JP2003027993A - Failure detection circuit for fuel injection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple failure detection circuit for a fuel injection system that can ensure a turnout operation by detecting each phase anomaly and interphase short circuit anomaly in a drive circuit of a solenoid valve for fuel injection in each cylinder of a multicylinder engine. SOLUTION: The failure detection circuit for a fuel injection system comprises a common switching element 11 or 21 for feeding solenoid valve driving electromagnetic coils 5 and 8, or 6 and 7 of groups discontinuous in fuel injection order, individual switching elements 13, 14, 23 and 24 related to the electromagnetic coils 5 to 8, and off-surge detection circuits 35 and 36 for forming a logical sum of off-surge signals Vs generated at a power interruption to electromagnetic coils of different groups. According to a drop determination and an overlap determination of off-surge signals corresponding to a driving signal pulse train generated by a microprocessor 9, the output of driving signal pulses to the electromagnetic coils 5 to 8 is stopped to disconnect the common switching element 11 or 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure detection circuit for a fuel injection device for an on-vehicle multi-cylinder engine or the like, and more particularly to a disconnection / short circuit of an electromagnetic coil for driving a fuel injection electromagnetic valve or a disconnection of a drive element or wiring of the electromagnetic coil. The present invention relates to a fuel injection device failure detection circuit for detecting a short circuit or the like and performing an abnormal alarm / display and a retract operation.

[0002]

2. Description of the Related Art Generally, rapid over-excitation control and operation hold control by a weak current are used together to control an electromagnetic coil for driving a fuel injection electromagnetic valve. Suppression is taking place. Further, a method of detecting a disconnection / short circuit failure of the electromagnetic coil, wiring, switching element, etc. by monitoring the voltage / current of each part of the electromagnetic coil drive circuit is adopted. Furthermore, the concept of simplifying signal processing by logically combining failure detection signals for loads of multiple channels is also known.

Japanese Unexamined Patent Publication No. 10-257799 discloses an output open detection device for a multi-channel output device, which supplies a minute current to a multi-channel load such as an exciting coil of a stepping motor when the load is not driven. By doing so, the disconnection detection is performed by utilizing the fact that the voltage across the load rises when the load circuit is disconnected, and the disconnection detection signal is not included in the diode OR circuit. Shows the concept of supplying a common comparison / determination circuit.

On the other hand, Japanese Unexamined Patent Publication No. 62-290111 "Failure detection circuit for fuel injection valve drive circuit for internal combustion engine"
According to the publication, the concept of collectively detecting disconnection / short-circuit failure of an electromagnetic coil, wiring, switching element, etc. by detecting an off-surge voltage generated when the energization of a fuel injection valve driving electromagnetic coil is cut off is disclosed. .

Further, according to Japanese Patent Laid-Open No. 9-112735, “Electromagnetic valve driving device”, for example, an electromagnetic coil for driving a fuel injection electromagnetic valve is provided with a boosting circuit for rapid driving and a weak current circuit for maintaining operation. It shows a concept of detecting disconnection / short-circuiting of a plurality of electromagnetic coils and their wirings by monitoring the charging voltage and discharging voltage of a capacitor in a booster circuit. In particular, in the case of this reference, a concept is shown in which a plurality of fuel injection valve driving electromagnetic coils are divided into groups, and the evacuation operation is smoothly performed based on the failure determination result.

In addition, according to Japanese Unexamined Patent Application Publication No. 10-318025 “Fuel Injection Injector Control Device”, one end of a plurality of injector coils whose fuel injection sequences are separated by two strokes or more and whose energization timings do not overlap is common. The concept of controlling the opening / closing by connecting to the drive output circuit and connecting the other end to individual switching means that is turned on / off at the energization timing of each injector coil is shown. Also,
In Japanese Patent Application No. 12-380652, "Abnormality detection device for vehicle-mounted electric load drive system", a method of separately detecting an abnormality detection signal combined with a logical sum in a microprocessor is shown, and the concept is also utilized in the present invention. It has become so.

[0007]

The above-mentioned prior arts include various methods of detecting abnormalities related to disconnection / short-circuiting of an electric load such as an electromagnetic coil and disconnection / short-circuiting of the switching control element and wiring of the electromagnetic coil. Has been presented. However, in any of the conventional techniques, a failure detection circuit for systematically performing abnormality determination is built for various abnormalities that are expected to occur, including abnormalities such as short-circuiting between phases of a large number of electric loads and ground faults. There is no problem.

The present invention has been made in order to solve the above-mentioned problems and to provide means including a countermeasure method associated with failure detection, and in particular, for fuel injection into each cylinder of a multi-cylinder engine. An object of the present invention is to provide a simple failure detection circuit for a fuel injection device, which can detect a failure in each phase of a drive circuit of a solenoid valve and an abnormality between short circuits between phases and perform a retract operation.

[0009]

A fuel injection device failure detection circuit according to the present invention includes a plurality of electromagnetic coils for driving a fuel injection electromagnetic valve for each cylinder of a multi-cylinder engine, a drive signal pulse train, and a rapid overexcitation. A microprocessor that generates a control signal, a plurality of individual switching elements that sequentially open and close in response to a drive signal pulse train from the microprocessor to drive the corresponding electromagnetic coils, and a rapid switch from the microprocessor. In response to the excitation control signal, a common switching element of a plurality of groups that collectively feeds and drives electromagnetic coils in a group consisting of at least a plurality of electromagnetic coils whose fuel injection sequence is separated by two strokes or more, and electromagnetic coils of at least different groups A plurality of off-surge voltages for detecting the off-surge voltage generated when the corresponding individual switching element is opened. And a surge detection circuit, the microprocessor compares the detection signals from the plurality of off-surge detecting circuit is for abnormality determination by missing and whether the duplication of the detection signal.

Further, each of the off-surge detection circuits detects the off-surge voltage by detecting that the voltage value across the individual switching element exceeds the voltage value of the voltage source when the individual switching element is opened. Is to do.

Further, in each of the off-surge detection circuits, when the individual switching element and the common switching element are opened, the voltage of the negative terminal of the electromagnetic coil is higher than the voltage of the power supply terminal connected to the common switching element. The off surge voltage is detected by detecting the high voltage.

