JPS5813155A - Electronic fuel injector for engine - Google Patents

Abstract

PURPOSE:To permit a flowmeter for detecting intake air amount of always operate in the range of high detecting accuracy by opening or closing a bypass path branched from an intake path in an engine. CONSTITUTION:While a first flowmeter 22 is inserted into an intake path of an engine to directly detect intake air amount, a second flowmeter 30 for indirectly detecting said intake air amount from two amounts out of the number of revolution of the engine, intake pressure and opening of a throttle valve is provided to control a fuel injector 29 according to the output signal from the second flowmeter 30 for a predetermined time in synchronization with the opening-closing change-over operation of a device 26 which opens and closes a bypass path 25 branched from the intake path to bypass the first flowmeter 22. Thus, in the change-over of opening and closing the device 26, the intake air amount can be indirectly detected for fuel injection by the second flowmeter 30 not affected by change in air flowing through the first flowmeter 22 and bypass path 25. Thus, combustion quality can be prevented from degradation in the change-over operation of opening and closing the device 26.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic fuel injection device for an engine, and more specifically, the present invention relates to an electronic fuel injection device for an engine, and more particularly, a flow meter that detects the amount of intake air by opening and closing a bypass passage branched from an intake passage of an engine is constantly operated to maintain detection accuracy. The present invention relates to an electronic fuel injection device for an engine operated in a high range.

Generally speaking, compared to an air flow meter or current meter as a measuring instrument, an engine intake air amount detection device is required to have a wider detection range, less pressure loss, and better response. .

Conventionally, as an intake air amount detection device for detecting the intake air amount of an engine, for example, there is
No. 1 (name of the invention: ``Engine intake air amount detection device'') is known.

As shown in FIG. 1, the above device includes a first vortex flowmeter 2 for detecting the intake air amount of an engine, and an on-off valve provided in a bypass passage 5 of the first vortex flowmeter 2. 6 and
The pipe 1 is equipped with the first vortex flowmeter 2 and a second vortex flowmeter 11 that detects the total amount of air flowing through the bypass passage 5.
0, the opening/closing valve 6 is opened and closed by the diaphragm 7 which communicates with the downstream side of the first vortex flow meter 2, and the first vortex flow meter 2 is operated with good detection accuracy when the amount of intake air is relatively small, and when the pressure is While the loss is not large, the second vortex flowmeter 11 has good detection accuracy when the amount of intake air is relatively large, and the pressure loss is small. This makes it possible to accurately detect the amount of intake air over a wide range, from a small flow rate of air when the engine is in use to a large flow rate when the load is full, without increasing pressure loss.

However, when the above-described intake air amount detection device is used as a flowmeter for detecting the intake air amount in an electronic fuel injection device of an engine, the first vortex flowmeter 2 and the second vortex flowmeter 2
In a transient state where the amount of air passing through the first vortex flowmeter 2 or the second vortex flowmeter 11 changes rapidly when the vortex flowmeter 11 is switched, that is, when the on-off valve 6 is switched on and off, the amount of air passing through the first vortex flowmeter 2 or the second vortex flowmeter 11 changes rapidly , turbulence occurs in the airflow, which deteriorates the flow rate detection of the first and second vortex flowmeters, and the followability of the first and second vortex flowmeters during switching operation deteriorates.

For this reason, the fuel injection accuracy of the electronic fuel injection device deteriorates for a while after the on-off valve 6 opens and closes.
For example, in a car engine where the on-off valve 6 is constantly opened and closed depending on the driving situation, the combustibility of the engine decreases and harmful substances such as NOx and HC are contained in exhaust gas and gas. There was a problem with the increase in

