JPH1182123A - Drive control device for fuel injection valve - Google Patents

Abstract

(57) [Object] To provide a drive control device for an electromagnetic fuel injection valve that can expand the dynamic range of the fuel injection valve with a simple and low-cost configuration. A control circuit (3) outputs a discharge current from a capacitor (5A) in a DC-DC converter (5) to a fuel injection valve coil (4).
During the period in which the S01 signal for supplying the capacitor 5A is ON, the charging operation of the capacitor 5A is stopped via the control signal S04. Thereby, the capacitor 5A
The charging operation (additional charge) to the DC-DC converter 5 is stopped, and the discharge characteristics from the capacitor 5A in the DC-DC converter 5 can be stabilized. Therefore, the current supplied to the coil 4 of the fuel injection valve during the valve opening period Can be stabilized. That is, with a simple and low-cost configuration, a substantial holding period can be stably achieved from an early stage.
Even if the pulse width is shortened, a stable valve closing operation can be performed, so that the dynamic range can be expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a drive control device for an electromagnetic (solenoid) fuel injection valve.

[0002]

2. Description of the Related Art A conventional drive control apparatus for an electromagnetic fuel injection valve used in an internal combustion engine is disclosed, for example, in Japanese Patent Application Laid-Open No.
There is one disclosed in Japanese Patent No. 75957. Such a conventional drive control device for a fuel injection valve generally operates as follows in order to improve the valve opening characteristics of the fuel injection valve.

That is, in the initial stage of valve opening (see the section a to c in FIG. 4), as shown in FIG. 9, based on an input signal SI1 from an engine control unit (ECU), the control circuit issues an S01 signal. And the S02 signal, the transistor TR1 is turned on by the S01 signal, the discharge current from the capacitor in the DC-DC converter, and the transistor TR2 is turned on by the S02 signal, and the current from the battery is used as the fuel injection valve coil ( Solenoid).

Thereafter, during the holding period (see the section c to d in FIG. 4), the control circuit performs switching (ON / OFF) of the transistor TR2 with the S02 signal based on the current detection result of the current detection circuit. By applying the battery voltage discontinuously, the current necessary for maintaining the open state of the fuel injector is supplied to the fuel injector coil.

[0005] Then, a valve closing period (refer to d in FIG. 4).
Then, the control circuit closes the transistor TR3 provided on the downstream side of the fuel injection valve coil by turning off the S03 signal, thereby causing a back electromotive force to be generated by the back electromotive absorption circuit, thereby promptly causing the fuel injection. The valve is closed to terminate the injection.

[0006]

In the meantime, there has been a demand that the dynamic range of the fuel injection valve be extended as much as possible (so that the fuel can be injected and supplied with high accuracy even with a small injection amount). The valve drive control device can quickly open and close the fuel injection valve, so that the dynamic range of the fuel injection valve can be expanded to some extent, but this alone has limitations and is not sufficient. .

Here, the dynamic range of the fuel injection valve is, as shown in FIG. 8, a region where the pulse width (valve opening period) and the fuel injection amount (fuel flow rate) are in a proportional relationship (linear region). Point to. In other words, in order to further expand the dynamic range with respect to the above-described conventional fuel injection valve drive control device, in addition to promptly opening and closing the fuel injection valve with good responsiveness, the dynamic range can be shortened. It is necessary to take measures to make the flow rate characteristics themselves linear with the pulse width.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a drive control apparatus for an electromagnetic fuel injection valve capable of expanding the dynamic range of the fuel injection valve with a simple and low-cost configuration. Aim.

[0009]

According to the present invention, the solenoid provided in the fuel injection valve is connected to the high pressure circuit for a predetermined period from the time when the fuel injection start command is input from the engine control unit. A relatively large valve-opening current composed of a discharge current from the capacitor and a current from the battery is supplied to open the fuel injection valve, and the valve-open state can be maintained after the predetermined period has elapsed. Applying a small holding current to the solenoid, until the fuel injection stop command is input from the engine control unit, in the drive control device of the fuel injection valve to maintain the holding current value, at the elapse of the predetermined period, High voltage circuit operation control means for controlling a charging operation of a capacitor in the high voltage circuit so that the valve opening current is stabilized at a predetermined current value. And to constitute comprise.

