JP4186934B2 - Solenoid valve drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine whether the coils of solenoid valves are shortcircuited or not in a solenoid valve drive device rapidly opening the solenoid valves by applying the high voltage of capacitors to the coils of the solenoid valves. <P>SOLUTION: In a fuel injection control device 40 drivingly controlling a plurality of injectors (hereafter, referred to as solenoid valves), the high voltage is applied to the capacitor Co of the coil L1 to rapidly open the solenoid valve. Also, the solenoid valve drive device determines whether a high voltage from the capacitor Co is generated or not in routes between the coils L2 to L4 of the other solenoid valves and transistors TR2 to TR4 corresponding to these coils. When the high voltage is not generated, the coil L1 is determined to be short-circuited. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a solenoid valve driving device that quickly opens a solenoid valve by applying a high voltage charged in a capacitor to a coil of the solenoid valve.

  2. Description of the Related Art Conventionally, as a fuel injection valve that injects and supplies fuel to each cylinder of an internal combustion engine of a vehicle, for example, an electromagnetic valve that includes a coil that forms an electromagnetic solenoid and is opened by energization of the coil has been used. And the fuel injection quantity and fuel injection timing to an internal combustion engine are controlled by controlling the electricity supply time and the electricity supply timing to a coil.

Then, as a conventional fuel injection control device that controls the fuel injection by driving such a fuel injection valve, a predetermined large current (peak current) is supplied at the start of energization of the coil to quickly open the fuel injection valve. Thereafter, a constant current (hold current) for holding the valve open is supplied to keep the fuel injection valve open during a desired injection period (for example, Patent Document 1, Patent) Reference 2).
JP 2002-303183 A JP-A-6-294346

By the way, in the fuel injection control device as described above, when an abnormality occurs in the coil or its energization path, it is necessary to detect the abnormality and implement some kind of fail safe.
For example, in Patent Document 1, a circuit for detecting a power supply short circuit in which the path is short-circuited to the power supply line and a ground short circuit in which the path is short-circuited to the ground line is provided in the energization path of the coil. It is configured to be able to.

However, a short circuit fault in the coil itself cannot be detected.
On the other hand, in the said patent document 2, it is comprised so that the short circuit failure of the coil of a solenoid valve can be detected. Specifically, at the end of energization of the coil, it is determined whether or not a flyback voltage has been generated in the coil. If it is determined that the flyback voltage has been generated, it is determined to be normal, and conversely the flyback voltage. If it is determined that no has occurred, it is determined that there is an abnormality. For this reason, if the coil itself is short-circuited and the inductance component is reduced or eliminated, the flyback voltage is not sufficiently generated and the coil short-circuit failure is detected.

  However, the flyback voltage tends to vary greatly depending on various conditions such as ambient temperature, power supply voltage (generally battery voltage), and characteristics of the coil itself. For this reason, in the technique of Patent Document 2 that detects the abnormality by determining the presence or absence of the flyback voltage, it is determined that the flyback voltage is not generated even though there is actually no abnormality and the flyback voltage is generated. In other words, there is a high possibility of erroneous determination that an abnormality has occurred. In addition, since a flyback does not occur even in the case of disconnection, it is impossible to distinguish between short-circuiting of the coil and disconnection.

  Therefore, the present invention relates to whether or not a short circuit failure has occurred in the solenoid valve coil in a solenoid valve driving device that quickly opens the solenoid valve by applying a high voltage charged in the capacitor to the solenoid valve coil. The purpose is to make it possible to accurately determine whether or not.

  In the electromagnetic valve driving device according to claim 1, which is made to achieve the above object, for each coil of the plurality of electromagnetic valves, an individual energization wiring for supplying a current to each coil is provided. An end portion on the upstream side of the coil of the energization wiring is connected to a common energization wiring for applying a voltage for energization to each coil. In addition, main switching elements are provided in series in paths downstream of the coils on the individual energization wires. Further, a sub switching element is provided between the common energization wiring and the DC power source.

  Further, the solenoid valve driving device includes high voltage generating means for generating a higher voltage than the DC power source by charging the capacitor, and switching for applying a high voltage to connect the capacitor to the common energizing wiring by turning on the capacitor. And an element.

  And this electromagnetic valve drive device is provided with a current supply control means for selectively opening any of the plurality of solenoid valves, and the current supply control means includes a plurality of main switching elements, By turning on a main switching element (hereinafter referred to as a driving target main switching element) corresponding to a coil of an electromagnetic valve to be opened (hereinafter referred to as an energization target coil) and a switching element for applying a high voltage, a capacitor Is applied to the common energization wiring to supply a peak current for quickly opening the solenoid valve to the energization target coil, and after the peak current is supplied, the high voltage application switching element is turned off. By turning on / off the sub-switching element, a constant current smaller than the peak current is supplied to the coil to be energized. The energization period is completed, and turns off the driven main switching element.

  In particular, the electromagnetic valve driving device according to claim 1 includes a coil short-circuit fault detecting means as means for detecting that the coil of each solenoid valve has a short-circuit fault. The coil short-circuit failure detection means is configured to detect main switching elements other than the driving target main switching element among the plurality of individual energization wirings when the driving target main switching element and the high voltage application switching element are turned on by the current supply control means. When it is determined that a high voltage of the capacitor has occurred in the path between the main switching element and the coil in the individual energization wiring provided with the switching element, and it has been determined that no high voltage has occurred. It is determined that the energization target coil has a short circuit failure.

  In such a solenoid valve drive device according to the first aspect, when the high voltage application switching element is turned on, the high voltage charged in the capacitor is applied to each coil of each individual energization wiring via the common energization wiring. Will be.