Further, the common switching element is provided with an OR circuit for OR-combining the detection signals output from the off-surge detection circuits for the electromagnetic coils of different groups, and the microprocessor outputs the output of the OR circuit. The abnormality determination is based on this.

Further, each of the common switching elements responds to a rapid overexcitation control signal from the microprocessor and a weak current holding control signal for holding the operation of the electromagnetic coil.

Further, an over-excitation booster circuit for boosting the power supply voltage is provided, and the common switching element operates by a high-voltage side switching element which feeds and drives the voltage coil through the over-excitation boosting circuit, and the electromagnetic coil. Is a low-voltage side switching element that drives the electromagnetic coil to feed power in response to a weak current holding control signal.

Further, each of the high-voltage side switching elements shares the above-mentioned over-excitation booster circuit, and this over-excitation booster circuit is shared by all the electromagnetic coils.

Further, when the microprocessor determines that there is an abnormality from the detection signal from the off-surge detection circuit, it shuts off the corresponding common switching element and the individual switching element connected in series with the common switching element. A group energization / interruption means is provided, and the retreat operation is performed by an electromagnetic coil other than the group in which the individual switching elements are disconnected.

Further, the microprocessor may shorten the energization period of the drive signal pulse train if there is an overlap in the energization periods of the electromagnetic coils that follow each other when the abnormality determination is made due to the lack of the off-surge voltage. is there.

Further, the microprocessor is provided with an abnormality reporting means for receiving an abnormality signal and reporting the occurrence of the abnormality.
When it is determined from the detection signal from the off-surge detection circuit that there is an abnormality, an abnormality signal is output to the abnormality reporting means.

The microprocessor has an interface circuit for connection with an external tool.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. FIG. 1 is a detailed electric circuit diagram of a failure detection circuit of a fuel injection device according to Embodiment 1 of the present invention, and this configuration will be described below. In FIG. 1, the fuel injection control device 1 is mainly configured by a microprocessor 9, a first drive circuit 10, a second drive circuit 20 and the like, which will be described later. The power switch 2 connects between the voltage source 3 such as a vehicle battery and the fuel injection control device 1.

The sensor group 4 is a crank angle sensor for determining the timing of fuel injection, the injection amount (injection period), etc.
It is composed of a cam angle sensor, a throttle opening sensor, etc., and an input signal from the sensor group 4 is supplied to the microprocessor 9. The first to fourth electromagnetic coils 5 to 8 are drive-controlled by the first and second drive control circuits 10 and 20, and the electromagnetic coils 5 to 8 are provided in each cylinder of the engine shown in FIG. 3 described later. It is for controlling the opening and closing of the fuel injection valve.

Next, the components of the first drive control circuit 10 will be described. The common switching element 11 is a transistor or the like connected between one end of each of the first and fourth electromagnetic coils 5 and 8 and the voltage source 3, and the commutation diode 12 has a load side of the common switching element 11 and the voltage source 3. It is connected between the negative terminals of. The individual switching element 13 is the first electromagnetic coil 5 described above.
Is a transistor or the like that is connected to the other end of the fourth electromagnetic coil 8 and is closed in response to the individual drive signal SW1 output from the microprocessor 9. Similarly, the individual switching element 14 is connected to the other end of the fourth electromagnetic coil 8. A transistor or the like that closes in response to the individual drive signal SW3 output from the microprocessor 9.

The current detection resistor 15 is the individual switching element 1 described above.
It is connected between the terminals 3 and 14 and the negative side terminal of the voltage source 3 so that the individual switching elements 13 and 14 are not closed at the same time. The logical sum element 16 responds to the rapid overexcitation control signal SW13 output from the microprocessor 9 to make the common switching element 11 conductive, and turns on / off the common switching element 11 by an output signal of a logical product element 18 described later. OFF control.

Further, the logical sum element 17 outputs the individual drive signals SW1 and SW3 as input signals to the logical product element 18, and the weak current holding control circuit 19 is the first (or fourth).
ON for supplying a weak current (weak current for holding operation) for holding the operation of the electromagnetic coil 5 (or 8) of
This is an OFF control circuit. Therefore, the weak current holding control circuit 19 outputs the weak current holding control signal DT13 when the voltage across the current detection resistor 15 is equal to or lower than a predetermined value, and outputs the weak current holding control signal DT13 through the logical product element 18 and the logical sum element 16 to make a common switching element. 11 is conducted.

As components of the second drive control circuit 20, 21 to 29 are the same as 11 to 19 described above, SW4 indicates a signal corresponding to SW1, SW2 indicates a signal corresponding to SW3, and INJ2 indicates INJ1. , INJ3 represent electromagnetic coils corresponding to INJ4, and therefore description thereof is omitted here.

Next, the diode 31 has its anode connected to the connection point between the first electromagnetic coil 5 and the individual switching element 13, and the diode 32 has the anode connected to the connection point between the second electromagnetic coil 6 and the individual switching element 23. Are connected. Similarly, the diode 33 is connected to the connection point between the third electromagnetic coil 7 and the individual switching element 24, and the diode 34 is connected to the connection point between the fourth electromagnetic coil 8 and the individual switching element 14 at the anode.

The off-surge detection circuit 35 is a comparison circuit 35a.
And the voltage dividing resistors 35b and 35c are connected to the diode 3
The supply voltage from the cathodes 1, 33 is divided. The off-surge detection circuit 36 includes a comparison circuit 36a (not shown), and the voltage dividing resistors 36b and 36c (not shown) divide the supply voltage from the cathodes of the diodes 34 and 32.

Here, the comparison circuit 35a includes the voltage dividing resistor 3
When the divided voltage by 5b and 35c is equal to or higher than the voltage of the voltage source 3, the detection signal IN13 of the logic level "L" is generated and supplied to the microprocessor 9, and in the same manner, the comparison circuit 36a is divided by the voltage dividing resistor 36b. , 36c, the divided voltage is equal to or higher than the voltage of the voltage source 3, and a detection signal IN42 of logic level "L" is generated and supplied to the microprocessor 9.

The external tool 40 is for writing a control program to the microprocessor 9 and for reading and displaying the contents of a data memory (not shown). The interface circuit 41 is provided between the external tool 40 and the microprocessor 9. It is provided in between. The abnormality alarm / display device 42 is driven based on the abnormality signal of the microprocessor 9 or the like.

