JPH09112735A - Solenoid valve drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the occurrence of abnormality accurately without being affected by a characteristic of a solenoid with which a solenoid valve is provided. SOLUTION: A device 10 is provided with a pressure increase circuit 32 which changes high voltage into a capacitor C1 to supply a peak current immediately after conducting electricity to solenoids L1 to Ln of a fuel injection valve which injects fuel into each cylinder of a diesel engine when it is started and hold current circuits 34a, 34b which supply hold current for holding an opened valve when electricity is conducted. In this case, if a voltage at both ends of the capacitor C1 immediately before each transistor TR for conducting electricity is turned on is not above a predetermined value, it is judged that a current flow passage of the solenoid L is short-circuited to any potential, and if a voltage at both ends of the capacitor C1 immediately after the transistor TR is turned off is not below a predetermined value, it is judged that the current flow passage of the solenoid L is disconnected. As a result, it is possible to detect an abnormality surely irrespective of changes of characteristics of the solenoid L.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve driving device for driving a solenoid valve, and more particularly to a solenoid valve driving device capable of detecting an abnormality in a current supply path to a solenoid solenoid provided in the solenoid valve. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, as a fuel injection valve for injecting and supplying fuel to each cylinder of an internal combustion engine, for example, an electromagnetic valve which has an electromagnetic solenoid and is opened by energizing the electromagnetic solenoid has been used. ing.

A drive circuit for driving such a fuel injection valve has, for example, as shown in FIG.
a, #b ... Electromagnetic solenoid L of fuel injection valve
Switching transistors TRa provided in series in the current supply paths of a, Lb, ..., A grounding resistor R for limiting the current flowing through the transistors TRa, ..., and electromagnetic solenoids La, Lb ,. Of a capacitor 52a provided in parallel with the current supply path of the power supply circuit and a booster circuit 52b for boosting the power supply voltage to charge the capacitor 52a. The diode is connected to the corresponding electromagnetic solenoid La, Lb, ... Immediately after the transistors TRa ,. When the transistors TRa, ... Are turned on, the peak current circuit 52 that supplies a predetermined peak current via Da is supplied to the corresponding electromagnetic solenoids La, Lb ,. And a hold current circuit 54.

That is, in the conventional drive circuit, when the transistors TRa, ... Are turned off, the capacitor 52a is charged by the booster circuit 52b, and when any of the transistors TRa ,. A large current (peak current) is made to flow from the condenser 52a to the solenoids La, Lb ..., The fuel injection valve of the corresponding cylinder is opened promptly, and then the hold current circuit 5
A constant current (hold current) for holding the valve open is supplied from 4 to maintain the open state of the fuel injection valve of the corresponding cylinder during the ON period of the transistors TRa.

In the conventional fuel injection control device having such a drive circuit, as shown in FIG. 11, the microcomputer 56 energizes the electromagnetic solenoids La, Lb ... In response to the operating state of the internal combustion engine. The fuel injection into the internal combustion engine is controlled by calculating the time and the energization start timing, and by selectively outputting the injection command pulse PCMD to each of the transistors TRa, ... According to the calculation result. There is.

That is, according to the drive circuit shown in FIG.
As shown in FIG. 12, when the injection command pulse PCMD input to any one of the transistors TRa, rises, the peak current circuit 52 (the capacitor 52a and the booster circuit 52).
By the operation of b), the corresponding electromagnetic solenoids La, L
The current (solenoid current ISOL) flowing through b, ... Abruptly rises to the peak current, and then the injection command pulse P
The solenoid current ISOL is held at the hold current until CMD falls. Therefore, the injection command pulse PCM
When D rises, the lift amount of the valve body (that is, the opening degree of the fuel injection valve) by the electromagnetic solenoids La, Lb, ... Increases rapidly to start the fuel injection, and thereafter, it corresponds to the pulse width of the injection command pulse PCMD. The fuel injection continues for the period of time that Therefore, in the conventional fuel injection control device, by controlling the pulse width and output timing of the injection command pulse PCMD output to the transistors TRa, ... Provided in the current supply paths of the electromagnetic solenoids La, Lb ... The fuel injection amount and the fuel injection timing are controlled for each cylinder of the internal combustion engine.

By the way, in such a conventional fuel injection control apparatus, when the electromagnetic solenoids La, Lb, ... Or the individual wirings Wa, Wb, ... For supplying a current to the electromagnetic solenoids La, Lb ,. Since it becomes impossible to drive the corresponding fuel injection valve, it is necessary to detect the abnormality and take some action.

Therefore, in the prior art, for example, FIGS.
2, the current flowing in the ground resistor R, that is, the electromagnetic solenoids La, L via the transistors TRa ,.
A current detection circuit 58 that outputs the detection signal SDG at a high level, for example, when the current flowing through b, ... Based on this, the presence or absence of abnormality is determined.

That is, in the conventional device, as shown in FIG. 12, the detection signal SDG from the current detection circuit 58 is read immediately after the injection command pulse PCMD is output to any of the transistors TRa, ... If SDG is at a high level, it is determined that the current normally flows through the electromagnetic solenoids La, ... Corresponding to the transistors TRa, ... Which output the injection command pulse PCMD, and conversely, the read detection signal SDG is at a low level. For example, it is determined that the electromagnetic solenoids La, ... Corresponding to the transistors TRa, ... Which output the injection command pulse PCMD, and the wiring Wa, ... For supplying a current to the electromagnetic solenoids La ,. It was

[0010]

However, the above-mentioned conventional device has a problem in that it is not possible to accurately detect the occurrence of an abnormality due to characteristic variations or characteristic changes of the electromagnetic solenoids La, ....

That is, as shown by the dotted line in FIG. 12, due to the characteristic variations and characteristic changes of the electromagnetic solenoids La, ...
When the rise of the solenoid current ISOL (peak current) with respect to the rise timing of the injection command pulse PCMD is delayed, the detection signal SDG from the current detection circuit 58 changes to the high level with a delay of the predetermined time t1.
The microcomputer 56 will determine that the detection signal SDG is at a low level, and will erroneously determine that an abnormality has occurred, although it is normal.

On the other hand, in this type of fuel injection control device, not only the disconnection abnormality as described above, but also the current supply path (wiring) of the electromagnetic solenoids La, ... It is desirable to be configured so that a short circuit to the electric potential) can be detected. Also in this case, it is conceivable that the presence / absence of abnormality is determined based on the value of the current flowing through the electromagnetic solenoids La, ... Via the transistors TRa ,.

However, for example, the electromagnetic solenoids La, ...
When the wiring on the upstream side is short-circuited to the battery voltage, a current according to the characteristics of the electromagnetic solenoid flows in each electromagnetic solenoid La, .... Therefore, it is extremely difficult to set the current determination value and the determination timing that can accurately determine such an abnormality, and it is also necessary to accurately detect the occurrence of the abnormality due to the characteristic variations of the electromagnetic solenoids La, ... I can't.

The present invention has been made in view of the above problems, and provides an electromagnetic valve drive device capable of accurately detecting the occurrence of an abnormality without being affected by the characteristics of the electromagnetic solenoid provided in the electromagnetic valve. It is intended to be provided.

[0015]

In the electromagnetic valve drive device of the present invention as set forth in claim 1, which is made to achieve the above object, the control means is a current of the electromagnetic solenoid of the electromagnetic valve. The switching element provided in series in the supply path is drive-controlled (switching drive) to open and close the solenoid valve. When the switching element is turned off by the control means, the peak current supply means
A capacitor provided in parallel with the current supply path of the electromagnetic solenoid is charged with a predetermined high voltage. Therefore, when the switching device is turned on by the control means, the peak current is supplied to the electromagnetic solenoid by the discharge of the capacitor charged with the high voltage, and the electromagnetic valve is quickly opened.
The hold current supply means supplies a hold current to the electromagnetic solenoid to maintain the open state of the electromagnetic valve.

