CN1292160C - Fault detecting circuit of fuel injection device - Google Patents

Abstract

The present invention discloses a fault detection circuit of a fuel injection device, which is provided with a common switching element (11 or 21) that feeds electromagnetic coils (5 and 8 or 6 and 7) for driving solenoid valves in intervals in the fuel injection sequence, The independent switching elements (13, 14, 23, 24) corresponding to each electromagnetic coil (5-8), and the surge of the logic sum of the open-circuit surge voltage signal (Vs) generated when the electromagnetic coils of different groups are energized and cut off The voltage detection circuit (35, 36), according to the absence judgment and repetition judgment of the open-circuit surge voltage signal corresponding to the driving signal pulse train generated by the microprocessor (9), stops outputting the voltage corresponding to the electromagnetic coil (5-8). The drive signal pulses to switch off the common switching element (11 or 12). Provides a simple fault detection circuit for a fuel injection device that detects abnormality of each phase and short circuit between phases of a drive circuit for a fuel injection solenoid valve for each cylinder of a multi-cylinder engine to enable emergency operation.

Description

Fault detection circuit of fuel injection device

technical field

The present invention relates to a fault detection circuit for a fuel injection device such as a vehicle-mounted multi-cylinder engine, and particularly relates to detection of a disconnection or short circuit of an electromagnetic coil for driving a solenoid valve for fuel injection, and detection of a disconnection or short circuit of a driving element and wiring of the electromagnetic coil, etc. The fault detection circuit of the fuel injection device for abnormal alarm and display for emergency operation (escaping operation).

Background technique

Generally, quick overexcitation control and operation holding control using weak current are used to control the solenoid coil that drives the solenoid valve for fuel injection, thereby improving the responsiveness of the solenoid valve and suppressing temperature rise. In conventional methods, disconnection and short-circuit faults of electromagnetic coils, wiring, switching elements, etc. are detected by monitoring the voltage and current of each part of the electromagnetic coil drive circuit. Furthermore, it is known to logically sum the fault detection signals for multi-channel loads to simplify signal processing.

Japanese Patent Laid-Open Publication No. 10-257799 "Output Open Circuit Detection Device of Multi-channel Output Device" shows the concept that for a multi-channel load such as an excitation coil of a stepping motor, the load is supplied with power when the load is not driven. A small current causes the load circuit to be disconnected, and the voltage across the load rises, and the disconnection is detected by this rise. Although it does not discuss the short-circuit detection of the load, it reveals such a concept that a disconnection detection signal is supplied to a common comparison and judgment circuit using a diode OR circuit.

On the contrary, Japanese Patent Laid-Open No. 62-290111 "Fault Detection Circuit of Fuel Injection Valve Drive Circuit for Internal Combustion Engine" shows such a concept, that is, by detecting the open circuit surge that occurs when the electromagnetic coil for fuel injection valve drive is energized and disconnected Voltage, to batch detect disconnection and short circuit faults of electromagnetic coils, wiring and switching elements.

Japanese Patent Laying-Open Publication No. 9-112735 "Solenoid Valve Driving Device" has shown such a concept: Regarding the solenoid coil for driving the solenoid valve for fuel injection, a boost circuit for fast driving and a weak current circuit for holding function are set, The charge voltage and discharge voltage of the capacitor in the booster circuit are used to detect disconnection and short circuit of multiple electromagnetic coils and wiring.

In particular, this example shows a concept of grouping a plurality of solenoid coils for driving fuel injection valves and performing emergency operation smoothly based on the failure judgment result.

In addition, Japanese Patent Laying-Open No. 10-318025 "Injector Control Device for Fuel Injection" shows the concept that one end of a plurality of injector coils whose fuel injection sequence is separated by more than two strokes and whose energization time does not overlap with a common The drive output circuit is connected, and the other end is connected to each switch device that performs ON/OFF in the energization sequence of each injector coil to realize switch control.

Japanese Patent Laying-Open No. 12-380652 "Abnormality Detection Device of Vehicle Electric Load Drive System" provides such a method, that is, the logic and processing abnormality detection signals are separated and detected within the microprocessor. This concept is also employed in the present invention.

Contents of the invention

In the above-mentioned background art, abnormality detection methods related to various methods such as disconnection and short circuit of electrical loads such as electromagnetic coils and disconnection and short circuit of switching control elements and wiring of the electromagnetic coils are proposed.

However, no matter what kind of technology is used in the past, there is such a problem: for the various abnormalities that are set for multiple electrical loads, including abnormalities such as phase-to-phase short-circuit and grounding, the system has not yet been configured as a Fault detection circuit for abnormal judgment.

The present invention is made to solve the above-mentioned problems and to provide devices including countermeasures and processing methods in fault detection, and its purpose is to provide a drive circuit for a solenoid valve for fuel injection in each cylinder of a multi-cylinder engine. It is a simple fault detection circuit of the fuel injection device that detects abnormality of each phase and phase-to-phase short-circuit abnormality for emergency operation.

The fault detection circuit of the fuel injection device of the present invention includes:

a plurality of electromagnetic coils for driving a solenoid valve for fuel injection for each cylinder of the multi-cylinder engine;

A microprocessor that generates drive signal pulse trains and fast overexcitation control signals;

sequentially driving a plurality of independent switching elements for switching the plurality of electromagnetic coils according to the driving signal pulse train generated from the microprocessor;

According to the fast overexcitation control signal generated from the microprocessor, multiple sets of common switching elements are collectively fed and driven to at least the electromagnetic coils in a group consisting of a plurality of electromagnetic coils separated by more than two strokes in the fuel injection sequence ;

a plurality of open circuit surge voltage detection circuits for detecting at least open circuit surge voltages generated when individual switching elements corresponding to different sets of electromagnetic coils are opened,

The microprocessor compares the detection signals generated from the plurality of open circuit surge voltage detection circuits, and determines abnormality according to whether the detection signals are missing or repeated.

In addition, each of the open-circuit surge voltage detection circuits detects the open-circuit surge voltage by detecting whether the voltage value at both ends of the independent switching element exceeds the voltage value of the voltage source when the independent switching element is open-circuited. .

In addition, each of the open-circuit surge voltage detection circuits detects whether the terminal voltage of the negative terminal of the electromagnetic coil is higher than that of the feeder connected to the common switching element when the independent switching elements and the common switching element are open-circuited. terminal voltage to detect the open circuit surge voltage.

