with the displacement position of It is composed of

In Fig. 1, when the throttle valve 5 suddenly closes or is close to closing when the engine decelerates, the inertia of the air that had passed through the dam plate 4 of the air amount detector 2 until it suddenly closed causes the throttle valve 5 to close suddenly or close suddenly. A certain amount of air flows from the downstream side of the dam plate 4 to the upstream part of the throttle valve 5, the pressure in this part A increases, and a force is applied to the dam plate 4 in the direction of arrow B in the figure, causing the dam plate 4 to The engine is displaced in the direction of decreasing the amount of air, outputs a signal Vs that is different from the amount of air that the engine is actually taking in (that is, indicates that the amount of air is less than the actual amount), and then returns to the normal state. Therefore, the air/fuel ratio (hereinafter referred to as A/F) set at that time shifts to a larger (leaner) side, resulting in a misfire or near misfire, and the engine's output torque decreases. When the signal returns to its normal state after a certain period of time has elapsed, the torque increases and the vehicle shakes (2), causing an unpleasant feeling to the driver.

FIG. 2 shows changes in the amount of air taken into the engine with respect to the movement of the throttle valve 5, and changes in the output signal of the air amount detector 2 that detects the amount of air. At point X in Figure 2, Figure 2 (])
When the throttle valve 5 is suddenly closed, the amount of air taken into the engine does not change rapidly because the volume from the throttle valve 5 to the intake valve of the engine is large as shown in Figure 2 (2), but the amount of air is There is no problem if the output signal V's of the detector 2 is as shown by the broken line in Fig. 2 (3), but for the reasons mentioned above, it is not possible to use the output signal V's as shown by the solid line in Fig. 2 (3) (the part shown with diagonal lines due to movement). A/F is shifted to the larger side by the corresponding amount.

The present invention has been made in consideration of the above points, and it inputs the output signal of the air amount detector and converts it into a predetermined filtered signal that is larger than normal only when the engine decelerates, and converts this signal into the output signal. By adjusting the amount of fuel according to this output signal, the problem of misfiring due to the A/F shifting to the larger side is eliminated, and drivability is improved, and there is no (3) harmful exhaust gas. The purpose of this invention is to innovate a four-fuel injection system for internal combustion engines, which will reduce the number of fuels.

An embodiment of the present invention shown in the drawings will be described below.
The air amount detector 2 of this embodiment has the same configuration as that shown in FIG. The first step for calculating the fuel injection amount
The control circuit 6 shown in the figure will be explained with reference to FIG. 60 is a terminal for detecting the engine speed based on the voltage waveform on the next side of the ignition coil of the internal combustion engine, 6I is a waveform shaping circuit 18J, 62 is a frequency dividing circuit, 63 is an arithmetic circuit, 64 is a multiplication circuit, and 65 is a voltage correction circuit. , 66 is an OR circuit, and 67 is an output circuit connected to the electromagnetic injection valve 7.Furthermore, on the 6th, the driving state of the vehicle is determined based on the change in the detection voltage Vs of the air amount detector 2, and when decelerating, the detection This is a smoothing circuit that applies a sufficiently larger filter to the voltage Vs than usual and outputs the filter.

Components other than the smoothing circuit 68 in the above configuration are known, for example, from Japanese Patent Application Laid-Open No. 49-67016, and the general operation thereof will be described below. The voltage waveform of the ignition coil applied to the terminal 60 is shaped by a waveform shaping circuit (4) 61, and divided by a frequency dividing circuit 62 with a frequency division ratio selected according to the number of fuel injections per engine revolution. , the pulse signal To has a time width inversely proportional to the engine speed. The calculation circuit 63 calculates the fuel injection amount based on the pulse signal To and the detection signal VS from the air amount detector 2, and generates a pulse signal T1 having a time width proportional to the air amount and inversely proportional to the rotation speed. A multiplication circuit 64 multiplies and corrects the pulse signal T1 by a signal corresponding to engine parameters such as engine cooling water temperature and air temperature to generate a pulse signal T2, and a voltage correction circuit 65 adjusts the amount of fuel injection to change due to fluctuations in power supply voltage. A pulse signal T3 is generated to correct the The time widths of these pulse signals TI, T2 and T3 are added in an OR circuit 66, and the solenoid valve 7 is driven to open via the output circuit 67 during the time width.