The present invention has been made in view of the above-mentioned circumstances regarding an electronic fuel injection system for an engine using a conventional intake air amount detection device, and the present invention is an electronic fuel injection system for an engine using a conventional intake air amount detection device. While the air amount is directly detected, two of the engine speed, intake pressure and throttle valve opening are detected.
A second flow meter that indirectly detects the amount of intake air from the first flow meter is provided, and the bypass passage branches off from the intake passage and bypasses the first flow meter.The bypass passage opens and closes for a predetermined period of time in synchronization with the opening/closing operation of the switching device. The fuel injection valve is controlled by the output signal of the second flowmeter, and the first
The flow meter and the second flow meter, which is unaffected by changes in the air flowing through the bypass passage, indirectly detect the amount of intake air and inject fuel, thereby reducing the combustibility of the engine when switching the opening/closing device. It is an object of the present invention to provide an electronic fuel injection device for an engine which prevents the above.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, 21 is an air cleaner, 22 is installed in the intake passage 24 of the engine 28, and directly controls the amount of intake air.
An air flow meter as a first flow meter for detection; 25, a bypass passage branching from the intake passage 24 and bypassing the air flow meter 22; 26, a solenoid valve as an opening/closing device for opening and closing the bypass passage 25 by a renoid 27; -8 is the above-mentioned intake passage 2 downstream of the air flow meter 22
4 two throttle valves; 29a is a fuel injection valve that injects fuel into the intake passage 24 between the throttle valve 28 and the engine 28; 80 is a second flow meter; 81 is a fuel injection control device; .

The second flowmeter 80 is composed of an engine speed detection circuit 82 and a throttle opening sensor 83, and in the embodiment shown in FIG. The engine speed signal and throttle opening signal outputted respectively are input to a map control calculation circuit 84 of the fuel injection control device 81, which will be described below, and the adult air amount is indirectly calculated using the map stored in the map control calculation circuit 34. Based on this intake air amount, the amount of fuel injected from the fuel injection valve 29° during the opening/closing operation of the solenoid valve 26 is controlled.

The fuel injection control device 31 includes a map control calculation circuit 84, a reference setting circuit 35, a comparison circuit 86.24137% calculation circuit 88, and a switching circuit 89.

As shown in FIG.
2, t3, t4, etc., find a region (map) in which the amount of intake air is almost equal, and calculate the amount of intake air for the engine speed and thrower and torque openings using these engine speeds and throttle openings as addresses. The written read-only memory (not shown, hereinafter abbreviated as ROM) and the above RO
It is composed of a fuel injection amount calculation circuit (not shown) that determines the fuel injection amount based on the intake air amount output from M,
As described above, the fuel injection amount is map-controlled based on the engine rotational speed signal and the throttle opening signal.

On the other hand, as shown in FIG. 4, the reference setting circuit 35 calculates the engine speed
This circuit outputs a reference signal of the throttle opening degree S relative to the throttle opening degree. The magnitude of the throttle opening signal is compared.

- The comparison circuit 86 operates at one engine speed X, as shown in FIG. The magnitude of the reference signal for
), and the actual throttle opening is set to 802', a "High" signal is output when S02>5(xo), and a "Lo" signal is output when S01<5(xo).
Outputs the signal w"".

The output signal of the comparison circuit 86 described above is input to the solenoid 27, the timer 87, and the arithmetic circuit 38.

The solenoid 27 is configured so that the output signal of the comparison circuit 86 is “H”.
igh"- to open the solenoid valve 26 and open the bypass passage 25.

On the other hand 1. The timer 3 detects the rising of the output signal of the comparator circuit 86 from &LOWl'' to “High” and the rise of the output signal “H”
The switching circuit 39 is triggered at the timing of falling from "high" to "LOW" and changes the fuel injection amount according to the output signal of the map control calculation circuit 84 for the settling time of the timer 37. I try to control it.

The calculation circuit 88 is a circuit that calculates the optimal fuel injection amount from the air flow rate signal input from the air flow meter 22 and the engine rotation speed signal input from the engine rotation speed detection circuit 82, and its output signal is based on the above-mentioned map. It is input to the switching circuit 89 together with the output signal of the control calculation circuit 84.