[0010] With this configuration, an adverse effect on the valve opening current after the predetermined period due to the charging operation of the capacitor in the high voltage circuit is suppressed, and the valve opening current after the predetermined period elapses. Since the current can be stabilized at the predetermined current value, the current difference between the valve opening current and the holding current can be reliably suppressed. Therefore, even if the fuel injection amount is reduced (even if the period from the input of the fuel injection start command to the input of the fuel injection stop command is shortened), a stable valve closing operation can be performed. The area in which the amount of fuel injected from the start of valve operation to the completion of valve closing can be expanded to the low injection amount (short pulse width) side, and thus the pulse width (valve opening period) and fuel injection amount (Dynamic range) where (fuel flow rate) is proportional to
Can be expanded to the low injection amount (short pulse width) side.

That is, according to the present invention, the dynamic range can be remarkably expanded as compared with the related art while having a simple and low-cost configuration. In the invention described in claim 2, the high-voltage circuit operation control means is configured to stop charging the capacitor in the high-voltage circuit for at least the predetermined period.

With this configuration, the operation and effect of the first aspect of the present invention can be reliably achieved, and the existing control signal can be used, so that the configuration can be simplified. According to the third aspect of the present invention, the predetermined period is configured to include a predetermined period setting unit that sets the predetermined period based on a detection result of an open state of the fuel injection valve during operation.

With this configuration, the operation and effect of the invention described in claim 1 can be achieved, and the transition to the holding period can be made earlier as compared with the case where the predetermined period is predetermined. Therefore, even if the pulse width is shortened, a stable valve closing operation can be performed. Therefore, in combination with the operation and effect of the first aspect of the present invention, the region in which the amount of fuel injected from the start of the valve closing operation to the completion of the valve closing can be further increased to the low injection amount (short pulse width) side. In addition, the region (dynamic range) in which the pulse width (valve opening period) and the fuel injection amount (fuel flow rate) are proportional to each other can be expanded to the low injection amount (short pulse width) side. Becomes

That is, according to the present invention, the dynamic range can be maximized. According to the fourth aspect of the present invention, as shown in FIG. 2, the solenoid provided in the fuel injection valve is discharged from the capacitor in the high voltage circuit for a predetermined period from when the fuel injection start command is input from the engine control unit. A relatively large valve-opening current consisting of a current and a current from a battery is supplied to open the fuel injection valve, and after a lapse of the predetermined period, a relatively small holding current capable of holding the valve-open state is used. In the drive control device for a fuel injection valve, which is applied to a solenoid to maintain the holding current value until a fuel injection stop command is input from the engine control unit, the predetermined period is controlled by the fuel injection valve during operation. A predetermined period setting means for setting based on the detection result of the valve opening state is included.

With such a configuration, it is possible to shift to the holding period earlier as compared with the case where the predetermined period is determined in advance, so that even if the pulse width is shortened, a stable valve closing operation can be performed. Can be done. Therefore, the region where the amount of fuel injected from the start of the valve closing operation to the completion of the valve closing can be made the same can be expanded to the low injection amount (short pulse width) side, and the pulse width (valve opening period) can be extended. The region (dynamic range) in which the fuel injection amount (fuel flow rate) is proportional to the fuel injection amount (fuel flow rate) can be expanded toward the low injection amount (short pulse width) side.

That is, according to the present invention, the dynamic range can be expanded.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
Description will be given based on the attached drawings. As shown in FIG. 3, a drive control device (injector drive [drive] unit) 1 for a solenoid-type fuel injection valve (injector) according to a first embodiment of the present invention operates in an engine control unit (ECU) 2. (Intake air flow,
An injection signal (pulse signal) set based on the engine speed, water temperature, target air-fuel ratio, etc.) is received as an input signal SI1, and the transistors TR1 and TR2 are controlled based on the input signal SI1 to control the fuel injection valve coil ( The control circuit 3 controls the drive current to the solenoid 4.

The control circuit 3 includes, for example,
The control shown in the timing chart of FIG. 4 is performed. That is, the valve opening period (FIG.
In the middle a to c sections, corresponding to the predetermined period of the present invention),
Based on the input signal SI1 from the engine control unit (ECU) 2, the control circuit 3
02 signal, and the transistor TR1 is turned on by the S01 signal to turn on the DC-DC converter (high voltage circuit).
The current from the battery 6 is supplied to the fuel injection valve coil (solenoid) 4 by discharging the current from the capacitor 5A in the battery 5 and turning on the transistor TR2 in response to the S02 signal. That is, in the early stage of the valve opening, the transistor TR1 and the transistor TR2 are turned on to apply a relatively large driving current (injector current; valve opening current) to the fuel injection valve coil (solenoid) 4, and the valve opening operation is started. It is designed to increase responsiveness.

Thereafter, during the holding period (sections c to d in FIG. 4), the control circuit 3 performs switching (ON / OFF) of the transistor TR2 by the S02 signal based on the current detection result of the current detection circuit 7, By applying the battery voltage discontinuously, the current (holding current) required to maintain the open state of the fuel injection valve is supplied to the fuel injection valve coil 4.