In addition, the fault detection circuit of the fuel injection device of the present invention further includes:

a logical sum circuit for performing logical sum processing on the detection signals output by the open circuit surge voltage detection circuits for the electromagnetic coils of the different groups of the common switching elements,

The microprocessor determines an abnormality based on the output of the logic sum circuit.

In addition, each of the common switching elements operates in response to a fast overexcitation control signal from the microprocessor and a weak current hold control signal for maintaining the operation of the electromagnetic coil.

In addition, the fault detection circuit of the fuel injection device of the present invention further includes:

A booster circuit for overexcitation that boosts the power supply voltage,

The common switching element is composed of a high-voltage end switching element and a low-voltage end switching element, the high-voltage end switching element feeds and drives the electromagnetic coil through the over-excitation boost circuit, and the low-voltage end switching element corresponds to the The weak current holding control signal for the operation of the electromagnetic coil operates to feed and drive the electromagnetic coil.

In addition, the high-voltage-side switching element shares the booster circuit for overexcitation, and the booster circuit for overexcitation is common to all the electromagnetic coils.

In addition, the fault detection circuit of the fuel injection device of the present invention further includes:

When the microprocessor determines that it is abnormal according to the detection signal generated by the open circuit surge detection circuit, it provides a group power cut-off device that cuts off the corresponding common switching element and the independent switching element connected in series with the common switching element ,

The emergency operation is performed by using the electromagnetic coils other than the group that cuts off the individual switching elements.

In addition, when the microprocessor determines that it is abnormal based on the absence of the open circuit surge voltage, if the energization time of successive electromagnetic coils overlaps, the energization time of the driving signal pulse train is shortened.

In addition, the fault detection circuit of the fuel injection device of the present invention also includes an abnormal alarm device, which receives an abnormal signal and gives an alarm for the abnormal occurrence,

The microprocessor outputs an abnormal signal to the abnormal alarm device when it is determined to be abnormal according to the detection signal generated by the open circuit surge voltage detection circuit.

In addition, the microprocessor has an interface circuit for connection with an external tool.

Description of drawings

Fig. 1 is a detailed circuit diagram of a failure detection circuit of a fuel injection device according to Embodiment 1 of the present invention.

Fig. 2 is a partial detailed diagram of a failure detection circuit of the fuel injection device according to Embodiment 1 of the present invention.

Fig. 3 is a diagram showing a cylinder arrangement of a failure detection circuit of the fuel injection device according to Embodiment 1 of the present invention.

Fig. 4 is a timing chart showing the normal operation of the failure detection circuit of the fuel injection device according to Embodiment 1 of the present invention.

Fig. 5 is a schematic block diagram showing an in-phase abnormality in the failure detection circuit of the fuel injection device according to Embodiment 1 of the present invention.

Fig. 6 is a timing chart showing an abnormal ground fault in the fault detection measurement path of the fuel injection system according to Embodiment 1 of the present invention.

Fig. 7 is a schematic block diagram showing an abnormal short-circuit between phases in the failure detection circuit of the fuel injection device according to Embodiment 1 of the present invention.

Fig. 8 is a timing chart showing an abnormal short-circuit between phases within a group in the failure detection circuit of the fuel injection device according to Embodiment 1 of the present invention.

Fig. 9 is a timing chart showing a phase-to-phase short circuit outside the group in the failure detection circuit of the fuel injection device according to Embodiment 1 of the present invention.

Fig. 10 is a timing chart showing the operation of the failure detection circuit of the fuel injection device according to Embodiment 1 of the present invention.

Fig. 11 is a detailed circuit diagram of a failure detection circuit in the fuel injection device according to Embodiment 2 of the present invention.

Fig. 12 is a detailed circuit diagram of a failure detection circuit of a fuel injection device according to Embodiment 3 of the present invention.

Label description

1. Fuel injection control device, 2. Power switch, 3. Voltage source, 4. Sensor group, 5-8 electromagnetic coils, 9. Microprocessor, 10. 1st drive control circuit, 11. Common switching element, 11a High voltage side common switching element, 11b Low voltage Terminal common switching element, 11c boost circuit, 11d common boost circuit, 12 commutation diode, 12a pull-down resistor, 13, 14 independent switching element, 13a, 14a Zener diode, 13b, 14b open-circuit surge voltage detection diode, 13c, 13d, 14c, 14d voltage divider resistors, 15 current detection resistors, 16, 17 logic sum devices, 18 logic product devices, 19 weak current holding control circuit, 20 second drive control circuit, 21 common switching element, 21a high voltage terminal 2 switching elements, 21b common switching element at the low-voltage end, 21c booster circuit, 22 commutation diodes, 23, 24 independent switching elements, 23b, 24b open-circuit surge voltage detection diodes, 23c, 23d, 24c, 24d voltage dividing resistors, 25 current detection resistor, 26, 27 logic sum device, 28 logic product device, 29 weak current holding control circuit, 31~34 diode, 35 open circuit surge voltage detection circuit, 35a comparison circuit, 35b, 35c voltage divider resistor, 36 open circuit Surge voltage detection circuit, 36a comparison circuit, 36b, 36c voltage dividing resistors, 37, 38 logic and devices, 39 open circuit surge voltage detection circuit, 40 external tools, 41 interface circuit, 42 abnormal alarm display device, 43-46 comparison Circuit, 50 Crankshaft, 51~54 Cylinder, 60 Grounding, 61 Load Short Circuit, 62~64 Broken Circuit, 65 Abnormal Current Waveform, 66 Repeated Current Waveform, 67 Missing Surge Voltage, 68 Missing Signal, 70, 71 Interphase Short circuit, 72 abnormal current waveform, 73, 74 repetitive current waveform, 75 abnormal current waveform, 76, 77 repetitive surge voltage, 78, 79 repetitive detection signal, 80 decaying current waveform, 81 missing surge voltage, 82 missing signal .

Detailed ways

Embodiment 1

Fig. 1 shows a detailed circuit diagram of a failure detection circuit of a fuel injection device according to Embodiment 1 of the present invention. Its structure is described below.