Particularly, in the present invention, the abnormality determining means determines whether or not an abnormality has occurred in the current supply path of the electromagnetic solenoid based on the voltage across the capacitor for supplying the peak current to the electromagnetic solenoid. . That is,
The capacitor is charged with a predetermined high voltage by the peak current supply means when the switching element is off, and is discharged through the electromagnetic solenoid and the switching element when the switching element is turned on.
The voltage across the capacitor changes depending on the driving state of the solenoid valve. However, for example, if the electromagnetic solenoid itself or its current supply path is disconnected, the capacitor does not discharge and the voltage across it remains high even when the switching element is turned on, and the current supply path of the electromagnetic solenoid peaks. When short-circuited to a voltage level lower than the high voltage applied to the capacitor by the current supply means, the voltage across the capacitor does not rise to the high voltage. Therefore, in the present invention, it is determined whether or not an abnormality has occurred in the current supply path of the electromagnetic solenoid based on the voltage across the capacitor.

Therefore, according to the electromagnetic valve driving device of the present invention as described above, it is possible to accurately detect the occurrence of the abnormality without being affected by the characteristics of the electromagnetic solenoid provided in the electromagnetic valve. Become. Next, in the solenoid valve drive device according to the present invention as defined in claim 2, in the solenoid valve drive device according to claim 1, the abnormality determination means includes a voltage detection means immediately after turning off and a disconnection determination means. The voltage detecting means immediately after turning off detects the voltage across the capacitor immediately after the switching element is turned off from the on state by the control means, and the disconnection judging means detects the voltage across the capacitor detected by the voltage detecting means immediately after off. Is less than a predetermined value, it is determined that the current supply path of the electromagnetic solenoid is broken. In the second aspect, the disconnection of the current supply path includes the disconnection of the electromagnetic solenoid itself.

That is, as described above, when the current supply path of the electromagnetic solenoid is disconnected, even if the switching element is turned on, the capacitor is not discharged and the voltage across the capacitor remains high. In the solenoid valve drive device described in the item (1), the voltage across the capacitor immediately after the switching element is turned off is not less than a predetermined value, and the current supply path of the electromagnetic solenoid is disconnected and the capacitor is not discharged. Is determined.

The timing at which the voltage detecting means immediately after turning off detects the voltage across the capacitor is normal, and after the switching element is turned off, the peak current supplying means raises the voltage across the capacitor to the above predetermined value. It should be within the period up to.

Therefore, according to the solenoid valve driving device of the second aspect, it is possible to accurately detect the disconnection of the current supply path of the electromagnetic solenoid without being affected by the characteristics of the electromagnetic solenoid. . Moreover, according to this solenoid valve driving device, since the voltage across the capacitor may be detected immediately after the switching element is turned off by the control means, the control means and the abnormality determination means (immediately after off voltage detection means and disconnection determination means). When is realized by the processing of the microcomputer, the execution timing of the processing corresponding to each means can be easily set.

Next, in the solenoid valve drive system according to the present invention as defined in claim 3, in the solenoid valve drive system according to claim 1, the abnormality determination means includes a voltage detection means immediately before turning on and a short circuit determination means. ing. Then, the voltage detection means immediately before turning on detects the voltage across the capacitor just before the switching element is turned on from the off state by the control means,
When the short-circuit determination means determines that the voltage across the capacitor detected by the voltage detection means immediately before turning on is not equal to or higher than a predetermined value,
It is determined that the current supply path of the electromagnetic solenoid is short-circuited to a voltage level lower than the high voltage applied to the capacitor by the peak current supply means.

That is, as described above, when the current supply path of the electromagnetic solenoid is short-circuited to a voltage level lower than the high voltage applied to the capacitor by the peak current supply means, the capacitor is not sufficiently charged and the voltage across the capacitor is above the above level. It will not rise to high voltage. Therefore, in the solenoid valve driving device according to the third aspect, if the voltage across the capacitor immediately before the switching element is turned on is not more than a predetermined value, the current supply path of the electromagnetic solenoid has some voltage level. Therefore, it is determined that the capacitor has not been charged by short-circuiting to.

Therefore, according to the solenoid valve driving device of the third aspect, it is possible to accurately determine that the current supply path of the electromagnetic solenoid is short-circuited to a certain voltage level without being affected by the characteristics of the electromagnetic solenoid. Can be detected.
Moreover, according to this solenoid valve driving device, the voltage across the capacitor may be detected immediately before the switching element is turned on by the control means. Therefore, the control means and the abnormality determination means (the voltage detection means immediately before turning on and the short circuit determination means) When is realized by the processing of the microcomputer, the execution timing of the processing corresponding to each means can be easily set.

Next, in the solenoid valve drive system according to the present invention as defined in claim 4, in the solenoid valve drive system according to claim 2, the abnormality determining means further includes the voltage detection circuit immediately before turning on according to claim 3. Means and short circuit determination means. Therefore,
According to the solenoid valve drive device of the fourth aspect, both the effect obtained by the device of the second aspect and the effect obtained by the device of the third aspect can be obtained together.

Next, in the solenoid valve drive system according to the fifth aspect, in the solenoid valve drive system according to the second aspect, each cylinder of the internal combustion engine is provided to inject fuel into each cylinder when the valve is opened. A plurality of fuel injection valves as the solenoid valve, and an electromagnetic solenoid of each fuel injection valve (electromagnetic valve) has a predetermined common line connected to a capacitor for peak current supply and a hold current supply means. A current is supplied from the common line through individual wirings corresponding to each electromagnetic solenoid, and a switching element is provided in series on each individual wiring. Then, the control means calculates the energization time and the energization start timing of each electromagnetic solenoid according to the operating state of the internal combustion engine, and selectively and sequentially drives each switching element according to the calculation result, whereby the internal combustion engine Control the fuel injection to the.

Further, in the solenoid valve drive device according to the present invention, when the disconnection judging means does not have the voltage across the capacitor detected by the voltage detecting means immediately after turning off at a predetermined value or less, the control means turns on the current time. It is determined that the individual wiring of the electromagnetic solenoid corresponding to the switching element turned off from is disconnected, and the correction means responds to the individual wiring that is not determined to be disconnected by the disconnection determination means according to the determination result by the disconnection determination means. The energization time of the electromagnetic solenoid calculated by the control means is corrected so that the internal combustion engine can be continuously operated by the normal fuel injection valve.

That is, the electromagnetic valve drive system according to the fifth aspect of the invention is a fuel injection control for controlling a fuel injection to an internal combustion engine by driving a plurality of fuel injection valves for respectively injecting and supplying fuel to each cylinder of the internal combustion engine. Each time the switching element is turned off from the on state by the control means, the voltage detection means immediately after turning off detects the voltage across the capacitor, and the disconnection determination means detects the voltage detection means immediately after turning off. If the applied voltage value is not less than the specified value,
The control means determines that the individual wiring corresponding to the switching element driven this time is broken.
Then, the correction unit corrects the energization time of the electromagnetic solenoid calculated by the control unit according to the determination result of the disconnection determination unit, so that the operation of the internal combustion engine can be performed by the remaining fuel injection valves that can be normally driven. We are making it possible to continue.

Therefore, according to the electromagnetic valve driving device of the fifth aspect, even if any of the individual wirings for supplying the current to the electromagnetic solenoid of each fuel injection valve is broken, the abnormality is described above. As described above, since the operation of the internal combustion engine can be reliably continued by the remaining fuel injection valves that can be normally driven, for example, the minimum traveling of the vehicle equipped with the internal combustion engine becomes possible. can do. Such an effect can be obtained not only when the individual wiring is broken, but also when the electromagnetic solenoid itself is broken.

Next, in the solenoid valve drive system according to a sixth aspect, in the solenoid valve drive system according to the fifth aspect, the plurality of fuel injection valves are preliminarily arranged in a plurality of groups capable of operating the internal combustion engine. They are divided, and a common line for current supply is provided corresponding to each of the groups.

When the disconnection determining means determines that the individual wirings corresponding to all the fuel injection valves belonging to any one of the plurality of groups are disconnected, it is determined that the common line corresponding to the group is disconnected. However, when the disconnection determination means determines that any of the common lines has been disconnected, the correction means causes the internal combustion engine to operate by the normal fuel injection valve corresponding to the common line that is not determined to be disconnected by the disconnection determination means. The energization time of the electromagnetic solenoid calculated by the control means is corrected so that the operation can be continued.

That is, in the solenoid valve drive system according to the sixth aspect, a common line for supplying current is provided for each group of a predetermined number of fuel injection valves, so that even if one common line is disconnected. , The fuel injection valve of a group connected to another common line is configured to be drivable, and the disconnection determination means is configured to disconnect individual wirings corresponding to all the fuel injection valves belonging to any group. If it is determined that the common line corresponding to the group is broken, it is determined. Then, when it is determined that any one of the plurality of common lines is broken, the correction unit corrects the energization time of the electromagnetic solenoid calculated by the control unit so that the remaining fuel that can be normally driven remains. The injection valve enables the internal combustion engine to continue operating.

