JP3446630B2 - Solenoid valve drive - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a fuel injection valve for injecting fuel into each cylinder of an automobile internal combustion engine, an electromagnetic valve that is opened by energizing an electromagnetic coil has been used.
Further, a fuel injection control device for controlling the fuel injection to an internal combustion engine by driving the fuel injection valve composed of such an electromagnetic valve to open and close is disclosed in JP-A-9-112735, for example. A constant current circuit that is connected to a current supply path for supplying a current to the electromagnetic coil of the valve) and that receives a power supply from a battery and outputs a constant current to the current supply path via a diode; A driving transistor provided in series on the ground line (potential of the negative electrode of the battery) side of the electromagnetic coil of the supply path and a constant current circuit side of the electromagnetic coil of the current supply path connected in parallel via a diode. And a booster circuit that boosts the voltage of the battery to charge the capacitor.

In this fuel injection control device, the capacitor is charged by the booster circuit before turning on the driving transistor, so that when the driving transistor is turned on, the capacitor is electromagnetically passed through the current supply path. Allow the capacitor discharge current to flow to the coil as a peak current to promptly open the fuel injection valve, and then apply a constant current (hold current) for holding the valve from the constant current circuit to drive it. The open state of the fuel injection valve is maintained during the ON period of the transistor. In other words, in order to improve the valve opening response of the fuel injection valve, the voltage of the battery that is the power source is boosted and stored in the capacitor, and the fuel injection valve can be driven at high speed by the large current accompanying the discharge of the capacitor. There is.

By the way, in an electromagnetic valve drive device represented by such a fuel injection control device, the current supply path (current supply wiring) to the electromagnetic coil is short-circuited to the ground line or the voltage of the battery, or disconnected. If this happens, the solenoid valve cannot be normally opened and closed, and it is necessary to detect such an abnormality and take some action.

Therefore, in the device disclosed in the above publication, the charging voltage of the capacitor immediately before the driving transistor is turned on is detected, and when the detected voltage is not a predetermined value or more, the current supply path to the electromagnetic coil is The ground line or the voltage of the battery is determined to be short-circuited. That is, when the current supply path is short-circuited to the voltage of the ground line or the battery, the charging voltage of the capacitor is clamped by the voltage at the short-circuited destination and does not rise to the predetermined high voltage in the normal state.

Further, in the device disclosed in the above publication, the charging voltage of the capacitor immediately after the driving transistor is turned off from the on state is detected, and when the detected voltage is not less than a predetermined value, the current to the electromagnetic coil is detected. It is determined that the supply path or the electromagnetic coil itself is broken. That is, if the current supply path or the electromagnetic coil itself is broken, the capacitor is not discharged even if the driving transistor is turned on.

[0007]

By the way, as in the device disclosed in the above publication, in the configuration in which the capacitor for peak current supply is always connected to the current supply path to the electromagnetic coil, the driving transistor is There is a constraint that the capacitor cannot be charged during the period when it is turned on. This restriction causes a demerit that it becomes difficult to charge the capacitor to a predetermined high voltage when the opening period of the solenoid valve is short and the opening time is long.

Therefore, the inventor of the present invention provides a switch between the capacitor and the current supply path to the electromagnetic coil so as to start opening the electromagnetic valve (specifically, from the time when the driving transistor is turned on). , A certain period of time when it is considered that the peak current from the capacitor flows through the electromagnetic coil, or
Until the charging voltage of the capacitor drops to the specified voltage)
Only, it was considered that the switch is turned on (short-circuited) to connect the capacitor and the current supply path to the electromagnetic coil. And with this configuration,
After the peak current is supplied from the capacitor to the electromagnetic coil, the capacitor can be disconnected from the current supply path and charged to the capacitor even during the opening period of the electromagnetic valve that turns on the driving transistor. become able to.

However, when the capacitor for supplying the peak current is configured to be separated from the current supply path to the electromagnetic coil by the switch, in the technique disclosed in the above publication, the current supply path is short-circuited to the ground line or the voltage of the battery. (Short circuit error) cannot be detected.

That is, since the capacitor disconnects from the current supply path by the switch, even if the current supply path is short-circuited to the voltage of the ground line or the battery, the capacitor is normally charged to a predetermined high voltage. This is because it is not possible to determine whether there is an abnormality from the charging voltage of the capacitor.

