JPS602506B2 - Fuel stop device for electronically controlled fuel injection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel stop device for an electronically controlled fuel injection system having a function of stopping fuel during deceleration of an internal combustion engine.

Conventionally, this type of device detects the opening degree of the throttle valve using a throttle switch provided on the throttle valve of the engine to stop fuel when the engine decelerates, and when the degree of opening of the throttle valve is less than or equal to a set value and the engine is rotating. However, in this case, when the throttle valve is detected by the throttle switch, the throttle valve should be set slightly higher than the idle function, such as during fast idling or when using a vehicle cooler. Considering that the rotation speed may be kept high, it is necessary to accurately detect a small opening angle of the throttle valve (for example, less than lo) in relation to the fuel cut rotation speed, which is disadvantageous in terms of cost and reliability. be.

In a region where the opening degree is slightly larger than the set opening of the throttle switch and the rotation speed is higher than the set speed, fuel cut is not performed, and the probability that the vehicle enters this region is high, depending on the flow rate characteristics of the electromagnetic injector and the engine speed. In relation to the cylinder volume, there is a strong possibility that linear control of the pulse time width and flow rate characteristics of the injection pulse signal applied to the electromagnetic injection valve will be impossible in the above region. In this case, in a range where the amount of intake air is small, the electromagnetic injection valve with a small flow rate is required, but it is impossible to manufacture something smaller than a certain level, and even if it could be manufactured, it would be slow and very expensive. Become something. In that case, there is a disadvantage that accurate control of the amount of fuel versus intake air is not possible, misfires are likely to occur, and a large amount of harmful components in the exhaust gas, particularly HC, is emitted. Furthermore, in the case of a misfire, there is a serious drawback that for vehicles equipped with a catalyst, reactor, etc. as an exhaust gas purification device, the heat load on the exhaust gas purification device increases and, in the worst case, it burns out. Therefore, in order to prevent the above-mentioned drawbacks, the current system includes a vacuum IJ transmitter that operates to inject air into the engine's intake manifold when the pressure drops below a certain negative pressure, and a dashpot that prevents the throttle valve from closing suddenly. is used, but it is not a complete solution. moreover,
Since the vacuum limiter is provided, there is a problem that the engine speed does not decrease even when the accelerator is not depressed, and this has major disadvantages in terms of increased cost and reliability.
The present invention has been made in view of the above-mentioned drawbacks, and is designed to be used when the pulse time width of the injection pulse signal, which is determined by the intake air amount and rotational speed of the engine, falls below the control range of the electromagnetic injection valve, that is, when the pulse time width of the injection pulse signal is determined by the intake air amount and engine speed If the pulse time width of the injection pulse signal falls below the set pulse time width that has been detected in advance to cause this state, the linear control of the electromagnetic injector by the injection pulse signal becomes impossible and misfires are likely to occur. Alternatively, when the injection pulse time width reaches the above state and is less than the set pulse time width and the engine rotation speed is higher than the set rotation speed, fuel injection to the engine is stopped, thereby preventing the occurrence of deceleration. The purpose of the present invention is to provide a fuel injection device that can detect a misfire region, stop the supply of fuel, and prevent the emission of unburned exhaust gas, and also eliminates the need to accurately control the throttle valve opening function, thereby reducing costs. It is something.

Furthermore, in the present invention, the conditions for stopping the fuel are as described above, but the conditions for injecting the fuel again during the fuel stop are such that the injection pulse signal becomes greater than or equal to the set pulse time width or the engine speed becomes less than or equal to the set number of revolutions. Even if you try to accelerate by opening the throttle valve from the deceleration castle where the fuel is stopped, the injection pulse signal will not exceed the set pulse time width immediately, and the fuel stop will be canceled and the injection will be resumed. In consideration of the possibility that a response delay may occur, causing a shock to the vehicle due to the engine torque difference and causing discomfort to the driver, if the throttle valve is opened more than the specified opening while the fuel is stopped, the fuel By adopting a configuration in which fuel is re-injected, the purpose is to prevent a delay in the response of fuel re-injection when switching from a fuel stop state to accelerated operation, and to prevent discomfort from being caused to the driver.

An embodiment of the present invention shown in the drawings will be described below.