In FIG. 1 , a fuel injection control device 1 is mainly composed of a microprocessor 9 , a first drive control circuit 10 , and a second drive control circuit 20 , which will be described later. The power switch 2 is connected between a voltage source 3 such as an on-vehicle battery and the above-mentioned fuel injection device 1 .

The sensor group 4 for determining the timing and injection quantity (injection time) of combustion injection, etc. is composed of a crank angle sensor, a cam angle sensor, and a throttle valve opening sensor. Input signals generated by the sensor group 4 are supplied to the above-mentioned microprocessor 9 .

The first to fourth electromagnetic coils 5 to 8 are driven and controlled by the above-mentioned first and second drive control circuits 10 and 20 . The solenoid coils 5 to 8 are used for on-off control of fuel injection valves provided in each cylinder of the engine shown in FIG. 3 described later.

The constituent elements of the above-mentioned first drive control circuit 10 will be described below. The common switching element 11 is a transistor or the like connected between one end of the first and fourth electromagnetic coils 5 and 8 and the voltage source 3 . The commutation diode 12 is connected between the load terminal of the common switching element 11 and the negative terminal of the voltage source 3 . The independent switching element 13 is connected to the other end of the above-mentioned first electromagnetic coil 5 , and the independent switching element 13 is a transistor or the like that is turned on in accordance with the independent driving signal SW1 output from the above-mentioned microprocessor 9 . Similarly, the independent switch element 14 is connected to the other end of the fourth electromagnetic coil 8, and the independent switch element 14 is a closed-circuit transistor or the like following the independent drive signal SW3 output by the microprocessor 9.

The current detection resistor 15 is connected between the above-mentioned independent switching elements 13, 14 and the negative terminal of the voltage source 3, so that the above-mentioned independent switching elements 13, 14 are not closed at the same time. The logical sum device 16 acts according to the fast overexcitation control signal SW13 output by the above-mentioned microprocessor 9, so that the above-mentioned common switching element 11 is turned on, and at the same time, the above-mentioned common switching element 11 is turned on by the output signal of the logical product 18 described later. /OFF control.

The logical sum device 17 inputs the aforementioned independent drive signals SW1 and SW3 to the aforementioned logical product element 18 as input signals. The weak current holding control circuit 19 is an ON/OFF control circuit for supplying a low current (weak current for operation holding) to maintain the operation of the first (or fourth) electromagnetic coil 5 (or 8). For this reason, the weak current holding control circuit 19 outputs the weak current holding control signal DT13 when the voltage across the above-mentioned current detection resistor 15 is lower than a specified value, and the common switching element 11 is turned on through the above-mentioned logical product device 18 and logical sum device 16. Pass.

Components 21 to 29 of the second drive control circuit 20 are the same as 11 to 19 described above. SW4 is equivalent to SW1. SW2 is equivalent to SW3. INJ2 represents an electromagnetic coil equivalent to INJ1. INJ3 represents an electromagnetic coil equivalent to INJ4. No further explanation here.

The anode of the diode 31 is connected to the junction of the first electromagnetic coil 5 and the independent switching element 13 , and the anode of the diode 32 is connected to the junction of the second electromagnetic coil 6 and the independent switching element 23 . Similarly, the anode of the diode 33 is connected to the junction of the third electromagnetic coil 7 and the independent switching element 24 , and the anode of the diode 34 is connected to the junction of the fourth electromagnetic coil 8 and the independent switching element 14 .

The open circuit surge voltage detection circuit 35 includes a comparison circuit 35a. The voltage dividing resistors 35b, 35c divide the voltage fed out from the cathodes of the diodes 31, 33 described above. The open circuit surge voltage detection circuit 36 includes a comparison circuit 36a not shown in the figure. Voltage dividing resistors 36b, 36c not shown in the figure divide the voltage fed out from the cathodes of the above-mentioned diodes 34, 32.

Here, the above-mentioned comparison circuit 35a is made into such a structure: when the divided voltage divided by the voltage-dividing resistors 35b and 35c is greater than the voltage of the voltage source 3, a detection signal IN13 of logic level "L" is generated and supplied to the above-mentioned microcomputer. Processor9. Similarly, the comparison circuit 36a, when the divided voltage divided by the voltage dividing resistors 36b and 36c is greater than the voltage of the voltage source 3, generates a detection signal IN42 of logic level "L", which is supplied to the microprocessor 9.

The external tool 40 can write a control program to the above-mentioned microprocessor 9, and can read and display the contents of the data memory not shown. The interface circuit 41 is provided between the external tool 40 and the above-mentioned microprocessor 9 . The abnormal alarm display device 42 is driven according to the abnormal signal of the above-mentioned microprocessor 9 and the like.

FIG. 2 shows a partial detailed view of the feed circuit corresponding to the first electromagnetic coil 5 in FIG. 1 . The structure is described below.

In FIG. 2 , the pull-down resistor 12 a is connected in parallel with the above-mentioned commutation diode 12 . The Zener diodes 13a, 14a can equivalently perform the function of limiting the OFF voltage of the independent switching elements 13, 14. The weak current Ih for operation maintenance is the current flowing through the first electromagnetic coil 5 .

The open surge voltage Vs occurs when both the common switching element 11 and the individual switching elements 13 are open. This open-circuit surge voltage Vs is generated by the counter electromotive force generated by the first electromagnetic coil 5 to maintain the weak current Ih for operation and maintenance just flowing, and its value is substantially equal to the limit voltage of the equivalent Zener diode 13a described above. .

However, this open-circuit surge voltage Vs drops rapidly as the operation-maintaining weak current Ih attenuates. After the voltage is determined by the pull-down resistor 12a, Vs=0.

When the independent switching element 13 is not open due to the abnormal short circuit of the independent switching element 13, etc., the common switching element 11 cuts off the feed, and because of the structure of the commutating circuit composed of the commutating diode 12 and the independent switching element 13, the excitation coil does not quickly cut off, so the open circuit surge voltage Vs does not occur.

On the other hand, when the individual switching element 13 is open, the individual switching element 14 is turned on to activate the common switching element 11 in order to feed power to the fourth electromagnetic coil 8 . A feed voltage Vb at the output of the common switching element 11 is generated, which appears as an apparent open-circuit surge voltage Vs as an output of the diode 31 . But the actual open-circuit surge voltage Vs is larger than the feed voltage Vb (Vb<Vs). Therefore, these voltages can be extracted separately by the comparison circuit 35a described above.

FIG. 3 is a cylinder arrangement diagram of a failure detection circuit of the fuel injection device shown in FIG. 1 . In FIG. 3 , 50 is the crankshaft of the engine, and 51 to 54 are the first to fourth cylinders for fuel injection by the above-mentioned electromagnetic coils 5 to 8 .

At the first moment, the individual switching element 13 and the common switching element 11 operate, and the fuel injection to the first cylinder 51 is realized by feeding power to the first electromagnetic coil 5 . Next, at the second moment, the individual switching elements 24 and the common switching element 21 operate, and the fuel injection to the third cylinder 53 is realized by feeding power to the third electromagnetic coil 7 . Thereafter, at the third moment, the individual switching element 14 and the common switching element 11 operate, and the fuel injection to the fourth cylinder 54 is realized by feeding power to the fourth electromagnetic coil 8 . Furthermore, at the fourth time point, the individual switching element 23 and the common switching element 21 operate, and the fuel injection to the second cylinder 52 is realized by feeding power to the second electromagnetic coil 6 .

In the arrangement described above, when the fuel injection of either the first cylinder 51 or the fourth cylinder 54 becomes abnormal, both the first cylinder 51 and the fourth cylinder 54 are stopped. Here, as a stable countermeasure, only the second cylinder 52 and the third cylinder 53 perform the emergency operation. When either the fuel injection of the second cylinder 52 or the third cylinder 53 becomes abnormal, both the second cylinder 52 and the third cylinder 53 are stopped. Here, as a stable countermeasure, only the first cylinder 51 and the fourth cylinder 54 perform the emergency operation. Common switching elements 11 and 21 in FIG. 1 are configured to correspond to such grouping.

The independent driving signals SW1-SW4 of the microprocessor 9 in FIG. 1 are numbered according to the order of fuel injection.

Fig. 4 is a timing chart for explaining the normal operation of the failure detection circuit of the fuel injection device according to the first embodiment. In Fig. 4, Fig. 4 (a) is the output characteristic of the fast overexcitation control signal SW13 of the microprocessor 9, Fig. 4 (b) is the output characteristic of the weak current holding control signal DT13, Fig. 4 (c) is the output characteristic of the microprocessor The output characteristic of the independent drive signal SW1 of 9, Fig. 4 (d) is the output characteristic of the independent drive signal SW3 of microprocessor 9, Fig. 4 (e) is the output characteristic of the fast overexcitation control signal SW42 of microprocessor 9, Fig. 4 (f) is the output characteristic of the weak current holding control signal DT42, Fig. 4 (g) is the output characteristic of the independent driving signal SW4 of the microprocessor 9, and Fig. 4 (h) is the independent driving signal SW2 of the microprocessor 9 output characteristics.

The independent drive signals SW1-SW4 are generated and output in sequence. The fast overexcitation signal SW13 generates a short-time output signal according to the output timing of the independent drive signals SW1 and SW3. Similarly, the fast overexcitation signal SW42 generates a short-time output signal according to the output timing of the independent drive signals SW4 and SW2.

Fig. 4(i) is the current waveform of the first electromagnetic coil 5, which is obtained by combining Fig. 4(a), (b) and (c). Similarly, FIG. 4(j) is a current waveform of the fourth electromagnetic coil 8, which is obtained by combining FIGS. 4(a), (b), and (d). Fig. 4(k) is a current waveform of the second electromagnetic coil 6, which is obtained by combining Fig. 4(e), (f), and (g). Fig. 4(1) is the current waveform of the third electromagnetic coil 7, which is obtained by combining Fig. 4(e), (f), and (h).

FIG. 4( m ) is the output waveform of the diode 31 . When the current of the first electromagnetic coil 5 in FIG. 4(i) is cut off, that is, when the output of the independent drive signal SW1 in FIG. 4(c) stops (logic level "L"), an open circuit surge voltage Vs is generated. When the electromagnetic coil 8 is energized, the waveform of the feed voltage Vb is generated according to the switching operation of the common switching element 11 .

Similarly, FIG. 4(n) is the output waveform of the diode 34. FIG. 4( o ) is the output waveform of the diode 32 . FIG. 4( p ) shows the output waveform of the diode 33 .

FIG. 4(q) is a waveform of the detection signal IN13. When the diodes 31 and 33 output the open-circuit surge voltage Vs, IN13 in FIG. 4(q) is logic level "L". Similarly, FIG. 4(r) is the waveform of the detection signal IN42. When the diodes 34 and 32 output the open-circuit surge voltage Vs, IN42 in FIG. 4(r) is at logic level "L".

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 for intra-phase anomalies. The ground 60 gives the state that the negative terminal of the first electromagnetic coil 5 is connected to the negative terminal of the voltage source 3 . When grounding occurs in this state, the current flowing through the electromagnetic coil 5 does not cut off quickly, and the open circuit surge voltage Vs does not occur.

This phenomenon is the same as the short-circuit abnormality of the independent switching element 13 . Even if the common switching element 11 cuts off the power supply, the excitation current flows back through the commutation diode 12 and the ground circuit 60 or the short-circuited individual switching element, so that the open circuit surge voltage Vs no longer occurs.

The load short circuit 61 gives a short circuit between the positive and negative terminals of the fourth electromagnetic coil 8 . When such a load short-circuit 61 occurs, the exciting current no longer flows through the electromagnetic coil 8, and therefore, when the independent switching element 14 is opened, the open-circuit surge voltage Vs does not occur.

In addition, when the load is short-circuited, the independent switching elements 13, 14, 23, 24 and the common switching elements 11, 21 are protected in a short time due to their own over-current protection function, and then the driving command signal is released by the microprocessor 9 , thus protecting it from burning.

62 ~ 64 have given the broken open circuit. In the event of wire breakage, coil breakage, and switch element open-circuit failure, the exciting current no longer passes through the electromagnetic coils 6 and 7. When the individual switching elements 23 and 24 are opened, the open circuit surge voltage Vs no longer occurs.

FIG. 6 is a timing chart for explaining the operation at the time of ground fault in FIG. 5 . Differences from the timing chart of normal operation shown in FIG. 4 will be mainly described below.