The present invention has been made in view of the above problems, and a capacitor for supplying a peak current to an electromagnetic coil of an electromagnetic valve is provided in a current supply path to the electromagnetic coil only when the valve opening drive of the electromagnetic valve is started. It is an object of the present invention to provide an electromagnetic valve drive device that can detect an abnormality that has occurred in a current supply path to an electromagnetic coil even if it is connected.

[0012]

Means for Solving the Problems and Effects of the Invention The electromagnetic valve driving device of the present invention as set forth in claim 1 for achieving the above object is for supplying a current to the electromagnetic coil of the electromagnetic valve. The switching element for driving, which is provided in series in the current supply path, and the control means for opening the electromagnetic valve by turning on the switching element and supplying a current to the electromagnetic coil are provided. The switching element is controlled by the control means. Before the switch is turned on, the capacitor is charged with a predetermined high voltage, and when the switching element is turned on, the discharge current of the capacitor is supplied as a peak current from the capacitor to the electromagnetic coil through the current supply path. , Open the solenoid valve promptly.

In the solenoid valve drive system of the present invention, the measuring means measures the time from when the switching element is turned on by the control means until the charging voltage of the capacitor drops to a preset set voltage, and an abnormality is detected. The determination means determines whether or not an abnormality has occurred in the current supply path based on the time measured by the measurement means.

That is, when the switching element is turned on, the capacitor charged with a predetermined high voltage is discharged through the current supply path, the electromagnetic coil, and the switching element. Therefore, the charging voltage of the capacitor is the electromagnetic coil. The impedance of the switching element causes the switching element to turn on and then decreases relatively slowly. However, when a short circuit abnormality occurs in which the current supply path to the electromagnetic coil is short-circuited to a voltage level lower than the high voltage to the capacitor, the capacitor is discharged without passing through the electromagnetic coil,
The charging voltage drops sharply. Further, when the current supply path to the electromagnetic coil or the electromagnetic coil itself is disconnected, even if the switching element is turned on, the capacitor is not discharged and its charging voltage remains high. This phenomenon is the same regardless of whether the capacitor is always connected in parallel to the current supply path or the capacitor is connected to the current supply path only at the start of the valve opening drive of the solenoid valve. Is.

Therefore, in the present invention, the time from when the switching element is turned on until the charging voltage of the capacitor drops to a preset set voltage is measured by the measuring means, and the electromagnetic coil is sent to the electromagnetic coil based on the measured time. That is, it is determined whether or not an abnormality has occurred in the current supply path.

More specifically, the abnormality determining means can be configured to determine that an abnormality has occurred in the current supply path when the measured time is not within the preset range. More specifically, the abnormality determining means is configured to determine that the current supply path to the electromagnetic coil or the electromagnetic coil itself is disconnected when the measured time is equal to or longer than the preset maximum time. Can
Further, as described in claim 2, when the measurement time (the time measured by the measurement means) is shorter than the preset time, the abnormality determination means determines that the current supply path to the electromagnetic coil is the capacitor. Can be configured to determine a short circuit to a voltage level lower than the high voltage to.

In particular, according to the second aspect of the invention,
Even if the capacitor is connected to the current supply path to the electromagnetic coil only when the opening operation of the solenoid valve is started, it is possible to detect a short circuit abnormality that has occurred in the current supply path to the electromagnetic coil. That is, as described above, in the conventional technique, if the capacitor is connected to the current supply path only at the start of the opening drive of the solenoid valve, the short circuit abnormality of the current supply path cannot be detected. Two
According to the solenoid valve driving device described in (1), it is possible to reliably detect a short circuit abnormality in the current supply path.

[0018] Normally, this type of device is configured to boost the voltage of a battery serving as its own power source to charge a capacitor. However, in the electromagnetic valve drive device according to claim 2, As described in Item 3, if the setting voltage used by the measuring means for measuring the time is set to a value larger than the voltage of the battery, the current supply path is short-circuited to the ground line (potential of the negative electrode of the battery). Not only in the case, but also when the current supply path is short-circuited to the voltage of the battery, the short-circuit abnormality can be surely detected.