Next, FIG. 2 is a partial detailed view of a power feeding circuit for the first electromagnetic coil 5 in FIG. 1, and the configuration will be described below. In FIG.
The pull-down resistor 12a is connected in parallel with the commutation diode 12, and the constant voltage diodes 13a and 14a equivalently represent the OFF voltage limiting function of the individual switching elements 13 and 14, and the weak current Ih for holding operation is the first. This is the current flowing through the first electromagnetic coil 5.

The off-surge voltage Vs is generated when both the common switching element 11 and the individual switching element 13 are opened, and this off-surge voltage Vs is intended to maintain the weak current Ih for maintaining the operation that the first electromagnetic coil 5 has been flowing until now. Is generated by the back electromotive force, which is approximately equal to the limit voltage of the equivalent constant voltage diode 13a. However, the off-surge voltage Vs rapidly decreases as the weak current Ih for maintaining operation is attenuated, and the voltage is determined by the pull-down resistor 12a to become Vs = 0. In addition, when the individual switching element 13 is not opened due to a short circuit abnormality of the individual switching element 13 and the power supply is cut off by the common switching element 11, the commutation diode 12 and the individual switching element 13 are disconnected.
Since the commutation open circuit is formed by, the exciting coil is not rapidly cut off and the off-surge voltage Vs is not generated.

On the other hand, when the individual switching element 13 is open, when the individual switching element 14 is turned on to supply power to the fourth electromagnetic coil 8 and the common switching element 11 operates, the common switching element 11 operates. The power supply voltage Vb at the output terminal is generated as the output of the diode 31 and appears as an apparent off-surge voltage Vs, but the actual off-surge voltage Vs is larger than the power-supply voltage Vb (Vb <Vs). Therefore, it is possible to separate and extract by the above-mentioned comparison circuit 35a.

FIG. 3 is a cylinder layout diagram of the failure detection circuit of the fuel injection device shown in FIG. In FIG. 3, 50
Are crankshafts 51 to 54 of the engine, and the first to fourth cylinders of which fuel injection is performed by the electromagnetic coils 5 to 8. At the first time, the individual opening / closing element 13 and the common opening / closing element 11 operate to supply power to the first electromagnetic coil 5, so that fuel injection into the first cylinder 51 is performed.
Next, at the second time, the individual switching element 24 and the common switching element 2
1 operates to feed power to the third electromagnetic coil 7, fuel is injected into the third cylinder 53, and then, at the third time point, the individual opening / closing elements 14 and the common opening / closing elements 11 operate to operate the fourth electromagnetic element. The fourth power is supplied to the coil 8.
Fuel is injected into the cylinder 54, and at the fourth time point, the individual opening / closing elements 23 and the common opening / closing elements 21 operate and the second
Power is supplied to the electromagnetic coil 6 of the second cylinder 52.
Fuel injection is performed.

In the case of the above arrangement, the first cylinder 5
When the fuel injection of either the first or fourth cylinder 54 becomes abnormal, both the first cylinder 51 and the fourth cylinder 54 are stopped, and the evacuation operation by only the second cylinder 52 and the third cylinder 53 is performed. It is stable to perform, and the second cylinder 52 or the third cylinder 53
When any one of the fuel injections becomes abnormal, it is stable to stop both the second cylinder 52 and the third cylinder 53 and perform the retract operation with only the first cylinder 51 and the fourth cylinder 54. . The common switching elements 11 and 21 in FIG. 1 have a structure corresponding to such grouping. Also, FIG.
Individual drive signals SW1 to SW1 of the microprocessor 9 in
SW4 is a number according to the fuel injection sequence.

Next, FIG. 4 is a time chart for explaining the normal operation of the failure detection circuit of the fuel injection device according to the first embodiment. 4, FIG. 4A is an output characteristic of the rapid overexcitation control signal SW13 of the microprocessor 9, FIG.
4B shows the output characteristics of the weak current holding control signal DT13, FIG.
4C shows an output characteristic of the individual drive signal SW1 of the microprocessor 9, FIG. 4D shows an output characteristic of the individual drive signal SW3 of the microprocessor 9, and FIG. 4E shows a rapid overexcitation control signal SW42 of the microprocessor 9. Output characteristics, Fig. 4
(F) is an output characteristic of the weak current holding control signal DT42, FIG.
4G shows the output characteristic of the individual drive signal SW4 of the microprocessor 9, and FIG. 4H shows the output characteristic of the individual drive signal SW2 of the microprocessor 9.

The individual drive signals SW1 to SW4 generate outputs in sequence, and the rapid overexcitation signal SW13 generates an output signal for a short time in accordance with the output timing of the individual drive signals SW1 and SW3. Similarly, the rapid overexcitation signal SW42 generates an output signal for a short time in accordance with the output timing of the individual drive signals SW4 and SW2.

FIG. 4 (i) shows the current waveform of the first electromagnetic coil 5, which can be obtained by combining FIGS. 4 (a), (b) and (c). Similarly, FIG. 4 (j) shows a current waveform of the fourth electromagnetic coil 8, and FIG.
4B is obtained by combining FIG. 4B and FIG. 4D, and FIG. 4K shows the current waveform of the second electromagnetic coil 6.
Obtained by synthesizing (e), (f), and (g), as shown in FIG.
Shows the current waveform of the third electromagnetic coil 7,
4 (e), (f), and (h) are synthesized and obtained.

FIG. 4 (m) shows the output waveform of the diode 31, and when the current to the first electromagnetic coil 5 of FIG. 4 (i) is cut off, that is, the individual drive signal SW of FIG. 4 (c).
When the output of 1 is stopped (logic “L”), the off-surge voltage Vs is generated, and the waveform of the power supply voltage Vb based on the opening / closing operation of the common switching element 11 is generated while the fourth electromagnetic coil 8 is energized. Similarly, FIG. 4 (n) shows the output waveform of the diode 34, FIG. 4 (o) shows the output waveform of the diode 32, and FIG.
(P) shows the output waveform of the diode 33.

FIG. 4 (q) shows the waveform of the detection signal IN13. In FIGS. 4 (m) and 4 (p), the diodes 31 and 33 are shown.
Is at the logic level "L" when the off-surge voltage Vs is output. Similarly, FIG. 4 (r) shows the detection signal I
It is a waveform of N42, and is at the logic level "L" when the diodes 34 and 32 output the off-surge voltage Vs in FIGS. 4 (n) and 4 (o).

