Fuel injection control device

Abstract

To appropriately diagnose operation of a feedback signal in a configuration for diagnosing failure of injection control using a feedback signal.SOLUTION: A fuel injection control device 1 for controlling fuel injection from an injector to an internal combustion engine includes: a control part for transmitting an injection drive signal; injection drive parts 3, 4 for driving an injector by transmitting a command signal to the injector and transmitting a feedback signal to the control part after successfully driving the injector, when receiving the injection drive signal transmitted from the control part; and a failure diagnostic part 2e for diagnosing the operation of the feedback signal based on communication status of the injection drive signal during the operation of the internal combustion engine and the communication status of the feedback signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fuel injection control device. [Background technology]

[0002] A fuel injection control device that controls fuel injection from an injector to an internal combustion engine includes a control unit that transmits an injection drive signal to the injection drive unit, and an injection drive unit that transmits a command signal to the injector to drive the injector when the injection drive signal transmitted from the control unit is received. In the fuel injection control device, it is necessary to diagnose a malfunction of the injection control from the viewpoint of functional safety. For example, Patent Document 1 discloses a method for diagnosing a malfunction of the injection control, which determines whether or not the calculation of the required injection amount has been performed normally based on a calculated required injection amount and a detection value in the operating state of the internal combustion engine, and determines whether or not the injection control based on the required injection amount has been performed normally based on the calculated required injection amount and a measurement result of the energization period of the injector drive current. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-238203 A Summary of the Invention [Problem to be solved by the invention]

[0004] Another method for diagnosing a malfunction of the injection control is to use a feedback signal. In the method using the feedback signal, the injection driver transmits a feedback signal to the control unit when the injection driver normally drives the injector. The control unit determines whether or not the injection control is normal by determining that the feedback signal transmitted from the injection driver has been received.

[0005] In such a method using a feedback signal, if the operation of the feedback signal is abnormal, it is impossible to diagnose the injection control, so it is necessary to diagnose the operation of the feedback signal. As a method for diagnosing the operation of the feedback signal, there is a method of forcibly driving the injector to check the reception of the feedback signal. In this case, if the injector is forcibly driven at a timing that does not affect the operation of the internal combustion engine, i.e., while the internal combustion engine is stopped, unburned fuel is injected into the internal combustion engine, which causes a problem of fouling the internal combustion engine. On the other hand, if the injector is driven while the internal combustion engine is operating, for example, when the vehicle is running downhill, the internal combustion engine may not inject fuel, and the operation of the feedback signal may not be properly diagnosed.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a fuel injection control device that can appropriately diagnose the operation of a feedback signal in a configuration that diagnoses injection control failures using a feedback signal. [Means for solving the problem]

[0007] According to the invention recited in claim 1, in a fuel injection control device (1) that controls fuel injection from an injector to an internal combustion engine, a control unit (2) transmits an injection drive signal. When an injection drive unit (3, 4) receives the injection drive signal transmitted from the control unit, it transmits a command signal to the injector to drive the injector, and when the injector is normally driven, it transmits a feedback signal to the control unit. A fault diagnosis unit (2e) diagnoses the operation of the feedback signal based on the communication state of the injection drive signal and the communication state of the feedback signal during operation of the internal combustion engine. When the on-state of the ejection drive signal occurs at least once within a diagnosis period, the fault diagnosis unit identifies an on-state in the ejection drive signal history indicating that the on-state of the ejection drive signal has occurred, and when the on-state of the feedback signal occurs at least once within a diagnosis period, identifies an on-state in the feedback signal history indicating that the on-state of the feedback signal has occurred, and diagnoses the operation of the feedback signal based on the ejection drive signal history indicating the communication state of the ejection drive signal and the feedback signal history indicating the communication state of the feedback signal.

[0008] The operation of the feedback signal is diagnosed based on the communication state of the injection drive signal and the communication state of the feedback signal while the internal combustion engine is operating. This eliminates the need to forcibly drive the injector while the internal combustion engine is stopped, and prevents the internal combustion engine from becoming dirty due to unburned fuel. It is also possible to distinguish and identify a situation in which the internal combustion engine is operating but not injecting fuel. This allows the operation of the feedback signal to be appropriately diagnosed in a configuration that uses the feedback signal to diagnose a malfunction in the injection control. [Brief description of the drawings]

[0009] [Figure 1] Functional block diagram showing one embodiment. [Diagram 2] flowchart [Diagram 3] flowchart [Figure 4] flowchart [Diagram 5] Time Chart DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment will be described below with reference to the drawings. The embodiment is embodied as a common rail fuel injection system for an on-vehicle four-cylinder diesel engine. High-pressure fuel is stored in the common rail at a predetermined fuel pressure, and the high-pressure fuel is injected and supplied from an electromagnetically driven injector to each cylinder. The present embodiment is not limited to diesel engines, and can also be applied to a direct injection type fuel injection system for gasoline engines. In this embodiment, for example, a configuration is assumed in which multi-stage injection and multiple injection are selectively performed, and the multi-stage injection includes pre-injection, pilot injection, main injection, and after-injection. The pre-injection is an injection performed mainly for in-cylinder activation. The pilot injection is an injection performed mainly for reducing NOx and combustion noise. The main injection is an injection performed mainly for determining the output of the internal combustion engine. The after-injection is an injection performed mainly for re-burning soot. Moreover, the post-injection for realizing multiple injection is an injection performed mainly for catalyst activation. Each of these injections is appropriately performed according to the operating state of the internal combustion engine, etc., for the purpose of improving exhaust emissions, etc.

[0011] As shown in Fig. 1, an electronic control unit (ECU: Electric Control Unit) 1 as a fuel injection control device includes a microcomputer (hereinafter referred to as a microcomputer) 2 as a control unit, and injection drive ICs 3 and 4 as injection drive units. The injection drive ICs 3 and 4 are configured on the premise that multiple injection will be performed, and drive the injectors 5 to 8 of all four cylinders in pairs. In the case of a common rail fuel injection system for an in-vehicle six-cylinder diesel engine, the injectors of all six cylinders are configured to be driven in pairs of three cylinders.

[0012] The microcomputer 2 has a CPU, a ROM, a RAM, an I / O, etc., and executes a computer program stored in a non-transient substantial storage medium to execute processing corresponding to the computer program and control the operation of the electronic control device 1. The microcomputer 2 includes a fuel injection amount calculation unit 2a, a drive time calculation unit 2b, an output terminal controller 2c, an input terminal controller 2d, and a fault diagnosis unit 2e for each function. The fuel injection amount calculation unit 2a, the drive time calculation unit 2b, the output terminal controller 2c, the input terminal controller 2d, and the fault diagnosis unit 2e are embodied by software, hardware, or a combination thereof.

[0013] The fuel injection amount calculation unit 2a inputs a rotation pulse signal (hereinafter referred to as an NE pulse signal) generated at equal crank angle intervals (for example, every 10° CA) from a crank angle sensor (not shown) and also inputs an accelerator opening signal from an accelerator opening sensor (not shown). The fuel injection amount calculation unit 2a specifies operating information of the internal combustion engine based on the input NE pulse signal and accelerator opening signal, and determines the injection requirements. After determining the injection requirements, the fuel injection amount calculation unit 2a calculates an optimal fuel injection amount that satisfies the determined injection requirements, and outputs the calculated fuel injection amount to the drive time calculation unit 2b.

[0014] When the drive time calculation unit 2b receives the fuel injection amount from the fuel injection amount calculation unit 2a, it calculates the drive time of each injector 5-8 based on the received fuel injection amount, and outputs the calculated drive time to the output terminal controller 2c. When the output terminal controller 2c receives the drive time from the drive time calculation unit 2b, it controls the on / off of the injection drive signal based on the received drive time, and transmits the injection drive signal to the corresponding injection drive ICs 3 and 4.

[0015] When the injection driving ICs 3 and 4 receive the injection drive signal transmitted from the output terminal controller 2c, they transmit a command signal to the corresponding injector 5-8 to drive the injector 5-8. When the injection driving ICs 3 and 4 have normally driven the corresponding injector 5-8, they control the on / off of the feedback signal following the on / off of the injection drive signal and transmit the feedback signal to the input terminal controller 2d. In this case, the injection driving IC 3 shares one feedback signal between the two injectors 5 and 6 and transmits it to the input terminal controller 2d. The injection driving IC 4 shares one feedback signal between the two injectors 7 and 8 and transmits it to the input terminal controller 2d. The feedback signal may be either an on / off binary signal or a serial communication signal.

[0016] In the above-described method using a feedback signal, if the operation of the feedback signal is abnormal, it becomes impossible to diagnose the injection control, and therefore it is necessary to diagnose the operation of the feedback signal. In this embodiment, the following configuration is provided in order to diagnose the operation of the feedback signal. Note that diagnosing the operation of the feedback signal means at least diagnosing a failure of a transmission circuit that transmits the feedback signal and a break in a signal line that transmits the feedback signal.

[0017] When the output terminal controller 2c switches the ejection drive signal history indicating that the ejection drive signal has been switched from off to on within a predetermined diagnostic period, the output terminal controller 2c switches the ejection drive signal history indicating that the ejection drive signal has been switched from off to on from off to on. The ejection drive signal history is a signal indicating the communication state of the ejection drive signal. The diagnostic period is, for example, 10 seconds. After switching the ejection drive signal history from off to on, the output terminal controller 2c holds the ejection drive signal history on until the diagnostic period ends, and switches the ejection drive signal history from on to off when the diagnostic period ends. The output terminal controller 2c may repeat switching the ejection drive signal from off to on and on to off multiple times within the diagnostic period. In that case, the output terminal controller 2c switches the ejection drive signal history from off to on in response to the first switching of the ejection drive signal from off to on within the diagnostic period, and holds the ejection drive signal history on until the diagnostic period ends.

[0018] When the input terminal controller 2d receives the feedback signal transmitted from the ejection driving ICs 3 and 4, it outputs a feedback signal history indicating that the feedback signal has been switched from off to on to the fault diagnosis unit 2e. The feedback signal history is a signal indicating the communication state of the feedback signal. When the input terminal controller 2d detects the feedback signal being switched from off to on during the above-mentioned diagnostic period, it switches the feedback signal history from off to on. After switching the feedback signal history from off to on, the input terminal controller 2d holds the feedback signal history on until the diagnostic period ends, and when the diagnostic period ends, it switches the feedback signal history from on to off. The input terminal controller 2d may repeat detection of the feedback signal being switched from off to on and the feedback signal being switched from on to off multiple times during the diagnostic period. In that case, when the input terminal controller 2d switches the feedback signal history from off to on in response to the first detection of the feedback signal being switched from off to on during the diagnostic period, it holds the feedback signal history on until the diagnostic period ends.

[0019] The fault diagnosis unit 2e monitors the time lapse of the diagnosis period by a measurement timer, and when the measurement timer counts up, it identifies the end of the diagnosis period and identifies that the diagnosis timing has been reached. That is, if the diagnosis period is, for example, 10 seconds, the fault diagnosis unit 2e identifies the diagnosis timing at 10-second intervals. When the fault diagnosis unit 2e identifies that the diagnosis timing has been reached, it determines whether or not a preset diagnosis condition is satisfied. The diagnosis conditions are that the rotation speed of the internal combustion engine is equal to or higher than idling, that the injection driving ICs 3 and 4 are not in a forced injection off state, that the battery voltage is equal to or higher than a threshold value, that the injection driving ICs 3 and 4 are normal, that the injectors 5 to 8 are normal, and that the injectors 5 to 8 are normally connected. The forced injection off state is a state in which fuel is not forcibly injected in order to detect an abnormality and to set the vehicle in a safe state for purposes other than the diagnosis of this embodiment.

[0020] If all of the above-mentioned conditions are satisfied, the fault diagnosis unit 2e determines that the diagnostic conditions are satisfied and performs a determination of normality or abnormality of the operation of the feedback signal, which will be described later. On the other hand, if any one of the above-mentioned conditions is not satisfied, the fault diagnosis unit 2e determines that the diagnostic conditions are not satisfied and does not perform a determination of normality or abnormality of the operation of the feedback signal. In other words, since there is a possibility of misdiagnosis even if the fault diagnosis unit 2e determines whether the operation of the feedback signal is normal or abnormal when the diagnostic conditions are not satisfied, the fault diagnosis unit 2e reduces the possibility of misdiagnosis by determining whether the operation of the feedback signal is normal or abnormal only when the diagnostic conditions are satisfied.

[0021] When the fault diagnosis unit 2e determines that the diagnosis condition is satisfied, it determines whether the feedback signal history is on or off, and determines whether the operation of the feedback signal is normal or abnormal. When the fault diagnosis unit 2e determines that the feedback signal history is on at the diagnosis timing, it determines that the operation of the feedback signal is normal. The fault diagnosis unit 2e measures the number of times that the operation of the feedback signal has been continuously determined to be normal using a normality counter, and when the measurement value of the normality counter reaches a first threshold value set in advance, it sets the diagnosis confirmation flag to normal and confirms the normal diagnosis of the feedback signal. In other words, when the fault diagnosis unit 2e determines that the operation of the feedback signal is normal a first predetermined number of times in succession, it confirms the normal diagnosis of the feedback signal. When the fault diagnosis unit 2e confirms the normal diagnosis of the feedback signal in this way, it holds the diagnosis result of normal diagnosis without re-diagnosing the operation of the feedback signal during the trip in which the normal diagnosis was confirmed.

[0022] On the other hand, when the fault diagnosis unit 2e determines that the feedback signal history is off at the diagnosis timing, it determines whether the injection drive signal history is on or off at the same timing, and when it determines that the injection drive signal history is on, it identifies that the operation of the feedback signal is abnormal. The fault diagnosis unit 2e measures the number of times that the feedback signal operation is continuously identified as abnormal using an abnormality counter, and when the measurement value of the abnormality counter reaches a second threshold value set in advance, it sets the diagnosis confirmation flag to abnormal and confirms the abnormal diagnosis of the feedback signal. That is, when the fault diagnosis unit 2e identifies the feedback signal operation as abnormal a second predetermined number of times in succession, it confirms the abnormal diagnosis of the feedback signal. When the fault diagnosis unit 2e confirms the abnormal diagnosis of the feedback signal in this way, it holds the diagnosis result of the abnormality diagnosis without re-diagnosing the operation of the feedback signal during the trip in which the abnormality diagnosis was confirmed. Note that the first threshold value for confirming the normal diagnosis and the second threshold value for confirming the abnormal diagnosis, i.e., the first predetermined number and the second predetermined number, may be the same value or different values.

[0023] Next, the operation of the above-mentioned configuration will be described with reference to FIGS. The microcomputer 2 determines whether a start condition for diagnostic processing is satisfied, and starts diagnostic processing when it determines that the start condition for diagnostic processing at a predetermined period is satisfied, for example. When the microcomputer 2 starts diagnostic processing, it determines whether a diagnosis determination flag is undetermined (S1). When the microcomputer 2 determines that the diagnosis determination flag is undetermined, that is, the diagnosis determination flag has not been set to normal or abnormal and the diagnosis result of normal diagnosis or abnormal diagnosis has not been determined (S1: YES), it determines whether a diagnosis timing has been reached (S2). When the microcomputer 2 determines that a diagnosis timing has not been reached (S2: NO), it continues counting up the measurement timer (S3), keeps the diagnosis determination flag undetermined (S4), ends diagnostic processing, and waits for the start condition for the next diagnostic processing to be satisfied.

[0024] On the other hand, when the microcomputer 2 determines that the diagnosis timing has been reached (S2: YES), it proceeds to a diagnosis condition satisfaction determination process (S5). When the microcomputer 2 starts the diagnosis condition satisfaction determination process, it determines whether the rotation speed of the internal combustion engine is equal to or higher than idling (S31). When the microcomputer 2 acquires the rotation speed of the internal combustion engine, and determines that the acquired rotation speed of the internal combustion engine is equal to or higher than idling (S31: YES), it determines whether the injection driving ICs 3 and 4 are in the injection forced off state (S32). When the microcomputer 2 acquires the state of the injection driving ICs 3 and 4, and determines that the injection driving ICs 3 and 4 are not in the injection forced off state (S32: NO), it determines whether the battery voltage is equal to or higher than a threshold value (S33). When the microcomputer 2 acquires the battery voltage, and determines that the acquired battery voltage is equal to or higher than a threshold value (S33: YES), it determines whether the injection driving ICs 3 and 4 are normal (S34). When the microcomputer 2 determines that the injection drive ICs 3, 4 are normal (S34: YES), it determines whether or not the injectors 5-8 are normal (S35). The microcomputer 2 acquires the status of each of the injectors 5-8, and when it determines that each of the injectors 5-8 is normal (S35: YES), it determines whether or not each of the injectors 5-8 is connected normally (S36). When it determines that each of the injectors 5-8 is connected normally (S36: YES), the microcomputer 2 determines that the diagnostic condition is met (S37), ends the diagnostic condition fulfillment determination process, and returns to the diagnostic process.

[0025] On the other hand, if the microcomputer 2 determines that the internal combustion engine speed is not above idle (S31: NO), if it determines that each of the injection drive ICs 3, 4 is in the forced injection off state (S32: YES), if it determines that the battery voltage is not above the threshold (S33: NO), if it determines that each of the injection drive ICs 3, 4 is not normal (S34: NO), if it determines that each of the injectors 5-8 is not normal (S35: NO), or if it determines that each of the injectors 5-8 is not connected normally (S36: NO), it determines that the diagnostic conditions are not satisfied (S38), terminates the diagnostic condition satisfaction determination process, and returns to the diagnostic process.

[0026] The microcomputer 2 judges the result of the diagnostic condition satisfaction judgment process and judges whether or not the diagnostic condition is satisfied (S6). If the microcomputer 2 judges that the diagnostic condition is not satisfied (S6: NO), it keeps the diagnosis determination flag undetermined (S4), ends the diagnostic process, and waits for the start condition of the next diagnostic process to be satisfied.

[0027] On the other hand, if the microcomputer 2 determines that the diagnostic condition is satisfied (S6: YES), it determines whether the feedback signal history is ON (S7). If the microcomputer 2 determines that the feedback signal history is ON (S7: YES), it determines that the operation of the feedback signal is normal (S8). The microcomputer 2 increments the measurement value of the normal counter (S9), clears the measurement value of the abnormal counter (S10), and determines whether the measurement value of the normal counter after the increment has reached a first threshold value (S11).

[0028] When the microcomputer 2 determines that the measurement value of the normal counter after the increment has not reached the first threshold value (S11: NO), it holds the diagnosis confirmation flag as undetermined (S4), ends the diagnostic process, and waits for the start condition of the next diagnostic process to be satisfied. On the other hand, when the microcomputer 2 determines that the measurement value of the normal counter after the increment has reached the first threshold value, that is, that the operation of the feedback signal has been identified as normal a first predetermined number of times in succession (S11: YES), it sets the diagnosis confirmation flag to normal, confirms the normal diagnosis of the feedback signal (S12), ends the diagnostic process, and waits for the start condition of the next diagnostic process to be satisfied. When the microcomputer 2 thus confirms the normal diagnosis of the feedback signal, since the diagnosis result of the normal diagnosis has been confirmed in the next and subsequent diagnostic processes, it determines that the diagnosis confirmation flag is not undetermined (S1: NO), holds the value of the diagnosis confirmation flag (S13), ends the diagnostic process, and waits for the start condition of the next diagnostic process to be satisfied.

[0029] On the other hand, when the microcomputer 2 determines that the feedback signal history is OFF and not ON (S7: NO), it determines whether the ejection drive signal history is ON or not (S14). When the microcomputer 2 determines that the ejection drive signal history is OFF and not ON (S14: NO), it holds the measurement value of the normal counter (S15), holds the measurement value of the abnormal counter (S16), holds the diagnosis determination flag as undetermined (S17), ends the diagnosis process, and waits for the establishment of the start condition of the next diagnosis process.

[0030] On the other hand, when the microcomputer 2 determines that the ejection drive signal history is ON (S14: YES), it determines that the operation of the feedback signal is abnormal (S18). The microcomputer 2 increments the measurement value of the abnormal counter (S19), clears the measurement value of the normal counter (S20), and determines whether the measurement value of the abnormal counter after the increment has reached a second threshold value (S21).