In FIG. 2, the output signal of the comparator circuit 86 is input to the arithmetic circuit 88 because when the solenoid valve 26 is opened and air also flows into the bypass passage 25, the amount of air passing through the air flow meter 22 is input to the arithmetic circuit 88. is the value obtained by subtracting the amount of air passing through the bypass passage 25 from the amount of intake air passing through the intake passage 24. Therefore, when the output signal of the comparison circuit 86 is "High" (when the bypass passage 25 is open), This is to switch the function of the fuel injection amount with respect to the air flow rate signal output from the air flow meter 22. Next, the operation of the electronic fuel injection system of the engine 28 shown in FIG. 2 will be described.

Now, when the engine 23 is rotating at idle, the throttle opening S of the throttle valve 28 is small.
It is within the area AO□ below the curve S (x) in FIG.

Therefore, the output signal of the comparison circuit 86 is "Low", the solenoid 27 is deenergized, the solenoid valve 26 closes the bypass passage 25, and the switching circuit 89
The fuel injection valve 29 is actuated by the output signal.

In the above state, as shown in FIG. When the throttle opening of the empty throttle valve 28 increases and the amount of intake air increases, and at time t1 the amount of intake air passing through the intake passage 24 exceeds the maximum allowable value Fmax that guarantees the accuracy of the air flow meter 22, the above The throttle opening S falls within the area AO2 above the curve 5(x) in FIG. 4, and the output signal of the comparison circuit 86 changes from "Low" to "
Rise to High"".

The output signal of the comparator circuit 86 is "Low'" as described above.
When the level rises from - to "High", the solenoid 27 is energized and the electromagnetic valve 26 opens, and arrows A26, A2 . The amount of air flowing through the air flow meter 22 is shown by curve n in FIG. As shown in FIG. Switch as shown by Iamo in Figure 6. In other words, the response delay of the solenoid valve 26,
When the electromagnetic valve 26 is opened, a predetermined proportion of air does not immediately flow into the bypass passage 26, and the opening degree of the measuring plate (not shown) of the air flow meter 22 is large, so that the actual output signal of the air flow meter 22 is curve n. .

Since there is a deviation from the air amount signal (line m.) at the time, the fuel injection amount relative to the intake air amount cannot be accurately controlled.

However, at this time, the timer 87 is triggered at time [1], and the fuel injection amount of the fuel injection valve 29 is changed by the switching circuit 8.
9, the time T until the time [2] when the output signal of the air flow meter 22 follows the amount of air passing through the air flow meter 22.

It is controlled by the output signal of the map control calculation circuit 84 only during this period.

Therefore, even if there is a response delay in the output signal of the air flow meter 22 as described above, the fuel injection amount of the fuel injection valve 29 is determined by the map calculation circuit 84 to be the optimum amount for the period from time t1 to time [20]. 1. Engine combustibility 4 will not decrease.

Next, at the above-mentioned time t2, the timer 37 has a settling time T.

When , the fuel injection amount of the fuel injection valve 29 is changed again to
It is controlled by the output signal of the arithmetic circuit 88.

However, at this time, since the bypass passage 25 is open and a predetermined amount of air is flowing, the function of the fuel injection amount relative to the output signal of the air flow meter 22 is constantly varied, and fuel is injected accurately.

After the intake air amount is constant from time t3 to time 14 in Fig. 5, the intake static I gradually decreases at time [4], and at time [, the throttle opening for that engine speed becomes
When entering the region λ0 below the curve S (X) in Fig. 4,
The output signal of the comparator circuit 86 changes from "High" to "Low"
The solenoid 27 is deenergized, the solenoid valve 26 is closed, and the bypass passage 25 is closed.
The amount of air passing through increases rapidly. As a result, the measuring plate of the air flow meter 220 opens rapidly and becomes larger than the opening corresponding to the actual amount of intake air.

The output signal of the air blow meter 22 at this time is larger than the output signal corresponding to the amount of intake air actually supplied to the engine 2゜L3, but in this case as well, due to the action of the timer 87 and the switching circuit 39, the fuel injection valve The fuel injection amount of 29 is controlled by the output signal of the map control calculation circuit 84, and is controlled to the optimum amount regardless of the response delay of the output signal of the air flow meter 22, so that the combustibility of the engine does not deteriorate.