  Here, with respect to the energization target coil, since the corresponding main switching element (that is, the drive target main switching element) is turned on, the energization path is established and the current flows. The voltage of the path between the switching elements is almost 0V. That is, the high voltage of the capacitor applied to the common energization wiring is not generated in the path between the energization target coil and the drive target main switching element.

  On the other hand, with respect to coils other than the coil to be energized, since the corresponding main switching element is turned off, the energization path is not established and no current flows, so the path between the coil and the main switching element is not Thus, the same voltage as the high voltage of the capacitor applied to the common energization wiring is generated. Since the high voltage of the capacitor is originally intended to quickly open the solenoid valve, it does not change greatly depending on various conditions like the flyback voltage, and it will surely occur for some time.

  However, if the energization target coil has a short circuit failure, the same voltage as the high voltage of the capacitor is not generated in the path between the coil other than the energization target coil and the main switching element.

  In other words, if the coil to be energized is short-circuited, when the switching element for high voltage application and the main switching element to be driven are turned on, the charge accumulated in the capacitor is almost directly transmitted via the driving target switching element. In addition, since the capacitors are instantaneously discharged, the high voltage of the capacitor does not occur at all in the common energizing wiring, or even if it occurs, only a very short time corresponding to a time constant that is extremely smaller than normal time appears. .

  Therefore, in the electromagnetic valve drive device according to claim 1, the coil short-circuit failure detection means is connected to the individual energization wiring provided with the main switching elements other than the drive target main switching elements (that is, the coils that are not the drive target coils are connected). In the individual energization wiring), it is determined whether or not the coil to be driven has a short-circuit fault by determining whether or not a high voltage of the capacitor has occurred in the path between the main switching element and the coil. It is.

  According to the electromagnetic valve driving apparatus of the first aspect, the short-circuit failure of the drive target coil is determined based on the presence or absence of a voltage that is greatly different between when the drive target coil is normal and when the short-circuit failure occurs. Therefore, it becomes possible to accurately determine whether or not a short circuit failure has occurred for each coil of the plurality of solenoid valves.

  By the way, although a path for detecting a voltage may be provided for each individual energization wiring, it is desirable to provide a common path for detecting the voltage as in the electromagnetic valve driving device according to claim 2. .

  That is, in the electromagnetic valve driving device according to claim 2, in the electromagnetic valve driving device according to claim 1, the coil short-circuit failure detection means has an anode connected to a path connecting the main switching element and the coil on each individual energization wiring. The cathode has a plurality of diodes commonly connected to each other, and when the main switching element to be driven and the switching element for high voltage application are turned on by the current supply control means, a capacitor is connected to the cathode of the plurality of diodes. When it is determined whether or not a high voltage has occurred, and it is determined that this high voltage has not occurred, it is determined that the coil to be energized is short-circuited.

  In such a solenoid valve drive device according to claim 2, each path connecting the main switching element and the coil is connected in common, but any one of the main switching elements (that is, the main switching element to be driven) is turned on. In this case, current wraparound such that current flows to a coil other than the drive target coil via the drive target main switching element is prevented by the diode. If such a current wraparound occurs, even if there is no short-circuit failure in the drive target coil, in the individual energization wiring provided with the main switching element other than the drive target main switching element, the main switching element and Although the high voltage of the capacitor does not occur in the path to the coil, such a malfunction is avoided by the diode.

Therefore, according to the electromagnetic valve driving device of the second aspect, the short circuit of the coil can be detected by detecting the voltage of one path, the circuit configuration becomes simple, and it can be configured at low cost.
Next, in the electromagnetic valve driving device according to claim 3, in the electromagnetic valve driving device according to claim 2, the coil short-circuit fault means has a filter circuit for removing a high-frequency component from the voltage of the cathodes commonly connected to the plurality of diodes. Whether or not a high voltage of the capacitor has occurred at the cathodes of a plurality of diodes is determined based on whether or not the output voltage of the filter circuit is greater than a specific determination voltage.

  In such a solenoid valve drive device according to claim 3, when detecting the voltage of each path between the main switching element and the coil, the filter circuit causes a high-frequency voltage generated when the coil is short-circuited or noise in the circuit. Since the components and the like are removed, it is possible to reliably determine whether or not the high voltage of the capacitor has occurred by simply comparing the output voltage of the filter circuit and the determination voltage with, for example, a comparator. Therefore, according to this electromagnetic valve drive device, it is possible to accurately determine whether or not a short circuit failure of the coil has occurred with a simple circuit configuration.

  Next, in the electromagnetic valve driving device according to a fourth aspect, in the electromagnetic valve driving device according to the third aspect, the coil short circuit failure detecting means compares the output voltage of the filter circuit with the determination voltage, and the output voltage of the filter circuit is When the voltage exceeds the determination voltage, the voltage comparison means whose output voltage changes in level, and the output voltage of the voltage comparison means is input as the monitoring target voltage, and when the monitoring target voltage changes in level, the level change is stored. History storage means.

  For this reason, if a high voltage of the capacitor is generated in each path between the main switching element other than the main switching element to be driven and the coil and the high voltage appears at the cathodes of the plurality of diodes, The output voltage changes in level, and this is stored in the level change history storage means.

  Therefore, the coil short-circuit failure detection means further clears the stored contents of the level change history storage means before the drive target main switching element is turned on by the current supply control means, and after the drive target main switching element is turned on. Until the drive target switching element is turned off, the stored content of the level change history storage means is read, and if the read stored content does not indicate that a level change has occurred in the monitoring target voltage, the energization target coil Is determined to have a short circuit fault.