That is, if the set voltage is set to a value lower than the voltage of the battery, the charging voltage of the capacitor does not fall below the set voltage when the current supply path is short-circuited to the voltage of the battery. The time measured by the means does not become shorter than the preset time, and the abnormality cannot be detected. On the other hand, when the set voltage is set to a value (higher value) larger than the voltage of the battery as described in claim 3, even when the current supply path is short-circuited to the voltage of the battery, the measuring means The time measured by is shorter than the preset time, and as a result, the occurrence of abnormality can be reliably detected.

On the other hand, in the solenoid valve drive system according to any one of claims 1 to 3, the connection switching means is provided as described in claim 4, and the connection switching means turns on the switching element by the control means. If the capacitor is configured to be connected to the current supply path to the electromagnetic coil only from the time when the predetermined condition is established until the predetermined condition is satisfied, "after the peak current is supplied from the capacitor to the electromagnetic coil, The effect that "the capacitor can be disconnected from the current supply path and the capacitor can be charged even during the opening period of the solenoid valve that turns on the switching element" and "current supply to the electromagnetic coil It is possible to obtain both effects of "the short circuit abnormality of the route can be reliably detected".

The connection switching means connects the capacitor to the current supply path for a certain period of time from the time when the driving switching element is turned on, when it is considered that the peak current from the capacitor sufficiently flows in the electromagnetic coil. Can be configured. In addition, the connection switching means connects the capacitor to the current supply path only from the time when the driving switching element is turned on until the charging voltage of the capacitor drops to a predetermined voltage lower than the set voltage. It can also be configured. Then, according to the latter configuration, it becomes possible to supply the optimum peak current from the capacitor to the electromagnetic coil without being affected by variations in the electrical characteristics of the capacitor, the current supply path, and the like.
More effective.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows that each cylinder of a vehicle diesel engine (hereinafter referred to as an internal combustion engine) is controlled by energizing an electromagnetic coil EB of a fuel injection valve as an electromagnetic valve for supplying and injecting fuel to each cylinder. It is a block diagram showing the structure of the fuel injection control apparatus 1 of embodiment which controls a fuel injection amount and a fuel injection timing.

As shown in FIG. 1, the fuel injection control device 1 of the present embodiment includes a toroidal coil 2 and an N channel MOS.
Transistors 3 and 4, capacitor 5, switch 6, constant current circuit 7, charging voltage detection circuit 8, buffer circuit 10, microcomputer (hereinafter referred to as CPU) 11, boost control circuit 12, current detection resistors R1 and R2, and It has diodes D1 to D4.

Here, one end of the toroidal coil 2 is connected to the plus terminal of the battery BATT mounted on the vehicle, and the other end of the toroidal coil 2 is grounded from the transistor 3 via the current detecting resistor R1. Along with
It is connected to the anode of the diode D1. And
Cathode of diode D1 (hereinafter referred to as node A)
Is grounded via the capacitor 5, and is also connected to one end of the switch 6 and the charging voltage detection circuit 8.

On the other hand, one end of each electromagnetic coil EB of the fuel injection valve (hereinafter referred to as an injector) provided for each cylinder of the internal combustion engine is connected to a common wiring CM arranged outside the fuel injection control device 1. Connected and its common wiring CM
Is a common terminal JC provided in the fuel injection control device 1.
Is connected to the cathodes of the diodes D2, D3, D4 via. The anode of the diode D2 is connected to the end of the switch 6 opposite to the node A side, the anode of the diode D3 is connected to the constant current circuit 7, and the anode of the diode D4 is grounded.

The other end of each electromagnetic coil EB is connected to an individual wiring W arranged outside the fuel injection control device 1, and each individual wiring W is connected to the fuel injection control device 1. Is connected to the drain of each transistor 4 as a switching element via an individual output terminal JW provided on the. The source of each transistor 4 is grounded via the current detection resistor R2.

Next, the constant current circuit 7 is composed of a PNP transistor 21 and a constant current control circuit 22. The transistor 21 is connected between the positive terminal of the battery BATT and the anode of the diode D3, and the base of the transistor 21 is connected to the constant current control circuit 22. Then, the constant current control circuit 22
Controls the on / off duty ratio of the transistor 21 so that the current flowing through the current detecting resistor R2 (that is, the current flowing through the electromagnetic coil EB when the transistor 4 is on) becomes a constant value. Switch operation.

Further, the charging voltage detection circuit 8 includes a comparator 23.
And four resistors R5, R6, R7 and R9. The node A is grounded via two resistors R5 and R6 for voltage division, and the node between the resistors R5 and R6 is the resistor R
It is connected to the non-inverting input terminal (plus input terminal) of the comparator 23 via 7. The threshold voltage VS for comparison is applied to the inverting input terminal (minus terminal) of the comparator 23, and the output terminal of the comparator 23 is connected to the output terminal of the fuel injection control device 1 via the resistor R9. It is pulled up to the internal power supply (not shown) side. Since the resistance values of the resistors R5 and R6 are set sufficiently large,
No current flows from node A to the ground side via 6.

On the other hand, to the CPU 11 as the control means,
Detection signals from a rotation sensor that detects the engine speed of the internal combustion engine, an accelerator opening sensor that detects the accelerator opening, an idling switch, and the like (not shown) are input via the buffer circuit 10. Furthermore, the output signal OS of the comparator 23 included in the charging voltage detection circuit 8 is input to the CPU 11.

Then, the CPU 11 detects the operating state of the internal combustion engine from the above detection signals, and based on the detection result and the output signal OS of the comparator 23, the control signal CS1 to the boost control circuit 12, The control signal CS2 to the boost control circuit 12 and the switch 6 and the drive signal CS3 to the gate of each transistor 4 are generated and output. Each transistor 4 is a CPU
It is turned on when the drive signal CS3 from 11 is at "High" level.

Further, the boost control circuit 12 has a CP
Both control signals CS1 and CS2 from U11 are "Lo
w ”level, the on / off duty ratio of the transistor 3 is controlled so that the current flowing through the current detection resistor R1 has a constant value, and the transistor 3 is switched. As a result, the battery BATT The voltage (24 ± 8 V in the present embodiment) is boosted and the capacitor 5
To charge. Then, the boost control circuit 12 causes the voltage of the node A (that is, the charging voltage of the capacitor 5) to reach a predetermined set value (about 120 V in the present embodiment) Ve by the switching operation of the transistor 3, or C
When at least one of the control signals CS1 and CS2 from the PU 11 becomes “High” level, the transistor 3
The switching operation of is stopped to stop charging the capacitor 5.

On the other hand, the switch 6 is turned on (short-circuited) when the control signal CS2 from the CPU 11 is at "High" level to connect the node A (that is, one end of the capacitor 5) and the anode of the diode D2. , The control signal CS
If 2 is "Low" level, turn it off (release),
The connection between the capacitor 5 and the anode of the diode D2 is cut off.

Next, the normal operation of the fuel injection control device 1 configured as described above will be described with reference to the time chart shown in FIG. First, the CPU 11 controls each control signal C when the injector is closed (when fuel injection is stopped).
The S1 and CS2 and the drive signal CS3 are output at the "Low" level.

Therefore, the transistor 4 is turned off and the switch 6 is turned off, so that the connection between the capacitor 5 and the anode of the diode D2 is cut off.
Further, the boost control circuit 12 operates so that the current flowing in the path of the battery BATT → the toroidal coil 2 → the transistor 3 → the current detection resistor R1 is changed to the current detection resistor R1.
The ON / OFF duty ratio of the transistor 3 is controlled so that the current is detected based on the voltage between the terminals 1 and becomes a constant value, and the switching operation is performed.

Here, in the switching operation of the transistor 3, when the transistor 3 is off, the current flowing from the battery BATT to the toroidal coil 2 is suddenly cut off, and the inductance of the toroidal coil 2 causes a large counter electromotive force in the direction of continuing energization. Since electric power is generated, the counter electromotive force generated in the toroidal coil 2 causes a current to flow in the path of battery BATT → toroidal coil 2 → diode D1 → capacitor 5 to charge the capacitor 5. Since this charging voltage rises to a voltage value for converting the electromagnetic energy of the toroidal coil 2 into electrostatic energy, if the capacitance value of the capacitor 5 is small, the number of the voltage of the battery BATT is irrelevant regardless of the voltage of the battery BATT. It will be a high value of double to several tens of times. Further, at this time, the switch 6 and the transistor 4 are in the off state, and the diode D1 for the non-return is provided, so that the electric charge does not flow out from the capacitor 5.

Therefore, with the switching operation of the transistor 3 by the boost control circuit 12, electric charge is gradually accumulated in the capacitor 5 and the charging voltage of the capacitor 5 gradually rises. Then, the boost control circuit 12 detects the voltage of the node A (that is, the charging voltage of the capacitor 5) VCHG by a predetermined detecting means (not shown), and the voltage VCHG is a set value Ve (a charging completion voltage of the capacitor 5). When it is determined that the voltage has risen to 120 V), the switching operation of the transistor 3 is stopped.

At this time, in the charging voltage detection circuit 8, the output terminal of the comparator 23 is pulled up by the resistor R9, and the voltage VCHG at the node A has risen to the set value Ve. The voltage of the non-inverting input terminal (plus input terminal) of is higher than the voltage of the inverting input terminal (minus input terminal). Therefore, the comparator 2
The output signal OS of 3 becomes "High" level.

Then, the CPU 11 controls the buffer circuit 10
When it is determined that the fuel injection timing of any cylinder has arrived, the drive signal CS3 to the transistor 4 corresponding to the cylinder is set to the "High" level as shown at time t1 in FIG. Control signal CS
Set 2 to "High" level.

Then, the drive signal CS3 of "High" level
, The switch 6 is turned on, and the capacitor 5 (node A) is connected to the anode of the diode D2. Therefore, capacitor 5
Is connected in parallel to the current supply path (that is, the common wiring CM and the individual wiring W) to the electromagnetic coil EB by the switch 6. In addition, the control signal CS2 becomes “Hi
"gh" level, boost control circuit 1
The operation of No. 2 (that is, the operation of boosting the voltage of the battery BATT to charge the capacitor 5) is stopped.

As a result, the charge of the capacitor 5 becomes a discharge current, and the switch 6 → diode D2 → common terminal JC →
The common wiring CM → injector electromagnetic coil EB → individual wiring W → individual output terminal JW → transistor 4 turned on → current detection resistor R2. Therefore, the current I flowing through the electromagnetic coil EB of the injector is
In accordance with the discharge characteristic of No. 1, the value of the electric field rapidly increases, reaches the peak value Ip, and then decreases. Then, by supplying the discharge current (peak current) of the capacitor 5 to the electromagnetic coil EB, the injector is quickly opened and the fuel is injected from the injector. At this time, since the non-return diode D3 is provided, the discharge current of the capacitor 5 does not flow into the battery BATT side via the transistor 21.

After that, as shown at time t2 in FIG. 2, the voltage VCHG of the node A decreases as the capacitor 5 is discharged, and a preset voltage VTH (in this embodiment, a voltage higher than that of the battery BATT) is set. If it becomes lower than 40 V (larger than 40 V), the output signal OS of the comparator 23 is inverted to "Low" level.

That is, since the voltage VCHG of the node A is divided by the two resistors R5 and R6 and applied to the non-inverting input terminal of the comparator 23, the divided voltage is applied to the inverting input terminal of the comparator 23. When it becomes lower than the threshold voltage VS which is set, the output signal OS of the comparator 23 becomes "Low" level. The threshold voltage VS is the set voltage VTH
It is set to a value obtained by multiplying (= 40V) by the voltage division ratio by the resistors R5 and R6. That is, when the voltage division ratio by the resistors R5 and R6 is 1 / K, the voltage VCHG of the node A is reduced by 1 / K times by the resistors R5 and R6, and applied to the non-inverting input terminal of the comparator 23. The threshold voltage VS is set to 1 / K times the set voltage VTH. Incidentally, the reason why the voltage VCHG of the node A is reduced by the resistors R5 and R6 and applied to the non-inverting input terminal of the comparator 23 is that the operating voltage of the comparator 23 is higher than the voltage VCHG of the node A ( This is because the power supply voltage) is low. Therefore, each resistor R5, R
The voltage division ratio by 6 is set corresponding to the ratio of the operating voltage of the comparator 23 and the voltage VCHG of the node A.

Next, the CPU 11 sets the control signal CS2 and the drive signal CS3 to the "High" level (time t
When it is determined from 1) that a certain period of time in which it is considered that the peak current from the capacitor 5 sufficiently flows in the electromagnetic coil EB has elapsed, as shown at time t3 in FIG.
Return 2 to the "Low" level.