Next, details of the smoothing circuit 68 will be explained with reference to FIG. The smoothing circuit 68 has a resistor R1+R2゜R3,R
4+ R51R61R7, capacitor C1, buffer ○
P+,) transistor Tl, T2. T3(5) and deceleration detection means 681. During acceleration or steady state, the deceleration detecting means 681 is set to generate a level signal and turn on the transistor T3, so that the analog switch 71 'T2 is ONL, R
2+ The detection voltage Vs is smoothed by a time constant determined by the parallel resistance of R3 and C+. Also, when decelerating, the deceleration detection means 681
generates an I level signal to turn off transistor T3 and analog switch T+, T2, so the detection voltage Vs is greatly blunted by the time constant determined by R2 and 0 (the time constant is larger during deceleration). It turns out. Therefore, the output of the smoothing circuit 68 provides a signal with no overshoot as shown in the characteristic (b) of FIG. 5(A), and even if this output signal is processed as is, the characteristic of As shown in (d), stable air-fuel ratio characteristics can be obtained. In this regard, in the past, if the output signal of characteristic (a) was processed as is, it would fluctuate as shown in characteristic (c), so an increase correction was performed during deceleration to stabilize the air-fuel ratio, but the calculation became complicated. was.

(6) The deceleration detection means 681 includes a device that forms a deceleration signal by determining the degree and direction of change in the output signal from the air amount detector, engine speed, intake pipe pressure, and fuel injection pulse duration. It is also possible to use a configuration that detects the value of and its change, or a combination of the above-mentioned value and a fully closed signal of the throttle opening, the throttle opening, and the opening of f1', which detects whether or not the opening degree of the opening is fully closed.

Next, another embodiment of the smoothing circuit 68 is shown in FIG. Since the Vs lightning voltage is high during acceleration or steady state, Vs is smoothed by a time constant determined by the parallel resistances R2 and R3 and C1. Also, during deceleration, the Vs lightning voltage becomes low, and at that time the diode D
1, Vs is greatly annealed by the time constant determined by R2 and C1 (the time constant is larger during deceleration).

Further, although the above embodiment shows an example constructed using an analog circuit, the present invention can be similarly applied to a fuel injection device using a microcomputer, a microcomputer, or the like. In that case, when the function of the smoothing circuit is provided outside the computer, the circuit configuration shown in FIG. 4 can be used as is, and (7) the calculation part of blocks 61 to 66 not shown in FIG. 3 can be realized by software. And it is sufficient.

Further, the function of the smoothing circuit can be included in a computer and processed by software I/ware.

As described above, the device of the present invention inputs the output signal of the air amount detector that detects the amount of intake air from the throttle valve 1 flow in the intake pipe of the internal combustion engine, and detects the air amount detector only when the internal combustion engine is decelerating. Since the output signal is generated as a signal after applying a predetermined filter that is larger than normal, it is equipped with a smoothing means, so it is possible to obtain an output signal commensurate with the intake air amount of the engine even during deceleration without performing complicated arithmetic processing. This makes it possible to obtain stable air-fuel ratio characteristics and improve drivability and exhaust purification.

[Brief explanation of the drawing]

Fig. 132 is a system configuration diagram and output waveform diagram used to explain the conventional technology, Fig. 3 is a block diagram showing an embodiment of the present invention, Fig. 1184 is a specific circuit diagram of the annealing circuit, and Fig. 5
The figure is an output wave (8) diagram for explaining the present invention, and FIG. 6 is a circuit diagram showing another example of the round circuit. 2... Air amount detector, 4... Dam plate, 5...
Throttle valve, 6... Control circuit, 7... Injection valve, 6
8... Smoothing circuit, 681... Deceleration detection means. Representative Patent Attorney Takashi Okabe (9) 263

Claims (1)

[Claims] An air amount detector that detects the amount of intake air upstream of a throttle valve in an intake pipe of an internal combustion engine, and a control means that adjusts the amount of fuel to be supplied to the internal combustion engine in accordance with an output signal of the air amount detector. In the fuel injection device for an internal combustion engine, the output signal of the air amount detector is converted into a predetermined filtered signal that is larger than that in normal times only when the internal combustion engine is decelerating, and this is generated as the output signal. 1. A fuel injection device for an internal combustion engine, comprising a smoothing means.