  According to the electromagnetic valve driving device of the fourth aspect, the determination as to whether or not the output voltage of the filter circuit has become larger than the determination voltage must be performed immediately after the driven main switching element is turned on. There is no time restriction, and the presence or absence of a short-circuit failure of the coil is determined by reading the stored contents of the level change history storage means at any timing from when the driven main switching element is turned on to when it is turned off. Therefore, the degree of freedom in device design can be improved. Further, since the history stored in the level change history storage means is always the latest, it is possible to prevent a situation in which the presence / absence of a short circuit failure of the energization target coil is determined based on the old history.

  Next, in the electromagnetic valve driving device according to claim 5, in the electromagnetic valve driving device according to claim 3, the coil short-circuit failure detection means has a voltage comparison means and a level change history storage means similar to those in the apparatus of claim 4. is doing.

  And the coil short circuit failure detection means clears the stored contents of the level change history storage means before the drive target main switching element is turned on by the power supply control means, as in the apparatus of claim 4. The point is different.

  That is, when the driving target main switching element is turned off after the driving target main switching element is turned on, the coil short-circuit fault detection means reads the storage content of the level change history storage means, and the read content is monitored. If it does not indicate that a level change has occurred in the voltage, it is determined that the coil to be energized is short-circuited.

  In such a solenoid valve drive device according to claim 5, when the driven main switching element is turned on, in the individual energization wiring provided with the main switching element other than the driven main switching element, the main switching element, the coil, It is also determined whether or not a high voltage has occurred in the path between the two, and whether or not a flyback voltage has occurred in the energization target coil when the drive target main switching element is turned off.

  Note that when the current flowing in the energization target coil is interrupted, that is, when the drive target main switching element is turned off, a flyback voltage is generated in the energization target coil. Even if the target main switching element is turned off, no current flows through the coil to be energized, and therefore no flyback voltage is generated. Therefore, if the flyback voltage is generated, it can be determined that the energization target coil is normal. Conversely, if the flyback voltage is not generated, it can be determined that the energization target coil is short-circuited.

  Therefore, according to the electromagnetic valve driving device of claim 5, it is further determined whether or not the coil to be energized is short-circuited by determining whether or not the flyback voltage is generated in addition to the high voltage of the capacitor. It can be judged with certainty. Of course, the same effect as that of the apparatus of claim 4 can be obtained.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a configuration diagram showing a schematic configuration of an entire fuel injection control apparatus 40 to which the present invention is applied, and four electromagnetic solenoid types that supply fuel to each cylinder # 1 to # 4 of a vehicular diesel engine. By controlling the energization time and energization timing to the coils L1, L2, L3, and L4 of a unit injector (hereinafter simply referred to as a solenoid valve), the fuel injection amount and the fuel injection to each cylinder # 1 to # 4 of the diesel engine It controls the time.

  As shown in FIG. 1, from the fuel injection control device 40 of the present embodiment, a common energization wiring Kc for applying a valve opening voltage to the coils L1 to L4 extends, and the common energization wiring Kc includes Individual energization wirings K1, K2, K3, and K4 for energizing the coils L1 to L4 are connected to the fuel injection control device 40 outside.

  The fuel injection control device 40 includes a known microcomputer (hereinafter referred to as “microcomputer”) 41 including a CPU, a ROM, a RAM, and the like that execute various control processes for fuel injection control according to a preset control program. The switching circuit 12 and the switching circuit 12 are connected to and disconnected from the energization paths of the coils L1 to L4 of the cylinders # 1 to # 4 by the injection pulse signals TQ1 to TQ4 from the microcomputer 41, respectively. Hold current circuit 11 that supplies a predetermined hold current (constant current) to one of the coils L1 to L4 through the diode D5, and a peak current that promptly opens the solenoid valve to the coils L1 to L4. The capacitor Co to be charged with a high voltage to be supplied and the capacitor Co when the switching circuit 12 is turned off The capacitors Co and a like charging circuit 10 for charging a high voltage of a predetermined voltage value Vp. Note that when the switching circuit 12 is off, it means that the transistors TR1 to TR4, which will be described later, constituting the switching circuit 12 are all off.

  The charging circuit 10 has a coil Lo applied to one end of a voltage (for example, 12V, hereinafter referred to as a battery voltage) VB of the battery 1 mounted on the vehicle, and a battery voltage VB having a drain of the coil Lo applied thereto. Connected to the other end opposite to one end, the source is grounded, and switched to the transistor TRo for boosting transistor TRo (MOS type transistor) that generates a high voltage at the other end of the coil Lo by high-speed switching A well-known booster circuit 17 that switches the transistor TRo in a short cycle by outputting a signal and a current backflow prevention diode Do that has an anode connected between the transistor TRo and the coil Lo are well known. Is.

The capacitor Co is connected to the cathode of the diode Do, and is charged via the diode Do.
The self-excited booster circuit 17 is controlled by a control signal from the microcomputer 41, operates during the energization-off period of the coils L1 to L4, and when the charging voltage value of the capacitor Co becomes the predetermined voltage value Vp. The operation is stopped (transistor TRo is turned off).

  The hold current circuit 11 is supplied with power from the battery 1, and the coil L <b> 1 to L <b> 4 in which the energization path is conducted (hereinafter also simply referred to as “coil L”) is used to hold the solenoid valve open. This is a constant current circuit for supplying a current. A source and a drain are connected between a power supply line of the battery voltage VB and a common energization wiring Kc, and the coil 1 (or coils L1 to L1) are turned on and off by turning on and off. A transistor TRh (MOS type transistor) that conducts and cuts off the energization path to L4), and a constant current control circuit 11a for turning on / off the transistor TRh to hold the current flowing through the coil L at a predetermined hold current. It is composed of

  The switching circuit 12 includes switching transistors TR1, TR2, TR3, and TR4 (in any case) provided in series on the downstream paths of the coils L1 to L4 on the individual energization wires K1 to K4 of the coils L1 to L4. These transistors TR1 to TR4 are controlled to be turned on / off by injection pulse signals TQ1, TQ2, TQ3, and TQ4 from the microcomputer 41. Hereinafter, each path between the coils L1 to L4 and the transistors TR1 to TR4 is referred to as KK1 to KK4.

  The sources of the transistors TR1 to TR4, which are the terminals opposite to the coils L1 to L4, are commonly connected to each other, and actually flow through the coil L to be energized between the sources and the ground potential. A current detection resistor R4 for detecting the current is connected.

  For this reason, when any of the transistors TR1 to TR4 is turned on, a coil energization path corresponding to the turned-on transistor is formed. Further, each of the constant current control circuit 11a in the hold current circuit 11 and an overexcitation current control circuit 20 described later detects the current of the coil L based on the voltage generated in the resistor R4. . The resistance value of the resistor R4 is set to a very small value such as less than 1Ω so that the voltage drop at the resistor R4 does not hinder the driving of the solenoid valve.

  By the way, even when the energization of the coils L1 to L4 is interrupted by the transistors TR1 to TR4, it is not preferable that the charging voltage of the capacitor Co is always applied to the coils L1 to L4. Therefore, a high voltage changeover switch TRk (MOS type transistor) is connected between the end of the capacitor Co on the diode Do side and the common energization wiring Kc. The high voltage changeover switch TRk is controlled to be turned on / off by the overexcitation current control circuit 20 that receives a control signal from the microcomputer 41.

  Thus, when the transistors TR1 to TR4 are turned off and the energization to the coils L1 to L4 is cut off, the high voltage changeover switch TRk is turned off so that the charging voltage of the capacitor Co is not applied to the coils L1 to L4. When any one of TR1 to TR4 is turned on, the high voltage changeover switch TRk is turned on at the same time, and the charging voltage of the capacitor Co is applied to the coil L in which the energization path is conducted to supply the peak current. .

  Note that the diode D7 in FIG. 1 is provided in order to prevent a current from flowing from the common energizing wiring Kc side to the capacitor Co side. The diode D5 is provided for preventing current from flowing from the capacitor Co side to the battery 1 side via the common energization wiring Kc. The diode D6 is provided to eliminate flyback energy generated in the coils L1 to L4 on the individual energization lines K1 to K4 connected to the common energization line Kc.

  By the way, in various electronic control devices for controlling energization of various electric loads mounted on a vehicle including the fuel injection control device 40, when an abnormality occurs in the electric load for some reason, the abnormality is usually detected. It is necessary to inform the driver.

  Therefore, the fuel injection control device 40 is also provided with an abnormality detection circuit 13 for detecting an abnormality when the abnormality occurs such that the coils L1 to L4 are short-circuited for some reason.

  As shown in FIG. 1, the abnormality detection circuit 13 includes a diode OR circuit 18, a voltage dividing circuit 15, a filter circuit 14 including a well-known integration circuit, and a comparator 16 that compares two voltage values. ing.

  The diode OR circuit 18 includes four diodes D1, D2, D3, and D4. The anodes of the diodes D1 to D4 are paths between the coils L1 to L4 and the transistors TR1 to TR4 (paths KK1 to KK4). ) Are connected correspondingly. The cathodes of the diodes D1 to D4 are connected in common.

The voltage dividing circuit 15 includes two resistors 15a and 15b, and divides the output voltage of the cathodes of the diodes D1 to D4 and inputs the divided voltage to the filter circuit 14.
The filter circuit 14 is a well-known integration circuit composed of a resistor 14a and a capacitor 14b. The filter circuit 14 blocks a narrow pulse signal, that is, transmission of a high-frequency component of voltage to the comparator 16.

  The comparator 16 compares the voltage input from the filter circuit 14 with the reference voltage Vth. If the voltage input from the filter circuit 14 is larger, the comparator 16 outputs a high signal to the microcomputer 41. When the reference voltage Vth is larger, a low signal is output to the microcomputer 41. The reference voltage Vth is set to a voltage value when the voltage dividing circuit 15 divides a predetermined determination voltage VH that is lower than the aforementioned Vp, which is the charging target voltage of the capacitor Co, and higher than the battery voltage VB. Yes. Therefore, a high signal is output from the comparator 16 to the microcomputer 41 when the high voltage of the capacitor Co is output from the cathodes of the diodes D1 to D4, and the high voltage of the capacitor Co is output from the cathodes of the diodes D1 to D4. If not, a low signal is output.

  In the present embodiment, the output signal of the comparator 16 is input to the edge input latch port of the microcomputer 41. In this edge input latch port, when a rising edge (that is, a level change from low to high) occurs in the input signal, pulse signal information, which is a history indicating that (that is, a rising edge has occurred), is stored in the microcomputer 41. It is a port provided in the microcomputer 41 for an edge automatic monitoring function such as being stored in a specific register (hereinafter referred to as a latch port register).

Next, the operation of the fuel injection control device 40 configured as described above will be described.
First, the case where the coil L1 is normal will be described with reference to FIG. Hereinafter, the case where the transistor TR1 is turned on and the coil L1 is energized, that is, the case where the injection pulse signal TQ1 is output in FIG. 2 will be described, but the same applies when the other transistors TR2 to TR4 are turned on. is there. In FIG. 2, VKc represents the voltage of the common energization wiring Kc, and V # 1, V # 2, V # 3, and V # 4 are the drain voltages of the transistors TR1, TR2, TR3, TR4, That is, the voltages of the paths KK1 to KK4 between the coils L1 to L4 and the transistors TR1 to TR4 are represented.