Hereinafter, the settling time T of the timer 87 is reached at time t6. After lapse of time, the fuel injection amount of the fuel injection valve 29 is determined again by the arithmetic circuit 8.
The engine enters idling rotation at time t.sub.8.

As described above, the fuel injection amount of the fuel injection valve 29 is optimally controlled by the output signals of the map control calculation circuit 84 and the calculation circuit 38.

In the embodiment shown in FIG. 2, the second flow meter 8Q is provided with an intake pressure sensor, and by combining the intake pressure sensor with the engine rotation speed detection circuit 32 or the throttle opening sensor 88, the intake air The amount can also be detected indirectly, and the reference setting circuit 85 is provided between the throttle opening sensor 88 and the comparison circuit 86, and outputs a reference carrot rotation speed signal corresponding to the throttle opening. In other words, one signal among the intake pressure, throttle opening, and engine rotational speed may be input to the reference setting circuit 85 and compared with the other signal.

Furthermore, in place of the solenoid valve 26 and solenoid 27, the diaphragm 8 and on-off valve 6 shown in FIG. 1 may be used.

The present invention can also be applied to a system in which a flow meter is interposed in the bypass passage 25 and the first flow meter 22 installed in the intake passage 24 is alternately operated. Can be used.

As is clear from the detailed explanation above, the present invention is designed to prevent static electricity flowing through the intake passage during the opening/closing operation of the switching device that opens and closes the bypass passage that branches from the intake passage and bypasses the first flowmeter. Since fuel injection is performed by indirectly detecting the amount of intake air using a second flowmeter that is not affected by sudden changes, the combustibility of the engine does not deteriorate even when switching the switchgear, and the amount of intake air can be controlled. Coupled with the fact that the first flowmeter that directly detects the flowmeter operates in a region with high detection accuracy, it is possible to reduce harmful components such as NOx and HC in the exhaust gas.

[Brief explanation of the drawing]

Fig. 1 is a diagram of a conventional engine intake air charge amount detection installation, Fig. 2 is a block diagram of an electronic fuel injection system for an engine according to the present invention, and Fig. 3 is a diagram of a system stored in the ROM of a map control calculation circuit. Fig. 4 is an explanatory diagram of the curve showing the reference signal of the throttle opening output from the reference setting circuit, and Fig. 5 is an explanatory diagram of the operation of the electronic fuel injection system of the engine shown in Fig. 2. Figure 6 is an explanatory diagram showing the relationship between the output signal of the air flow meter corrected by the calculation circuit 88 and the actual output signal of the air flow meter. . 22... Air flow meter (1st i5fEt meter), 2
8... Engine, 24... Power absorption passage, 25... Bypass passage, 26... Solenoid valve, 27... Solenoid, 29... Fuel injection valve, 80... Second flow meter , 31
...Fuel injection control device, 34...Map control calculation circuit, 87...Timer, 88...Arithmetic circuit, 89...
・Switching circuit. Patent Applicant: Toyo Kogyo Co., Ltd. Agent: Patent Attorney: Mr. Hajime and 2 others No. 1 II

Claims (1)

[Claims] (The first flow meter is installed in the intake passage of the engine and directly detects the amount of intake air, and the amount of intake air is indirectly measured by a combination of two of the engine speed, intake pressure, and throttle valve opening.) a second flow meter that detects the flow rate, a bypass passage that branches from the intake passage and bypasses the first flow meter, an opening/closing device that opens and closes the bypass passage during a specific operation of the engine, and an output of the first flow meter. Fuel injection control that controls the fuel injection valve according to the signal, and controls the fuel injection valve according to the output signal of the second flowmeter for a predetermined period of time in synchronization with the operation of the opening/closing device when the opening/closing device is operated. An electronic fuel injection device for an engine, characterized by comprising: