CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

Abstract

An internal combustion engine control device comprising a fuel injection valve drive circuit that applies a drive current to each of the fuel injection valves and controls an internal combustion engine, the internal combustion engine control device comprising: a control section that prohibits the starting of the internal combustion engine when it detects the supply of the drive current based on a drive signal associated with each of the fuel injection valves to the fuel injection valve driving circuit in a case of sending a drive prohibition signal associated with each of the fuel injection valves to the fuel injection valve driving circuit before starting the internal combustion engine and sending the drive signal associated with each of the fuel injection valves to the fuel injection valve driving circuit.

Description

Technical field

[0001] The present invention relates to a control device for an internal combustion engine for controlling a fuel injection valve that supplies fuel to each combustion chamber of an internal combustion engine, and more particularly, to a control device for an internal combustion engine having a function that confirms the normality of a fuel injection cut-off function. background

[0002] When an abnormality / fault in a mechanical component or a control component affecting engine torque is detected, an ECU for an internal combustion engine notifies an operator of the abnormality in an internal combustion engine and executes limp-home functions, including a fuel injection cutoff function, an ignition control cutoff function, and a throttle opening fixed setting function. However, in a case where the internal combustion engine enters a state requiring limp-home functions without confirming whether the limp-home functions are operating normally, the internal combustion engine may enter a state where abnormal engine torque is generated when the limp-home functions are not functioning. Therefore, it is necessary to confirm whether the limp-home functions are operating normally.

[0003] For example, JP 2009-127574 A (Patent Document 1) discloses a control device for an internal combustion engine that performs abnormal diagnosis of a fuel injection cut-off function to confirm whether the fuel injection cut-off function operates normally during limp home operation by setting a diagnosis period for diagnosing the fuel injection cut-off function within a period in which an internal combustion engine stops operation, outputting a fuel injection cut-off signal to a fuel injection valve drive circuit in the diagnosis period of the fuel injection cut-off function, and monitoring a signal state of an operation state monitoring terminal (disabling terminal) of the fuel injection valve control circuit at that time. State of the art documentPatent document

[0004] Patent Document 1: JP 2009 - 127 574 A Further control devices for internal combustion engines related to the present invention are disclosed in the laid-open publications DE 10 2008 044 066 A1 and DE 10 2014 212 491 A1. Overview of the inventionProblem to be solved by the invention

[0005] The control device for an internal combustion engine disclosed in Patent Document 1 monitors the signal state of the operating state monitoring terminal in the fuel injection valve drive circuit. However, the control device for an internal combustion engine disclosed in Patent Document 1 is unable to distinguish, in the determination, the stop for driving each fuel injection valve by the normal fuel injection shut-off function from the stop of the fuel injection valve due to abnormalities in the fuel injection valve drive circuit and in a fuel injection control device that controls the fuel injection valve drive circuit.For this reason, the internal combustion engine control device disclosed in Patent Document 1 has a problem that the fuel injection control device considers the fuel injection shutoff function to be abnormal and prevents the internal combustion engine from starting even though the fuel injection shutoff function is actually operating normally. Note that in a case where the fuel injection valve stops due to an abnormality other than the abnormality in the fuel injection shutoff function, a different diagnostic function is used in the diagnosis.

[0006] An object of the present invention is to provide a control device for an internal combustion engine which can ensure a diagnosis as to whether a fuel injection cut-off function operates normally and which further prohibits the starting of an internal combustion engine when it is determined that the fuel injection cut-off function does not operate normally. Means to solve the problem

[0007] The present invention solves this problem by the features of the independent patent claims. Advantageous developments of the invention are described in the subclaims.

[0008] In the present invention, starting of an internal combustion engine is prohibited when, in a case of sending a drive prohibition signal associated with each of the fuel injection valves to a fuel injection valve drive circuit before starting the internal combustion engine and sending the drive signal associated with each of the fuel injection valves to the fuel injection valve drive circuit, the conduction of a drive current based on a drive signal associated with each of the fuel injection valves to the fuel injection valve drive circuit is detected. Advantages of the invention

[0009] According to the present invention, by sending the drive signal associated with each of the fuel injection valves to the fuel injection valve drive circuit in a state of sending the drive signal associated with each of the fuel injection valves to the fuel injection valve drive circuit to actuate the fuel injection cut-off function, and by monitoring whether the current based on the drive signal is supplied to each of the fuel injection valves, it is possible to ensure a diagnosis of whether the fuel injection cut-off function operates normally. Brief description of the drawings Fig. 1 is a configuration diagram showing an overall configuration of a fuel injection system of an internal combustion engine to which the present invention is applied. Fig. 2 is a circuit diagram showing a configuration of a Fig. 1 shows the fuel injection valve control section. Fig. 3 is a control flowchart for determining the normality of a fuel injection cut-off function according to a first embodiment of the present invention. Fig. 4 is an explanatory diagram of a diagnostic drive signal applied to each fuel injector at a diagnostic time. Fig. 5 is a timing chart in a case where fuel injection cut-off function does not operate normally. Fig. 6 is a timing chart in a case where the fuel injection cut-off function operates normally and an abnormality occurs in one of the fuel injection valves. Fig. 7 is a timing chart in a case where it is unclear whether the fuel injection cut-off function operates normally. Fig. 8 is a timing chart in a case where the fuel injection cut-off function according to the first embodiment operates normally. Fig. 9 is a control timing chart for determining the normality of the fuel injection cut-off function according to a modification of the first embodiment. Fig. 10 is an explanatory diagram of an interval length between multiple diagnostic drive signals applied to the same fuel injector at diagnostic times. Fig. 11 is a control flowchart for determining the normality of the fuel injection cut-off function according to a second embodiment of the present invention. Fig. 12 is a timing chart in a case where the fuel injection cut-off function according to the second embodiment operates normally. Fig. 13 is a control flowchart for determining the normality of the fuel injection cut-off function according to a third embodiment of the present invention. Modes for carrying out the invention

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings. It should be noted that the present invention is not limited to the embodiments described below, but includes various modifications and application examples within a technical concept of the present invention. First embodiment

[0011] While a first embodiment of the present invention with reference to Fig. 1 to 11, a configuration of a control device for an internal combustion engine to which the present invention is applied will be described with reference to Fig. 1 roughly described. While Fig. 1 illustrates that the present invention is applied to a direct injection internal combustion engine in which each fuel injection valve is mounted on each cylinder, the present invention is also applicable to an internal combustion engine in which each fuel injection valve is mounted on an intake manifold.