According to the solenoid valve drive system of the sixth aspect, even if any of the common lines is broken, the internal combustion engine is driven by the remaining fuel injection valves connected to the other common line. Can be reliably continued.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. It is needless to say that the embodiments of the present invention are not limited to the following examples, and can take various forms as long as they belong to the technical scope of the present invention.

First, FIG. 1 shows n (n is an even number) electromagnetic solenoid type unit injectors (hereinafter simply referred to as injectors) for injecting fuel into each cylinder # 1, # 2, ... #n of a vehicle diesel engine. ) Of the electromagnetic solenoids L1, L2, ...
It is a block diagram showing the whole fuel injection control apparatus 10 of an Example which controls the fuel injection amount and fuel injection timing to #n.

As shown in FIG. 1, the fuel injection control device 10 of the present embodiment is a CPU, RO that executes various control processes for fuel injection control according to a preset control program.
Well-known microcomputer 20 including M, RAM, etc.
And a detection circuit 12 for waveform-shaping an output signal from a rotation sensor that generates a rotation signal for each predetermined rotation angle of the diesel engine and inputting it to the microcomputer 20, and an operating state of the diesel engine. From the microcomputer 20, the buffers 14 and 16 for inputting the signals from the sensors and switches to the microcomputer 20 and the drive circuit 30 for energizing the electromagnetic solenoids L1 to Ln to drive the injectors of the cylinders # 1 to #n, respectively. The interface 22 for outputting the injection command pulse of 1 to the drive circuit 30 and the power supply circuit 26 which receives power supply from the battery BT and supplies a predetermined power supply voltage (constant voltage) to each of the above parts.

Here, the fuel injection control device 10 of the present embodiment.
, Ln are selected according to the operating state of the diesel engine in the order corresponding to the first cylinder # 1, the second cylinder # 2, ... The nth cylinder #n. By supplying electricity, fuel is supplied to the diesel engine. The electromagnetic solenoids L1, L2, ... L
n are electromagnetic solenoids L1, L3, ... Ln-1 corresponding to odd-numbered cylinders # 1, # 3, ... # n-1, and electromagnetic solenoids corresponding to even-numbered cylinders # 2, # 4 ,. Solenoid L2
L4, ..., Ln are grouped in advance.

The odd numbered cylinders # 1, # 3, ... #
The electromagnetic solenoids L1, L3, ... Ln-1 corresponding to n-1 correspond to the first common line CM1 and the electromagnetic solenoids L1, L3, ... Ln-1 from the first common line CM1. A driving current is supplied through the branched individual wirings W1, W3, ... Wn-1, and similarly, the electromagnetic waves corresponding to the even-numbered cylinders # 2, # 4 ,. Ln to the solenoids L2, L4, ... Ln, and the electromagnetic solenoids L2, 4, ... From the second common line CM2.
Individual wirings W2, W4, ... Branched corresponding to each Ln.
A drive current is supplied via Wn.

In the above electromagnetic solenoid group, when one of the first common line CM1 and the second common line CM2 is broken, the most stable operation is possible by the injector corresponding to the other common line. Are allocated so that Next, in the drive circuit 30, the individual wirings W1 to Wn of the electromagnetic solenoids L1 to Ln are electrically connected / interrupted in response to the injection command pulses P1 to Pn from the microcomputer 20 input via the interface 22. A switching circuit 36, a hold current circuit 34a for supplying a predetermined hold current (constant current) to the electromagnetic solenoids L1, L3, ... Ln-1 connected to the first common line CM1 via a diode D2, and a second common Hold current circuit 34b for supplying a predetermined hold current (constant current) to electromagnetic solenoids L2, L4, ... Ln connected to line CM2 via diode D4, common lines CM1, C
A capacitor C1 for supplying a peak current, which is connected in parallel to M2 via diodes D1 and D3, and a high voltage is charged in the capacitor C1 when the switching circuit 36 is turned off. When the individual wiring W of L is turned on, the capacitor C
The booster circuit 32 is provided as a peak current supply means for supplying a peak current to the corresponding electromagnetic solenoid L by the high voltage charged to 1.

Further, in the drive circuit 30, the voltage across the capacitor C1 is detected by the voltage dividing resistors R1 and R2, and the detected voltage is output from the power supply circuit 26 by the voltage dividing resistors R3 and R4. It is determined whether or not the voltage (constant voltage) is equal to or higher than a reference voltage obtained by dividing the voltage, and the comparator COM that outputs the determination result to the microcomputer 20 and the voltage of the first common line CM1 have predetermined values (in the present embodiment, the battery BT voltage). A voltage monitoring circuit 38a that outputs a high-level signal SK1 to the microcomputer 20 if it is higher than approximately half of the voltage) or a low level if it is lower than the predetermined value, and the second common line CM2 similarly to the voltage monitoring circuit 38a. Voltage monitoring circuit that outputs a high-level signal SK2 to the microcomputer 20 if the voltage is higher than the predetermined value, and a low level if it is lower than the predetermined value. 38b is provided.

In FIG. 1, D5 is the first common line C
Electromagnetic solenoids L1, L3, ... Ln-1 connected to M1
D6 is a diode for absorbing the flyback voltage generated in the second common line CM2, and D6 is a diode for absorbing the flyback voltage generated in the electromagnetic solenoids L2, L4, ... Ln connected to the second common line CM2. .

Here, the booster circuit 32 includes a booster transformer Lo to which a battery voltage is applied to one end of a primary winding, and a drive pulse of a high frequency (several tens kHz in this embodiment) inputted from the outside. By switching at high speed with, the other end of the primary winding of the transformer Lo is grounded at high frequency,
A boosting transistor TRo that generates a high voltage in the secondary winding of the transformer Lo and a diode Do that charges the capacitor C1 by outputting the high voltage generated in the secondary winding of the transformer Lo to the capacitor C1. The electromagnetic solenoids L1 to Ln are operated by the command signal SC input from the microcomputer 20 via the interface 22 during the off period.

The switching circuit 36 includes switching transistors TR1 and TR provided in series on the individual wirings W1 to Wn of the electromagnetic solenoids L1 to Ln, respectively.
2, ... TRn and each of these transistors TR1 to TRn
Ground side terminal (in this embodiment, transistors TR1 to T
A grounding resistor Reo connected to an emitter terminal (because an NPN transistor is used for Rn) and injection command pulses P1 to Pn for each cylinder input from the interface 22 are transmitted to corresponding transistors TR1 to TRn.
Input resistors Ra1, Ra2, ...
It is composed of Ran.

On the other hand, the hold current circuit 34a receives power supply from the battery BT and receives the transistors TR1 and TR1.
Individual wiring W1, W by any of TR3, ... TRn-1
3, ... Electromagnetic solenoids L1, L3 with Wn-1 conducted
Is a constant current circuit that supplies a hold current for maintaining the injector valve opening to Ln-1, and as shown in FIG. 2, the first common line C from the battery voltage + B via the diode D2.
The switching element 40 is turned on so that the voltage across the switching element 40 for connecting / disconnecting the current path to M1 and the ground resistor Reo connected to the ground side terminals of the transistors TR1 to TRn becomes a predetermined voltage. And a constant current control circuit 42 for turning it off.
In FIG. 2, only the electromagnetic solenoid L1 and the corresponding transistor TR1 are shown.

The hold current circuit 34b has the same structure as the hold current circuit 34a.
Ln to which the individual wirings W2, W4, ... Wn are made conductive by any of the transistors TR2, TR4, ... TRn is supplied with a hold current for holding the injector open.

Further, the comparator COM is provided with a detection voltage obtained by the voltage dividing resistors R1 and R2 and a voltage dividing resistor R.
By comparing with the reference voltage obtained by 3 and R4, it is determined whether the voltage across the capacitor C1 charged by the booster circuit 32 is, for example, 60 V or more, which is a half of the upper limit voltage 120 V in the normal state. If the voltage is 60 V or more, the high level detection signal SDG is output, and if the voltage is less than 60 V, the low level detection signal SDG is output.