Then, the switch 6 is turned off, the capacitor 5 is disconnected from the anode of the diode D2, the operation of the boost control circuit 12 is restarted, and the transistor 3 is switched.
Voltage (charging voltage of the capacitor 5) VCHG gradually increases again.

Further, the constant current control circuit 22 of the constant current circuit 7 detects the current I flowing through the electromagnetic coil EB based on the voltage across the terminals of the current detecting resistor R2, and the current I
Since the switching operation of the transistor 21 is performed so that the battery voltage becomes a constant value, the battery BATT → the transistor 21
-> Diode D3-> common terminal JC-> common wiring CM-> injector electromagnetic coil EB-> individual wiring W-> individual output terminal JW-> turned-on transistor 4-> current detection resistor R2. Therefore, the battery B
A constant current I is supplied as a hold current from the ATT to the electromagnetic coil EB of the injector via the constant current circuit 7 so that the valve open state of the injector is maintained and the valve body bounces when the valve opens. The valve state is prevented from becoming unstable.

Further, thereafter, as shown at time t4 in FIG. 2, the voltage VCHG of the node A is charged by charging the capacitor 5.
Exceeds the set voltage VTH, the output signal OS of the comparator 23
Is inverted to "High" level. Then, the CPU 11
When it is determined that the fuel injection end timing has come, as shown at time t5 in FIG. 2, the drive signal CS3 to the transistor 4 which has been turned on is set to the “Low” level. Then, the transistor 4 that was on until then turns off,
The current I flowing through the electromagnetic coil EB is cut off and the injector is closed.

The capacitor 5 has its charging voltage V by the time the transistor 4 and the switch 6 are turned on next time.
It is charged so that CHG becomes the set value Ve. by the way,
The charge accumulated in the capacitor 5 is discharged via the electromagnetic coil EB when the transistor 4 and the switch 6 are turned on, so that the charging voltage VCHG of the capacitor 5 is from the time t1 to the time t3 in FIG. As indicated by, the impedance of the electromagnetic coil EB decreases relatively slowly. Therefore, after the transistor 4 and the switch 6 are turned on, the discharge of the capacitor 5 is started, and then the charging voltage VCHG thereof is equal to the set voltage VTH (= 40).
V) until time TΔ (time t1 in FIG. 2)
To the time t2) is a value within a predetermined range that is determined mainly by the capacitance of the capacitor 5 and the impedance of the electromagnetic coil EB.

On the other hand, a short circuit in which the current supply path to the electromagnetic coil EB is short-circuited to the ground line (potential of the negative electrode of the battery BATT) or the battery voltage (voltage of the battery BATT) at the common terminal JC and the common wiring CM. When an abnormality occurs, the capacitor 5 is discharged without passing through the electromagnetic coil EB. Therefore, as shown in FIG. 3, the charging voltage VCHG of the capacitor 5 is set after the transistor 4 and the switch 6 are turned on. The time TΔ until the voltage drops to VTH (the time from time t1 to time t2 ′ in FIG. 3) is significantly shorter than the above-mentioned predetermined range.

Therefore, the fuel injection control device 1 of the present embodiment
Then, the CPU 11 executes the abnormality detection process shown in FIG. 4 to determine whether or not an abnormality has occurred in the current supply path to the electromagnetic coil EB. The CPU 11
It has a well-known free running counter (hereinafter referred to as FRC) that is constantly counted up, and when the drive signal CS3 to the transistor 4 and the control signal CS2 to the switch 6 are set to "High" level. F
The count value of RC is stored in the first internal register as the time Ty at that time, and the count value of FRC at the time when the output signal OS of the comparator 23 is inverted from the “High” level to the “Low” level. The time Tx at that time is stored in the second internal register. Then, the abnormality detection process of FIG. 4 is executed as an interrupt process every time the output signal OS of the comparator 23 is inverted from the “High” level to the “Low” level or every predetermined time. .

As shown in FIG. 4, when the CPU 11 starts executing the abnormality detection processing, first, at step (hereinafter simply referred to as "S") 110, the output signal of the comparator 23 is output from the second internal register. The time when the OS is inverted from the “High” level to the “Low” level (that is, the time when the charging voltage VCHG of the capacitor 5 drops to the set voltage VTH) T
Read x.