The abnormal current waveform 65 of FIG. 6(i) INJ1 shows that the excitation current for the first electromagnetic coil 5 does not pass through the current detection resistor 15 (refer to FIG. 1 ) due to the ground 60, so that the low current drive control for operation maintenance is not performed. current waveform. The repeated current waveform 66 shows that the current is basically the same as that of the fourth electromagnetic coil 8 of INJ4 in FIG. status.

The missing surge voltage 67 of D31 in FIG. 6(m) shows that the exciting current of the first electromagnetic coil 5 is not cut off quickly due to the grounding 60, so that the open circuit surge voltage Vs that should have occurred does not occur. The missing signal 68 of IN13 in FIG. 6(q) shows a state where there is no detection signal that should have been generated due to the aforementioned missing surge voltage 67 .

As described above, when the absence of the open circuit surge voltage Vs caused by various intra-phase abnormalities is detected, as shown in FIG. 10 described later, the common switching element of the missing phase or all the independent switching elements are switched off. Fuel injection as emergency operation is carried out by the remaining set of solenoid coils.

However, when the loss of the open circuit surge voltage Vs occurs in both groups, all the switching elements are cut off, and the engine cannot be operated.

Fig. 7 is a simplified block diagram regarding phase-to-phase anomalies. In FIG. 7 , a phase-to-phase short circuit 70 shows a short circuit between the negative terminals of the first and fourth electromagnetic coils 5 and 8 . The phase-to-phase short circuit 71 gives a short circuit between the negative terminals of the second and fourth electromagnetic coils 6 , 8 . The interphase short circuit 70 is an intra-group interphase short circuit between electromagnetic coils driven by the same common switching element 11 , and the interphase short circuit 71 is an intergroup interphase short circuit between electromagnetic coils driven by different common switching elements.

FIG. 8 is a timing chart for explaining the operation when the phase-to-phase short-circuit within the group in FIG. 7 is abnormal. Differences from the timing chart of normal operation shown in FIG. 4 will be mainly described below.

The abnormal current waveforms 72 and 75 of Fig. 8 (i) INJ1 and (j) INJ4 show the state in which the weak current Ih for operation maintenance is halved because the phase-to-phase short circuit 70 makes the first and fourth electromagnetic coils 5 and 8 connected in parallel.

The repetitive current waveforms 73 and 74 in Fig. 8 (i), (j) are redundant repetitive current waveforms that should not flow due to the parallel connection of the first and fourth electromagnetic coils 5 and 8 due to the phase-to-phase short circuit 70 .

The repetitive surge voltages 76 and 77 in (m) D31 and (n) D34 of FIG. 8 represent the open circuit surge voltage Vs accompanying the cut-off of the above-mentioned repetitive current waveforms 73 and 74 . The repetitive signals 78 and 79 of (q) IN13 and (r) IN42 in FIG. 8 represent repetitive detection signals accompanied by the above-mentioned repetitive surge voltages 76 and 77 .

FIG. 9 is a timing chart for explaining an operation when a phase-to-phase short circuit between banks in FIG. 7 is abnormal. The difference from the timing chart of normal operation shown in FIG. 4 will be mainly described below.

In a phase-to-phase short-circuit across a group such as the phase-to-phase short-circuit 71, when all the individual switching elements 13, 14, 23, 24 are not in the state of conduction simultaneously with each other (that is, the fuel injection time period is short), each electromagnetic coil 5 to 8 are all subject to normal control, and perform the same actions as those in the sequence diagram in Fig. 4 . But the difference is that it cannot detect the abnormal state of phase-to-phase short circuit.

In contrast, FIG. 9 shows a time chart when the fuel injection time is long and adjacent sequential solenoid coils are turned on at the same time.

The attenuation current waveform 80 of Fig. 9 (j) INJ4 shows that after the independent switch element 14 and the common switch element 11 are opened, the action-maintaining weak current Ih flowing through the fourth electromagnetic coil 8 passes through the commutation diode 12, the interphase short-circuit switch 71 and the independent switch element 12. Switching element 23 and the attenuated state. The missing surge voltage 81 in FIG. 9(n) D34 represents a state where the open circuit surge voltage Vs that should have occurred does not occur because the fourth electromagnetic coil 8 is not cut off quickly. Similarly, the missing signal 82 of IN42 in FIG. 9( r ) indicates a state in which a detection signal that should have occurred does not occur due to the aforementioned missing surge voltage 81 .

There are 4 types of interphase short-circuit abnormalities between straddling groups with respect to the negative terminal arrangement of the above-mentioned electromagnetic coils. However, in either case, the open-circuit surge voltage Vs is lost on the first-action side of the solenoid valves that operate sequentially in time. When cutting off the common switching element or independent switching element that drives the electromagnetic coil on one side first, the countermeasure method is the same as the abnormal situation in the phase in Fig. 5, so the treatment method can be unified and is convenient.

However, regarding such phase-to-phase short circuit between groups, if the fuel injection time period is shortened without overlapping the injection time, it is not necessary to cut off the common switching element and the individual switching elements. Even if the common switching element and the individual switching element are turned off, the common switching element and the individual switching element on the side that operates later will not be affected.

Next, the overall operation of the failure detection circuit of the fuel injection system according to the first embodiment will be described with reference to the operation sequence of the microprocessor 9 shown in FIG. 10 .

In Fig. 10, 100 is a work start step, 101 is a step of judging whether there is a reset command input from the external tool 40 following the start step 100, and 102 is the step of being stored in the RAM memory in the microprocessor 9 when the judging step 101 is YES. The step of resetting the fault information, step 103 is to determine whether the action of step 102 ends or when the above-mentioned step 101 is NO (that is, it is not connected with the external tool 40, or it is connected but does not output a reset command) whether there is a readout output from the external tool 40 instruction steps.

104 is the step that the fault information stored in the RAM memory in the microprocessor 9 is sent to the external tool 40 when the judgment step 103 is YES, and the 105 step is when the action of the judgment step 104 ends or when the above-mentioned step 103 is NO (that is, no Connect to an external tool, or connect but do not output a read command) independent drive signals SW1 to SW4 are being generated or not. When the above step 105 is NO (that is, fuel injection is not performed), transition to the end step 106 and return to the start step 100 again.

Step 107 updates and obtains the latest occurrence status of the repeated independent drive signals SW1-SW4 when the above step 105 is YES, step 108 updates and acquires the latest input status of detection signals IN13 and IN42 after step 107, step 110 continues After the step 108, judge whether the lower edge change point (the time change point of the logic level "H"→"L") of the independent driving signals SW1～SW4 detects whether the signal IN13, IN42 is missing, and the step 111 determines whether the step 110 is YES. In step 105, it is judged whether there is overlap in the energization time cycle of the electromagnetic coils whose driving time is sequential on the drive signal pulse train obtained by updating, and step 112 stores the state and shortens the energization time when the determination step 111 is YES thereafter, At the same time, an alarm and display output are generated to the abnormal alarm display device 42 . The stored information is stored until reset by step 102.

In step 113, when the above step 111 is NO, determine and store the information of which independent drive signal the absence of the open circuit surge voltage Vs of the above step 110 corresponds to, and which phase the open circuit surge voltage Vs of the electromagnetic coil is missing. Step 114 follows this step to cut off the common switching element driving the electromagnetic coil of the missing phase of the open circuit surge voltage, and step 115 generates an alarm display output to the abnormal alarm display device 42 . When this step 115 ends or the above-mentioned step 110 is NO or the operation of the above-mentioned step 112 ends, it transitions to step 120 .

In step 113, in-phase faults such as short circuit, disconnection, and open circuit of electromagnetic coils, wiring, and drive elements are detected. In step 114, the group is de-energized for switching off the common switching element 11 (or 21 ) and (for safety) switching off the individual switching elements 13, 14 (or 23, 24).

In step 112, the successive electromagnetic coils are not energized for an overlapping time as injection time suppression means for preventing the abnormality of the phase-to-phase short circuit 71 between groups in FIG. 7 .

Step 120 determines whether excessive detection signals IN13, IN42 repeatedly occur after the falling edge change point (time change point of logic level "H"→"L") of independent drive signals SW1-SW4, and step 121 is in this judgment step 120 When YES, the repetition of the open circuit surge voltage Vs corresponding to which independent drive signal, and which phase the electromagnetic coil is short-circuited between phases are specified and stored. In step 122, after step 121, the common switching element driving the electromagnetic coil short-circuited between phases is cut off, and in step 123, an alarm display output is generated to the abnormal alarm display device 42 . When the step 123 ends or the step 120 above is NO, enter the end step 106 and return to the start step 100 again.

Step 121 is as for the phase-to-phase short circuit 70 in the group of Fig. 7 is captured as the abnormality of the first and fourth electromagnetic coils 5, 8, and the step 122 cuts off the common switching element 11 and (for safety reasons) cuts off the independent switching element 13 , 14 groups are energized and cut off.

The electromagnetic coil number of the phase or the cylinder number of the engine after abnormality determination in the above-mentioned steps 113 and 121 is stored in a non-volatile memory such as RAM memory or EEPROM that can be retained by a battery during a power failure. During maintenance and inspection, it is read and displayed by the external tool 40 in step 104, and reset to the initial state by step 102.

Implementation form 2

Fig. 11 is a detailed circuit diagram of a failure detection circuit of the fuel injection device according to Embodiment 2 of the present invention. The difference from Embodiment 1 will be mainly described below.

In Fig. 11, in the first drive control circuit 10, the switching element 11a at the high-voltage side is energized by the fast overexcitation control signal SW13, and the switching element 11b at the low-voltage side is output by the same weak circuit holding control circuit 19 as the first embodiment above. The weak current maintains the control signal DT13 and operates to perform power-on control. The boost circuit 11c is a circuit that boosts the voltage of the voltage source 3 . The diode 16a feeds power to the first and fourth electromagnetic coils 5 and 8 from the booster circuit 11c through the high-voltage side switching element 11a. On the other hand, the diode 16b feeds power to the first and fourth electromagnetic coils 5 and 8 from the voltage source 3 through the low-voltage side switching element 11b. In Fig. 11, it is the state that the common switch element 11 shown in Fig. 1 is divided into a high-voltage end switch element 11a and a low-voltage end switch element 11b, but they are all common to the first and fourth electromagnetic coils 5, 8. Switching elements, this does not change. The structure of the second drive control circuit 20 is the same as that of the above-mentioned first drive control circuit 10, so it will not be described again here.

The operation of the above configuration will be described in detail below.

In the fault detection circuit of the fuel injection device with the structure shown in FIG. 11 , the voltage source 3 is, for example, a DC12V vehicle battery, and the booster circuits 11c and 21c are, for example, generating a DC120V high-voltage power supply from the DC12V to rapidly drive the electromagnetic coil.

The low-voltage side switching elements 11b, 21b are used to supply the weak current Ih for maintaining the operation of the electromagnetic coil, and the temperature rise of the booster circuits 11c, 21c is suppressed by directly feeding power from the voltage source 3 .

In the failure detection circuit of the second embodiment, compared with the failure detection circuit of the above-mentioned first embodiment, the excitation current of the electromagnetic coils 5 to 8 is reduced, so that the temperature rise of the common switching elements and individual switching elements can be reduced.

Implementation form 3

Fig. 12 is a detailed circuit diagram of a failure detection circuit of the fuel injection device according to Embodiment 3 of the present invention. The difference from the case in Fig. 1 will be mainly described below.

In FIG. 12 , a booster circuit 11 d is a circuit that boosts the power supply voltage of the voltage source 3 . The switching element 11a at the high voltage side is energized by the fast overexcitation control signal SW13, and the switching element 11b at the low voltage side is energized by the weak current holding control signal DT13. The diode 16a feeds power to the first and fourth electromagnetic coils 5 and 8 from the booster circuit 11d through the high-voltage side switching element 11a. On the other hand, the diode 16b feeds power to the first and fourth electromagnetic coils 5 and 8 from the voltage source through the low-voltage side switching element 11b.

Similarly, the switching element 21a at the high voltage side is energized by the fast excitation control signal SW42, and the switching element 21b at the low voltage side is energized by the weak current holding control signal DT42. The diode 26a feeds power to the second and third electromagnetic coils 6 and 7 from the booster circuit 21d through the high-voltage side switching element 21a. On the other hand, the diode 26b feeds power to the second and third electromagnetic coils 6 and 7 from the voltage source 3 through the low-voltage side switching element 21b.