Next, the operation of the fuel injection control device 10 thus constructed will be described with reference to FIGS. In the following description, the electromagnetic solenoids L1 to
Ln, transistors TR1 to TRn, injection command pulse P
1 to Pn, and the common lines CM1 and CM2, when the respective lines are not particularly distinguished from each other, the codes are “L” and “T”.
“R”, “P”, and “CM” are used. 3 to 5, VC1 represents the voltage across the capacitor C1, and ISOL represents the current (solenoid current) flowing in the electromagnetic solenoid L.

First, the microcomputer 20 reads various detection signals representing the operating state of the diesel engine, which are input from the detection circuit 12, the buffer 14 and the buffer 16, and based on the read detection signals, the energization time of the electromagnetic solenoid L. And the energization start timing is calculated. Then, as shown in FIG. 4, the injection command pulses P1 to Pn of each cylinder are sequentially output at a pulse width corresponding to the calculated energization time and at the calculated energization start timing.

Further, the microcomputer 20 is shown in FIG.
Further, as shown in FIG. 4, when the injection command pulse P is not output, the booster circuit 32 of the drive circuit 30 is operated by outputting the command signal SC at a high level. In other words, the microcomputer 20 stops the operation of the booster circuit 32 by setting the command signal SC to the low level, and then outputs the injection command pulse P, and the injection command pulse P
When the output of is completed, the command signal SC is returned to the high level again to operate the booster circuit 32.

Therefore, in the drive circuit 30, as shown in FIG. 3, when all the injection command pulses P from the microcomputer 20 input to the switching circuit 36 via the interface 22 are in the off state, the peak current is supplied. The capacitor C1 for charging is charged to a predetermined upper limit voltage (120 V in this embodiment) by the booster circuit 32.
Then, in order to energize the electromagnetic solenoid L of any of the cylinders, the injection command pulse P is supplied from the microcomputer 20.
Is output, the transistor TR of the corresponding cylinder is turned on, the voltage charged in the capacitor C1 is discharged through the electromagnetic solenoid L within a predetermined discharge time TDCHG, and a peak current flows through the electromagnetic solenoid L. After that, the electromagnetic solenoid L connected to the first common line CM1
Hold current circuit 3 when energizing 1, L3, ... Ln-1
4a, or when the electromagnetic solenoids L2, L4, ... Ln connected to the second common line CM2 are energized, the hold current circuit 34b operates so that a hold current flows through the energized electromagnetic solenoid L, and the microcomputer 20 Due to this, when the output of the injection command pulse P is stopped, the energization of the electromagnetic solenoid L is cut off. Further, when the electromagnetic solenoid L is de-energized in this way, the command signal SC from the microcomputer 20 becomes high level and the booster circuit 32 operates again. After that, the capacitor C1 becomes the upper limit within the predetermined charging time TCHG. The battery is charged to the voltage and the peak current can be supplied when the injection command pulse P is input next.

As described above, in the fuel injection control device 10 of this embodiment, the booster circuit 32 is operated when the injection command pulse P is not output and all the transistors TR are turned off.
When the injection command pulse P turns on one of the transistors TR, the capacitor C1 is charged by
The peak current flows from the capacitor C1 to the corresponding electromagnetic solenoid L so that the injector of the corresponding cylinder is quickly opened, and thereafter the hold current circuit 34
A hold current for holding the valve open is made to flow from either a or 34b, and the valve open state of the injector of the corresponding cylinder is held during the ON period of the transistor TR.

On the other hand, as described above, the injection command pulse P is output from the microcomputer 20 and the capacitor C
1 is discharged, and as shown in FIG. 3, when the voltage VC1 across the capacitor C1 becomes equal to or lower than a predetermined value Vth (60 V which is half the upper limit voltage in this embodiment), the comparator COM
Detection signal S output from the microcomputer to the microcomputer 20
DG changes from high level to low level. Then, after that, when the output of the injection command pulse P is stopped and the high-level command signal SC is output from the microcomputer 20, the voltage VC1 across the capacitor C1 becomes the predetermined value Vth or more within the predetermined charging time TCHG, The detection signal SDG output from the comparator COM to the microcomputer returns to the high level.

On the other hand, as shown in FIGS. 3 and 6, the microcomputer 20 sends the injection command pulses P1 and P.
, Pn-1 is output, and the hold current circuit 34a causes the electromagnetic solenoids L1, L3 ,.
When the hold current is supplied to any one of Ln−1, the voltage monitoring circuit 38a causes the microcomputer 20 to
The signal SK1 output to outputs the level change repeatedly. Similarly, the injection command pulse P is sent from the microcomputer 20.
2, P4, ... Pn is output and the hold current circuit 34b supplies a hold current to any of the electromagnetic solenoids L2, L4, ... Ln, the voltage monitoring circuit 38b outputs it to the microcomputer 20. The signal SK2 to be repeated repeats the level change.

That is, as shown in FIG. 2, in the hold current circuits 34a and 34b, the switching element 40 is turned on / off so that a constant current flows through the grounding resistor Reo (that is, the electromagnetic solenoid L) of the transistor TR. It is configured as a current circuit. Therefore, for example, the injection command pulse P causes the transistors TR1, TR3, ... TRn-1.
Is turned on and the electromagnetic solenoids L1, L3, ...
When any one of Ln-1 is energized, the first common line CM
The level of the voltage of No. 1 changes according to ON / OFF of the switching element 40 provided in the hold current circuit 34a,
Along with this, the output signal SK1 of the voltage monitoring circuit 38a changes in level. And, in exactly the same way, the transistor TR2
When any one of TR4, ... TRn is turned on and any one of the electromagnetic solenoids L2, L4 ,.
The voltage of the second common line CM2 changes its level according to the on / off state of the switching element 40 provided in the hold current circuit 34b, and the output signal SK2 of the voltage monitoring circuit 38b changes its level accordingly.

Next, in the fuel injection control device 10 of the present embodiment, when an abnormality occurs in the common lines CM1 and CM2 and the individual wiring W for flowing the drive current to the electromagnetic solenoid L, the comparator COM outputs. Detection signal S
How the DG and the signals SK1 and SK2 output from the voltage monitoring circuits 38a and 38b respectively change will be described.

First, of the electromagnetic solenoids L1 to Ln, for example, when the electromagnetic solenoid L1 itself or the individual wiring W1 of the electromagnetic solenoid L1 is disconnected, as shown in FIG.
The injection command pulse P1 corresponding to the electromagnetic solenoid L1 is output from the microcomputer 20 and the transistor T
Even when R1 is turned on, the current (solenoid current ISOL1) does not flow in the electromagnetic solenoid L1 and the capacitor C1 is not discharged, so that the voltage VC1 across the capacitor C1 remains the upper limit voltage. Therefore, in this case, even if the injection command pulse P1 is output from the microcomputer 20,
The detection signal SDG output from the comparator COM remains high level. The dotted line in FIG. 4 represents the waveform of each part under normal conditions. That is, in a normal state, when the injection command pulse P is output from the microcomputer 20, the capacitor C1 is discharged, the detection signal SDG of the comparator COM changes to the low level, and the injection command pulse P
Is stopped and the command signal SC to the booster circuit 32 becomes high level, the comparator CO
The detection signal SDG of M returns to the high level, but if any of the electromagnetic solenoids L themselves or any of the individual wirings W are disconnected, the injection corresponding to the electromagnetic solenoid L in which the disconnection failure has occurred from the microcomputer 20. Even if the command pulse P is output, the detection signal SDG of the comparator COM
Remains at the high level.

Next, the first common line CM1 and the second common line C
If, for example, the first common line CM1 of M2 is disconnected, as shown in FIG. 5, the electromagnetic solenoids L1 and L connected from the microcomputer 20 to the first common line CM1 are connected.
3, ... Injection command pulses P1, P corresponding to Ln-1 respectively
3, ... Pn-1 is output, the capacitor C1 is not discharged, and the detection signal SDG of the comparator COM remains at the high level. As in the case of FIG. 4, the dotted line in FIG. 5 represents the waveform of each part under normal conditions.

On the contrary, when the second common line CM2 is disconnected, the microcomputer 20 releases the second common line CM2.
.. Pn corresponding to the electromagnetic solenoids L2, L4, ... Ln connected to, the detection signal SDG of the comparator COM remains high level.