Next, specific failure detection by the failure detection circuit of the fuel injection control device in the first embodiment will be described. FIG. 5 is a simplified block diagram of the in-phase abnormality. The ground fault 60 shows a state in which the negative side terminal of the first electromagnetic coil 5 is connected to the negative side terminal of the voltage source 3, and when such a ground fault occurs, The current flowing through the electromagnetic coil 5 is not rapidly interrupted and the off surge voltage Vs is not generated. This is the same phenomenon as in the case of the short circuit abnormality of the individual switching element 13, and even when the power supply is cut off by the common switching element 11, the exciting current circulates through the commutation diode 12 and the ground fault circuit 60 or the shorted individual switching element. Therefore, the off-surge voltage Vs does not occur.

Further, the load short circuit 61 is caused by the fourth electromagnetic coil 8
Shows a state in which the positive and negative terminals are short-circuited, and when such a load short-circuit 61 occurs, the exciting current does not flow in the electromagnetic coil 8, so that the off-surge voltage Vs does not occur when the individual switching element 14 is opened. When the load is short-circuited, the individual switching elements 13, 14, 23, 24 and the common switching element 1
1, 21 are protected by the overcurrent protection function of their own for a short time, and are protected from being burned by the microprocessor 9 releasing the drive command signal. Reference numerals 62 to 64 indicate open circuit breaks. When a wire break, a coil break, an open failure of the switching element, etc. occur, the exciting current to the electromagnetic coils 6 and 7 stops flowing, and an off surge occurs when the individual switching elements 23 and 24 open. The voltage Vs does not occur.

FIG. 6 is a time chart for explaining the operation when the ground fault is abnormal in FIG. 5, and the difference from the time chart of the normal operation shown in FIG. 4 will be mainly described.
The abnormal current waveform 65 shown in FIG. 6 (i) shows that the weak current drive control for maintaining the operation is performed because the exciting current for the first electromagnetic coil 5 does not flow through the current detection resistor 15 (see FIG. 1) due to the ground fault 60. It shows a current waveform which is not broken. Also,
The overlapping current waveform 66 is almost the same current as that of the fourth electromagnetic coil 8 of FIG. 6 (j), and is a current that does not originally flow in the first electromagnetic coil 5 that is grounded by the operation of the common switching element 11. Is flowing.

The missing surge voltage 67 shown in FIG.
0 indicates that the exciting current of the first electromagnetic coil 5 is not rapidly interrupted, and thus the off-surge voltage Vs that should be generated is not generated. In addition, FIG.
The missing signal 68 of (q) indicates a state in which there is no detection signal that should originally occur due to the missing surge voltage 67.

When the lack of the off-surge voltage Vs due to the abnormality in each phase is detected as described above, the common switching element of the missing phase and all the individual switching elements connected in series with the common switching element are detected as will be described later with reference to FIG. The elements are shut off, and the remaining group of electromagnetic coils performs fuel injection as a retreat operation. However, the off surge voltage V in both groups
When s is missing, all the switching elements are shut off and the engine cannot be operated.

Further, FIG. 7 is a simplified block diagram regarding the interphase abnormality. In FIG. 7, an interphase short circuit 70 shows a state in which the negative side terminals of the first and fourth electromagnetic coils 5 and 8 are short-circuited.
An interphase short circuit 71 indicates a state in which the negative side terminals of the second and fourth electromagnetic coils 6 and 8 are short-circuited. The inter-phase short circuit 70 is an intra-group inter-phase short circuit generated between electromagnetic coils driven by the same common switching element 11, and the inter-phase short circuit 71 is an inter-group inter-phase short circuit generated between electromagnetic coils driven by different common switching elements. Has become.

FIG. 8 is a time chart for explaining the operation when the intra-group short circuit is abnormal in FIG. 7, and the difference from the time chart of the normal operation shown in FIG. 4 will be mainly described. In the abnormal current waveforms 72 and 75 of FIGS. 8 (i) and 8 (j), the operation-holding weak current Ih is halved as a result of the interphase short circuit 70 connecting the first and fourth electromagnetic coils 5 and 8 in parallel. It shows the state.

The overlapping current waveforms 73 of FIGS. 8 (i) and 8 (j),
Reference numeral 74 indicates an extra overlapping current waveform that should not flow originally as a result of the first and fourth electromagnetic coils 5 and 8 being connected in parallel by the interphase short circuit 70. Figure 8
The overlapping surge voltages 76 and 77 in (m) and (n) indicate the off-surge voltage Vs associated with the interruption of the overlapping current waveforms 73 and 74, and the overlapping signals 78 and 79 in FIGS. The duplication detection signal accompanying the surge voltages 76 and 77 is shown.

FIG. 9 is a time chart for explaining the operation when the inter-phase short circuit between the groups in FIG. 7 is abnormal, and the difference from the time chart of the normal operation shown in FIG. 4 will be mainly described. In the inter-phase short circuit across groups such as the inter-phase short circuit 71, all the individual switching elements 13, 14, 23, 2 are connected.
4 is in a state where they do not conduct simultaneously with each other (that is, the fuel injection period is relatively short), the electromagnetic coils 5 to 8 are all controlled normally, and the same operation as the time chart of FIG. 4 is performed. However, instead, it is also impossible to detect an interphase short circuit abnormality. On the other hand, a time chart in the case where the fuel injection period is long and electromagnetic coils in adjacent orders may be energized simultaneously is shown in FIG.

In the damping current waveform 80 of FIG. 9 (j), after the individual switching element 14 and the common switching element 11 are opened, the operation maintaining weak current Ih flowing in the fourth electromagnetic coil 8 is the commutation diode. 12 and phase short circuit open circuit 71 and individual switching element 23
Shows the state of being attenuated through. The missing surge voltage 81 in FIG. 9 (n) indicates a state in which the off-surge voltage Vs, which should be generated originally, is not generated because the fourth electromagnetic coil 8 is not shut off at high speed. Similarly, FIG.
The missing signal 82 in (r) shows a state in which a detection signal that should originally be generated is not generated due to the influence of the missing surge voltage 81.