[0012] In Fig. 1, a fuel injection system 100 of an internal combustion engine is constituted by a fuel injection control unit (hereinafter referred to as "ECU") 101, and the ECU 101 has a function of generating a drive control signal associated with each fuel injection valve 109. An internal combustion engine is, for example, an inline four-cylinder gasoline internal combustion engine.

[0013] The ECU 101 performs various processing based on various input signals. For example, the ECU 101 controls each electromagnetic fuel injection valve 109. Note that the fuel injection valve 109 is a direct fuel injection type fuel injection valve that injects fuel into each cylinder.

[0014] The ECU 101 is configured with a control section 102 having an injection pulse width changing function and a drive waveform changing function, a fuel injection cut-off function section 103 having a fuel injection cut-off function, a fuel injection valve drive circuit 111 formed of a drive IC circuit 106 and fuel injection valve drive sections 108, a high-voltage generating section 107, and a fuel injection valve operation monitoring section 112. A battery voltage supplied from a battery power supply 110 is supplied to the high-voltage generating section 107 and the high-side fuel injection valve drive section 108a via fuses 104 and a relay 105.

[0015] The control section 102 is constituted, for example, by a microcomputer including a CPU, a memory, and an I / O port. The control section 102 constituted by the microcomputer has a pulse signal calculation function section 102a and a drive waveform command function section 102b. Furthermore, the control section 102 outputs a fuel cut command and a fuel cut cancellation command to the fuel injection cutoff function section 103 to perform fuel cutoff diagnosis.

[0016] The pulse signal calculation function section 102a determines a fuel injection pulse width (=current conduction time) for driving each fuel injection valve 109 based on an input operating parameter of the internal combustion engine (for example, a sensor value detected by a sensor or the like) and outputs the fuel injection pulse width to the drive IC circuit 106. Examples of the input operating parameter include a fuel temperature, a cooling water temperature, a lubricant temperature, and a fuel pressure. Furthermore, the drive waveform command function section 102b determines a drive waveform of a current for driving each fuel injection valve 109 based on the above-described operating parameter and outputs the drive waveform as a command (request) to the drive IC circuit 106.

[0017] A drive period (= current conduction time) of each fuel injection valve 109, the selection of a drive voltage (either the high voltage generated by the high-voltage generation section 107 or the battery voltage from the battery power supply 110), and a target value of a drive current are set to the drive IC circuit 106 in the fuel injection valve drive circuit 111 based on an output signal from the pulse signal calculation function section 102a and the command from the drive waveform command function section 102b. The drive IC circuit 106 controls the high-voltage generation section 107 and the fuel injection valve drive sections 108a and 108b according to this setting.

[0018] At a time of opening a valve element provided in each fuel injection valve 109, the high-voltage generation section 107 boosts the battery voltage to generate the high voltage to be supplied to the fuel injection valve 109, and supplies the high voltage to the high-side fuel injection valve driving section 108a. Specifically, the high-voltage generation section 107 boosts the battery voltage supplied from the battery power supply 110 based on a command from the driving IC circuit 106 so that the voltage reaches a desired target high voltage and generates the high voltage higher than the battery voltage.With this configuration, two system voltages, that is, the high voltage to provide a force to open the valve element and the battery voltage to keep the valve element open to prevent the valve element from being closed after opening, are prepared as power supplies for supplying the voltage to each fuel injection valve 109.

[0019] The high-side fuel injection valve driving section 108a is electrically connected to an upstream side of an excitation coil of each fuel injection valve 109. The high-side fuel injection valve driving section 108a controls the supply of voltage to the fuel injection valve 109 and selects the voltage to be supplied (either the high voltage generated by the high-voltage generating section 107 or the battery voltage from the battery power supply 110).

[0020] Furthermore, the low-side fuel injection valve driving section 108b is electrically connected to a downstream side of the excitation coil of each fuel injection valve 109. The low-side fuel injection valve driving section 108b switches between grounding the excitation coil of the fuel injection valve 109 and non-grounding the excitation coil of the fuel injection valve 109 based on the control of the drive IC circuit 106.

[0021] Next, the configurations of the fuel injection valve driving sections 108a and 108b will be described with reference to Fig. 2. The high-side fuel injection valve drive section 108a is formed with a combined circuit of a diode 201 and a drive circuit 203 and a combined circuit of a diode 202 and a drive circuit 204.

[0022] One end of the diode 201 is electrically connected to the high-voltage generating section 107, and the other end is electrically connected to the driving circuit 203. The diode 201 prevents current from flowing back to the high-voltage generating section 107. The driving circuit 203 is, for example, a transistor; a collector is electrically connected to the diode 201, a base is electrically connected to the driving IC circuit 106, and an emitter is electrically connected to one end of the exciting coil of each fuel injection valve 109. The driving circuit 203 controls the supply of current from the high-voltage generating section 107 to the fuel injection valve 109 via the diode 201 based on a signal input to the base from the driving IC circuit 106.

[0023] One end of the diode 202 is electrically connected to the battery power supply 110, and the other end is electrically connected to the drive circuit 204. The diode 202 prevents current from flowing back to the battery power supply 110. The drive circuit 204 is, for example, a transistor; a collector is electrically connected to the diode 202, a base is electrically connected to the drive IC circuit 106, and an emitter is electrically connected to each fuel injector 109. The drive circuit 204 controls the supply of current from the battery power supply 110 to the fuel injector 109 via the diode 202 based on a signal input to the base from the drive IC circuit 106.

[0024] The high-side fuel injection valve driving section 108a applies the high voltage generated by the high-voltage generating section 107 to each fuel injection valve 109 in a case where a signal for turning on the drive circuit 203 is input to the high-side fuel injection valve driving section 108a based on an output and a command from the control section 102, and on the other hand, applies the battery voltage from the battery power supply 110 to the fuel injection valve 109 in a case where a signal for turning on the drive circuit 204 is input to it from the drive IC circuit 106.

[0025] The low-side fuel injection valve driving section 108b is formed with a drive circuit 205 and a shunt resistor 206. The drive circuit 205 is, for example, a transistor, a collector is electrically connected to each fuel injection valve 109, a base is electrically connected to the drive IC circuit 106, and an emitter is electrically connected to the shunt resistor 206. The drive circuit 205 controls the supply of current from the other end of the excitation coil of the fuel injection valve 109 to the shunt resistor 206 based on a signal input to the base from the drive IC circuit 106. One end of the shunt resistor 206 is electrically connected to the drive circuit 205, and the other end is grounded.The shunt resistor 206 detects a current passed through the resistor, and the current is output to the fuel injector operation monitoring section 112 via an amplifier 207 as a diagnostic monitoring current.

[0026] The low-side fuel injection valve driving section 108b detects the diagnostic monitoring current passed through the shunt resistor 206 when a signal for turning on the drive circuit 205 is input from the drive IC circuit 106 to the low-side fuel injection valve driving section 108b based on a command from the control section 102.

[0027] In the control section 102, a drive current profile is preset in a storage element of the drive waveform command function section 102b based on the characteristics of each fuel injection valve 109 for driving the fuel injection valve 109, and the drive current profile is stored to correspond to the injection amount characteristics of the fuel injection valve 109. The drive current profile from the drive waveform command function section 102b is output to the drive IC circuit 106.

[0028] Furthermore, the pulse signal calculation function section 102a in the control section 102 calculates the drive timing (pulse width) of opening the fuel injection valve 109 based on a running state quantity (an intake air amount, a rotational speed, or the like) of the internal combustion engine and the fuel injection amount characteristic of the fuel injection valve 109, generates an ON / OFF signal as a pulse signal, and outputs the pulse signal to the drive IC circuit 106. The drive IC circuit 106 turns on the pulse signal from a timing of the desired injection timing calculated by the control section 102 and applies a current to each fuel injection valve 109 according to the drive current profile stored in advance in the control section 102.

[0029] The drive current profile is formed from a plurality of target current values, including a current value of a valve-opening peak current for opening each fuel injector 109, a current value of a first holding current for holding the fuel injector 109 to be opened, and a current value of a second holding current lower than the current value of the first holding current. The drive IC circuit 106 applies a drive current in response to the drive current profile to the fuel injector 109 from a time the pulse signal is turned on to a time the pulse signal is turned off, based on a preset control sequence.

[0030] The fuel injection valve operation monitoring section 112 will be described next. The fuel injection valve operation monitoring section 112 is configured with at least a monitoring current detection section 112a that detects that the diagnostic monitoring current supplied to the fuel injection valve 109 reaches a predetermined value, and a detection result transmission section 112b that transmits a detection result to the fuel injection shutoff function section 103. Since the diagnostic monitoring current has a current value lower than the above-described holding current value, a current threshold value lower than the holding current value is set in the monitoring current detection section 112a. Furthermore, the fuel injection shutoff function section 103 outputs the detection result to the control section 102.

[0031] It is noted that the detection result may be output to the control section 102 directly and not via the fuel injection cut-off function section 103.

[0032] At a diagnosis time of the fuel injection cutoff function, the drive current is supplied to each fuel injection valve 109 by intentionally supplying a drive signal (pulse signal) to the fuel injection valve drive sections 108a and 108b. Since the drive signal is used in the diagnosis of the fuel injection cutoff function, the drive signal will be described below as a diagnosis drive signal. Furthermore, the drive current supplied to the shunt resistor 206 is also used in the diagnosis of the fuel injection cutoff function to correspond to the diagnosis drive signal; therefore, the drive current will be described below as a diagnosis monitor current.

[0033] In addition, the fuel injection valve operation monitoring section 112 monitors the diagnosis monitor current supplied from the shunt resistor 206 and determines that the diagnosis drive signal is output from the drive IC circuit 106 in a case where the diagnosis monitor current based on the diagnosis drive signal is detected, and that the diagnosis drive signal is not output from the drive IC circuit 106 in a case where the diagnosis monitor current is not detected.

[0034] It is noted here that the diagnostic drive current based on the diagnostic drive signal, as in Fig. 2, is supplied from the battery power supply 110, and yet the current-carrying time of the diagnostic drive signal is set to a pulse time for which each fuel injector 109 is not allowed to open. Furthermore, the diagnostic monitoring current detected by the shunt resistor 206 is set to a value lower than the second holding current value described above. Although the drive current is set as a detection target value, the detection target value may be a drive voltage.

[0035] Next, with reference to Fig. 3, a concrete diagnostic procedure for diagnosing whether the fuel injection cut-off function according to the present embodiment is operating normally is described. It is noted that timing charts and the diagnostic procedure in the case of executing a diagnostic procedure of Fig. 3 also with reference to the Fig. 5 to 8 are described.

[0036] The Fig. 5 to 8 show the timing charts of diagnosis drive signals (pulse signals) Tdig output from the drive IC circuit 106, a fuel injection cutoff setting / cancellation signal Scut output from the fuel injection cutoff function section 103 to the drive IC circuit 106, and a diagnosis monitor current Idig detected by the fuel injection valve operation monitor section 112.

[0037] In the Fig. 5 to 8 compare a state in which the fuel injection cutoff function is set and the diagnosis drive signals are output (hereinafter referred to as the fuel injection cutoff set state) with a state in which the fuel injection cutoff function is canceled and the diagnosis drive signals are output (hereinafter referred to as the fuel injection cutoff canceled state). While a sequential order of outputting the diagnosis drive signals is set to a sequential order of actuating the cylinders, the order may be disregarded because the internal combustion engine is basically inactive. Note that the following control flow is a function executed by the microcomputer of the control section 102.

[0038] <<Schritt S10> > In step S10, a diagnosis function (function safety diagnosis) in the fuel injection cutoff function is activated before the engine starts. Therefore, if it is determined that the timing is not before the engine starts, the processing goes to END and waits for the arrival of the next start timing. On the other hand, if it is determined that the timing is before the engine starts, the diagnosis of the fuel injection cutoff function is executed. Activation is performed based on (synchronous with) an ON signal for turning on an ignition switch, and it is specified that the control steps to be described later up to steps S16 to S19 for diagnosing the fuel injection cutoff function are completed within the time before a starter motor is activated.If the diagnosis function is enabled in the fuel injection cutoff function, the processing proceeds to step S11.

[0039] <<Schritt S11> > In step S11, a drive prohibition signal Scut associated with each fuel injection valve 109 is sent to the drive IC circuit 106, so that the fuel injection cutoff function section 103 sets the fuel injection cutoff function and the drive IC circuit 106 is placed in the fuel injection cutoff set state. Even if the drive signal from the control section 102 and the fuel injection cutoff function section 103 is input to the drive IC circuit 106, no fuel is injected if the fuel injection cutoff function is normal and the drive IC circuit 106 is placed in the fuel injection cutoff set state. Upon placing the drive IC circuit 106 in the fuel injection cutoff set state, the processing proceeds to step S12.

[0040] <<Schritt S12> > In step S12, the control section 102 sends a command signal to the drive IC circuit 106 so that the drive IC circuit 106 outputs the diagnostic drive signal Tdig (see Fig. 4). In response to the command signal, the drive IC circuit 106 outputs the diagnostic drive signal Tdig to the fuel injection valve drive sections 108a and 108b. In this case, the drive circuit 204 in the high-side fuel injection valve drive section 108a is turned on to select the battery power supply 110, and the drive circuit 205 in the low-side fuel injection valve drive section 108b is turned on.

[0041] Note that the conduction time of the diagnostic drive signal Tdig is set to the conduction time for which each fuel injection valve 109 is not allowed to open. Diagnosis is performed before starting the engine, and this setting is intended to prevent a situation in which unburned fuel stagnates in a combustion chamber when each fuel injection valve 109 is driven, and in which the fuel is discharged to the outside as an unburned component at the time of starting.

[0042] Fig. 4 shows the diagnosis drive signal Tdig, and the current conducting time of the diagnosis drive signal Tdig is specified to fall within a diagnosis drive signal setting time range TBdig that is shorter than the injection-disabled time Tda and longer than a time detection threshold Trs set by the microcomputer.

[0043] Note that the injection-disabled time Tda is the time during which the valve element does not operate even when a predetermined drive current is applied from the battery power supply 110 to each fuel injection valve 109, and that the valve element reversely operates when the drive current is applied to the fuel injection valve 109 for a time equal to or longer than the injection-disabled time Tda. Since the injection-disabled time Tda varies depending on each fuel injection valve 109, an appropriate injection-disabled time Tda can be set.

[0044] In this way, in the present embodiment, the control section 102 sends the drive signal Tdig in which the current conducting time is set shorter than the injection-disabled time for which the fuel injection valve 109 is not allowed to be opened, to the fuel injection valve drive circuit 111.

[0045] Furthermore, in a case of normal control, the fuel injection system 100 of the internal combustion engine is configured to supply the high voltage generated by the high-voltage generating section 107 to open each fuel injection valve 109. However, since the present embodiment is applied to the direct injection engine and there is no need to use the diagnostic drive signal Tdig to open the fuel injection valve 109, the fuel injection system 100 of the internal combustion engine is configured to supply the current for the diagnostic drive signal Tdig from the battery power supply 110. This makes it possible to ensure that an operation of opening each fuel injection valve 109 is avoided.

[0046] In this way, in the present embodiment, before starting the engine, the control section 102 sends a drive prohibition cancellation signal associated with each fuel injection valve to the fuel injection valve drive circuit 111, and exercises control such that the drive current supplied from the fuel injection valve drive circuit 111 to the fuel injection valve 109 is not supplied from the battery power supply 110 via the high voltage generating section 107 in the case of sending the drive signal Tdig associated with the fuel injection valve 109 to the fuel injection valve drive circuit 111.

[0047] Furthermore, the current value at the time of application of the diagnosis drive signal is limited to the current value lower than the above-described second holding current value. In a case where the second holding current value is not set and only the first holding current value is set, the current value at the time of application of the diagnosis drive signal is limited to a current value lower than the first holding current value. In a case of the internal combustion engine in which the fuel injection valves are arranged in the intake manifold, the high-voltage generation section is not provided, and the battery power supply is used without using the high-voltage generation section; therefore, a length of the diagnosis drive signal Tdig to be adapted to the battery power supply can be specified.

[0048] In this way, according to the present embodiment, the current value of the drive current supplied to each fuel injection valve 109 from the fuel injection valve drive circuit 111 based on the drive signal Tdig is set to a level at which the fuel injection valve 109 is not allowed to be opened.

[0049] Furthermore, the diagnosis drive signals Tdig are applied to the fuel injection valves of the cylinders according to the order of actuation of the cylinders. In a case of a four-cylinder engine, for example, the diagnosis drive signals Tdig are applied to the fuel injection valves in an order of first cylinder → third cylinder → fourth cylinder → second cylinder. Needless to say, there is no need to match the order to an intake stroke and a compression stroke in a compression cycle because the internal combustion engine is not rotating at this time; therefore, the diagnosis drive signals Tdig can be applied to the fuel injection valves 109 of the cylinders at predetermined time intervals. When the application of the diagnosis drive signals is over, the processing proceeds to step S13.

[0050] <<Schritt S13> > In step S13, it is determined whether the diagnostic drive current has been supplied to each fuel injection valve 109 based on the diagnostic drive signal set / output in step S12. In this case, Fig. 2, the drive circuit 204 in the high-side fuel injection valve drive section 108a is turned on, and the drive circuit 205 in the low-side fuel injection valve drive section 108b is turned on. Therefore, the diagnostic monitoring current Idig is passed through the shunt resistor 206 in a case where the fuel injection shutoff function does not normally shut off the fuel injection or in a case where the fuel injection shutoff function is canceled.

[0051] Note that determinations are made on all fuel injection valves, and the determinations are made according to the order of cylinder actuation, as shown in steps S13a to S13d. For example, if the diagnosis monitor current Idig is observed in the fuel injection valve 109 of the first cylinder in step S13a, processing proceeds to step S18. On the other hand, if the diagnosis monitor current Idig is not observed in the fuel injection valve 109 of the first cylinder, it is determined in step S13b whether the diagnosis monitor current Idig is observed in the fuel injection valve 109 of the third cylinder. If the diagnosis monitor current Idig is observed in the fuel injection valve 109 of the third cylinder, processing proceeds to step S18.Similar determinations are subsequently made in steps S13c and S13d for the fuel injection valves 109 of the fourth cylinder and the second cylinder.

[0052] In this way, the control section 102 according to the present embodiment exercises control in such a manner that the current detection section 112a, which detects the current passed through the excitation coil of each fuel injection valve 109, detects the drive currents Idig based on the drive signals Tdig.

[0053] Fig. 5 shows a case where a diagnosis monitor current Idig was observed in the fuel injection cutoff set state. While in this case, the fuel injection cutoff function must be executed for all fuel injectors 109, a diagnosis monitor current Idig is observed only in the fuel injector 109 of the second cylinder. Thus, it is determined that the fuel injection cutoff function is not operating normally, and engine startup is prohibited in the following step S18. Note that the diagnosis monitor currents Idig are observed to correspond to the diagnosis drive signals Tdig because the fuel injection cutoff cancellation state is normal.

[0054] The fuel injection cutoff function is set in step S11. Therefore, if the diagnostic monitoring current Idig is observed in at least one fuel injector in steps S13, it is determined that the fuel injection cutoff function is not operating normally, and processing proceeds to step S18.

[0055] In this way, the control section 102 according to the present embodiment prohibits the starting of the internal combustion engine when detecting the supply of the drive current Idig based on the drive signals Tdig to one of the fuel injection valves 109 in a case of sending the drive signals Tdig associated with the plurality of fuel injection valves 109 to the fuel injection valve driving circuit 111 in the sequential order at predetermined intervals in a state where the drive prohibition signal associated with each fuel injection valve 109 is sent to the fuel injection valve driving circuit 111.

[0056] On the other hand, a case where the diagnosis monitor currents Idig are not observed in step S13 may correspond to any one of a case where the fuel injection cutoff function is set and operates normally and the diagnosis monitor signals have not been detected, and a case where the diagnosis monitor signals Idig are not detected due to an abnormality in a control component constituting one of the fuel injection valves 109 or the ECU 101.

[0057] Fig. 6 shows a case where the diagnosis monitor signal Idig is observed only in the first-cylinder fuel injection valve 109 in the fuel injection cut-off cancellation state due to an abnormality in the control component constituting one of the fuel injection valves 109 or the ECU 101. In this case, the diagnosis monitor signal Idig corresponding to the diagnosis drive signal Tdig associated with the first-cylinder fuel injection valve is not observed in the fuel injection cut-off set state because the fuel injection cut-off shutdown function is normal.

[0058] On the other hand, Fig. 7 illustrates a case where the diagnosis monitor signals Idig are not observed in any of the fuel injection valves 109 of the cylinders in the fuel injection cut-off cancellation state due to the abnormality in the control component constituting one of the fuel injection valves 109 or the ECU 101. In this case, the diagnosis drive signals Idig are not observed in the fuel injection cut-off set state, regardless of whether the fuel injection cut-off function is normal or not.

[0059] Therefore, as in the Fig. 6 and Fig. 7, it is impossible to distinguish the case where the fuel injection cutoff function is set and operating normally and the diagnostic monitor signals Idig are not detected from the case where the diagnostic monitor signals Idig are not detected due to an abnormality in the control component constituting one of the fuel injection valves or the ECU 101. To correct the problem and to distinguish the cases, processing proceeds to step S14, and cancellation of the fuel injection cutoff function is performed in step S14.

[0060] <<Schritt S14> > In control steps, that is, step S14 and subsequent steps, the fuel injection cutoff function is canceled, and the normality of the fuel injection cutoff function is further confirmed. In step S14, the control section 102 and the fuel injection cutoff function section 103 send the prohibition cancellation signal to the drive IC circuit 106 to cancel the fuel injection cutoff function, and the fuel injection cutoff set state of the drive IC circuit 106 is canceled. Upon cancellation of the fuel injection cutoff function set state, the processing proceeds to step S15.