That is, when the common lines CM1 and CM2 are broken, the same phenomenon occurs as when all the electromagnetic solenoids L themselves connected to the broken common line or all of their individual wirings W are broken. On the other hand, at least one of the first common line CM1 and the second common line CM2 has a battery voltage + B (normally 10V to 15V) or a ground potential (G).
ND: 0V), the capacitor C1 is not sufficiently charged by the booster circuit 32, the voltage VC1 across the capacitor C1 does not reach the predetermined value Vth (60V), and the detection signal SDG of the comparator COM is always at the low level. Becomes

Further, when such a short-circuit fault occurs, if, for example, the first common line CM1 of both common lines CM1 and CM2 is short-circuited to the ground potential, it is shown in FIG. As described above, when the signal SK1 output from the voltage monitoring circuit 38a remains at the low level, and conversely, when the first common line CM1 is short-circuited to the battery voltage + B, the signal SK1 output from the voltage monitoring circuit 38a. Remains high level. Similarly, when the second common line CM2 is more short-circuited to the ground potential, the voltage monitoring circuit 3
When the signal SK2 output from 8b remains low level and the second common line CM2 is short-circuited to the battery voltage + B, the signal SK2 remains high level.

As described above, the fuel injection control device 1 of this embodiment
At 0, if any abnormality occurs in the current supply path of the electromagnetic solenoid L (that is, each of the common lines CM1 and CM2 and the individual wiring W), depending on the abnormality occurrence state (hereinafter, also referred to as an abnormality mode), Detection signal SDG from the comparator COM and output signals SK of the voltage monitoring circuits 38a and 38b
1 and SK2 show changes different from those in the normal state. Therefore,
In the fuel injection control device 10 of the present embodiment, the microcomputer 20 executes the process described below to inject fuel into the cylinders # 1 to #n of the diesel engine and an abnormality occurs in the current supply path. If it is determined that an abnormality has occurred, a measure is taken according to the abnormality.

Therefore, the processing executed by the microcomputer 20 will be described below with reference to the flow charts shown in FIGS. First, FIG. 7 is a flowchart showing a fuel injection process executed by the microcomputer 20. The fuel injection process is repeatedly executed after the diesel engine is started. Further, in parallel with this processing, the microcomputer 20 reads various detection signals representing the operating state of the diesel engine as described above, and calculates the energization time and the energization start timing of the electromagnetic solenoid L.

As shown in FIG. 7, when execution of the fuel injection process is started, first, step (hereinafter simply referred to as S) 1
At 10, the command signal SC is output at a high level until the calculated energization start timing (that is, the time when the injection command pulse P should be output next) arrives, and the booster circuit 32 is output.
Activate

Then, when the energization start timing of any one of the electromagnetic solenoids L arrives, the process proceeds to S120, the command signal SC is output at a low level to stop the operation of the booster circuit 32, and at the subsequent S130, from the comparator COM. It is determined whether or not the detection signal SDG of is at high level.
When it is determined that the detection signal SDG is not at the high level, at least one of the first common line CM1 and the second common line CM2 is short-circuited to the battery voltage + B or the ground potential, and the voltage VC1 across the capacitor C1 is reached. Is a predetermined value Vt
It is determined that the number has not reached h or more, and in the subsequent S140, the short-circuit abnormality flag FA is set to "1" indicating the occurrence of abnormality.

When the process of S140 is executed or when it is determined that the detection signal SDG is at the high level in S130, the process proceeds to S150, and the injection command pulse P to be output this time is the first For counting electromagnetic solenoids L1, L3, ... Ln-1 connected to the common line CM1, to count the number of level changes (the number of pulses of the signal SK1) that occur in the output signal SK1 of the voltage monitoring circuit 38a. If the injection command pulse P to be output this time corresponds to the electromagnetic solenoids L2, L4, ... Ln connected to the second common line CM2, the output signal SK2 of the voltage monitoring circuit 38b is output. A counting operation for counting the number of level changes (the number of pulses of the signal SK2) that occur is started. Then, in subsequent S160, among the injection command pulses P1 to Pn, the injection command pulse P to be output this time
Is output with a pulse width corresponding to the energization time calculated above.

Next, when the output of the injection command pulse P is completed by executing S160, the routine proceeds to S170, where it is judged whether or not the detection signal SDG from the comparator COM is at the low level. When it is determined that the detection signal SDG is not at the low level, the electromagnetic solenoid L itself corresponding to the injection command pulse P output this time or the individual wiring W of the electromagnetic solenoid L is disconnected, and the capacitor C1 is not discharged, It is determined that the voltage VC1 across the voltage remains at or above the predetermined value Vth, and in the subsequent S180,
Disconnection abnormality flag FBm (m is any of 1 to n) of the electromagnetic solenoid L corresponding to the injection command pulse P output this time
Is set to "1" indicating that an abnormality has occurred. The disconnection abnormality flag FBm is provided corresponding to each of the electromagnetic solenoids L1 to Ln, and in the following description, unless otherwise distinguished, it is simply referred to as the disconnection abnormality flag FB.

When the processing of S180 is executed, or when it is determined that the detection signal SDG is at the low level in S170, the process proceeds to S190 and it is determined that a short circuit abnormality has occurred, as described later. When the short-circuit abnormality flag FA is "1", the abnormality mode identification processing (FIG. 9) for identifying the abnormality mode is executed so that an appropriate action can be taken. When the execution is completed, in a succeeding S200, the short circuit abnormality flag F
It is determined whether A is "1". When it is determined that the short-circuit abnormality flag FA is not "1", that is, the short-circuit abnormality has not occurred, in the subsequent S210, among the n disconnection abnormality flags FB corresponding to the respective electromagnetic solenoids L, If it is determined whether or not there is one that is "1" and it is determined that there is no disconnection abnormality flag FB that is "1", S
Returning to 110, the above process is repeated.

On the other hand, if it is determined in S210 that the disconnection abnormality flag FB of "1" is present, the process proceeds to S220, and after the first abnormality occurrence process shown in FIG. 8 is executed,
Return to S110. Here, as shown in FIG. 8, when the execution of the first abnormality occurrence process is started, it is first determined in S310 whether or not there is one disconnection abnormality flag FB that is "1". If it is determined that the number is one, the subsequent S3
At 20, the injection command pulse P for energizing the electromagnetic solenoid L corresponding to the disconnection abnormality flag FB which is "1"
Is set so as not to be output thereafter, and the drive to the electromagnetic solenoid L is prohibited. Then, S33 continues
At 0, a fail display indicating that an abnormality has occurred is displayed, and then the first abnormality occurrence process is ended. In the present embodiment, the fail display is performed by turning on a lamp in a meter panel provided in the driver's seat of the vehicle, thereby informing the vehicle driver of the occurrence of the abnormality.

On the other hand, if it is determined in S310 that there is not one disconnection abnormality flag FB which is "1", S3 is selected.
Moving to 40, the first common line CM1 and the second common line CM
Of n, it is determined whether or not only n / 2 disconnection abnormality flags FB corresponding to the electromagnetic solenoids L connected to one common line CM are all "1". , It is determined that the common line CM connected to the electromagnetic solenoid L corresponding to the disconnection abnormality flag FB of “1” is disconnected, and the process proceeds to S350. Then, in S350, only the n / 2 electromagnetic solenoids L connected to the other normal common line CM are energized to perform fuel injection, and the process of the reduced cylinder operation mode is executed, and then the process proceeds to S330. Then, after the fail display is performed, the first abnormality occurrence process is ended.

The process of the reduced cylinder operation mode executed in S350 is set so that the injection command pulse P corresponding to the electromagnetic solenoid L connected to the common line CM which is determined to be disconnected is not output thereafter. At the same time, the electromagnetic solenoid L connected to the normal common line CM is corrected by increasing the energization time of the electromagnetic solenoid L calculated based on the operating state of the diesel engine by a predetermined multiple (for example, 1.5 times).
The pulse width of the injection command pulse P corresponding to
It is executed in such a procedure.

If a negative determination is made in S340,
After shifting to S360, the disconnection abnormality flag FB that is "1"
Is n / 2 or less, and if it is n / 2 or less, the process proceeds to S320, and “1” is set.
Electromagnetic solenoid L corresponding to the disconnection abnormality flag FB
The injection command pulse P for energizing the solenoid valve is set so as not to be output thereafter, the drive to the electromagnetic solenoid L is prohibited, and in the subsequent S330, after fail display is performed, when the first abnormality occurs. The process ends.