  In this fuel injection control device 40, the capacitor Co is charged to a predetermined high voltage when all the transistors TR <b> 1 to TR <b> 4 are off according to a command from the microcomputer 41. Then, when a command for energizing the coil L1, that is, an injection pulse signal TQ1 is inputted from the microcomputer 41 to the transistor TR1, and the transistor TR1 is turned on, a control signal (not shown) is turned on from the microcomputer 41 at the same time. Are also output to the overexcitation current control circuit 20. Then, the overexcitation current control circuit 20 turns on the high voltage changeover switch TRk. The injection pulse signal TQ1 is output in synchronization with the rotation of the crankshaft of the engine under the control of the microcomputer 41.

  When the high voltage changeover switch TRk is turned on by the overexcitation current control circuit 20, the voltage charged in the capacitor Co (in other words, the accumulated charge) is applied to each of the coils L1 to L4 via the common energization wiring Kc. The

  At this time, since the transistor TR1 is on, a peak current corresponding to the high voltage of the capacitor flows through the coil L1 and the path KK1. As described above, the current flowing through the coil L1 and the path KK1 is detected by the constant current control circuit 11a and the overexcitation current control circuit 20 in the form of a voltage generated in the resistor R4.

  When the value of the peak current flowing through the coil L1 reaches a predetermined set value due to the discharge of the capacitor Co, the overexcitation current control circuit 20 turns off the high voltage changeover switch TRk. Thereafter, the hold current circuit 11 causes a hold current to flow to the coil L1 to keep the solenoid valve open. That is, when the high voltage changeover switch TRk is turned off by the overexcitation current control circuit 20 and the current flowing through the coil L1 decreases and becomes smaller than a predetermined target value, the constant current control circuit 11a turns on the transistor TRh, and the battery The voltage VB is applied to the common energization wiring Kc (and thus the end of the coil L1). When the current by the battery voltage VB is supplied to the coil L1 and the current value becomes larger than the target value, the constant current control circuit 11a turns off the transistor TRh and turns on the current from the battery 1 to the coil L1. Cut off. In this way, the constant current control circuit 11a turns on / off the transistor TRh, and conducts or cuts off the energization path from the battery 1 to the coil L1 via the common energization wiring Kc. Is to be supplied.

When the energization period to the coil L1 ends, the microcomputer 41 turns off the transistor TR1 and interrupts the energization to the coil L1.
When the energization of the coil L1 is interrupted, the capacitor Co is rapidly charged again to a predetermined high voltage by the operation of the charging circuit 10, and then when any of the coils L1 to L4 is energized, the capacitor Co to the coil L1. The peak current can be supplied to any one of L4.

  By the way, when the coil L1 is normal as described above, when the transistor TR1 is turned on by the microcomputer 41 and the high voltage changeover switch TRk is turned on by the overexcitation current control circuit 20, the path KK1 has a resistance value. Since it is connected to the ground potential via a very small resistor R4, the voltage appearing on the path KK1 is almost 0 V as shown by V # 1 in FIG. On the other hand, since the paths KK2 to KK4 are cut off from the ground potential, the paths KK2 to KK4 are applied to the common energization wiring Kc as shown by V # 2, V # 3, and V # 4 in FIG. The high voltage of the capacitor Co appears almost as it is.

  When the high voltage switching switch is turned off by the overexcitation current control circuit 20, a pulsation voltage appears in the common energization wiring Kc by the operation of the hold current circuit 11 as described above. As a result, similar pulsation voltages appear in the paths KK2 to KK4 (V # 2, V # 3, V # 4 in FIG. 2). Further, the voltage of the path KK1 remains substantially 0 V (V # 1 in FIG. 2).

  As described above, if the coil L1 is normal, when the high voltage of the capacitor Co is applied to each of the coils L1 to L4 via the common energization wiring Kc, the path of the capacitor Co is connected to the path KK2 to the path KK4. A high voltage appears and thereafter a predetermined pulsating voltage appears.

  These voltages are output from the diode OR circuit 18 (from the cathodes of the diodes D1 to D4) and input to the comparator 16 through the voltage dividing circuit 15 and the filter circuit 14 described above.

  Therefore, when the coil L1 is normal and the transistor TR1 is turned on and the high voltage of the capacitor Co appears in the path KK2 to the path KK4, as shown in the lowermost stage of FIG. A high signal is output to the input latch port. In the microcomputer 41, when the rising edge occurs in the edge input latch port in accordance with the high signal from the comparator 16, the above-described pulse signal information is stored in the latch port register.

  When the energization period of the coil L1 ends and the transistor TR1 is turned off by the microcomputer 41, the current has been flowing through the coil L1, and therefore, as shown by V # 1 in FIG. 2, the paths KK1 to KK4. Among them, a flyback voltage is generated in the path KK1 corresponding to the coil L1. The flyback voltage is input from the diode D1 to the non-inverting input terminal of the comparator 16 via the voltage dividing circuit 15 and the filter circuit 14, and the input voltage (( That is, if the output voltage of the filter circuit 14 becomes the above-described reference voltage Vth, a high signal is output from the comparator 16 to the microcomputer 41 as shown in the lowermost stage of FIG.