In the valve closing period (after d in FIG. 4),
Based on the input signal SI1 from the engine control unit (ECU) 2, the control circuit 3 changes the S03 signal to O
By performing the FF, by closing the transistor TR3 provided on the downstream side of the fuel injection valve coil 4, a back electromotive force is generated by the back electromotive absorption circuit 8, thereby closing the fuel injection valve promptly. The injection is terminated. That is, when the valve is closed, the back electromotive force is generated in the fuel injection valve coil (solenoid) 4 by the back electromotive absorption circuit 8 to increase the responsiveness of the valve closing operation.

During the valve opening period (ac in FIG. 4), the transistor TR2 is supplied by the discharge current from the capacitor 5A in the DC-DC converter 5 and the signal S02.
Is turned on to supply the current from the battery 5 to the fuel injection valve coil (solenoid) 4. During this time, as in the conventional case, for the opening operation of the other fuel injection valve and the next fuel injection, When the DC-DC converter 5 is operated and the capacitor 5A is charged, FIG.
As shown in the timing chart of (B), during the valve opening period (corresponding to a to c in FIG. 4), there is a possibility that the current supplied to the coil 4 of the fuel injection valve does not drop smoothly. That is, the charging operation to the capacitor 5A (additional charging)
Therefore, there is a concern that the discharge characteristics from the capacitor 5A in the DC-DC converter 5 become unstable.

For this reason, even if the same SI1 signal (pulse width) is given, the current supplied to the coil 4 of the fuel injection valve drops smoothly as shown in the timing chart of FIG. In comparison, the start of the section maintained at the holding current is delayed, and the period (substantial holding period) maintained at the holding current may be shortened. (FIG. 5B)
Refer to the timing chart of｝.

When the current supplied to the coil 4 of the fuel injection valve increases, the energy stored in the coil 4 increases accordingly, and the energy to be released from the coil 4 for closing the valve increases. The time required from the start of the valve operation to the completion of the valve closing becomes longer. That is, when the DC-DC converter 5 is operated and the capacitor 5A is charged during the valve opening period, as shown in the timing chart of FIG.
If the valve closing timing is to be advanced (to reduce the pulse width), the time required from the start of the valve closing operation to the completion of the valve closing may vary (change in length). Since the amount of fuel injected from the time of the valve closing to the completion of valve closing differs (changes in magnitude), the proportional relationship between the pulse width (valve opening period) and the fuel injection amount (fuel flow rate) cannot be obtained, and the dynamic range Cannot be expanded. In other words, the flow rate characteristics with a short pulse width cannot be made linear, and the dynamic range cannot be expanded sufficiently.

Therefore, the control circuit 3 according to the present invention, which also has a function as a high-pressure circuit operation control means, is intended to further increase the dynamic range of the fuel injection valve by making the flow characteristic itself with a short pulse width linear. The following control is performed. That is, in the present embodiment, the control circuit 3 controls the operation of the DC-DC converter 5 (the operation of charging the capacitor 5A) from the control circuit 3.
Is sent to the DC-DC converter 5.

Then, as shown in the timing chart of FIG. 4, the control circuit 3 turns ON the S01 signal for supplying the discharge current from the capacitor 5A in the DC-DC converter 5 to the fuel injection valve coil 4 (transistor). TR1
Is ON) during the control signal S04.
Is used as a stop signal for stopping the operation of the DC-DC converter 5 (the operation of charging the capacitor 5A).
The data is transmitted to the converter 5.

As a result, the charging operation (additional charge) to the capacitor 5A is stopped, and the discharge characteristic from the capacitor 5A in the DC-DC converter 5 can be stabilized. As shown in the timing chart, during the valve opening period, the current supplied to the coil 4 of the fuel injection valve is reliably reduced.

Therefore, when the same SI1 signal (pulse width) is given, the current from the start of the valve opening to the end of the valve opening period (initial of the holding period) (ie, near c in FIG. 4) is to be stably reduced. Therefore, the energy stored in the coil 4 of the fuel injection valve can be stably reduced, and the time required from the start of the valve closing operation to the completion of the valve closing can be stably reduced.

That is, according to the present embodiment, a substantial holding period can be stably achieved from an early stage with a simple and low-cost configuration, so that a stable valve closing operation can be performed even if the pulse width is shortened. Therefore, the region in which the amount of fuel injected from the start of the valve closing operation to the completion of the valve closing can be increased to the low injection amount (short pulse width) side. The region (dynamic range) where the fuel injection amount (fuel flow rate) is proportional to the fuel injection amount (period) can be expanded toward the low injection amount (short pulse width) side.