On the other hand, if it is determined in S360 that the disconnection abnormality flag FB, which is "1", is not less than n / 2, the majority of the n injectors cannot be driven and the diesel engine no longer operates. When it is determined that driving is impossible, the process proceeds to S370. Then, in S370, the setting is made so that all the injection command pulses P are not output, the drive to all the electromagnetic solenoids L is prohibited, and the subsequent S380.
At, the execution of the fuel injection process is stopped after performing the fail display.

By the way, in S200, when it is determined that the short-circuit abnormality flag FA is "1", that is, at least one of the first common line CM1 and the second common line CM2 is the battery voltage + B or When it is determined that the short circuit is made to the ground potential, the process proceeds to S230, the second abnormality occurrence process shown in FIG. 10 is executed based on the execution result of the abnormal mode identification process executed in S190, and thereafter, S110.
The process returns to S120 without executing the process of (i.e., without operating the booster circuit 32).

That is, in this embodiment, the injection command pulse P
If the voltage VC1 across the capacitor C1 immediately before is output is not greater than or equal to the predetermined value Vth, the two common lines CM1, C
It is determined that at least one of M2 is short-circuited to the battery voltage + B or the ground potential.
There are four possible abnormal modes (d). Even if the following abnormalities (a) to (d) do not occur, the voltage VC1 across the capacitor C1 does not rise to a predetermined value Vth or higher when the booster circuit 32 itself has an abnormality. .

(A) The first common line CM1 has a battery voltage +
When short-circuited to B. (A) When the first common line CM1 is short-circuited to the ground potential. (C) When the second common line CM2 is short-circuited to the battery voltage + B. (D) When the second common line CM2 is short-circuited to the ground potential.

Therefore, in the fuel injection process, the abnormal mode identification process (FIG. 9) is executed in S190 to identify and detect the occurrence of the abnormal modes (a) to (d). , S230 in the second abnormality occurrence process, the above-mentioned (A) to
When any of the abnormalities in (d) is detected, the corrective action is taken, and none of the above abnormalities (a) to (d) is detected by executing the abnormal mode identification process. In such a case, it is determined that an abnormality has occurred in the booster circuit 32, and an action is taken according to the abnormality.

Therefore, first, the abnormal mode identification processing executed in S190 will be described. As shown in FIG.
When the execution of this abnormal mode identification process is started, first,
At S410, the electromagnetic solenoids L1, L3, ... Ln connected to the first common line CM1 by the execution of S160 this time.
−1, the injection command pulses P1, P3, ... Pn−1 are determined, and the injection command pulses P1, P3 ,.
If it is determined that any one of Pn-1 is output, the subsequent S
At 420, it is determined whether the output signal SK1 of the voltage monitoring circuit 38a is at high level. When it is determined that the level is not the high level, it is determined that the first common line CM1 is short-circuited to the ground potential as described with reference to FIG. 6, and in the subsequent S430, the ground short-circuit flag FC1 is set to First
After setting "1" indicating that the common line CM1 is short-circuited to the ground potential, the abnormal mode identification process is ended.

If it is determined in S420 that the output signal SK1 of the voltage monitoring circuit 38a is at high level, S
The process proceeds to 440, and the count number at which the counting operation is started in S150 described above, that is, in this case, outputs one of the injection command pulses P1, P3, ... It is determined whether or not the number of times the level of the output signal SK1 has changed (the number of pulses of the output signal SK1) is larger than a predetermined number M. Then, when it is determined that the number is not larger than the predetermined number M, as described with reference to FIG.
It is determined that the common line CM1 is short-circuited to the battery voltage + B, the process proceeds to S450, and the power supply short-circuit flag FD1 is set to
"1" indicating that the common line CM1 is short-circuited to the battery voltage + B is set.

When the process of S450 is executed, or when it is determined in S440 that the count number is larger than the predetermined number M, the abnormal mode identification process is ended. If a negative determination is made in S410, that is,
If the injection command pulses P2, P4, ... Pn corresponding to the electromagnetic solenoids L2, L4, ... Ln connected to the second common line CM2 are output by the execution of S160 this time, S
Moving to 460, the output signal SK2 of the voltage monitoring circuit 38b
Is at a high level. Then, when it is determined that the second common line CM2 is not at the high level, it is determined that the second common line CM2 is short-circuited to the ground potential, and in the subsequent S470,
After setting the ground short-circuit flag FC2 to "1" indicating that the second common line CM2 is short-circuited to the ground potential, the abnormal mode identification process is ended.

On the other hand, if it is determined in S460 that the output signal SK2 of the voltage monitoring circuit 38b is at high level, S
480, the output signal of the voltage monitoring circuit 38b while outputting the count number that started the counting operation in S150, that is, in this case, any of the injection command pulses P2, P4, ... Pn. It is determined whether or not the number of times SK2 has changed in level (the number of pulses of the output signal SK2) is larger than a predetermined number M. Then, when it is determined that the second common line CM2 is not larger than the predetermined number M, it is determined that the second common line CM2 is short-circuited to the battery voltage + B, the process proceeds to S490, and the second common line CM2 is set in the power supply short-circuit flag FD2. "1" is set to indicate that the battery voltage + B has been short-circuited.

If the process of S490 is executed, or if it is determined in S480 that the count number is larger than the predetermined number M, the abnormal mode identifying process is terminated. Next, the second abnormality occurrence process executed in S230 will be described. As shown in FIG. 10, when the execution of the second abnormality occurrence process is started, first, in S510, it is determined whether or not one of the ground short-circuit flags FC1 and FC2 is “1”. If it is determined that both are not "1", the process proceeds to S520, and it is determined whether or not any one of the power supply short-circuit flags FD1 and FD2 is "1".

Then, in S520, the power supply short-circuit flag F
When it is determined that both D1 and FD2 are not "1", the voltage VC1 across the capacitor C1 has not risen to the predetermined value Vth or more, although both common lines CM1 and CM2 are normal. Therefore, it is determined that an abnormality has occurred in the booster circuit 32 itself, and the process proceeds to S530. Then, in S530, a process for performing energization control by only the hold current is executed for all the electromagnetic solenoids L1 to Ln, and in the subsequent S540, the same failure as in S330 and S380 of the first abnormality occurrence process. After making the display,
The second abnormality occurrence process is ended.

In the process for energization control based only on the hold current, which is executed in S530, the energization time of the electromagnetic solenoid L calculated based on the operating state of the diesel engine is corrected to be increased by a predetermined time, The pulse width of the injection command pulse P is set larger than that at the normal time, and the energization start timing calculated based on the operating state of the diesel engine is corrected so as to be advanced by a predetermined time to advance the rising timing of the injection command pulse P. , Etc.

That is, when the short-circuit abnormality flag FA is set to "1" and the second abnormality occurrence process is executed,
Since the capacitor C1 cannot be charged and the electric current can be supplied only to the hold current circuits 34a and 34b to the electromagnetic solenoid L, the valve opening time of the injector and the fuel injection amount are reduced, or the fuel injection is started. Problems such as delays occur. Therefore, in this case, the holding current is supplied to each electromagnetic solenoid L for a longer time to prevent the fuel injection amount from the injector from decreasing, and the valve opening timing of the injector is advanced to shorten the fuel injection start timing. It is trying to prevent delays.

On the other hand, in S510, the ground short-circuit flag FC1,
When it is determined that any one of FC2 is "1" (that is, when one of both common lines CM1 and CM2 is short-circuited to the ground potential), or the power supply short-circuit flag FD is determined in S520.
When it is determined that any one of 1 and FD2 is "1" (that is, one of the common lines CM1 and CM2 is short-circuited to the battery voltage + B), the process proceeds to S550.

Then, in this S550, both common lines CM
Only the hold current is applied to only the n / 2 electromagnetic solenoids L connected to the normal common line CM of which one of the ground short-circuit flag FC and the power-supply short-circuit flag FD is “0” among CM1 and CM2. A process for performing energization control is executed, and then the process proceeds to S540 to perform a fail display and then the second abnormality occurrence process is ended.

In the process executed in S550, the injection command pulse P corresponding to the electromagnetic solenoid L connected to the abnormal common line CM is set so as not to be output thereafter, and the diesel engine is operated. The energization time and the energization start timing of the electromagnetic solenoid L calculated based on the state are corrected in the same manner as in the process of S530. As a result, the energization time of the hold current to the n / 2 electromagnetic solenoids L connected to the normal common line CM is lengthened, and the energization start timing of the electromagnetic solenoids L is advanced to n / 2. It enables stable operation of the diesel engine with only one injector.