Next, the operation when a short-circuit failure has occurred in the coil L1 will be described with reference to FIG.
When a high voltage of the capacitor Co is applied to each of the coils L1 to L4 via the common energization wiring Kc (assuming that TR1 is turned on), there is almost no inductance component of the coil L1 due to a short circuit. The high voltage of the capacitor Co is instantaneously discharged through the transistor TR1. That is, the high voltage of the capacitor does not appear at all in the common energization wiring Kc and the paths KK2 to KK4, or even if it appears, only a very short time appears (in this embodiment, VKc, V # 2, FIG. 3). As shown in V # 3 and V # 4, the minute time appears). Since the path KK1 is conductive, the voltage of the path KK1 is approximately 0V as indicated by V # 1 in FIG.

  When the high voltage changeover switch TRk is turned off by the overexcitation current control circuit 20, the hold current circuit 11 as described above operates. However, since there is no inductance component of the coil L1, there is no constant current supply. When the transistor TRh is turned on, the energization current of the coil L1 detected by the resistor R4 instantaneously exceeds the target value, and when the transistor TRh is turned off, the energization current of the coil L1 detected by the resistor R4 instantaneously becomes zero. As a result, the voltages appearing on the common energization wiring Kc and the paths KK2 to KK4 are very fine as shown in VKc, V # 2, V # 3, and V # 4 in FIG. Voltage.

  As described above, when the coil L1 is short-circuited, the high voltage of the capacitor Co does not appear in the paths KK2 to KK4, and therefore the high signal from the comparator 16 is not input to the microcomputer 41 (the signal from the comparator 16). Remains low).

  Note that since the coil L1 has almost no inductance component due to a short circuit, no flyback voltage is generated in the coil L1 even when the transistor TR1 is turned off. Therefore, similarly, the microcomputer 41 does not receive a high signal from the comparator 16 due to the flyback voltage.

  Next, processing executed by the microcomputer 41 of the fuel injection control device 40 will be described. 4 to 6 described below is performed for each cylinder, but here, for convenience, a coil Ln (n is 1 to 4) corresponding to a certain cylinder #n. Any one of them will be described.

FIG. 4 is a flowchart showing a main process executed at regular time intervals.
In this main process, first, in S100, it is determined whether or not the injector short abnormality counter that counts the number of short-circuit faults detected in the coils Ln (L1 to L4) is greater than a predetermined number N. That is, it is determined whether or not the number of short-circuit faults detected in the coil Ln is greater than a predetermined N times. If it is determined that the number of times is N or less, the process is temporarily terminated. On the other hand, if it is determined that there are more than N times, the process proceeds to S110, where a warning lamp provided in the vehicle is turned on to notify the driver of the abnormality, and fail-safe processing is executed. Note that the fail-safe process is not directly related to the present invention, and thus detailed description thereof is omitted here. The injector short abnormality counter is a counter that is incremented in S350 of FIG.

  Next, FIG. 5 is a flowchart showing an interrupt process executed by the microcomputer 41. The start timing of this process is before the output of the injection pulse signal TQn (TQ1 to TQ4) corresponding to the coil Ln, as shown in (1) of FIG. The start timing of this interrupt process is also set in synchronization with the rotation of the crankshaft of the engine, like the output timing and output time of each injection pulse signal TQ1 to TQ4.

  In this process, first, in S200, it is determined whether or not an injection pulse set has been performed. That is, it is determined whether or not preparation is made to output the injection pulse signal TQn. If it is determined that the injection pulse set has not been performed, the process is temporarily terminated.

  On the other hand, if it is determined in S200 that the injection pulse set has been performed, the process proceeds to S210, where the latch data of the edge input latch port provided in the microcomputer 41 is cleared. That is, the microcomputer 41 deletes the pulse signal information stored in the aforementioned latch port register.

Then, the process proceeds to S220, and an edge check execution flag is set. Thereafter, the process ends.
Next, FIG. 6 is a flowchart showing interrupt processing executed by the microcomputer 41, as in FIG. The start timing of this process is in the middle of the injection pulse signal TQn being at the high level as shown in (2) of FIG. 7, specifically, immediately before the timing at which the injection pulse signal TQn falls. Set to The start timing of this interrupt process is also set in synchronization with the rotation of the crankshaft of the engine, like the output timing and output time of each injection pulse signal TQ1 to TQ4.

In this process, first, in S300, it is determined whether or not there is an edge check execution flag. This edge confirmation execution flag is set in S220 of FIG.
Next, the process proceeds to S310, where it is determined whether there is a latch in the edge input latch port of the microcomputer 41, that is, whether pulse signal information is stored in the latch port register.

  If it is determined that there is a latch, then the process proceeds to S320, where it is determined that the injector (solenoid valve) of cylinder #n is not short-circuited, that is, normal. That is, since the high signal corresponding to the high voltage of the capacitor Co is input from the comparator 16 to the microcomputer 41, the current coil Ln to be energized is normal. Then, the process proceeds to S330, and the injector short abnormality counter is cleared. Thereafter, the process is temporarily terminated.

  On the other hand, if it is determined in S310 that there is no latch in the edge input latch port, the process proceeds to S340, where it is determined that the injector of cylinder #n has a short-circuit fault, that is, is abnormal. That is, since a high signal corresponding to the high voltage of the capacitor Co is not input from the comparator 16 to the microcomputer 41, the coil Ln to be energized is short-circuited. Then, the process proceeds to S350, and 1 is added to the injector short abnormality counter. Thereafter, the process is temporarily terminated.