There are four types of inter-phase short circuit abnormalities that cross the groups relating to the negative side wiring of the electromagnetic coil as described above, but in any case, on the preceding operating side of the electromagnetic valve that operates in chronological order. Since the off surge voltage Vs is lost, if the common switching element or the individual switching element that drives the preceding operation side electromagnetic coil is cut off, the same countermeasure method as in the case of the in-phase abnormality of FIG. It is convenient to be unified.

However, for such a phase-to-phase short circuit between the groups, if the fuel injection period is shortened so that the injection periods do not overlap, it is not necessary to shut off the common switching element or the individual switching elements. Even if the individual opening / closing element is cut off, the common opening / closing element on the lagging operation side or the individual opening / closing element may be used.

The overall operation of the failure detection circuit of the fuel injection device according to the first embodiment described above will be described with reference to the flowchart showing the operation of the microprocessor 9 shown in FIG. In FIG. 10, 100 is an operation start step, 101 is a step following the start step 100, and a step for determining the presence or absence of a reset command from the external tool 40, and 102 is a RAM memory in the microprocessor 9 when the determination step 101 is YES. Step for resetting the failure information stored in step 103, step 1
02 ends, or if the step 101 is NO and the external tool 40 is not connected, or is connected but does not issue a reset command, it is determined whether or not there is a read instruction from the external tool 40. It is a step.

The step 104 is a step for transmitting the failure information stored in the RAM memory in the microprocessor 9 to the external tool 40 when the decision step 103 is YES, and the step 105 is for ending the operation of the step 104 or the above step 103. Is NO and the external tool 40 is not connected, or if it is connected but does not issue a read command, it is a step of determining whether the individual drive signals SW1 to SW4 are being generated. Step 10
When 5 is NO and fuel injection is not performed, the process proceeds to the end step 106 and returns to the start step 100 again.

Reference numeral 107 denotes individual drive signals SW1 to SW4 that repeatedly operate when step 105 is YES.
The step 108 of updating and acquiring the latest occurrence status of the signal, 108 is a step of updating and acquiring the latest input status of the detection signals IN13 and IN42 following step 107, and 110 is the step of falling of the individual drive signals SW1 to SW4 following step 108. Immediately after the edge (the time point when the logic changes from “H” to “L”), it is determined whether or not the detection signals IN13 and IN42 are missing. 111 is a step 105 when the determination step 110 is YES. In the updated drive signal pulse train, a step of determining whether or not the energization periods of the electromagnetic coils that are driven one after another in time overlap, 112 indicates this state if the determination step 111 is YES. Is stored and the energization period is shortened and an alarm / display output is issued to the abnormality alarm / display device 42. A step of, the stored information is arranged to continue storing until reset by step 102.

When the step 111 is NO, 113 is a missing of the off surge voltage Vs due to which phase of the electromagnetic coil depending on which individual drive signal the missing of the off surge voltage Vs of the above step 110 corresponds to. Step 114 for deterministically storing whether or not there is a step, 114 is a step for shutting off the common switching element for driving the electromagnetic coil of the off surge voltage missing phase, 115 is a step for generating an alarm / display output to the abnormality alarm / display device 42 It is a step to do. When step 115 is completed or step 110 is NO, or when the operation of step 112 is completed, the process proceeds to step 120.

In step 113, an in-phase failure such as a short circuit, disconnection, or opening of the electromagnetic coil or wiring / driving element is detected, and in step 114, the common switching element 11 (or 2) is opened.
In addition to shutting off 1), for safety, individual switching elements 13,
Group energization interruption is also performed in which 14 (or 23, 24) is also interrupted. Further, in step 112, there is no energization overlapping period of the electromagnetic coils before and after each other, which is an injection period suppressing means for preventing an abnormal occurrence in the inter-group short circuit 71 in FIG.

Reference numeral 120 is a step for determining whether or not the excessive detection signals IN13 and IN42 have been overlapped immediately after the falling edges of the individual drive signals SW1 to SW4 (at the time of change from logic "H" to "L"). , 121 is a step of definitely storing which phase of the electromagnetic coil is short-circuited depending on which individual drive signal overlaps the off-surge voltage Vs when the determination step is YES. 122 is a step following step 121, which is a step of shutting off the common switching element that drives the electromagnetic coil short-circuited between phases, and 123 is a step of generating an alarm / display output to the abnormality alarm / display device 42. Is this step 123 completed or the above step 120 is NO.
If it is, the process proceeds to the end step 106 and then to the start step 100 again.

At step 121, for example, for the intra-group short circuit 70 between phases, it is considered that the first and fourth electromagnetic coils 5 and 8 are abnormal, and at step 122, the common switching element 11 is cut off. For safety, the individual switching elements 13 and 14 are also cut off to cut off the group energization. In addition, the above steps 113 and 121
The electromagnetic coil number or the cylinder number of the engine for which the abnormality has been determined by the above is stored in the RAM memory held by the battery or the non-volatile memory such as the EE-PROM, and is read out and displayed in step 104 at the time of maintenance inspection. The initialization is reset in step 102.

Embodiment 2. FIG. 11 is a detailed electric circuit diagram of the failure detection circuit of the fuel injection device according to the second embodiment of the present invention, and the differences from the first embodiment will be mainly described.

In FIG. 11, the first drive control circuit 10
Then, the high-voltage side switching element 11a has a rapid overexcitation control signal SW.
The energization is controlled by 13, and the low-voltage side switching element 11b is energized in response to the weak current holding control signal DT13 output by the weak current holding control circuit 19 similar to that of the first embodiment. The booster circuit 11c is a circuit that boosts the voltage of the voltage source 3. The diode 16a is the booster circuit 1 described above.
Power is supplied from 1c to the first and fourth electromagnetic coils 5, 8 via the high-voltage side switching element 11a. On the other hand, diode 1
6b supplies electric power from the voltage source 3 to the first and fourth electromagnetic coils 5 and 8 via the low voltage side switching element 11b. In FIG. 11, the common switching element 11 shown in FIG. 1 is in a state of being divided into a high voltage side switching element 11a and a low voltage side switching element 11b, but both are the first and fourth electromagnetic coils 5, 8 It is still a common switching element that supplies power to. The second drive control circuit 20 also has the above first
Since the drive control circuit 10 has the same configuration as that of the drive control circuit 10, the description thereof is omitted here.