In this embodiment, the voltage dividing resistor R1
To R4, the comparator COM, and the processes of S170 and S180 of the fuel injection process (FIG. 7) correspond to the voltage detection means immediately after turning off and the disconnection determination means, and the voltage dividing resistors R1 to R.
4, S13 of the comparator COM and the fuel injection process
The processing of 0 and S140 corresponds to the voltage detection means immediately before turning on and the short circuit determination means. The processing of S350 of the first abnormality occurrence processing (FIG. 8) executed during the fuel injection processing corresponds to the correction means.

As described above, in the fuel injection process of this embodiment, as shown at the timing TA in FIGS. 3 to 5 and 7, the injection command pulses P1 to Pn are output to turn on any of the transistors TR. The comparator CO
Based on the detection signal SDG of M, the voltage V across the capacitor C1
It is determined whether C1 is greater than or equal to a predetermined value Vth (S13
0) and not equal to or more than the predetermined value Vth (S130: N
O), it is determined that at least one of the first common line CM1 and the second common line CM2 is short-circuited to the battery voltage + B or the ground potential, and the short-circuit abnormality flag FA indicates "1" indicating that an abnormality has occurred. Is set (S14
0).

Further, in the fuel injection processing of this embodiment, as shown in FIG.
As shown at timing TB in FIGS. 5 and 7, immediately after the output of the injection command pulses P1 to Pn is stopped and the corresponding transistor TR is turned off, both ends of the capacitor C1 are detected based on the detection signal SDG of the comparator COM. Voltage VC1
Is below a predetermined value Vth (S17).
0) and not equal to or less than the predetermined value Vth (S170: N
O), it is determined that the electromagnetic solenoid L itself corresponding to the injection command pulse P output this time or the individual wiring W of the electromagnetic solenoid L is disconnected, and the electromagnetic solenoid L corresponding to the injection command pulse P output this time is disconnected. Abnormal flag FB
Is set to "1" indicating the occurrence of abnormality (S180).

Therefore, according to this embodiment, the common lines CM1 and CM2 for supplying the drive current to the electromagnetic solenoid L are short-circuited to the battery voltage + B or the ground potential, and
The disconnection of any one of the electromagnetic solenoids L itself or the individual wiring W of each of the electromagnetic solenoids L can be accurately and reliably detected.

That is, as described above with reference to FIGS. 11 and 12, in the conventional device, a short circuit or disconnection occurs in the current supply path of the electromagnetic solenoid L based on the value of the current actually flowing in the electromagnetic solenoid L. Therefore, it has been impossible to accurately detect the occurrence of an abnormality due to the characteristic variation or characteristic change of the electromagnetic solenoid L. On the other hand, in this embodiment, the voltage VC1 across the peak current supply capacitor C1 is equal to the electromagnetic solenoid L.
Paying attention to the fact that it changes according to the driving state of the (injector), based on the voltage VC1 across the capacitor C1,
Since the presence / absence of abnormality is determined, it is possible to reliably detect the abnormality that has occurred in the current supply path of the electromagnetic solenoid L (that is, the common line CM, the electromagnetic solenoid L itself, and the individual wiring W). .

Moreover, according to the present embodiment, the voltage VC1 across the capacitor C1 (detection signal SDG of the comparator COM) may be detected immediately before and after the injection command pulse P is output. The execution timing of the processing can be easily set.

Further, in the injection control process of this embodiment, by the process of S170, any electromagnetic solenoid L itself or the individual wiring W of any electromagnetic solenoid L is obtained.
If it is determined that the wire breakage has occurred and "1" is set to any of the wire breakage abnormality flags FB by the processing of S180 (S210: YES), the first abnormality occurrence processing (S2)
20: FIG. 8) is executed and the energization time of the electromagnetic solenoid L is corrected according to the set state of the disconnection abnormality flag FB corresponding to each electromagnetic solenoid L, so that the diesel engine can be driven normally only by the injector. The engine is being operated continuously.

Specifically, the two common lines CM1 and CM2
Among them, when it is determined that all the n / 2 electromagnetic solenoids L connected to one common line CM have a disconnection failure (S34
0: YES), it is determined that the common line CM to which the electromagnetic solenoid L is connected is broken, and the energization time of the electromagnetic solenoid L is increased by a predetermined factor (S3).
50), whereby more fuel is injected from the injector corresponding to the electromagnetic solenoid L connected to the normal common line CM than in the normal case.

Therefore, the fuel injection control device 10 of the present embodiment.
According to this, it is possible to reliably detect the disconnection of one of the two common lines CM1 and CM2, and even if one of the common lines CM is disconnected, the remaining common line CM is connected to the other common line CM. The injector corresponding to the electromagnetic solenoid L can surely continue the operation of the diesel engine. Therefore, even in such a case, it is possible to allow the vehicle equipped with the diesel engine to travel a minimum amount of time.

In the present embodiment, if any one of the electromagnetic solenoids L has a disconnection abnormality (S310: YE).
S), or when a disconnection abnormality occurs in less than n / 2 electromagnetic solenoids L, and in the electromagnetic solenoids L connected to the two common lines CM1 and CM2, a total of n / 2 electromagnetic solenoids L are disconnected. If an abnormality occurs (S360:
YES), the injection command pulse P corresponding to the electromagnetic solenoid L in which the disconnection abnormality has occurred is not simply output (S320). In such a case, for example, depending on the number of electromagnetic solenoids L in which the disconnection abnormality has occurred, Then, the energization time for the remaining normal electromagnetic solenoid L may be corrected.

On the other hand, the fuel injection control device 10 of this embodiment is provided with voltage monitoring circuits 38a and 38b for monitoring the voltage levels of the two common lines CM1 and CM2, respectively.
By the abnormal mode identification process (S190: FIG. 9) during the fuel injection process, the short circuit abnormal mode of each common line CM1, CM2 is identified and detected.

That is, in this embodiment, FIG. 3, FIG. 6 and FIG.
As shown at timing TC of
Immediately after the output of Pn is stopped and the corresponding transistor TR is turned off, the signal level of the output signal SK1, SK2 of the voltage monitoring circuits 38a, 38b corresponding to the electromagnetic solenoid L driven this time is detected. (S410, S420,
S460), if the detected signal level is low level (S420 or S460: NO), it is determined that the common line CM connected to the electromagnetic solenoid L driven this time is short-circuited to the ground potential, and the common line CM The ground short-circuit flags FC1 and FC2 corresponding to are set to "1" (S430, S470). Furthermore, as shown in the period K of FIGS. 3, 6 and 7, the injection command pulses P1 to P
During the output period of n, the number of level changes occurring in one of the output signals SK1 and SK2 of the voltage monitoring circuits 38a and 38b corresponding to the electromagnetic solenoid L driven this time is counted (S
150), if the count number is not larger than the predetermined number M (S440 or S480: NO), it is determined that the common line CM connected to the electromagnetic solenoid L driven this time is short-circuited to the battery voltage + B, The power supply short-circuit flags FD1 and FD2 corresponding to the common line CM are set to "1" (S450, S490).

In the injection control process of this embodiment, S
By the processing of 130, at least one of the first common line CM1 and the second common line CM2 is equal to the battery voltage +
When it is determined that a short circuit has occurred to B or the ground potential and the short-circuit abnormality flag FA is set to "1" by the processing of S140 (S200: YES), the second abnormality occurrence processing (S230: FIG. 10). To execute the above flag FC1,
The treatment according to the set state of FC2, FD1 and FD2 is performed.

Specifically, the ground short-circuit flags FC1 and FC
2 and "1" to either of the power supply short-circuit flags FD1 and FD2
If is set (S510 or S520:
YES) Assuming that either one of the two common lines CM1 and CM2 is really short-circuited to the battery voltage + B or the ground potential, only n / 2 electromagnetic solenoids L connected to the normal one CM2 are connected. In addition to the control target, the energization control is performed only by the hold current in which the energization time and the energization start timing are corrected (S550).
If C1, FC2, FD1, FD2 are all "0" (S510 and S520: NO), both common lines CM1, C
It is determined that M2 is normal and an abnormality has occurred in the booster circuit 32 itself, and all the electromagnetic solenoids L1 to Ln are controlled, and energization control is performed only by the hold current with the energization time and the energization start timing corrected. (S530).