[0031] When the microcomputer 2 determines that the measurement value of the abnormality counter after increment has not reached the second threshold value (S21: NO), it holds the diagnosis confirmation flag as undetermined (S17), ends the diagnostic process, and waits for the start condition of the next diagnostic process to be satisfied. On the other hand, when the microcomputer 2 determines that the measurement value of the abnormality counter after increment has reached the second threshold value, that is, that an abnormality in the operation of the feedback signal has been identified a second predetermined number of times in succession (S21: YES), it sets the diagnosis confirmation flag to abnormal, confirms the abnormal diagnosis of the feedback signal (S22), ends the diagnostic process, and waits for the start condition of the next diagnostic process to be satisfied. When the microcomputer 2 confirms the abnormal diagnosis of the feedback signal in this way, since the diagnosis result of the abnormality diagnosis has been confirmed in the next and subsequent diagnostic processes, it determines that the diagnosis confirmation flag is not undetermined (S1: NO), holds the value of the diagnosis confirmation flag (S13), ends the diagnostic process, and waits for the start condition of the next diagnostic process to be satisfied.

[0032] As shown in FIG. 5, if the second threshold is set to "3", for example, the microcontroller 2 determines that the operation of the feedback signal is normal at the diagnostic timings "t1" and "t2", and if it determines that the operation of the feedback signal is abnormal three times consecutively at the diagnostic timings "t4" to "t6" before confirming the normal diagnosis of the feedback signal, it confirms the abnormal diagnosis of the feedback signal.

[0033] As described above, according to this embodiment, the following advantageous effects can be obtained. In the electronic control device 1, occurrences of switching of the injection drive signal from off to on are generated as injection drive signal history, occurrences of switching of the feedback signal from off to on are generated as feedback signal history, and the operation of the feedback signal is diagnosed based on the injection drive signal history and the feedback signal history during operation of the internal combustion engine. There is no need to forcibly drive each of the injectors 5 to 8 while the internal combustion engine is stopped, and it is possible to prevent a situation in which fuel is not burned and the internal combustion engine becomes dirty. In addition, it is possible to distinguish and identify a situation in which the internal combustion engine is operating but not injecting fuel. As a result, in a configuration in which a feedback signal is used to diagnose a malfunction of the injection control, it is possible to appropriately diagnose the operation of the feedback signal.

[0034] If the ejection drive signal is switched from off to on at least once within a diagnosis period, the ejection drive signal history is identified as on. In a configuration in which the operation of the feedback signal is diagnosed every time the ejection drive signal is switched from off to on, the processing load increases and there is a possibility of misdiagnosis due to a delayed response of the feedback signal, but by diagnosing the operation of the feedback signal based on a certain period of history, it is possible to avoid an increase in the processing load and reduce the possibility of misdiagnosis.

[0035] If the feedback signal is switched from off to on at least once within a diagnosis period, the feedback signal history is identified as on. In a configuration in which the operation of the feedback signal is diagnosed every time the feedback signal is switched from off to on, the processing load increases and there is a possibility of misdiagnosis due to a response delay of the feedback signal, but by diagnosing the operation of the feedback signal based on the history for a certain period, it is possible to avoid an increase in the processing load and reduce the possibility of misdiagnosis.

[0036] When all of the following conditions are met: the engine speed is equal to or higher than idling, the injection drive ICs 3, 4 are not in a forced injection off state, the battery voltage is equal to or higher than a threshold, the injection drive ICs 3, 4 are normal, the injectors 5 to 8 are normal, and the injectors 5 to 8 are normally connected, it is determined that the diagnostic conditions are met and the operation of the feedback signal is diagnosed. A configuration in which the operation of the feedback signal is diagnosed when the diagnostic conditions are not met may result in an erroneous diagnosis, but by setting the diagnostic conditions, the possibility of an erroneous diagnosis can be reduced.