FIG. 1 is a block diagram showing a calculation section of an electronically controlled fuel injection device according to the present invention. In Fig. 1, 1 is the primary side terminal of the ignition coil that detects the engine speed signal in the form of a voltage waveform, 2 is the waveform shaping circuit that shapes the voltage waveform to prevent malfunction, and 3 is the 6-cylinder In this case, it is a 1/3 frequency division circuit to operate the electromagnetic injection valve 11 that injects fuel once per engine rotation, and when the electromagnetic injection valve 11 is operated more than once per engine rotation, other frequency division circuits are used. Of course, a circumferential ratio is required. 4 is an arithmetic circuit which inputs a signal corresponding to the amount of intake air from the intake air amount meter 5 and divides the amount of intake air of the engine by the engine speed;
Pulse time width tp proportional to the amount of air sucked in during the stroke
The pulse signal T. It is used to create and output.

6 is a multiplication circuit which increases or multiplies the pulse time width tp of the pulse signal T output from the arithmetic circuit 4 by various signals from the operating state detection means T for detecting engine water temperature, intake air temperature, etc., to produce a pulse. A pulse signal T2 having a time width tm is generated.

Reference numeral 8 denotes a voltage correction circuit which inputs the pulse signal L from the multiplication circuit 6 and produces a voltage correction pulse signal T3 having a pulse time width tu to correct changes in the fuel injection amount due to the engine voltage of the electromagnetic injection valve 11. It is something that creates

9 is an OR circuit which receives pulse signals T,, T2, T from the arithmetic circuit 4, the multiplication circuit 6, and the voltage correction circuit 8;
3 to generate a pulse signal T having a pulse time width (tp+tm+tu) and supply it to the output circuit 10'.
+tu) to supply the optimum amount of fuel into the engine according to the operating condition.

Further, the multiplier circuit 6 is configured so that the pulse signal T2 has the same time width as the pulse signal T when there is no increase in the amount of each type, and the circuit is configured such that the amount of increase is proportional to the flowing current. Further, reference numeral 12 designates a monostable multipipelator, which is triggered by the pulse signal T outputted from the arithmetic circuit 4 and outputs a pulse signal having a predetermined pulse time width A to the comparator circuit 13. The predetermined pulse time width A of this pulse signal is a pulse time width that provides a state close to the control limit where linear control is impossible with respect to the pulse time width of the injection pulse signal to which the injection characteristics of the electromagnetic injection valve are applied. This is the pulse time width of the injection pulse signal that gives the engine a state in which the engine is in a misfire region where it is very likely to misfire during deceleration, and the fuel stop pulse time width is, for example, 0.7 msec. Therefore, the Hi-Same circuit 12 inputs the pulse signal T having the pulse time width tp from the arithmetic circuit 4 and the pulse signal having the predetermined pulse time width A, and determines the magnitude of both pulse time widths tp and A.
When the two pulse time widths tp,A are tp>A, the output of the comparison circuit 13 is set to "0" level, and the two pulse time widths tp and A are set to the "0" level.
When p and A are tp<A, the output of the comparison circuit 13 is set to the "1" level. Further, the output of the comparison circuit 13 is fed back to the monostable multipipulator 12, and hysteresis is provided between the pulse time width A that determines fuel stop and the pulse time width B (B>A) that causes fuel to be injected again. On the other hand, a monostable multipipulator 14 and a comparison circuit 15 are connected to the frequency division circuit 3, and the comparison circuit 15 has a time width n inversely proportional to the engine rotational speed inputted from the frequency division circuit 3.
2 pulse signal N2 and a predetermined time width n inputted from the monostable multipipulator 14 in synchronization with this pulse signal.
, by comparing the time width ratios, n, with the pulse signals N, of n. It is configured to generate a "0" voltage when <n2 (that is, the engine speed is below the set speed) and to generate a "1" voltage when n,>Q (that is, the engine speed is above the set speed). The output of the Riko comparator circuit 15 is fed back to the monostable multivibrator 4, so that the rotational speed as well as the injection pulse width has hysteresis.

Note that the time width n of the pulse signal N corresponds to the set rotational speed that determines fuel stop, and the comparator circuit 15 generates a "1" voltage only when the engine rotation is equal to or higher than the set rotational speed. Reference numeral 16 denotes a throttle opening degree detector interlocked with the throttle valve of the engine, and is configured to generate a "1" voltage only when the throttle valve degree is less than a set value.