[0061] <<Schritt S15> > In step S15, each diagnostic drive signal Tdig is set and outputted similarly to step S12. Since step S15 is similar to step S12, the description of step S15 is omitted. When each diagnostic drive signal Tdig is outputted, the processing proceeds to step S16.

[0062] In this way, according to the present embodiment, in the case of sending the drive prohibition cancellation signal associated with each fuel injection valve 109 to the fuel injection valve drive circuit 111, after sending the drive prohibition signal and sending the drive signal Tdig associated with the fuel injection valve 109 to the fuel injection valve drive circuit 111, the control section 102 sets the current value of the current supplied to each fuel injection valve 109 to the level at which the fuel injection valve is not allowed to open.

[0063] Moreover, according to the present embodiment, in both the fuel injection cut-off setting state and the fuel injection cut-off cancellation state, the control section 102 sends the drive signal Tdig, in which the current conducting time is set to be shorter than the injection-disabled time for which each fuel injection valve 109 is not allowed to be opened, to the fuel injection valve drive circuit.

[0064] <<Schritt S16> > In step S16, based on the diagnostic drive signal Tdig set / output in step S15, it is determined whether each fuel injection valve 109 has been supplied with current from the battery power supply 110. In this case, Fig. 2, similarly to step S13, the drive circuit 204 in the high-side fuel injection valve drive section 108a is turned on to select the battery power supply 110, and the drive circuit 205 in the low-side fuel injection valve drive section 108b is turned on. Therefore, the diagnostic monitoring current Idig in the case where the fuel injection cutoff function is canceled is passed through the shunt resistor 206.

[0065] Note that the determinations are performed on all fuel injectors 109, and the determinations are made according to the cylinder actuation order, as shown in steps S16a to S16d. Since the fuel injection cutoff function is canceled in step S14, it is determined whether the diagnostic monitoring current Idig supplied to at least one fuel injector 109 is being observed according to the sequential order of cylinder actuation in step S16.

[0066] For example, if the diagnostic monitor current Idig is observed in the fuel injector 109 of the first cylinder in step S16a, processing proceeds to step S17. On the other hand, if the diagnostic monitor current Idig is not observed in the fuel injector 109 of the first cylinder, it is determined in step S16b whether the diagnostic monitor current Idig is observed in the fuel injector 109 of the third cylinder. If the diagnostic monitor current Idig is observed in the fuel injector 109 of the third cylinder, processing proceeds to step S17. Similar determinations are subsequently made in steps S16c and S16d for the fuel injectors 109 of the fourth cylinder and the second cylinder.

[0067] In other words, in the case where the diagnosis monitor currents Idig are not observed at all in the fuel injection cutoff set state, it is assumed that the fuel injection cutoff function is normal, or the abnormality occurs in the control component constituting one of the fuel injection valves 109 or the ECU 101. In the case where the diagnosis monitor current is observed in a fuel injection valve 109 in the fuel injection cutoff cancellation state, it is determined that the fuel injection cutoff function is normal. This makes it possible to distinguish between these cases.

[0068] In this way, in the case where the diagnosis monitor current Idig is observed in the fuel injection cutoff cancellation state in at least one fuel injection valve 109, it is determined that the fuel injection cutoff function is normal. On the other hand, in a case where the diagnosis monitor current Idig is not observed in any of the fuel injection valves 109, it is assumed that an abnormality other than the fuel injection cutoff function occurs, the processing proceeds to step S19, and the starting of the internal combustion engine is prohibited in step S19. In this way, it is determined whether to prohibit starting in steps S18 and S19 based on different conditions.

[0069] Therefore, observing the diagnostic monitoring current Idig supplied to each fuel injector 109 makes it possible to diagnose whether the fuel injection cut-off function is operating normally based on the setting / cancellation of the fuel injection cut-off function.

[0070] Fig. 8 shows a case where it is determined in step S13 that the diagnosis monitor currents Idig are not observed at all in the fuel injection valves, and in step S16 that the diagnosis monitor currents Idig are observed in all the fuel injection valves, that is, a case where the fuel injection cutoff function functions normally. Since the fuel injection cutoff function is normal even if the diagnosis drive signals Tdig are output in the fuel injection cutoff set state, the diagnosis monitor currents Idig are not output to any of the fuel injection valves 109. Similarly, since the fuel injection cutoff function is canceled upon the output of the diagnosis drive signals Tdig in the fuel injection cutoff cancellation state, the diagnosis monitor currents Idig are output to all the fuel injection valves 109.

[0071] <<Schritt S17> > In step S17, it is generally and definitively determined that the fuel injection shutoff function is normal and starting of the internal combustion engine is permitted, since it is determined in step S13 that the setting of the fuel injection shutoff function is normal, and it is determined in step S16 that the diagnostic monitoring current has been supplied to at least one fuel injector 109. The internal combustion engine is thereby started by activating the starter motor.

[0072] In this way, the control section 102 according to the present embodiment includes: a function that cancels the fuel injection cutoff state and causes the fuel injection valve drive circuit 111 to enter the fuel injection cutoff cancellation state when no supply of the drive current Idig based on the drive signal Tdig is detected in the fuel injection cutoff set state; a function that sends the drive signal Tdig to the fuel injection valve drive circuit 111 in the fuel injection cutoff cancellation state and detects whether the drive current Idig based on the drive signal Tdig has been supplied to each of the fuel injection valves 109; and a function that allows the engine to start when it detects supply of the drive current Idig based on the drive signal Tdig to one of the fuel injection valves 109 in the fuel injection cutoff cancellation state.

[0073] <<Schritt S18> > In step S18, engine start-up is prohibited because it is determined in step S13 that the fuel injection cut-off function setting is abnormal. Note that it is possible to prohibit engine start-up at an early stage when the diagnosis monitor current Idig is confirmed in the present embodiment because the control steps, that is, steps S11 to S13 of setting the fuel injection cut-off function, are executed earlier.

[0074] In this way, according to the present invention, after sending the drive prohibition signal to the fuel injection valve drive circuit 111 before starting the engine, the control section 102 sends the drive prohibition cancellation signal to the fuel injection valve drive circuit 111.

[0075] As described so far, the fuel injection control system for the internal combustion engine according to the present embodiment is constituted by the engine control device 101 for the internal combustion engine including the fuel injection valve drive circuit 111 which applies a drive current to each of the fuel injection valves 109 and controls the internal combustion engine.Furthermore, the internal combustion engine control device 101 is formed with the control section 102, 103, 112 which prevents the starting of the internal combustion engine when it detects the conduction of the drive current Idig based on the drive signal Tdig, which is associated with each of the fuel injection valves 109, to the fuel injection valve drive circuit 111 in a case of sending the drive prohibition signal associated with the fuel injection valve 109 to the fuel injection valve drive circuit 111 before starting the internal combustion engine and sending the drive signal Tdig associated with the fuel injection valve 109 to the fuel injection valve drive circuit 111.

[0076] More specifically, the fuel injection control unit 101 is configured with the control section 102 having: a function of sending the drive signal Tdig associated with each of the fuel injection valves 109 to the fuel injection valve drive circuit 111 in a state of setting the fuel injection cut-off set state before starting the engine; a function of detecting whether the drive current Idig based on the drive signal Tdig has been supplied to the fuel injection valve 109 by an operation of the fuel injection valve drive circuit 111; and a function of prohibiting the engine from starting when the supply of the drive current Idig in the fuel injection cut-off set state is detected.

[0077] <<Schritt S19> > In step S19, it is determined that the control component constituting one of the fuel injection valves 109 or the ECU 101 is abnormal, and starting of the engine is prohibited because it is determined in step S16 that the diagnosis monitor current Idig is not observed in any of the fuel injection valves 109 and that the fuel injection cutoff function is abnormal.

[0078] In this way, the control section 102 according to the present embodiment includes: a function that cancels the fuel injection cut-off set state and causes the fuel injection valve drive circuit 111 to enter the fuel injection cut-off cancellation state when no supply of the drive current Idig based on the drive signal Tdig is detected in the fuel injection cut-off set state; a function that sends the drive signal Tdig to the fuel injection valve drive circuit 111 in the fuel injection cut-off cancellation state and detects whether the drive current Idig based on the drive signal Tdig has been supplied to each of the fuel injection valves 109; a function that allows the engine to start when it detects supply of the drive current Idig based on the drive signal Tdig to one of the fuel injection valves 109 in the fuel injection cut-off cancellation state;and a function that prevents the engine from starting when it detects that the drive current Idig based on the drive signal Tdig has not been supplied to any of the fuel injection valves 109 in the fuel injection cutoff cancellation state.;

[0079] In this way, by sending the diagnosis drive signal Tdig to the drive IC circuit 106 from the control section 102 and further monitoring whether the diagnosis monitor current Idig based on the diagnosis drive signal Tdig is supplied to each of the fuel injection valves 109 in the state of sending the drive prohibition signal associated with the fuel injection valve 109 to the drive IC circuit 106 to set the fuel injection cut-off function or in the state of sending the prohibition cancellation signal associated with the fuel injection valve 109 to the drive IC circuit 106 to cancel the fuel injection cut-off function, it is possible to ensure a diagnosis of whether the function of interrupting the fuel injection cut-off function operates normally.

[0080] It is noted here that, while the diagnosis drive signals are output to the fuel injection valves to execute the diagnosis at time intervals, the diagnosis of the fuel injection cut-off function can be executed for the fuel injection valves simultaneously in a case where the simultaneous diagnosis can be executed by a plurality of CPUs or the like.

[0081] Next, a modification of the first embodiment will be described with reference to Fig. 9 and Fig. 10. As described in Fig. 9, according to the modification, for the purpose of increasing the diagnostic accuracy within the time before the starter is activated, several diagnostic control signals Tdig are applied to a fuel injection valve 109. As shown in Fig. 3, at the time of setting the fuel injection cutoff function, steps S11 to S13 may be executed for a first diagnosis, and processing may return to steps S11 to S13 to re-execute steps S11 to S13 for a second diagnosis. Similarly, at the time of canceling the fuel injection cutoff function, steps S14 to S16 may be executed for the first diagnosis, and processing may return to steps S14 to S16 to re-execute steps S14 to S16 for the second diagnosis.

[0082] According to the modification, similarly to the first embodiment, since the diagnosis at the time of setting the fuel injection cut-off function is executed earlier than the diagnosis at the time of canceling the fuel injection cut-off function, it is possible to determine the state in which the fuel injection cut-off function does not operate normally at an early stage.

[0083] In addition, as in Fig. 10, a predetermined interval length is set between the timing of applying one diagnostic drive signal Tdig to a fuel injector and the timing of applying another diagnostic drive signal Tdig to the same. If the interval length is short, the fuel injector 109 may be opened with the subsequent diagnostic drive signal Tdig for reasons such as needle instability in a closed valve position and residual magnetism in the needle.

[0084] For this reason, the diagnostic drive signals Tdig are applied to the fuel injectors 109 in the order of cylinders for the purpose of stabilizing the needle in the closed valve position and for dissipating the magnetism in the needle, and the interval length is set in such a way that the diagnostic drive signals Tdig to be applied to the other fuel injectors 109 are present between at least continuous diagnostic drive signals Tdig to be applied to a fuel injector 109.