That is, the fuel injection control device 10 of the present embodiment.
Then, the voltage VC across the peak current supply capacitor C1
Since the short circuit abnormality of the common line CM is detected based on 1, when the abnormality occurs in the booster circuit 32 itself, even if both the common lines CM1 and CM2 are normal, the common line CM1, There is a risk that one of the CMs 2 may have a short circuit failure. Therefore, in the present embodiment, the voltage monitoring circuit 3
By monitoring the voltage levels of the common lines CM1 and CM2 by 8a and 38b, respectively, when the voltage VC1 across the capacitor C1 does not rise above a predetermined value Vth, it is caused by a short circuit failure of the common lines CM1 and CM2. Therefore, it is possible to determine whether it is due to a failure of the booster circuit 32 itself.

Therefore, the fuel injection control device 10 of the present embodiment.
According to this, it is possible to reliably determine which one of the two common lines CM1 and CM2 has a short circuit failure and the booster circuit 32 has a failure, and to execute the action according to each abnormal mode. be able to. Then, in the present embodiment, as a measure, when an abnormality of the booster circuit 32 is detected, the energization time of the hold current to all the electromagnetic solenoids L is lengthened and the energization start timing is accelerated. When one of the common lines CM1 and CM2 has a short-circuit fault, the energization time of the hold current to the n / 2 electromagnetic solenoids L connected to the normal common line CM is lengthened. Together with the electromagnetic solenoid L
The energization control is performed only by the hold current, such that the timing of starting energization to is corrected so as to be advanced.

Therefore, according to the present embodiment, the booster circuit 32
Even when the capacitor C1 cannot be charged due to a failure due to a failure to supply the peak current to all the electromagnetic solenoids L, the valve opening time of the injector and the fuel injection amount are reduced, or the start of fuel injection is delayed. This prevents the diesel engine from operating stably.
In addition, even when a short-circuit failure occurs in one of the common lines CM and the capacitor C1 cannot be charged, and the peak current cannot be supplied to the electromagnetic solenoid L connected to the other normal line CM, the normal operation is performed. It is possible to operate the diesel engine as stably as possible by using only n / 2 injectors corresponding to the electromagnetic solenoid L connected to the common line CM.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an overall configuration of a fuel injection control device of an embodiment.

FIG. 2 is a configuration diagram showing a configuration of a hold current circuit of FIG.

FIG. 3 is an explanatory diagram illustrating an operation of the fuel injection control device according to the embodiment.

FIG. 4 is an explanatory diagram illustrating an operation when any one of the electromagnetic solenoids or any of the individual wirings is broken.

FIG. 5 is an explanatory diagram illustrating an operation in the case where any one of common lines that supply current to a plurality of electromagnetic solenoids is disconnected.

FIG. 6 is an explanatory diagram illustrating an operation in the case where any one of common lines that supply current to a plurality of electromagnetic solenoids is short-circuited to a battery voltage or a ground potential.

FIG. 7 is a flowchart showing a fuel injection process executed by the microcomputer 20 of the embodiment.

FIG. 8 is a flowchart showing a first abnormality occurrence process executed during the fuel injection process.

FIG. 9 is a flowchart showing an abnormal mode identifying process executed during the fuel injection process.

FIG. 10 is a flowchart showing a second abnormality occurrence process executed during the fuel injection process.

FIG. 11 is a schematic configuration diagram showing a configuration of a conventional fuel injection control device.

FIG. 12 is an explanatory diagram for explaining the operation of the conventional fuel injection control device and its problems.

[Explanation of symbols]

10 ... Fuel injection control device 20 ... Microcomputer 30 ... Drive circuit 32 ... Booster circuit C1 ... Capacitors 34a, 34
b ... Hold current circuit 36 ... Switching circuit TR1-TRn ... Transistor COM ... Comparator 38a, 38b ... Voltage monitoring circuit L1-Ln ... Electromagnetic solenoid CM1 ... First common line
CM2 ... Second common line W1 to Wn ... Individual wiring

Claims (6)

[Claims] 1. An electromagnetic valve having an electromagnetic solenoid, which opens when the electromagnetic solenoid is energized, a switching element provided in series in a current supply path of the electromagnetic solenoid, and drive control of the switching element. A control means for opening and closing the solenoid valve, a capacitor provided in parallel with a current supply path of the electromagnetic solenoid, and the switching element by charging the capacitor with a predetermined high voltage when the switching element is off. A peak current supply means for supplying a peak current from the capacitor to the electromagnetic solenoid when the switch is turned on to quickly open the electromagnetic valve; and after the peak current is supplied to the electromagnetic solenoid by the capacitor, the electromagnetic A hold current smaller than the peak current is applied to the solenoid to cause the solenoid valve to A solenoid valve drive device comprising: a hold current supply means for holding a valve state; and an abnormality determination means for determining whether or not an abnormality has occurred in the current supply path based on the voltage across the capacitor. , A solenoid valve drive device characterized by the following. 2. The solenoid valve drive system according to claim 1, wherein the abnormality determination means detects a voltage immediately after turning off the capacitor immediately after the switching means is turned off by the control means. And a disconnection determination unit that determines that the current supply path is disconnected when the voltage across the capacitor detected by the voltage detection unit immediately after turning off is not a predetermined value or less. Solenoid valve drive device. 3. The solenoid valve drive system according to claim 1, wherein the abnormality determining means detects a voltage across the capacitor immediately before the switching element is turned on from the off state by the control means. Short-circuit determination that determines that the current supply path is short-circuited to a voltage level lower than the predetermined high voltage when the voltage across the capacitor detected by the detection means and the voltage detection means immediately before turning on is not higher than a predetermined value. An electromagnetic valve drive device comprising: 4. The solenoid valve drive system according to claim 2, wherein the abnormality determining means further includes, in addition to the immediately-off-state voltage detecting means and the disconnection determining means, the control means to change the switching element from an off state. Immediately before ON voltage detection means for detecting the voltage across the capacitor immediately before being turned on, and when the voltage across the capacitor detected by the immediately before ON voltage detection means is not more than a predetermined value, the current supply path And a short-circuit determination means for determining that the voltage has been short-circuited to a voltage level lower than the high voltage. 5. The solenoid valve drive system according to claim 2, further comprising a plurality of solenoid valves, each solenoid valve being provided in each cylinder of an internal combustion engine to supply fuel to each cylinder when the valves are opened. It is configured as a fuel injection valve for injecting and supplying, and the electromagnetic solenoid of each fuel injection valve corresponds to a predetermined common line connected to the capacitor and the hold current supply means and each electromagnetic solenoid from the common line. Current is supplied through the branched individual wiring, and each of the individual wirings is provided with the switching element in series, and the control means further controls each of the individual wirings according to the operating state of the internal combustion engine. The fuel injection time to the internal combustion engine is controlled by calculating the energization time and the energization start timing of the electromagnetic solenoid and selectively driving the switching elements sequentially in accordance with the calculation result. If the voltage across the capacitor detected by the voltage detection means immediately after turning off is not less than or equal to a predetermined value, the disconnection determination means is turned off from the on state this time by the control means. It is determined that the individual wiring of the electromagnetic solenoid corresponding to the switching element is disconnected, and the normal fuel corresponding to the individual wiring not determined to be disconnected by the disconnection determining means according to the determination result by the disconnection determining means. An electromagnetic valve drive device comprising: a correction unit that corrects the energization time of the electromagnetic solenoid calculated by the control unit so that the internal combustion engine can be continuously operated by the injection valve. . 6. The solenoid valve drive system according to claim 5, wherein the plurality of fuel injection valves are divided in advance into a plurality of groups capable of operating the internal combustion engine, and the common line is A plurality of wires are provided corresponding to each group, and the disconnection determination means determines that the individual wirings corresponding to all the fuel injection valves belonging to any of the plurality of groups are disconnected. Then, it is determined that the common line corresponding to the group is disconnected, the correction means, when the disconnection determination means determines that any of the common lines are disconnected, the disconnection determination means disconnection The energization time of the electromagnetic solenoid calculated by the control means is supplemented so that the internal combustion engine can be continuously operated by the normal fuel injection valve corresponding to the common line that is not determined to be A fuel injection control device for an internal combustion engine, characterized by: