JPS59200024A - Drive current control device for electromagnetic fuel injection valves in internal combustion engines - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive current control device for an electromagnetic fuel injection valve in an internal combustion engine.

As a conventional drive current control device, there is one shown in FIG. 1, for example.

This is an electromagnetic fuel injection valve 1 connected to a battery power source.
By controlling the base voltage of the drive transistor 2 connected in series to the fuel injection valve 1, the valve opening current required for opening the fuel injection valve 1 at the initial stage of opening the valve and the valve opening current value continuously. A holding current that maintains a small valve open state is supplied to the fuel injection valve in order to save power and improve the responsiveness of the fuel injection valve.

That is, FIG. 2 (A
) The injection pulse (H level signal) shown in Terminal 3, DN
The signal T-A is applied to one terminal of the first NOR circuit 5 via the OT circuit 4 as an L level signal for a predetermined period of time. At the start of this input, the detection voltage between the driving transistor 2 and the current detection resistor 6 and the setting current (
The detection voltage is compared with the IMAX reference voltage corresponding to the IMAX (hereinafter referred to as IMAX), and if the detected voltage becomes equal to or higher than the 〃IMAX comparator that continuously outputs level signals The detection voltage and the holding current (IHoI!d in FIG. 2(B)) are set to 11 (oI!d reference voltage). Compare and detect voltage is ■Ho1
If the voltage exceeds the d reference voltage, it outputs the "Llj level signal," while if it falls below the voltage, it outputs the "H//level signal.
The signals output from the o1d switching comparator 8 and the second NOR circuit 9 are both "H//".

Therefore, at the start of input, the output of the second NOR circuit 9 becomes "IjI," so the output of the first NOR circuit 5 becomes "IjI."
Since this is input to the base, a large current necessary for opening the fuel injection valve 10 flows through the collector of the driving transistor 2, and the opening operation of the fuel injection valve 1 is performed. Since a voltage higher than the IHoJd reference voltage and the HMAX reference voltage is input to the iMAX comparator 7 and the Ho1d switching comparator 8, IHot! The output of the d-switching comparator 8 becomes Ls, the output of the iMAX comparator T becomes Ll/, and the output of the second ONOR circuit 9 becomes Htt. As a result, the output of the first NOR circuit 5 becomes 'Ly' and the base voltage of the i-active transistor 2 decreases, so that the operation of the driving transistor 2 stops. .

Then, when the current flowing through the fuel injection valve 1 decreases and the detected voltage becomes less than the ■Ho1d reference voltage, ■II.

The output of the Jd switching comparator 8 becomes 〃Htt, and ■
Since the output of the MAX comparator 7 is held at <Ltt, the output of the second NOR circuit 9 becomes <LI. Therefore, the output of the first NOR circuit 5 becomes HI/, and the collector current of the driving transistor 2 tries to flow, but due to the inertia of the inductance of the injection valve 1, a large current does not flow instantly, and During startup, the output of the IHo1d switching comparator 8 becomes 〃L//, so the output of the second NOR circuit 9 becomes 〃H//, and the output of the second NOR circuit 5 becomes 〃L//. / and the base voltage of the transistor 2 for driving the gate 1 decreases. Therefore, after reaching IMAX, IH
Current control is performed near oJFd, and the valve is kept open with a small amount of electric power.
・10 is a flywheel transistor whose collector and emitter are connected in parallel to the fuel injection valve 1 and which is controlled to be turned on during the Ho1d control by the control circuit 11 based on the injection pulse. , the back electromotive force generated when the fuel injection valve 1 is demagnetized keeps the F/I valve open during the work Ho1d period.

However, in such conventional drive current control devices, a control method is adopted in which the opening current is raised to the opening current value required to open the fuel injector at the beginning of the injection pulse, and then instantaneously lowered to the holding current value. Therefore, the energization time of the valve opening current is determined by the time constant of the electromagnetic coil of the fuel injection valve. Unfortunately, if you use a fuel injector's electromagnetic coil with a small time constant, the opening current that flows through the fuel injector will cause the coil to generate heat.

There was a problem in that when the IMAX value determined by the withstand capacity was reached, the energization time was short and the power necessary for the valve opening operation was not supplied, and the current was switched to the trench holding current before the valve opening operation was completed. .

The present invention has been made in view of such conventional problems, and includes a means for detecting a valve opening current, a timer means that is operated by the means and can variably adjust the operating time, and a timer means for detecting the valve opening current. and a holding means for holding the valve opening current during the operation of the timer means, thereby making it possible to vary the energization time of the valve opening current by adjusting the timer means when the time constants of the stain magnetic coils are different. The purpose is to provide

The present invention will be described below based on an embodiment shown in Figure $3. Incidentally, the same elements as those in the conventional example are given the same reference numerals as in FIG. 1, and only the different parts will be explained.