In this embodiment, the signal S01 for supplying the discharge current from the capacitor 5A in the DC-DC converter 5 to the fuel injector coil 4 is ON (the transistor TR1 is ON). , DC
-The operation of the DC converter 5 (the operation of charging the capacitor 5A) has been described as being stopped. However, it is only necessary to stably reduce the current near c in FIG. As long as the valve opening operation and the next fuel injection are not adversely affected, D
It is also possible to configure to stop the operation of the C-DC converter 5 (the operation of charging the capacitor 5A).
Further, since it is sufficient that the current near c in FIG. 4 can be stably reduced, in some cases, even after the S01 signal is turned on (the transistor TR1 is turned on), for example, for a while (for example, FIG. In the case of middle b), it is possible to control the DC-DC converter 5 to operate (charging operation of the capacitor 5A).

Next, a second embodiment of the present invention will be described. In the second embodiment, as shown in FIG.
A lift sensor 9 for detecting a lift amount of an iron core (and a valve body) of the fuel injection valve coil 4 is provided in the configuration according to the first embodiment shown in FIG. The detection signal of the lift sensor 9 is input to the control circuit 3.

By the way, during the valve opening period (the period during which the S01 signal is ON in FIG. 7), the discharge current from the capacitor 5A in the DC-DC converter 5 and S02
The signal turns on the transistor TR2 to turn on the battery 5
From the fuel injection valve coil (solenoid) 4
, There is a current difference between the holding current required to maintain the valve open state.

If the current difference is present, as described above, the valve closing characteristics are not a little different, so that if the valve closing timing is advanced (the pulse width is shortened), the valve closing is performed. Since the amount of fuel injected from the start of operation to the completion of valve closing differs (changes in magnitude), a proportional relationship between the pulse width (valve opening period) and the fuel injection amount (fuel flow rate) is obtained. Can not be.

Therefore, for example, as in the first embodiment,
Even if the operation of the DC-DC converter 5 (the operation of charging the capacitor 5A) is stopped during the period when the S01 signal is ON (the transistor TR1 is ON), the dynamic range can be expanded due to the current difference. The limit will come. Therefore, the control circuit 3 having the function of the predetermined period setting means according to the present invention performs the following control based on the detection signal of the lift sensor 9.

That is, when the valve body of the fuel injection valve is lifted by a predetermined amount or more (for example, when the valve is changed from the closed state to the fully opened state), the operation is shifted to the holding period. Specifically, as shown in FIG. 7, in the control circuit 3, based on the detection signal of the lift sensor 9, the lift amount of the iron core (and, consequently, the valve body) of the fuel injection valve coil 4 has exceeded a predetermined value. Is detected, the S01 signal and the S02 signal are turned off once, and based on the current detection result of the current detection circuit 7, the S02 signal is turned off.
Switching of transistor TR2 (ON
OFF), and the battery voltage is discontinuously applied, thereby immediately shifting to a holding period for supplying a current necessary for maintaining the open state of the fuel injection valve.

In this way, as in the prior art, S01
Since it is possible to shift to the holding period earlier than when the signal and the signal S02 are turned off in advance, for example, a stable valve closing operation can be performed even if the pulse width is shortened. Therefore, the region where the amount of fuel injected from the start of the valve closing operation to the completion of the valve closing can be made the same can be expanded toward the low injection amount (short pulse width) side, and the pulse width (valve opening period) And the fuel injection amount (fuel flow rate) is proportional to the dynamic range, which can be expanded toward the low injection amount (short pulse width) side.

The present embodiment, the first embodiment,
Can be used in combination, and in this case, the valve closing operation can be performed stably even if the pulse width is shortened, so that the pulse width (valve opening period) and the fuel injection amount (fuel flow rate) Can be further expanded toward the low injection amount (short pulse width) side.

In each of the above embodiments, the configuration provided with the current detection circuit 7 and the back electro-absorption circuit 8 has been described. Therefore, the present invention can be applied to a device without the current detection circuit 7 and the back electro-absorption circuit 8.

[0038]

As described above, according to the first aspect of the present invention, it is possible to suppress the adverse effect on the valve opening current after the lapse of the predetermined period due to the charging operation of the capacitor in the high voltage circuit. Thus, the valve opening current after the lapse of the predetermined period can be stabilized at a predetermined current value, so that the current difference between the valve opening current and the holding current can be reliably suppressed. Therefore, even if the fuel injection amount is reduced, a stable valve closing operation can be performed. Therefore, the region where the amount of fuel injected from the start of the valve closing operation to the completion of the valve closing can be made equal to the low injection amount side. Accordingly, a region (dynamic range) in which the pulse width (valve opening period) and the fuel injection amount (fuel flow rate) are in a proportional relationship can be expanded toward the low injection amount side.