On the other hand, the gate circuit 17 has the circuit configuration shown in FIG. A trigger circuit 17g composed of a capacitor C2 and an R-S flip-flop (R
-S/FF) 17d and an OR gate 17e.

The operation of this gate circuit 17 is such that the outputs of the comparison circuits 13 and 15 are introduced into the NAND gate 17a, and the comparison circuit 13
, 15 is “1” (i.e., when fuel is stopped) N
The output of the AND gate 17a becomes "0". Also element R,
, R2, C, the trigger circuit 17f is a NAND
When the output of the gate 17a is inverted from "1" to "0", R-S FF 17d is set;
The output Q of 17d becomes ``0''.On the other hand, the OR gate 17
The output of e is "0" only when the output of the NAND gate 17a is "0" and the output Q of the R-S FF 17d is "0", and the output is connected to the OR circuit 9 to stop the fuel. Note that the output of the OR gate 17e is an OPEN collector, and only when the output is "0", the output of the OR circuit 9 is "0".
", and when it is "1", it is configured so as not to affect the output of the OR circuit 9. On the other hand, the output of the throttle opening detector 16 is connected to inverters 17b and 17c, and the output of the inverter 17c is The output is reversed from "1" to "0" when the throttle valve reaches the set temperature from below to above, and trigger circuit 17 consisting of elements R3, R4, and C2
Reset R-S・FF17d by g
The output Q of F17d becomes "1", the output of OR gate 17e becomes "1", and the fuel stop ends. Also R-S・FF
17d is configured to act only when the outputs of the trigger circuits 17f and 17g generate voltages in the negative direction. Next, FIG. 3 shows details of the circuit section of the comparison circuit 13, which is one of the main parts of the present invention, and which determines whether the pulse time width is less than or equal to the set pulse time width.

The pulse signal T generated by the arithmetic circuit 4 is sent to the comparator circuit 13 (D
-Flip-flop; Texas Instrument Co., Ltd. SN
Comparison is made by inputting an output pulse of a predetermined time width A of a known monostable multi-piper 12, which is triggered by the rising edge of the pulse of the signal T, into the ○ terminal. Output Q of circuit 13
The relationship between the time width A and the pulse time width tp of the signal T is A>
It produces "1" when tp, and "0" when A<tp.
On the other hand, in order to provide hysteresis to this predetermined pulse time width A, an output Q opposite to the output Q of the self-comparison circuit 13 is fed back to the monostable multivibrator 2. As a result, when A>tp, the output Q becomes "0", and the time width of the pulse output from the monostable multipipulator 12 is changed from A to B (A<B), thereby providing hysteresis. The comparator circuit 15 and the monostable multipipelator 14 have almost the same configuration as the circuits 13 and 12 above, and can determine whether or not the rotation speed is higher than the set rotation speed. The time width of the pulse signal N, is changed from n, to n,'(n.<n,') to provide hysteresis.

Next, the operation of the above configuration will be explained. A pulse signal whose time width tp of the pulse signal T of the arithmetic circuit 4, which is determined by the intake air amount and engine speed of the engine, is smaller than the predetermined pulse time width A set by the monostable multipipulator 12 and whose speed is equal to the engine speed. The time width n2 of N2 is monostable multipipulator 1
When the engine is decelerating by 4.4 times from the predetermined time width n of the pulse signal N, which is determined by The output of the NAND gate 17a of the circuit 17 is “
0", the trigger circuit 17f sets the R-S FF 17d to set the output Q to "0", and as a result, the OR gate 1
The output of 7e becomes “0” and the output of OR circuit 9 becomes “0”.
and stop the fuel. During this fuel stop state during deceleration, the throttle valve is opened to accelerate the engine again, and when the temperature exceeds the set value, the output of the throttle opening detector 16 becomes "0".
The output of the inverter 17c is also reversed to "0",
The trigger circuit 17g resets the R-S•FF 17d and sets the output Q to "1".

Therefore, the output of the OR gate 17e becomes "1", and the OR circuit 9 outputs the injection pulse signal T to the output circuit 1, thereby operating the electromagnetic injection valve 11 again and restarting fuel injection. Furthermore, during fuel stop during engine deceleration, the engine speed decreases and the time width tp of the pulse signal T of the arithmetic circuit 4 is changed to have hysteresis.
is greater than or equal to the time width B of the pulse signal of When the engine speed increases (that is, the engine speed becomes smaller than the predetermined speed determined by the time width n,'), the output of the NAND gate 17a of the gate circuit 17 becomes "1".
”, the output of the OR gate 17e also becomes “1”, and O
The R circuit 9 outputs the injection pulse signal T to the output circuit 1 to operate the electromagnetic injection valve 11 again to resume fuel injection. In the above embodiment, the fuel stop is performed based on both the time width of the pulse signal that determines the fuel injection amount and the engine rotation speed signal, but it is determined that only the time width of the pulse signal that determines the fuel injection amount is determined. Of course, it is also possible to make the determination and stop the fuel.

Further, in the above embodiment, the output signal of the arithmetic circuit 4 is used as the pulse signal for determining the fuel injection (supply) amount, but it is also possible to use the output signal of the multiplication circuit 6.

Furthermore, in the above-described embodiment, the gate circuit 17 sends a fuel stop control signal to the stage after the OR circuit 9 to control the stop of the operation of the electromagnetic injection valve. May be controlled.

As described above, the device of the present invention includes a circuit that calculates the time width of the injection pulse signal applied to the electromagnetic injection valve according to the engine operating state, and a circuit that calculates whether the time width of the pulse signal from this circuit is less than or equal to the set time width. a comparison circuit for comparison; a throttle relation detector for detecting whether the relation of the throttle valve of the engine is equal to or higher than a set relation; the outputs of the comparison circuit and the throttle relation detector are input; When the time width is less than or equal to the set time width, the operation of the electromagnetic injection valve is stopped to stop the fuel supply, and when the coefficient of the throttle valve becomes equal to or higher than the set coefficient during fuel stop, the electromagnetic injection is restarted. It has a configuration that includes a gate circuit that operates a valve to inject fuel, and has the excellent effect of detecting a misfire region during deceleration and stopping fuel injection, thereby preventing the emission of combustible exhaust gas. Furthermore, there is no need for complicated detection processing functions such as detecting the throttle opening and engine speed and stopping the fuel as in conventional devices, and there is an excellent effect that cost reduction is possible.・Furthermore, with conventional devices that control fuel stop using the throttle opening and engine speed, in order to operate the engine smoothly when starting at low temperatures, the amount of air is supplied to the engine by bypassing the throttle through an air valve, and the engine speed is increased. Since it is a system called "first idle" that increases the engine speed, the engine's water temperature, etc. is detected and the set engine speed, which determines fuel stop, is changed according to this water temperature. However, in the device of the present invention, the fuel injection amount is determined because the amount of air increases during fast idling compared to the set time width for determining the fuel stop. As the pulse time width increases, fuel stop is no longer performed automatically, and there is no need to adjust the set rotation speed to be higher than the engine speed at first idle, as with conventional pupil systems, and a simple configuration is sufficient. .

In addition, in the device of the present invention, the fuel stop is canceled depending on the throttle opening degree, and when the throttle valve is opened in the fuel stop state and the engine shifts to accelerating operation, fuel injection is performed immediately without response delay. May be resumed.

As a result, there is an effect that no vehicle body shock is caused and no discomfort is given to the driver.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an electric circuit diagram of the gate circuit shown in FIG. 1, and FIG. 3 is an electric circuit diagram of the comparison circuit shown in FIG. 1. 4... Arithmetic circuit, 6... Multiplier circuit, 11... Electromagnetic injection valve, 13... Comparison circuit, 16... Throttle opening detector, 17... Gate circuit. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In an electronically controlled fuel injection device that defines the amount of fuel supplied to an internal combustion engine by the time width of an injection pulse signal applied to an electromagnetic injection valve, means for calculating the time width of the injection pulse signal according to the engine operating state. a comparison means for comparing whether the time width of the pulse signal from the means is less than or equal to a set time width; and a throttle opening detector for detecting whether or not the opening of the throttle valve of the engine is at least the set opening. , the outputs of the comparison means and the throttle opening detector are input, and when the time width of the pulse signal is less than or equal to a set time width, the operation of the electromagnetic injection valve is stopped to stop the fuel supply, and the fuel is stopped. and gate means for operating the electromagnetic injection valve again to inject fuel when the opening degree of the throttle valve becomes equal to or higher than a set opening degree. Device.