In the figure, one input terminal of the second NOR circuit 9 has a Hoed switching comparator 8, which has the same function as the conventional one.
is connected to the other input terminal, and the INAX reference voltage corresponding to the IMAX current input to the inverting input terminal is compared with the voltage of the current detection resistor 6 input to the non-inverting input terminal. The output of a comparator 22 is connected to which the output of the switching comparator 21 is input to an inverting input terminal and the IMAX reference voltage is input to a non-inverting input terminal. Further, between these comparators 21 and 22, the comparator 21 operates when the output is low, and after operating for an adjustable predetermined time, changes the input level of the comparator 220 inverting side input to the L level. The timer circuit 23 forcibly holds the
is interposed. Incidentally, when the injection time T elapses, the forced holding by the timer circuit 23 is discharged by an internally provided discharging circuit, and a reset state is established. However, the switching comparator 21 represents a comparator with a certain hysteresis in its operation.

According to the drive current control device having such a configuration, the injection pulse inputted to the terminal 3 (see FIG. 4(A)) is transmitted to the NOT circuit 4.
is input to the first NOR circuit 5 via the second NOR circuit 5.
Since the output of the OR circuit 9 is "L" at the initial stage of input as in the conventional case, the output of the first NOR circuit 5 becomes "H", and this flows into the base and the collector of the driving transistor 2. A large current is applied to the fuel injection valve 1 by the valve opening current (IM
AX) is played. At this time, when the current value flowing through the fuel injection valve 1, that is, the detection signal exceeds the MAX reference voltage, the output of the switching comparator 21 becomes "H".
//, and at the same time as the timer circuit 23 starts operating, the comparator 22 outputs 〃LI/, and the output of the second ONOR circuit 9 becomes 〃L.

Therefore, since the ``L tt'' and ``Hit level signals are respectively input to the first NOR circuit 5, its output is ``.
Since LI flows into the base, the collector current of the driving transistor 2 decreases.

Therefore, when the detection voltage becomes lower than the IMAX reference voltage due to this decrease, the output of the comparator 21 becomes "L", the comparator 22 becomes "H" output, and the output of the second NOR circuit 9 becomes "L". becomes // LI.As a result, the output of the first NOR circuit 5 becomes Htt p) A large current flows through the collector of the transistor 2 again. Unless the timer circuit 23 operates for a predetermined time p) The valve opening current is controlled by switching for the predetermined time period near IMAX. Then, when the timer circuit 23 operates for the predetermined time period, the comparison is performed by the timer circuit 23 regardless of the detected voltage input to the non-inverting side terminal of the comparator 21. When the voltage at the inverting side input terminal of the converter 22 reaches the level
After that, the output of the comparator 22 is forcibly held at the La level.

As a result, even if the current value of the collector section becomes l:MAX or less, the output of the first NOR circuit 5 does not become 'Htt', and the switching comparator 8 does not become 'Htt' until the current value becomes less than ■Ho/'d. The output becomes “Hit”.

As a result, the output of the second NOR circuit 9 becomes "LI" and the output of the first NOR circuit 5 becomes "Hz", so that the collector current of the driving transistor 2 increases. The voltage increases and the output of the switching comparator 8 becomes '
When it comes to L I, it's the second N.

This switching operation is repeated until the output of the R circuit 9 becomes 'H7', the collector current decreases again, and the injection pulse signal ends.

Further, when the time constant of the electromagnetic coil of the fuel injection valve 1 is small, by greatly varying the predetermined time of the timer circuit 23, it is possible to ensure the energization time of the valve opening current that matches the time constant υ.

As explained above, in this embodiment, by variably adjusting the predetermined time of the timer circuit 23, the valve opening current can be applied for a time that matches the time constant of the stain magnetic coil, etc. In the case of a coil, by increasing the energization time, the current will not switch to the holding current until the fuel injection valve is completely opened.

Still, since the energization time can be set to match the time constant of the electromagnetic coil, power consumption due to the valve opening current, which is a large current, can be reduced.

As explained above, the present invention allows the energization time of the valve opening current of the fuel injection valve to be variably adjusted. By adjusting the time, the valve opening current can be applied until the valve is completely opened. Furthermore, since the valve opening current can be applied for a time that matches the time constant of the fuel injection valve, the valve opening current, which is a large current, is not passed for longer than the necessary time, and the power consumption of the control device can be reduced.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional example of a drive current control device;
Figures (A) and (B) are operating state diagrams for explaining the apparatus shown in Figure 1, Figure 3 is a circuit diagram showing an example of the implementation method of the present invention, and Figure 4 is a diagram for explaining the apparatus shown in Figure 3. FIG. 1... Electromagnetic fuel injection valve 2... Drive transistor 5... First NOR circuit 8... I H
o1d switching comparator 21... Engineering MAX switching comparator 22... Comparator 23... Timer circuit patent applicant Fujio Sasashima, patent attorney representing Japan Electronics Co., Ltd. Figure 1 Figure 2 (A ) Figure 2 (B) Figure 3 Figure 4 (A)

Claims (1)

[Claims] An electromagnetic fuel injection valve in which an opening current is applied to the electromagnetic fuel injection valve to open the fuel injection valve at the initial stage of opening, and a holding current is then applied to maintain the valve in a smaller open state. In the drive current control device, there is provided a means for detecting the valve opening current, an evening/timer means which is operated frequently by the means and whose operating time can be variably adjusted, and a means for detecting the valve opening current during the operation of the timer means. 1. A drive current control device for an electromagnetic fuel injection valve in an internal combustion engine, comprising: holding means for holding current.