In the above range, compared with the above-mentioned second embodiment, the only difference is that the booster circuits 11c and 21c are combined to form a common boosted voltage 11d.

The pull-down resistor 12a is connected in parallel with the commutation diode 12, and the voltage dividing resistors 12b and 12c divide the voltage of the voltage source 3. The compensation 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 applied to the non-inverting input terminals of the comparison circuits 43 and 44 .

The resistance value R12a of the pull-down resistor 12a is much smaller than the resistance values R12b, R12c, R12d of the voltage dividing resistors 12b, 12c and the compensation resistor 12d.

Similarly, the pull-down resistor 22a is connected in parallel with the commutation diode 22, and the voltage dividing resistors 22b and 22c divide the voltage of the voltage source 3. The compensation resistor 22d is connected between the pull-down resistor 22a and the voltage dividing resistor 22c, 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 much smaller than the resistance values R22b, R22c, R22d of the voltage dividing resistors 22b, 22c and the compensation resistor 22d.

13b is a diode for open-circuit surge voltage detection, and 13c and 13d are voltage dividing resistors. The diode 13b and the voltage dividing resistors 13c and 13d are connected in series and connected between the negative terminal of the first electromagnetic coil 5 and the negative terminal of the voltage source 3 . The voltage of the voltage dividing resistor 13d is applied to the inverting input terminal of the comparison circuit 43 .

Similarly, 14b, 23b, and 24b are diodes for open-circuit surge voltage detection, and 14c, 14d, 23c, 23d, 24c, and 24d are voltage dividing resistors. Similarly, the voltages of the voltage dividing resistors 14d, 23d, and 24d are applied to the inverting input terminals of the comparison circuits 44-46, respectively.

Even if one of the outputs of the comparison circuit 43 or 46 is at the logic level “L”, the logical sum circuit 37 supplies the detection signal IN13 of the logic level “L” to the microprocessor 9 . Similarly, even if one of the outputs of the comparison circuit 44 or 45 is at the logic level “L”, the logical sum circuit 38 supplies the detection signal IN42 of the logic level “L” to the microprocessor 9 .

The open circuit surge voltage detection circuit 39 is composed of the comparison circuits 43 and 44 and the comparison circuits 45 and 46 described above.

The operation of the above-described configuration will be described below focusing on the operation of the comparator circuit 43 .

First, the high-voltage side switching element 11a and the independent switching element 13 are turned on, and the first electromagnetic coil 5 operates rapidly. Next, the high-voltage-side switching element 11a is turned off, and the low-voltage-side switching element 11b performs low-current control for a holding operation.

Soon, the independent drive signal SW1 becomes logic level "L", and when the low-voltage end switching element 11b and the independent switching element 13 are cut off, an open-circuit surge voltage Vs shown in FIG. 2 is generated at the negative end of the first electromagnetic coil 5 , the divided voltage divided 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 comparator circuit 43 at this point in time, since the voltage across the pull-down resistor 12a is substantially zero, becomes the resistance value R12b and (R12c//R12d) to divide the power supply voltage. low value after compression. (R12c//R12d) is the parallel combined resistor of resistors R12c and R12d.

Therefore, as the input voltage of the comparison circuit 43, the non-inversion input terminal is lower than the inversion input terminal, and the output of the comparison circuit 43 produces a normal detection signal of logic level "L".

However, due to the short-circuit circuit 140, when the contacts of the first and fourth electromagnetic coils 5 and 8 are short-circuited on the power line, the divided voltage applied to the non-inverting input terminals of the comparison circuits 43 and 44 will become a resistance value ( R12b//R12d) and R12c divide the power supply voltage to a high value. (R12b//R12d) is a parallel combined resistor of resistors R12b and R12d.

Therefore, as the input voltage of the comparison circuit 43, the non-inverting input terminal is a high voltage, the output of the comparison circuit 43 is logic level "H", and the detection of the open circuit surge voltage is not performed.

In this way, if the failure detection circuit of the fuel injection device shown in FIG. 12 is used, it is possible to detect a short-circuit abnormality on the side of the common switching element, and the same is true for other electromagnetic coils.

For this short circuit anomaly, in step 113 of FIG. 10 , the missing phase is determined and stored, and the common switching element 11 and the individual switching elements 13 , 14 are kept disconnected by step 114 .

In addition, when the common contacts of the first and fourth electromagnetic coils 5 and 8 and the common contacts of the second and third electromagnetic coils 6 and 7 are short-circuited due to the short circuit 141 between groups, the energization time of successive electromagnetic coils is not repeated. At this time, no abnormality occurs, and the presence of the short circuit 141 is not detected.

On the other hand, when the energization times of successive electromagnetic coils overlap, and when the individual switching elements are open, the voltage at the non-inverting input terminals of the comparison circuits 13b, 14b, 23b, and 24b in FIG. 12 rises, so it becomes impossible to detect In the state of the open circuit surge voltage Vs, the process of shortening the energization time is performed in step 112 of FIG. 10 , and emergency operation is realized by this process.

Embodiment 4

In Embodiments 1 to 3 described above, the contingency measures of suppressing the injection time are adopted for interphase short circuit between banks. However, it is also possible to cut off the energization of the group by turning off the common switching element or the like without performing the process of suppressing the injection time.

In the above, 4 cylinders were used for the explanation, but even for 6-cylinder and 8-cylinder engines, 2 sets of common switching elements, or 3 sets (6 cylinders) and 4 sets (8 cylinders) of common switching elements for each group can be used .

Further, when the engine is a gasoline engine, when the fuel injection control device includes the ignition control function of the engine, in addition to correcting the fuel injection control, the ignition time can also be corrected to perform shortened driving operation when an abnormality occurs, which can be more stable. emergency operation.

In addition, the abnormal alarm display device can display the state of shortened driving operation, the state of completely stopping fuel injection due to abnormality of the whole group, or the fuel injection stop processing due to disconnection, short circuit, misfire, etc. of the ignition device group, etc. That is, the abnormal alarm display device can perform comprehensive and hierarchical alarm and display.

As described above, with the failure detection circuit of the fuel injection device according to the present invention, it is not only possible to comprehensively detect the short circuit and disconnection of the electromagnetic coil for fuel injection control, its switching elements, wiring, etc. through a simple open circuit surge voltage detection circuit. line, open circuit, and can also detect phase-to-phase short-circuit faults through the absence of open circuit surge voltage judging device and repeated judging device. Furthermore, stable emergency operation can be realized by grouping common switching elements.

Since the current control for the electromagnetic coil is performed on the common switching element side, the open circuit surge voltage can be easily detected by monitoring the voltage across the individual switching elements.

Since the open-circuit surge voltage is detected by the potential at both ends of the electromagnetic coil, it is also easy to detect short-circuit abnormalities of common switching elements and mutual short-circuits between groups.

Since the open circuit surge voltage detection circuit is appropriately logically AND processed by the logical sum circuit, repetition of the open circuit surge voltage can be judged, and the number of input points and hardware of the microprocessor can be reduced.

Since the common switching element can be used to independently perform fast overexcitation control and weak current control for operation maintenance, the feeding control circuit is simplified, and good results can be obtained even if the withstand voltage of the electromagnetic coil is low.

Since the common switching element can be divided into rapid overexcitation control for high voltage and weak current control for maintaining operation at low voltage, the amount of current flowing to the common switching element is reduced, heat generation is reduced, and the size of the device is reduced.

Since a single step-up circuit for overexcitation can be used to quickly overexcite all the electromagnetic coils, the device is small and the cost is low.

Since the common switching elements can be appropriately grouped when the common switching elements are turned off according to the occurrence of an abnormality, stable emergency operation can be realized by the electromagnetic coils related to the remaining common switching elements.

For a short-circuit abnormality between different groups, more stable emergency operation can be realized by shortening the energization time of the above-mentioned drive signal pulse train.

Since the alarm and display are performed according to the absence/repeated abnormal occurrence of the open surge circuit, it is possible to issue an alarm for all failures that are generally assumed, thereby improving safety. Because the microprocessor has an interface circuit for connection with external tools, it can read and display the identification information of the abnormal electromagnetic coil to the external tool, thereby improving the work efficiency of maintenance, and at the same time, it can be stored from the external tool. The information is conveniently returned to the initial state.

Claims (11)

1. the fault-detecting circuit of a fuel injection system is characterized in that, comprising:

Driving is sprayed a plurality of electromagnetic coils of using solenoid valve for the fuel of each cylinder of multicylinder engine;

Produce the microprocessor of drive signal impulse row and quick overexcitation control signal;

Drive signal impulse row according to producing from described microprocessor drive a plurality of independent switch elements that described a plurality of electromagnetic coil carries out switch motion successively;

According to the quick overexcitation control signal that produces from described microprocessor, at least by the fuel injection sequence many groups common switch element that electromagnetic coil in one group that two a plurality of electromagnetic coils more than the stroke form carries out the integral feed driving of being separated by;

At least a plurality of open circuit surge voltage testing circuits of detecting of the open circuit surge voltage that produces to independent switch element open circuit that on the same group electromagnetic coil is not corresponding the time,

Described microprocessor compares the testing signal that produces from described a plurality of open circuit surge voltage testing circuits, has or not disappearance and repeats to judge unusual according to this testing signal.

2. the fault-detecting circuit of fuel injection system as claimed in claim 1 is characterized in that,

Whether the described surge voltage testing circuit of respectively opening a way has surpassed the magnitude of voltage of voltage source by means of the both end voltage value that detects described independent switch element when the described independent switch element open circuit, detects described open circuit surge voltage.

3. the fault-detecting circuit of fuel injection system as claimed in claim 1 is characterized in that,

The described surge voltage testing circuit of respectively opening a way, whether the terminal voltage of the negative terminal of described electromagnetic coil is higher than the voltage of the feed end that is connected with described public switch element during by means of described independent switch element of detection and described common switch element open circuit, detects described open circuit surge voltage.

4. the fault-detecting circuit of fuel injection system as claimed in claim 1 is characterized in that, comprising:

Logic and circuit, to carrying out logic and processing by testing signal for the open circuit surge voltage testing circuit output of the electromagnetic coil of the different group of described common switch element,

Described microprocessor is judged according to the output of described logic and circuit unusually.

5. the fault-detecting circuit of fuel injection system as claimed in claim 1 is characterized in that,

Described each common switch element is corresponding to moving from the quick overexcitation control signal of described microprocessor and the light current retentive control signal that is used to keep described electromagnetic coil to move.

6. the fault-detecting circuit of fuel injection system as claimed in claim 1 is characterized in that, comprising:

The overexcitation booster circuit that supply voltage is boosted,

Described common switch element is made up of high side switch element and low voltage terminal switching element, the high side switch element carries out feed with booster circuit to described electromagnetic coil by described overexcitation and drives, the low voltage terminal switching element keeps the light current retentive control signal of described electromagnetic coil action to move corresponding to being used to, and drives described electromagnetic coil is carried out feed.

7. the fault-detecting circuit of fuel injection system as claimed in claim 6 is characterized in that,

Described high side switch element share described overexcitation booster circuit, and described overexcitation is public with booster circuit to all electromagnetic coils.

8. the fault-detecting circuit of fuel injection system as claimed in claim 1 is characterized in that, comprising:

Described microprocessor is being judged to be according to the testing signal that is produced by described open circuit surge testing circuit when unusual, and one group of shut-off means of switching on that the common switch element of correspondence and the independent switch element that be connected in series with this common switch element are cut off is provided,

Utilization is carried out emergency operation with the group electromagnetic coil in addition that described independent switch element cuts off.

9. the fault-detecting circuit of fuel injection system as claimed in claim 8 is characterized in that,

Described microprocessor is judged to be when unusual in the disappearance according to described open circuit surge voltage, if there have have the current"on"time of electromagnetic coil successively to be overlapping, then to shortening current"on"time of described drive signal impulse row processing.

10. the fault-detecting circuit of fuel injection system as claimed in claim 1 is characterized in that, comprising:

Anomaly alarming device receives abnormal signal and reports to the police to unusual,

Described microprocessor is being judged to be according to the testing signal that is produced by described open circuit surge voltage testing circuit when unusual, to described anomaly alarming device output abnormality signal.

11. the fault-detecting circuit of fuel injection system as claimed in claim 1 is characterized in that,

Described microprocessor has the interface circuit that is connected usefulness with external tool.

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