JPS5857036A - Drive circuit of solenoid injection valve in fuel injection device classified by cylinder - Google Patents

Abstract

PURPOSE:To easily form constitution of a circuit, by flowing an electric current in a solenoid coil of an injection valve at valve opening time and holding period in accordance with a number of injection cylinders, setting voltage corresponding to said electric current and controlling the solenoid coil in accordance with a compared result between the setting voltage and actual voltage. CONSTITUTION:A distributor signal, for distributing an injection pulse to solenoid coils L1-L4 of an injection valve through AND gates G1-G4 and switching elements Q1-Q4, is generated by a distributor signal generator circuit 1, and a valve opening reference voltage generator circuit 2 and holding reference voltage generator circuit 3 of both similar constitution are connected to the distributor signal generator circuit 1. Then a driving pulse generator circuit 4 is connected to output ends of these generator circuits 2, 3. This circuit 4 is constituted such that a driving pulse is generated until voltage, in accordance with an electric current flowing in each coil L1-L4 at generation of an injection pulse, becomes larger than valve opening reference voltage, and then the driving pulse is interruptedly generated to equalize the voltage of the above described coils L1-L4 to the holding reference voltage until the injection pulse disappears.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic injection valve drive circuit for a cylinder-specific fuel injection system.

BACKGROUND ART Recently, there is a cylinder-specific fuel injection system that does not inject fuel into all cylinders of an internal combustion engine at the same time, but injects fuel into each cylinder or some cylinders at different times to suppress harmful components contained in exhaust gas.

Such a cylinder-specific fuel injection system is provided with an electromagnetic injection valve drive circuit that separately drives each electromagnetic injection valve so that fuel is injected into a designated cylinder of the engine.

FIG. 1 shows an example of a conventional electromagnetic injection valve drive circuit for a four-cylinder engine. In FIG. 1, a portion surrounded by a broken line is a drive circuit, and 1 is a distribution signal generation circuit that generates a distribution signal specifying a cylinder of the engine. The distribution signal generating circuit 1 has the number of cylinders, that is, four output ends, and the output ends are each connected to one end of AND gates G1 to G4, and the fuel injection pulses are connected to the other ends of AND gates Gs to G4, respectively. Supplied. The bases of transistors Q1 to G4, which are switching elements, are connected to the output terminals of the AND gates G1 to G4 via resistors R4 to R4.

An electromagnetic coil 1 of an electromagnetic injection valve and a current limiting resistor are connected in series between the collector and emitter of the transistor Ql, and similarly transistors Q2 to G4, electromagnetic coils L2 to R4, and resistors R6 to R8 are connected in series. It is connected to the. A power supply voltage V9 is supplied between both ends of each series circuit.

In the electromagnetic injection valve drive circuit having such a configuration, the distribution signal generation circuit 1 generates a distribution signal so that the output end corresponding to the cylinder to which fuel is to be injected is set to a high level according to various engine parameters such as the crank rotation angle. . When one end is at a high level, the Φ gates G1 to G4 allow the fuel injection pulse to pass through. For example, when one end of AND gate GI is at a high level according to the distribution signal and a fuel injection pulse occurs, melon gate GI supplies the fuel injection pulse to the base of transistor Q. Therefore, the transistor Q is turned on and the electromagnetic coil L is excited.

By the way, in the electromagnetic injection valve drive circuit for simultaneous injection in all cylinders,
As described above, current control does not supply fuel injection pulses with the same pulse width to the switching element, but instead controls the duty ratio by distinguishing the current flowing through the electromagnetic coil between when the valve is opened and during the valve-open holding period by turning on and off the switching element. There is a method.

This current control method has the advantage of saving power. However, when the current control method is used in the drive circuit of a cylinder-specific fuel injection system, there is a problem that the total current flowing through the electromagnetic coil during valve opening and during the holding period changes depending on the number of injection cylinders, resulting in a complicated circuit configuration. Ta.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electromagnetic injection valve drive circuit for a cylinder-based fuel injection system that uses a simple circuit configuration to control the current flowing through an electromagnetic coil by distinguishing between the valve opening time and the valve open holding period. .

In the electromagnetic injection valve drive circuit according to the present invention, the current detection means generates a voltage according to the current flowing through a plurality of electromagnetic coils, and a fuel injection pulse is generated by setting a valve opening reference voltage and a holding reference voltage according to a distribution signal. At the same time, the switching element is turned on until the output voltage of the current detection means becomes higher than the valve opening reference voltage, and then intermittently so that the output voltage of the current detection means becomes equal to the holding reference voltage until the fuel injection pulse disappears. The switching element is turned on at the same time.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

In FIG. 2, gates G1 to G4 are connected to lines t1 to 14 connected to each output terminal of the distribution signal generation circuit 1, respectively, and gates G1 to G4 are connected to the valve opening reference voltage generation circuit 2 and the holding reference voltage generation circuit 3. is connected. The valve opening reference voltage generation circuit 3 is connected to an operational amplifier OP and a resistor to RI.
3, transistors Q5 to Q that are turned on according to the distribution signal to ground one end of the resistors R10 to R13, and their base resistors R14.
to R17. In addition,
A voltage Va is applied to the positive input terminal of the operational amplifier op1.

On the other hand, the holding reference voltage generation circuit 3 has the same circuit configuration as the valve opening reference voltage generation circuit 2, including an operational amplifier OP2 and a resistor R.
A voltage vb is applied to the positive input terminal of the operational amplifier OP2 through the transistors Q9 through Q10. A drive pulse generation circuit 4 is connected to each output terminal of the valve opening reference voltage generation circuit 2 and the holding reference voltage generation circuit 3. The drive pulse generation circuit 4 includes a comparison circuit 5,
6. NOR gate G5. G6 and a NOT circuit 7, one input terminal of the comparison circuit 5 is applied with the output voltage of the valve opening reference voltage generation circuit 2, and one input terminal of the comparison circuit 6 is applied with the output voltage of the holding reference voltage generation circuit 3. Output voltage is applied. The voltage across the resistor R27 is applied to the other input terminal of each of the comparison circuits 5 and 6, and the output terminals are connected to the NOR gate G5. The output terminal of NOR gate G5 is connected to one input terminal of NOR gate G6, and the fuel injection pulse is supplied to the other input terminal of NOR gate G6 via NOT circuit 7.

The output terminal of NOR gate G6 is connected to the input terminals of MO gates G1 to G4. Incidentally, the resistor R27 is connected between the emitters of the transistors Q1 to G4 and the ground, and generates a voltage between both ends thereof corresponding to the total current flowing through the electromagnetic coils L1 to R4. The other configuration of the electromagnetic injection drive circuit using a valve according to the present invention is the same as that shown in FIG. .

In the electromagnetic injection valve drive circuit configured as described above, for example, the distribution signal generated by the distribution signal generation circuit l
is at a high level and lines t2 to t4 are at a low level, transistor Q5 is turned on;
The valve-opening reference voltage, which is the output voltage of the valve-opening reference voltage generating circuit 2, is (1+t)Vα 10 . In addition, the transistor Q9 is also in the ON state, and the output voltage of the holding reference voltage generation circuit 3, that is, the holding reference voltage becomes 18 (1/19) V''.The voltage across the resistor R27 is lower than the valve opening and holding reference voltage. , the output of comparator circuit 5 becomes high level, and the output of comparator circuit 6 becomes low level.The outputs of comparator circuits 5 and 6 are logically summed by NOR gate G5.
output will be at a low level. Here, when a fuel injection pulse as shown in FIG. 3 (cL) occurs, the NOR gate G6
The output becomes a high level, and this high level becomes a driving pulse that passes through the AND gate G1 and turns on the transistor Q.

Therefore, a current begins to flow through the electromagnetic coil Ll, and the current gradually increases. When the current flowing through the electromagnetic coil L1 reaches the current Thuxm as shown by waveform A in FIG. 3(5), the output of the comparator circuit 5 is reversed from high level to low level. The current IMAXto is a current value required to open one electromagnetic injection valve, and the voltage across the resistor R27 caused by the current IMAX+l+ flowing through the electromagnetic coil L is equal to the valve opening reference voltage. When the output of comparator circuit 5 becomes low level, NO
The output of R gate G becomes high level, and therefore the output of NOR gate G becomes I level, so transistor Q
! turns off, and the current flowing through the electromagnetic coil L1 gradually decreases. Next, this current becomes the current ■HOLD (1)
When it reaches , the output of the comparator circuit 6 is inverted from low level to high level. The current IHOLD+11 is the minimum current value required to hold one electromagnetic injection valve open, and the voltage across the resistor R27 caused by the current IHoLpm flowing through the electromagnetic coil Ll is the holding reference voltage 18 (1+") Vl).When the output of the comparator circuit 6 becomes high level, NO
The output of the R gate G5 remains at a low level, and therefore the output of the NOR gate G6 becomes a high level again, so that the transistor Ql is turned on and the current flowing through the electromagnetic coil Ll increases. Since the comparison circuit 6 has hysteresis in its comparison function, the output is inverted to a low level when the current flowing through the electromagnetic coil L1 increases by a predetermined amount, as shown by waveform A in FIG. 3(b). Therefore, while the fuel injection pulse is present, the output of the comparator circuit 6 repeats inversion, so the transistor Q1 is intermittently turned on, so the current flowing through the electromagnetic coil L1 is as shown in waveform A in FIG. 3(h). Almost current IH
It becomes equal to OLDfl+.

Next, the distribution signal generated by the distribution signal generation circuit 1 is applied to the line 1. When all of the transistors Q5 to G8 are at a high level, the transistors Q5 to G8 are turned on, and the valve opening reference voltage becomes 9 (1+) Va RlozR,,7R+2//R+3. In addition, transistors R9 to R12 are also turned on, and the holding reference voltage becomes 18" + R19/R20/"21/R22)"b. This valve opening reference voltage level is the level required to open the four electromagnetic injection valves. Current ■MAX (1) (Waveform B in Figure 3(b)
) is the voltage generated across the resistor R27, and the holding reference voltage level is the minimum current value JHQLDI41 (Fig. 3 (b)
) is the voltage generated across the resistor R27 due to the waveform B). Therefore, the electromagnetic coil L is the same as when only the electromagnetic coil L is excited.

The current flowing through L4 is controlled as shown in waveform B in FIG. 3(b) according to the valve opening and holding reference voltages.

Note that the comparator circuit 6 has an integrating circuit at its input stage that integrates the voltage across the resistor R27.

As described above, according to the electromagnetic injection valve drive circuit according to the present invention, the voltage corresponding to the current flowing through the electromagnetic coil of the electromagnetic injection valve during valve opening and during the holding period is set according to the number of injection cylinders, and the voltage and the actual voltage are set. Since the current flowing through the electromagnetic coil is controlled by comparing the current flowing through the electromagnetic coil with the corresponding voltage, a simple circuit configuration can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional example of an electromagnetic injection valve drive circuit, FIG. 2 is a circuit diagram showing an embodiment of the electromagnetic injection valve drive circuit of the present invention, and FIGS. FIG. 3 is an operation waveform diagram of the circuit shown in the figure. Explanation of symbols of main parts 1...Distribution signal generation circuit 2...
... Valve opening reference voltage generation circuit 3 ... Holding reference voltage generation circuit 4 ... Drive pulse generation circuit 5.6 ... Comparison circuit Applicant: Nippon Electronics Co., Ltd. Motohiko Fujimura, Patent Attorney, Agent Co., Ltd.

Claims (1)

[Claims] a switching element that is connected in series with the electromagnetic coils of the plurality of electromagnetic injection valves in a one-to-one ratio and is turned on in response to a drive pulse, and between both ends of each of the plurality of series circuits of the electromagnetic coil and the switching element; a current detection means that generates a voltage according to the current flowing through the plurality of electromagnetic coils; and a valve opening reference that generates a valve opening reference voltage according to a distribution signal that specifies a cylinder of the engine. voltage generating means; holding reference voltage generating means for generating a holding reference voltage according to the distribution signal; and holding reference voltage generating means for generating a holding reference voltage according to the distribution signal; and then intermittently generates the drive pulse so that the output voltage of the current detection means becomes equal to the holding reference voltage until the fuel injection pulse disappears; An electromagnetic injection valve drive circuit comprising gate means for interrupting the drive pulse to any one of the switching elements.