That is, according to the present invention, the dynamic range can be remarkably expanded as compared with the related art while having a simple and low-cost configuration. According to the second aspect of the invention, the operation and effect of the first aspect of the invention can be reliably achieved, and an existing control signal can be used, so that the configuration can be simplified. it can.

According to the invention described in claim 3, according to claim 1
And the effect of the invention described in
As compared with the case where a predetermined period is set in advance, etc., it is possible to shift to the holding period earlier, so that
Even if the pulse width is shortened, a stable valve closing operation can be realized. That is, in combination with the operation and effect of the invention described in claim 1, the region where the amount of fuel injected from the start of the valve closing operation to the completion of the valve closing can be further expanded to the low injection amount side, As a result, a region (dynamic range) where the pulse width (valve opening period) and the fuel injection amount (fuel flow rate) are in a proportional relationship can be expanded toward the low injection amount side. That is, according to the present invention, the dynamic range can be maximized.

According to the fourth aspect of the present invention, it is possible to shift to the holding period earlier than in the case where the predetermined period is determined in advance, so that the pulse width can be shortened accordingly. A stable valve closing operation can be realized.
Therefore, the region where the amount of fuel injected from the start of the valve closing operation to the completion of the valve closing can be made the same can be expanded to the low injection amount side, and the pulse width (valve opening period) and the fuel injection amount (fuel (Dynamic flow range) in which the flow rate is proportional to the flow rate can be expanded toward the low injection amount side. That is, according to the present invention, the dynamic range can be expanded.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration according to the first embodiment;

FIG. 2 is a block diagram according to the invention of claim 4;

FIG. 3 is a system configuration diagram according to the first embodiment of the present invention.

FIG. 4 is a timing chart illustrating drive control of a fuel injection valve in the embodiment.

FIG. 5A is a timing chart for explaining the operation and effect of the drive control of the fuel injection valve in the embodiment.
(B) is a timing chart illustrating the operation and effect of the conventional drive control of the fuel injection valve.

FIG. 6 is a system configuration diagram according to a second embodiment of the present invention.

FIG. 7 is a timing chart illustrating the operation and effect of the drive control of the fuel injection valve in the embodiment.

FIG. 8 is a diagram illustrating a dynamic range of a fuel injection valve.

FIG. 9 is a system configuration diagram of a conventional control device.

[Explanation of symbols]

 Reference Signs List 1 injector drive unit 2 engine control unit (ECU) 3 control circuit 4 injector solenoid (fuel injection valve coil) 5 DC-DC converter (high voltage circuit) 5A capacitor 6 battery 7 current detection circuit 8 back electromotive absorption circuit 9 lift sensor TR1 transistor TR2 Transistor TR3 Transistor

Claims (4)

[Claims] The present invention relates to a solenoid provided in a fuel injection valve for a predetermined period from the time when a fuel injection start command is input from an engine control unit, wherein a solenoid comprising a discharge current from a capacitor in a high voltage circuit and a current from a battery. A large valve opening current is supplied to open the fuel injection valve. After the predetermined period has elapsed, a relatively small holding current capable of maintaining the valve opening state is applied to the solenoid, and fuel injection from the engine control unit is performed. In the drive control device for a fuel injection valve, which maintains the holding current value until a stop command is input, the valve opening current is stabilized after the predetermined period has elapsed, A drive control device for a fuel injection valve, comprising a high voltage circuit operation control means for controlling a charging operation to a capacitor. 2. The fuel injection valve drive control device according to claim 1, wherein the high-pressure circuit operation control means stops the charging operation of the capacitor in the high-voltage circuit for at least the predetermined period. . 3. The apparatus according to claim 1, further comprising a predetermined period setting means for setting the predetermined period based on a detection result of an open state of the fuel injector during operation. A drive control device for a fuel injection valve as described in the above. 4. A relatively long period of time from the input of a fuel injection start command from an engine control unit to a solenoid provided in a fuel injection valve, comprising a discharge current from a capacitor in a high voltage circuit and a current from a battery. A large valve opening current is supplied to open the fuel injection valve. After the predetermined period has elapsed, a relatively small holding current capable of maintaining the valve opening state is applied to the solenoid, and fuel injection from the engine control unit is performed. In the fuel injection valve drive control device configured to maintain the holding current value until a stop command is input, the predetermined period is set based on a detection result of a valve opening state of the fuel injection valve during operation. A drive control device for a fuel injection valve, comprising a predetermined period setting means.