Next, the operation of the above configuration will be described in detail. In the failure detection circuit of the fuel injection device having the configuration shown in FIG. 11, the voltage source 3 is, for example, a DC12V system vehicle battery, while the booster circuits 11c and 21c are used.
Generates a high voltage source of, for example, DC12V to DC120V to rapidly drive the electromagnetic coil. The low-voltage side switching elements 11b and 21b are for supplying a weak current Ih for holding the operation of the electromagnetic coil, and by directly supplying power from the voltage source 3, the temperature rise of the booster circuits 11c and 21c is suppressed. In the failure detection circuit according to the second embodiment, since the exciting currents of the electromagnetic coils 5 to 8 are reduced as compared with the failure detection circuit according to the first embodiment, the temperature rise of the common switching element and the individual switching elements is reduced. Can be made.

Embodiment 3. FIG. 12 shows a detailed electric circuit diagram of a failure detection circuit of the fuel injection device according to the third embodiment of the present invention, and the description will focus on the differences from that of FIG. In FIG. 12, a booster circuit 11d is a circuit for boosting the power supply voltage by the voltage source 3, the high-voltage side switching element 11a is energized by a rapid overexcitation control signal SW13, and the low-voltage side switching element 11b is a weak current holding control signal D.
The energization is controlled in response to T13. Diode 16
a supplies power to the first and fourth electromagnetic coils 5 and 8 from the booster circuit 11d through the high voltage side switching element 11a, while the diode 16b supplies the low voltage side switching element 1 from the voltage source 3.
Power is supplied to the first and fourth electromagnetic coils 5 and 8 via 1b.

Similarly, the high voltage side switching element 21a is energized by the rapid overexcitation control signal SW42, and the low voltage side switching element 21b is energized by responding to the weak current holding control signal DT42. The diode 26a is the booster circuit 21.
power is supplied from d to the second and third electromagnetic coils 6 and 7 via the high-voltage side switching element 21a, while the diode 26b is supplied.
Supplies power to the second and third electromagnetic coils 6 and 7 from the voltage source 3 via the low-voltage side switching element 21b. In the range of the above description, the booster circuit 11 is different from that of the second embodiment.
The only difference is that c and 21c are shared to form a common booster circuit 11d.

Subsequently, the pull-down resistor 12a is connected in parallel with the commutation diode 12, and the voltage dividing resistors 12b and 1b are connected.
2c is for dividing the voltage of the voltage source 3. A correction resistor 12d is connected between the pull-down resistor 12a and the voltage dividing resistor 12c, and the voltage of the voltage dividing resistor 12c is the comparison circuit 4
It is applied to the non-inverting input terminals of 3,44. The resistance value R12a of the pull-down resistor 12a is the resistance values R12b, R of the other voltage dividing resistors 12b, 12c and the correction resistor 12d.
12c and R12d are set to a sufficiently small value.

Similarly, the pull-down resistor 22a is connected in parallel with the commutation diode 22, and the voltage dividing resistor 22a
Reference numerals b and 22c divide the voltage of the voltage source 3. The correction resistor 22d includes the pull-down resistor 22a and the voltage dividing resistor 2
2c, and the voltage of the voltage dividing resistor 22c is applied to the non-inverting input terminals of the comparison circuits 45 and 46. The resistance value R22a of the pull-down resistor 22a is the resistance value R22 of the other voltage dividing resistors 22b and 22c and the correction resistor 22d.
b, R22c, and R22d are set to sufficiently small values.

13b is a diode for off-surge detection,
13c and 13d are voltage dividing resistors,
b and the voltage dividing resistors 13c and 13d are connected in series with each other and connected between the negative side terminal of the first electromagnetic coil 5 and the negative side terminal of the voltage source 3, and the voltage of the voltage dividing resistor 13d is the inverting input of the comparison circuit 43. Applied to the terminal. Similarly, 14b, 23b, 2
4b is a diode for off-surge detection, 14c, 14
Reference numerals d, 23c, 23d, 24c, and 24d denote voltage dividing resistors, and the same applies to the voltage dividing resistors 14d and 23.
The voltages of d and 24d are applied to the inverting input terminals of the comparison circuits 44 to 46.

The OR circuit 37 is the comparison circuit 43.
Whichever of the outputs of the comparators 46 or 46 becomes the logic level "L", the detection signal IN13 of the logic level "L" is supplied to the microprocessor 9, and the OR circuit 38 similarly outputs either of the comparison circuits 44 or 45. Even if the output becomes the logic level "L", the detection signal IN42 of the logic level "L" is supplied to the microprocessor 9. The off-surge detection circuit 39 includes the comparison circuits 43 and 44 and the comparison circuits 45 and 46.
It is composed by.

Next, the operation of the above configuration will be described focusing on the operation of the comparison circuit 43. First, the high-voltage side switching element 11a and the individual switching element 13 are conducted, the first electromagnetic coil 5 operates at high speed, and subsequently the high-voltage side switching element 11a is cut off and the low-voltage side switching element 11b weakens the operation. Current control is performed. Eventually, when the individual drive signal SW1 becomes the logical level “L” and the low-voltage side switching element 11b and the individual switching element 13 are cut off, the negative surge terminal shown in FIG. Vs is generated, and the divided voltage by the voltage dividing resistors 13c and 13d is supplied to the inverting input terminal of the comparison circuit 43.

On the other hand, the voltage at the non-inverting input terminal of the comparison circuit 43 at this point is that the voltage across the pull-down resistor 12a is approximately 0 V, so the power supply voltage is the resistance value R12.
It is a low value divided by b and (R12c // R12d). Where (R12c // R12d) is the resistance R1
It is a parallel combined resistance of 2c and R12d. Therefore, as the input voltage of the comparison circuit 43, the voltage on the non-inverting input terminal side is lower than that on the inverting input terminal side, and the output of the comparison circuit 43 generates a normal detection signal of logic level "L".

However, the short circuit 140 causes the first
When the connection point of the fourth electromagnetic coils 5 and 8 is short-circuited to the power supply line, the divided voltage applied to the non-inverting input terminals of the comparison circuits 43 and 44 changes the power supply voltage to the resistance value (R12b // R12).
d) and R12c are divided into high values. Where (R
12b // R12d) is a parallel combined resistance of the resistors R12b and R12d. Therefore, the input voltage of the comparison circuit 43 is high on the non-inverting input terminal side, the output of the comparison circuit 43 is at the logic level "H", and the off surge detection is not performed.