Next, at S120, the time when the drive signal CS3 to the transistor 4 and the control signal CS2 to the switch 6 are set to the "High" level from the first internal register (that is, one of the transistors 4). The time Ty at which the switch 6 is turned on to start the discharge of the capacitor 5) is read, and the difference TΔ (= Tx-Ty) is calculated by subtracting the time Ty from the time Tx read in S110.

Then, in subsequent S130, the above S120 is performed.
It is determined whether or not the difference TΔ calculated in step 3 is larger than a preset setting time (100 μsec. In the present embodiment, actually, the number of FRC counts corresponding to that time). If it is also larger, the value of the counter Nf for counting the number of times of abnormality detection is reset to "0" in S140, and then the processing ends.

When it is determined in S130 that the difference TΔ calculated in S120 is not larger than the set time (= 100 μsec.), The process proceeds to S150, and the value of the counter Nf is incremented by 1 (+1). ) Do. Then, in subsequent S160, it is determined whether or not the value of the counter Nf is smaller than a predetermined abnormality determination number Nstop. If the value of the counter Nf is smaller than the abnormality determination number Nstop, the abnormality detection process is performed as it is. However, if the value of the counter Nf is not smaller than the abnormality determination number Nstop, it is determined that the common terminal JC or the common wiring CM is short-circuited to the ground line or the battery voltage, and the process proceeds to S170.

Then, in S170, the control signal CS
1 is set to "High" level and the boost control circuit 12
(For example, the operation of boosting the voltage of the battery BATT to charge the capacitor 5) is forcibly stopped, and the drive signal CS3 to the transistor 4 is held at the "Low" level. After performing the abnormality occurrence processing such as turning on the warning lamp, the abnormality detection processing is ended.

That is, in this abnormality detection process, the time TΔ from when the transistor 4 and the switch 6 are turned on and the discharge of the capacitor 5 is started until the charging voltage VCHG of the capacitor 5 decreases to the set voltage VTH is measured. (S11
0, S120), when the measured time TΔ is shorter than a preset time (= 100 μsec.) (S120).
130: NO), it is determined that the current supply path to the electromagnetic coil EB is short-circuited with the ground line or the battery voltage (short circuit abnormality has occurred). And
When this abnormality determination is continuously performed by the abnormality determination number Nstop (S160: NO), it is determined that an abnormality has really occurred, and the abnormality occurrence process (S170) is performed.

Then, the fuel injection control device 1 of the present embodiment
According to the above, the electromagnetic coil EB is activated when the transistor 4 is turned on.
Since the switch 5 connects the capacitor 5 to the current supply path of the electromagnetic coil EB only for a certain period of time when it is considered that the peak current from the capacitor 5 flows sufficiently, the peak current from the capacitor 5 to the electromagnetic coil EB is increased. Is supplied, it is possible to charge the capacitor 5 by disconnecting the capacitor 5 from the current supply path even during the valve opening period of the injector that turns on the transistor 4. As described above, although the capacitor 5 is connected to the current supply path of the electromagnetic coil EB only when the valve opening drive of the injector is started, the abnormality detection process is performed, so that the current supply path to the electromagnetic coil EB is changed. It is possible to reliably detect the short circuit abnormality that has occurred.

Further, in the fuel injection control device 1 of the present embodiment, since the set voltage VTH is set to a value (= 40V) larger than the battery voltage, the current supply path of the electromagnetic coil EB is the ground line. Not only when the battery is short-circuited, but also when the battery voltage is short-circuited, the short-circuit abnormality can be reliably detected.

In the present embodiment, the charging voltage detection circuit 8
4 and the processes of S110 and S120 of FIG. 4 correspond to the measuring unit, and the process of S130 of FIG. 4 corresponds to the abnormality determining unit. Further, the switch 6 and the processing portion of the CPU 11 that switches the logic level of the control signal CS2 to the switch 6 correspond to the connection switching means.

Although one embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to each of the above-mentioned embodiments and can take various forms. For example, in the above embodiment, when the difference TΔ calculated in S120 of FIG. 4 is equal to or longer than the preset maximum time, it is determined that the current supply path to the electromagnetic coil EB or the electromagnetic coil EB itself is disconnected. It may be done. That is, when the current supply path to the electromagnetic coil EB or the electromagnetic coil EB itself is disconnected, the capacitor 5 is not discharged even when the transistor 4 is turned on, and the charging voltage VCHG
Is still higher than the set voltage VTH.

In the above embodiment, the transistor 4 is used.
Although the switch 6 is turned on for a fixed time from when the transistor 5 is turned on, the charging voltage VCHG of the capacitor 5 is detected and the charging voltage VCHG of the capacitor 5 is set to a predetermined value near the battery voltage from the time when the transistor 4 is turned on. Only until the voltage (for example, 24V) is reduced to the switch 6
Can also be configured to turn on. With this configuration, the peak current can be supplied from the capacitor 5 to the electromagnetic coil EB for an optimum time without being affected by variations in the electrical characteristics of the capacitor 5 and the current supply path. , Effective.

On the other hand, as the boosting circuit for boosting the battery voltage to charge the capacitor 5, another circuit such as a circuit using a transformer may be used. Further, the fuel injection control device 1 of the above-described embodiment is configured such that the capacitor 5 and the current supply path to the electromagnetic coil EB are connected / disconnected by the switch 6, but in the present invention, the capacitor is an electromagnetic coil. The same can be applied to a device which is always connected in parallel to the current supply path to the.

Furthermore, the present invention can be applied in the same manner to devices other than the fuel injection control device for the internal combustion engine.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a configuration of a fuel injection control device according to an embodiment.

FIG. 2 is a time chart illustrating an operation of the fuel injection control device according to the embodiment at a normal time.

FIG. 3 is a time chart illustrating an operation of the fuel injection control device according to the embodiment when an abnormality occurs.

FIG. 4 is a diagram showing C provided in the fuel injection control device according to the embodiment.
It is a flow chart showing abnormality detection processing performed in PU.

[Explanation of symbols]

1 ... Fuel injection control device, 2 ... Toroidal coil, 3, 4
... N-channel MOS transistor, 5 ... Capacitor,
6 ... Switch, 7 ... Constant current circuit, 8 ... Charge voltage detection circuit, 10 ... Buffer circuit, 11 ... Microcomputer (CPU), 12 ... Boost control circuit, 21 ... PN
P transistor, 22 ... Constant current control circuit, 23
Comparator, D1 to D4 ... Diode, R1, R2 ... Current detection resistance, R5 to R7, R9 ... Resistor, BATT ... Battery, EB ... Electromagnetic coil, CM ... Common wiring, W ... Individual wiring, JC ... Common terminal , JW… Individual output terminal

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02D 41/22 380 F02D 41/20 380 F02M 51/06

Claims (4)

(57) [Claims] 1. A switching element provided in series in a current supply path for supplying a current to an electromagnetic coil of an electromagnetic valve, and the electromagnetic valve by turning on the switching element to flow a current to the electromagnetic coil. A control means for opening the valve; a capacitor is charged with a predetermined high voltage before the switching element is turned on by the control means, and the current supply path is supplied from the capacitor when the switching element is turned on. In the solenoid valve drive device configured to supply the discharge current of the capacitor to the electromagnetic coil via the electromagnetic coil to quickly open the solenoid valve, the capacitor is provided after the switching element is turned on by the control means. Measuring means for measuring the time until the charging voltage of the battery drops to a preset set voltage, and the measuring means Has been based on the time, the electromagnetic valve driving device, characterized in that abnormality in the current supply path is provided with, and an abnormality judging means for judging whether the occurred. 2. The solenoid valve drive system according to claim 1, wherein the abnormality determining unit determines that the current supply path is in a case where the time measured by the measuring unit is shorter than a preset set time. A solenoid valve drive device, wherein it is determined that a short circuit has been made to a voltage level lower than the predetermined high voltage. 3. The solenoid valve drive device according to claim 2, wherein the device is configured to boost the voltage of a battery to charge the capacitor, and the set voltage is more than the voltage of the battery. The solenoid valve drive device is characterized in that it is also set to a large value. 4. The solenoid valve drive system according to claim 1, from a time point when the switching element is turned on by the control means until a predetermined condition is established. A solenoid valve drive device is provided with a connection switching means for connecting the capacitor to the current supply path.