[0037] When the operation of the feedback signal is identified as normal a first predetermined number of times in succession, a normal diagnosis of the feedback signal is confirmed. After eliminating the influence of disturbances and response delays of the feedback signal, a normal diagnosis of the feedback signal can be confirmed, and the accuracy of confirming the normal diagnosis can be improved. The same applies to the case of confirming an abnormal diagnosis; when the operation of the feedback signal is identified as abnormal a second predetermined number of times in succession, an abnormal diagnosis of the feedback signal is confirmed. After eliminating the influence of disturbances and response delays of the feedback signal, an abnormal diagnosis of the feedback signal can be confirmed, and the accuracy of confirming the abnormal diagnosis can be improved.

[0038] When the feedback signal operation is diagnosed as normal or abnormal, the diagnosis result is retained during the trip in which the diagnosis was confirmed, without re-diagnosing the feedback signal operation. By retaining the diagnosis result, if an abnormality diagnosis is confirmed, the driver can be continuously notified that the feedback signal operation is abnormal and be prompted to make repairs, which leads to functional safety.

[0039] One feedback signal is shared by the two injectors 5 and 6, and one feedback signal is shared by the two injectors 7 and 8. This reduces the number of wires and simplifies the configuration compared to a configuration in which feedback signals are provided individually for the injectors 5 to 8.

[0040] Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure.

[0041] Although the configuration has been exemplified in which the fault diagnosis unit 2e that diagnoses the operation of the feedback signal is provided inside the microcomputer 2, a configuration in which a functional block that diagnoses the operation of the feedback signal is provided outside the microcomputer 2 may also be used. A configuration in which a functional block that diagnoses the operation of the feedback signal is provided, for example, between the microcomputer 2 and the ejection driving ICs 3 and 4 may also be used.

[0042] The control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. Also, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer. [Explanation of symbols]

[0043] In the drawing, 1 is an electronic control device (fuel injection control device), 2 is a microcomputer (control unit), 2e is a failure diagnosis unit, 3 and 4 are injection drive ICs (injection drive unit), and 5 to 8 are injectors.

Claims

1. A fuel injection control device (1) for controlling fuel injection from an injector to an internal combustion engine, A control unit (2) that transmits an ejection drive signal; an injection driving unit (3, 4) that, upon receiving an injection driving signal transmitted from the control unit, transmits a command signal to the injector to drive the injector, and, upon normally driving the injector, transmits a feedback signal to the control unit; a fault diagnosis unit (2e) that diagnoses an operation of the feedback signal based on a communication state of the injection drive signal and a communication state of the feedback signal during operation of the internal combustion engine, The fuel injection control device, wherein the fault diagnosis unit, when the injection drive signal turns on at least once within a diagnosis period, identifies an on in the injection drive signal history indicating that the injection drive signal has turned on, and, when the feedback signal turns on at least once within a diagnosis period, identifies an on in the feedback signal history indicating that the feedback signal has turned on, and diagnoses the operation of the feedback signal based on the injection drive signal history indicating the communication state of the injection drive signal and the feedback signal history indicating the communication state of the feedback signal.

2. 2. The fuel injection control device according to claim 1, wherein the fault diagnosis unit diagnoses the operation of the feedback signal when all of the following conditions are met: the internal combustion engine speed is equal to or higher than idle, the injection drive unit is not in a forced injection off state, the battery voltage is equal to or higher than a threshold value, the injection drive unit is normal, the injector is normal, and the injector is normally connected.

3. 3. A fuel injection control device as described in claim 1 or 2, wherein the fault diagnosis unit determines whether the operation of the feedback signal is normal or abnormal multiple times, and confirms a normal diagnosis of the feedback signal when the operation of the feedback signal is determined to be normal a first predetermined number of times in succession, and confirms an abnormal diagnosis of the feedback signal when the operation of the feedback signal is determined to be abnormal a second predetermined number of times in succession.

4. 4. A fuel injection control device as described in any one of claims 1 to 3, wherein when the fault diagnosis unit confirms a normal or abnormal diagnosis of the operation of the feedback signal, it retains the diagnosis result without re-diagnosing the operation of the feedback signal during the trip in which the diagnosis was confirmed.

5. A fuel injection control device described in any one of claims 1 to 4, wherein the injection drive unit individually transmits the command signal to multiple injectors to drive the multiple injectors individually, and the multiple injectors share a single feedback signal and transmit it to a control unit.

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