In this way, the fault detection circuit of the fuel injection device shown in FIG. 12 can detect a short circuit abnormality on the common switching element side, and the same applies to other electromagnetic coils. With respect to this short circuit abnormality, the missing phase is definitely stored in step 113 of FIG. 10, and the common switching element 11 and the individual switching element 1 are processed in step 114.
3, 14 will be blocked and held.

Further, when the connection common point of the first and fourth electromagnetic coils 5 and 8 and the connection common point of the second and third electromagnetic coils 6 and 7 are short-circuited and connected by the short circuit 141 between the groups. When there is no overlap in the energization periods of the electromagnetic coils that are adjacent to each other, no abnormality occurs and the presence of the short circuit 141 is not detected. On the other hand, when there is an overlap in the energization periods of the electromagnetic coils that are adjacent to each other, the comparison open circuits 13b, 14b, and 23 of FIG.
Since the voltage at the non-inverting input terminals of b and 24b is high, the off-surge voltage Vs cannot be detected.
In step 112 of 0, the energization period is shortened, and the escape operation is performed by this treatment.

Fourth Embodiment In the first to third embodiments described above, the evacuation operation method is used to cope with the inter-phase short circuit between the groups by suppressing the injection period. However, the common switching element or the like is cut off without performing the injection period suppressing process. The group energization may be cut off by. Also, although the description has been given using a 4-cylinder engine, even in the case of a 6-cylinder or 8-cylinder engine, a common switching element of 2 groups is used, or 3 groups (6 cylinders) or 4 groups (8 cylinders) are used. It is also possible to use a common switching element for each group.

Further, when the engine is a gasoline engine and the fuel injection control device includes the ignition control function of the engine, in addition to the correction of the fuel injection control in the thinning operation when an abnormality occurs, the ignition timing is also added. It is possible to improve so that more stable evacuation operation can be performed by also performing the correction of. In addition, the abnormality alarm / display device is based on, for example, an indication that thinning operation is in progress, a state where there is an abnormality in all groups and fuel injection is completely stopped, or disconnection / short circuit / misfire of the ignition device group. It is also possible to comprehensively and hierarchically warn and display measures for stopping fuel injection.

[0075]

As described above, according to the failure detection circuit of the fuel injection device according to the present invention, the fuel injection control electromagnetic coil and its switching element are provided by a simple off-surge detection circuit.
Not only can short-circuits, disconnections, and opens of wiring be detected collectively, but also an intersurge short-circuit failure can be detected by the off-surge lack determination means and the overlap determination means. Moreover,
Stable evacuation operation can be performed by grouping by the common switching element.

Further, since the current control for the electromagnetic coil is performed on the common switching element side, the off-surge voltage can be easily detected by monitoring the voltage across the individual switching elements.

Since the off-surge voltage is detected by the potential across the electromagnetic coil, it is possible to easily detect a short circuit abnormality between the common switching elements and a mutual short circuit between the groups.

Further, since the off-surge detection circuit is appropriately OR-combined by the OR circuit, it is possible to judge the overlap of the off-surge voltage, and further it is possible to reduce the number of input points of the microprocessor and the hardware.

Since the common switching element alone performs the rapid over-excitation control and the weak current control for maintaining the operation, the power supply control circuit is simplified and the withstand voltage of the electromagnetic coil may be low.

Further, since the common switching element is divided to perform rapid over-excitation with a high voltage and operation holding control with a low voltage, the amount of current to the common switching element is reduced, heat generation is reduced, and the device is downsized. Can be converted.

Further, since a single over-excitation booster circuit is used to enable rapid over-excitation for all the electromagnetic coils, there is an effect that the device can be made compact and inexpensive.

Further, when the common switching elements are shut off due to the occurrence of an abnormality, proper grouping is performed.
A stable retract operation can be performed by the electromagnetic coil connected to the remaining common switching element.

Further, by taking measures to shorten the energization period of the drive signal pulse train for short circuit abnormality between different groups, a more stable retreat operation can be performed.

Further, since the alarm / display is carried out based on the occurrence of the off / surge abnormality of the off-surge voltage, the warning can be given for any generally assumed failure and the safety can be improved.

Further, since the microprocessor is provided with the interface circuit for connection with the external tool, the efficiency of maintenance and inspection work can be improved by reading and displaying the identification information of the electromagnetic coil in which the abnormality has occurred on the external tool. , The stored information can be easily initialized from an external tool.

[Brief description of drawings]

FIG. 1 is a detailed electric circuit diagram of a failure detection circuit of a fuel injection device according to a first embodiment of the present invention.

FIG. 2 is a partial detailed view of a failure detection circuit of the fuel injection device according to the first embodiment of the present invention.

FIG. 3 is a cylinder layout diagram of a failure detection circuit of the fuel injection device according to the first embodiment of the present invention.

FIG. 4 is a time chart during normal operation of the failure detection circuit of the fuel injection device according to the first embodiment of the present invention.

FIG. 5 is a simplified block diagram when an in-phase abnormality occurs in the failure detection circuit of the fuel injection device according to the first embodiment of the present invention.

FIG. 6 is a time chart at the time of a ground fault abnormality in the failure detection circuit of the fuel injection device according to the first embodiment of the present invention.

FIG. 7 is a simplified block diagram when an interphase short circuit abnormality occurs in the failure detection circuit of the fuel injection device according to the first embodiment of the present invention.

FIG. 8 is a time chart when an intra-group short circuit abnormality occurs in the failure detection circuit of the fuel injection device according to the first embodiment of the present invention.

FIG. 9 is a time chart at the time of abnormalities in a short circuit between group external phases in the failure detection circuit of the fuel injection device according to the first embodiment of the present invention.

FIG. 10 is an operation flowchart in the failure detection circuit of the fuel injection device according to the first embodiment of the present invention.

FIG. 11 is a detailed electric circuit diagram of a failure detection circuit of the fuel injection device according to the second embodiment of the present invention.

FIG. 12 is a detailed electric circuit diagram of a failure detection circuit of the fuel injection device according to the third embodiment of the present invention.

[Explanation of symbols]

1 Fuel Injection Control Device, 2 Power Switch, 3 Voltage Source, 4 Sensor Group, 5-8 Electromagnetic Coil, 9 Microprocessor, 10 First Drive Control Circuit, 11 Common Switching Element, 11a High Voltage Side Common Switching Element, 11b Low Voltage Side Common switching element, 11c booster circuit, 11d common booster circuit, 12 commutation diode, 12a pull-down resistor,
13, 14 Individual switching elements, 13a, 14a constant voltage diode, 13b, 14b Off surge detection diode, 13c, 13d, 14c, 14d Voltage dividing resistor, 15
Current detection resistor, 16, 17 OR element, 18 AND element, 19 weak current holding control circuit, 20 second drive control circuit, 21 common switching element, 21a high voltage side common switching element, 21b low voltage side common switching element, 21c Step-up circuit, 22 Commutation diode, 23, 24 Individual switching element, 23b, 24b Off surge detection diode, 2
3c, 23d, 24c, 24d voltage dividing resistance, 25 current detection resistance, 26, 27 OR element, 28 AND element,
29 weak current holding control circuit, 31-34 diode,
35 off-surge detection circuit, 35a comparison circuit, 35
b, 35c Voltage dividing resistor, 36 Off surge detection circuit, 3
6a Comparator circuit, 36b, 36c Voltage dividing resistors, 37, 3
8 OR circuit, 39 OFF surge detection circuit, 40 external tool, 41 interface circuit, 42 abnormality alarm / display device, 43-46 comparison circuit, 50 crankshaft, 51-54 cylinder, 60 ground fault, 61 load short-circuit, 62- 64 disconnection circuit, 65 abnormal current waveform, 66
Overlapping current waveform, 67 Missing surge voltage, 68 Missing signal, 70, 71 Phase short circuit, 72 Abnormal current waveform, 7
3,74 overlapping current waveform, 75 abnormal current waveform, 76,
77 overlapping surge voltage, 78, 79 overlapping detection signal, 8
0 decay current waveform, 81 missing surge voltage, 82 missing signal.

Continued front page    F term (reference) 3G084 AA03 BA11 DA26 DA27 DA28                       DA33 EA07 EA11 EB22 EB23                       FA10 FA38 FA39                 3G301 HA06 JB01 JB02 JB07 LB02                       LC01 LC10 MA11 NA07 NB06                       NB18 PA11Z PE03Z PE04Z                       PG02Z

Claims (11)

[Claims] 1. A plurality of electromagnetic coils for driving a fuel injection electromagnetic valve for each cylinder of a multi-cylinder engine, a microprocessor for generating a drive signal pulse train and a rapid over-excitation control signal, and a drive signal pulse train from the microprocessor. In response to a rapid overexcitation control signal from the microprocessor and a plurality of individual switching elements that sequentially open and close to drive the corresponding electromagnetic coils, and the fuel injection sequence is at least two strokes apart. The off-surge voltage generated when the common switching elements of multiple groups that collectively drive the electromagnetic coils in the group consisting of multiple electromagnetic coils and the individual switching elements corresponding to the electromagnetic coils of at least different groups are opened. And a plurality of off-surge detection circuits for detecting, By comparing the detection signal from the off-surge detecting circuit number, the failure detection circuit of the fuel injector, characterized in that the abnormality determination by the lack and the presence or absence of overlap of the detection signal. 2. The failure detection circuit for a fuel injection device according to claim 1, wherein in each of the off-surge detection circuits, a voltage value between both ends of the individual switching element is a voltage value of a voltage source when the individual switching element is opened. A failure detection circuit for a fuel injection device, wherein the off-surge voltage is detected by detecting that the fuel cell has exceeded the limit. 3. The failure detection circuit for a fuel injection device according to claim 1, wherein each of the off-surge detection circuits has a voltage at a negative terminal of the electromagnetic coil when the individual switching element and the common switching element are opened. By detecting that the voltage is higher than the voltage of the power supply terminal connected to the common switching element,
A failure detection circuit for a fuel injection device, which detects the off-surge voltage. 4. The failure detection circuit for a fuel injection device according to claim 1, wherein the common switching element logically combines the detection signals output from the off-surge detection circuits for the electromagnetic coils of different groups. A failure detection circuit for a fuel injection device, wherein the microprocessor determines an abnormality based on an output of the OR circuit. 5. The failure detection circuit for a fuel injection device according to claim 1, wherein each of the common switching elements holds a rapid overexcitation control signal from the microprocessor and an operation of the electromagnetic coil. Failure detection circuit for a fuel injection device, characterized in that it responds to the weak current holding control signal of the above. 6. The failure detection circuit for a fuel injection device according to claim 1, further comprising: an over-excitation step-up circuit for stepping up a power supply voltage, wherein the common switching element includes the voltage coil via the over-excitation step-up circuit. And a low-voltage side switching element that drives and drives the electromagnetic coil in response to a weak current holding control signal for holding the operation of the electromagnetic coil. Injection device failure detection circuit. 7. The failure detection circuit for a fuel injection device according to claim 6, wherein each high-voltage side switching element shares the over-excitation booster circuit, and the over-excitation booster circuit is provided for all electromagnetic coils. A failure detection circuit for a fuel injection device, characterized in that it is commonly used. 8. The failure detection circuit for a fuel injection device according to claim 1, wherein when the microprocessor determines that there is an abnormality from a detection signal from the off-surge detection circuit, the corresponding common switching element and Failure detection of a fuel injection device, comprising group energization cutoff means for cutting off individual switching elements connected in series with the common switching element, and performing retreat operation by electromagnetic coils other than the group in which the individual switching elements are cut off circuit. 9. The failure detection circuit for a fuel injection device according to claim 8, wherein when the microprocessor determines an abnormality due to a lack of the off-surge voltage, if there is an overlap between the energization periods of the electromagnetic coils that follow each other. A failure detection circuit for a fuel injection device, characterized in that the power supply period of the drive signal pulse train is shortened. 10. The failure detection circuit for a fuel injection device according to claim 1, further comprising an abnormality reporting means for reporting the occurrence of an abnormality upon receipt of an abnormal signal, wherein the microprocessor outputs the abnormality from the off-surge detection circuit. A failure detection circuit for a fuel injection device, which outputs an abnormality signal to the abnormality reporting means when it is determined from the detection signal that the abnormality has occurred. 11. The failure detection circuit for a fuel injection device according to claim 1, wherein the microprocessor includes an interface circuit for connection with an external tool.