  In the fuel injection control device 40 of this embodiment, the transistors TR1 to TR4 correspond to main switching elements, the high voltage changeover switch TRk corresponds to a switching element for high voltage application, and the transistor TRh corresponds to a sub switching element. The charging circuit 10 corresponds to a high voltage generating means, the battery 1 corresponds to a DC power supply, the charging circuit 10, the hold current circuit 11, the overexcitation current control circuit 20, the high voltage changeover switch TRk, and the microcomputer 41 are currents. It corresponds to supply control means, the comparator 16 corresponds to voltage comparison means, the diode OR circuit 18, the voltage dividing circuit 15, the filter circuit 14, the comparator 16, and the microcomputer 41 correspond to coil short-circuit fault detection means, and the microcomputer 41 Edge input latch port and latch port register level change history It corresponds to the 憶 means.

  As described above, in the fuel injection control device 40 of this embodiment, whether or not the high voltage of the capacitor Co is generated in the paths KK1 to KK4 between the coils L1 to L4 of each cylinder and the transistors TR1 to TR4. Based on this determination, it is determined whether or not there is a short circuit failure in the coil to be driven.

  Then, according to the fuel injection control device 40 of the present embodiment, the short-circuit failure of the drive target coil depends on the presence or absence of the high voltage of the capacitor Co that is greatly and reliably different between when the drive target coil is normal and when the short-circuit failure occurs. Therefore, it is possible to accurately determine whether or not a short circuit failure has occurred for each of the coils L1 to L4 of the plurality of solenoid valves.

  Further, the fuel injection control device 40 of the present embodiment has a diode OR circuit 18, and the anodes of the diodes D1 to D4 of the diode OR circuit 18 are connected corresponding to the paths KK1 to KK4, respectively. The cathodes of the diodes D1 to D4 are connected in common.

  Therefore, when the transistor to be driven among the transistors TR1 to TR4 is turned on, it is possible to prevent the current from flowing in that the current flows to a coil other than the coil to be driven through the transistor to be driven, As a result, since the short circuit of the coils L1 to L4 can be detected by detecting the voltage of one path, the circuit configuration is simplified and the circuit can be configured at low cost.

  Further, in the fuel injection control device 40 of the present embodiment, when detecting the voltage of the paths KK1 to KK4, the filter circuit 14 causes a high frequency voltage generated when one of the coils L1 to L4 is short-circuited, or noise in the circuit. Ingredients are removed. Then, the output voltage of the filter circuit 14 and the reference voltage Vth are compared in magnitude by the comparator 16 to determine whether or not a high voltage of the capacitor Co has occurred.

  As described above, in the fuel injection control device 40 of the present embodiment, since it is possible to determine whether or not a short-circuit failure has occurred in the coils L1 to L4 with a simple circuit configuration, the circuit is configured at low cost. Can do.

  Further, in the fuel injection control device 40 of the present embodiment, a high signal from the comparator 16 is input to the edge input latch port of the microcomputer 41 and stored in the latch port register. Then, the microcomputer 41 reads the stored contents stored in the latch port register, and determines whether or not there is a short circuit failure in the coils L1 to L4 based on the stored contents. Specifically, if the generation of the high signal is stored, it is determined that the driving target coil is normal. Conversely, if the generation of the high signal is not stored, the driving target coil has a short circuit failure. Judgment can be made.

Therefore, according to the fuel injection control device 40 of the present embodiment, it is determined whether or not the high voltage of the capacitor Co is generated in a path other than the path corresponding to the drive target coil and the drive target transistor among the paths KK1 to KK4. Can be performed at an arbitrary timing without any time restriction that must be performed immediately after the transistor to be driven is turned on, so that the degree of freedom in device design can be improved.
[Second Embodiment]
Next, the fuel injection control apparatus 40 of 2nd Embodiment is demonstrated. The fuel injection control device 40 of the second embodiment differs from the first embodiment in the execution timing of the interrupt process in FIG. Only this point will be described below.

In the fuel injection control device 40 of the second embodiment, the interruption process of FIG. 6 is performed after the falling of the injection pulse signals TQ1 to TQ4, as shown in (2 ′) of FIG.
For this reason, it is determined whether or not a high voltage or flyback voltage of the capacitor Co has occurred in the paths KK1 to KK4, so that it is possible to double-check whether there is a short circuit failure in the energization target coil. In other words, in addition to the high voltage of the capacitor Co, whether or not a flyback voltage has occurred is also monitored to determine whether or not the coil to be energized has a short circuit failure. The possibility of erroneously determining that the coil is short-circuited can be more reliably eliminated. Therefore, it is possible to obtain the fuel injection control device 40 that can more accurately determine the presence or absence of a short circuit failure in the energization target coil.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various form can be taken within the technical scope of this invention.
For example, in the above-described embodiment, the cathodes of the diodes D1 to D4 are connected in common. However, as individual energization paths, the voltage distribution circuit 15, the filter circuit 14, and the comparator 16 may be provided in each energization path. Good.

  In the above embodiment, an integrating circuit is used for the filter circuit 14, but the high frequency component of the voltage output from the cathodes of the diodes D <b> 1 to D <b> 4, noise in the circuit, and the like using a digital signal processing technique. It is good also as a structure which removes.

It is a block diagram showing the structure of the whole fuel-injection control apparatus of 1st Embodiment. In the fuel-injection control apparatus of 1st Embodiment, it is explanatory drawing explaining operation | movement of a circuit when the coil of a solenoid valve is normal. In the fuel-injection control apparatus of 1st Embodiment, it is explanatory drawing explaining operation | movement of a circuit when a short circuit failure generate | occur | produces in the coil of a solenoid valve. It is a flowchart showing the main process which the microcomputer of the fuel-injection control apparatus of 1st Embodiment repeatedly performs. It is a flowchart showing the 1st interruption process which the microcomputer of the fuel-injection control apparatus of 1st Embodiment performs. It is a flowchart showing the 2nd interruption process which the microcomputer of the fuel-injection control apparatus of 1st Embodiment performs. It is explanatory drawing showing the execution start timing of the interruption process which the microcomputer of the fuel-injection control apparatus of 1st and 2nd embodiment performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery, 10 ... Charging circuit, 11 ... Hold current circuit, 11a ... Constant current control circuit, 12 ... Switching circuit, 13 ... Abnormality detection circuit, 14 ... Filter circuit, 14a ... Resistance, 14b ... Capacitor, 15 ... Divided voltage Circuit: 15a, 15b: Resistance, 16: Comparator, 17: Self-excited booster circuit, 18: Diode OR circuit, 20 ... Overexcitation current control circuit, 40 ... Fuel injection control device, 41 ... Microcomputer, Co ... Capacitor, Do , D1, D2, D3, D4, D5, D6, D7 ... diode, Kc ... common energization wiring, K1, K2, K3, K4 ... individual energization wiring, KK1, KK2, KK3, KK4 ... path, Lo, L1, L2 , L3, L4 ... coil, R4 ... resistor, TR1, TR2, TR3, TR4, TRh, TRo ... transistor, TRk ... high voltage selector switch

Claims (5)

Provided for each coil of a plurality of solenoid valves, a plurality of individual energization wiring for flowing current to each of the coils,
Commonly connected to the ends of the individual energized wires upstream of the coils, and a common energized wire for applying a voltage for energization to the coils,
A plurality of main switching elements provided in series in a path downstream from the coil on each individual energization wiring;
A sub-switching element connected between the DC power source and the common energization wiring;
A high voltage generating means that has a capacitor and generates a high voltage having a predetermined voltage value higher than the power supply voltage of the DC power supply by charging the capacitor;
By switching on, the high voltage application switching element for connecting the capacitor to the common energization wiring,
A means for selectively opening any one of the plurality of solenoid valves, and corresponding to a coil of the solenoid valve to be opened (hereinafter referred to as a current application coil) among the plurality of main switching elements. By turning on a main switching element (hereinafter referred to as a driving target main switching element) and the high-voltage applying switching element, the high voltage of the capacitor is applied to the common energization wiring and applied to the energization target coil. Supplying a peak current for promptly opening the solenoid valve, and after supplying the peak current, turning off the high-voltage applying switching element and controlling the on / off of the sub-switching element, the energization When a constant current smaller than the peak current is supplied to the target coil and the energization period to the energization target coil is finished, A current supply control means for turning off the dynamic object main switching element,
In a solenoid valve drive device comprising:
When the drive target main switching element and the high voltage application switching element are turned on by the current supply control means, a main switching element other than the drive target main switching element is provided among the plurality of individual energization wirings. In the individual energization wiring, it is determined whether or not a high voltage of the capacitor has occurred in the path between the main switching element and the coil, and when it is determined that the high voltage has not occurred, Having a coil short-circuit failure detection means for determining that the coil to be energized has a short-circuit failure;
A solenoid valve driving device characterized by the above. In the electromagnetic valve drive device according to claim 1,
The coil short-circuit fault detection means is
A plurality of diodes each having an anode connected to a path connecting the main switching element and the coil on each individual energization wiring and having cathodes commonly connected to each other, are driven by the current supply control means When the main switching element and the switching element for applying a high voltage are turned on, it is determined whether or not a high voltage of the capacitor is generated at the cathodes of the plurality of diodes, and it is determined that the high voltage has not been generated. The current-carrying coil is configured to determine that a short-circuit fault has occurred,
A solenoid valve driving device characterized by the above. In the solenoid valve drive device according to claim 2,
The coil short-circuit fault detection means is
A filter circuit for removing a high-frequency component from the voltage of the cathode; whether the high voltage of the capacitor is generated at the cathode; whether the output voltage of the filter circuit is greater than a specific determination voltage Judging by
A solenoid valve driving device characterized by the above. In the electromagnetic valve drive device according to claim 3,
The coil short-circuit fault detection means is
Voltage comparison means for comparing the output voltage of the filter circuit and the determination voltage, and the output voltage of the filter circuit changes in level when the output voltage of the filter circuit becomes larger than the determination voltage;
When the output voltage of the voltage comparison means is input as a monitoring target voltage, and the monitoring target voltage changes in level, it has level change history storage means for storing that,
Before the drive target main switching element is turned on by the current supply control means, the stored contents of the level change history storage means are cleared, and after the drive target main switching element is turned on, the drive target main switching element Until the turn-off is turned off, the stored content of the level change history storage means is read, and if the read stored content does not indicate that a level change has occurred in the monitored voltage, the energization target coil Configured to determine that a short circuit has occurred,
A solenoid valve driving device characterized by the above. In the electromagnetic valve drive device according to claim 3,
The coil short-circuit fault detection means is
Voltage comparison means for comparing the output voltage of the filter circuit and the determination voltage, and the output voltage of the filter circuit changes in level when the output voltage of the filter circuit becomes larger than the determination voltage;
When the output voltage of the voltage comparison means is input as a monitoring target voltage, and the monitoring target voltage changes in level, it has level change history storage means for storing that,
Before the drive target main switching element is turned on by the current supply control means, the stored contents of the level change history storage means are cleared, and after the drive target main switching element is turned on, the drive target main switching element Is turned off, the stored content of the level change history storage means is read, and if the read stored content does not indicate that a level change has occurred in the monitored voltage, the energization target coil has a short circuit failure. Is configured to determine that
A solenoid valve driving device characterized by the above.