[0085] In a Fig. In the example shown in Figure 9, the interval length is set in such a way that the diagnostic drive signals Tdig to be applied to the three remaining fuel injectors 109 are present between the at least continuous diagnostic drive signals Tdig to be applied to the one fuel injector 109. Furthermore, the interval length corresponding to the modification for the diagnostic time can be used for the other fuel injectors 109; therefore, the modification in the diagnostic time is advantageous.

[0086] In this way, the control section 102 according to the present embodiment sets the interval length to the continuous drive signals Tdig in such a manner that the drive signals Tdig to be applied to the other fuel injection valves are present between the at least continuous drive signals Tdig to be applied to the one fuel injection valve 109. Second embodiment

[0087] While a second embodiment of the present invention will be described with reference to the Fig. 11 and Fig. As described in FIG. 12, the present embodiment differs from the first embodiment in that the cancellation of the fuel injection cutoff function is executed earlier than the setting of the fuel injection cutoff function. In the first embodiment, in which the fuel injection cutoff function is set earlier, an abnormality in the fuel injection cutoff function can be discriminated at an early stage if the abnormality occurs; however, the first embodiment has a problem in that the diagnosis time is long in a normal state.

[0088] To solve the problem, according to the second embodiment, the cancellation of the fuel injection cut-off function is carried out earlier than the setting of the fuel injection cut-off function, thereby making it possible to shorten the diagnosis time. While the second embodiment is based on a Fig. 11, the same control steps are used as in the control flow shown in Fig. 3 shown control flow is not described.

[0089] <<<Schritt S20> > to <<<Schritt S21> > Since step S20 is identical with step S10 Fig. 3, the description of step S20 is omitted. Since step S21 is identical to steps S14 and S15 of Fig. 3, the description of step S21 is also omitted.

[0090] <<Schritt S22> > In step S22, the diagnostic monitoring current Idig supplied to each fuel injector 109 is monitored in the fuel injection cutoff cancellation state. Since the presence of the diagnostic monitoring current Idig is monitored in this way in the fuel injection cutoff cancellation state, it is possible to diagnose earlier whether the control component of one of the fuel injectors 109 or the ECU 101 is operating normally.

[0091] If the diagnostic monitor current Idig is observed in the fuel injector 109 of the first cylinder in step S22a, processing proceeds to step S23a. On the other hand, if the diagnostic monitor current Idig is not observed in the fuel injector 109 of the first cylinder, it is determined in step S22b whether the diagnostic monitor current Idig is observed in the fuel injector 109 of the third cylinder. If the diagnostic monitor current Idig is observed in the fuel injector 109 of the third cylinder, processing proceeds to step S23b. Similar determinations are subsequently made in steps S22c and S22d for the fuel injectors 109 of the fourth cylinder and the second cylinder. If the diagnostic monitor current Idig is observed in either of the control steps, processing proceeds to step S23c or S23d.

[0092] Therefore, if the diagnostic monitoring current Idig is first observed in the fuel injection valve 109 of the first cylinder, for example, in step S22a, the control components constituting the fuel injection valve 109 and the ECU 101 can operate normally, and the execution of the following control steps, that is, steps S22b to S22d, can be omitted. If the diagnostic monitoring current Idig is not observed in step S22a, the processing proceeds to step S22b, and the same determination is made in step S22b. The following steps S22c and S22d are executed similarly.

[0093] In this way, if the diagnosis monitoring current Idig is observed first, the subsequent control steps in step S22 can be omitted, and it is advantageously possible to shorten the diagnosis time. Furthermore, if the diagnosis monitoring current Idig cannot be observed in any of steps S22a to S22d, it is determined that the control components constituting the fuel injection valves 109 and the ECU 101 cannot operate normally, and the processing proceeds to step S28, where engine start-up is prohibited.

[0094] <<Schritt S23> > In step S23, the cylinder in which the diagnostic monitoring current Idig is first observed in one of steps S23a to S23d is selected because the diagnostic monitoring current Idig can be observed in one of steps S22a to S22d. Therefore, if the diagnostic monitoring current Idig in the fuel injection valve 109 of the first cylinder is first observed in step S23a, the execution of the following control steps, that is, steps S23b to S23d, can be omitted. After selecting one of the cylinders, processing proceeds to step S24.

[0095] <<Schritt S24> > Since step S24 corresponds to steps S11 and S12 of Fig. 3, the description of step S24 is omitted. Note that in this case, the diagnostic drive signal Tdig is applied only to the fuel injection valve 109 of the selected cylinder, and the application of the diagnostic drive signals Tdig to the remaining fuel injection valves 109 can be omitted. Upon setting the fuel injection cutoff function and outputting the diagnostic drive signal Tdig, processing proceeds to step S25.

[0096] <<Schritt S25> > In step S25, based on the diagnostic drive signal Tdig set / output in step S24, it is determined whether current has been supplied from the battery power supply 110 to the fuel injection valve 109 of the selected cylinder. If the diagnostic monitor current Idig is observed in the control step, it is determined that the fuel injection cutoff function is not operating normally, and processing proceeds to step S27, where engine startup is prohibited. On the other hand, if the diagnostic monitor current Idig is not observed, it is determined that the fuel injection cutoff function is operating normally, and processing proceeds to step S26, where engine startup is permitted.

[0097] As in Fig. As shown in FIG. 12, in both the fuel injection cutoff cancellation state and the fuel injection cutoff setting state, for example, the diagnosis drive signal Tdig is output only to the fuel injection valve 109 of the first cylinder, the diagnosis monitor current Idig is monitored to correspond to the output diagnosis drive signal Tdig in the fuel injection cutoff cancellation state, and the diagnosis monitor current Idig corresponding to the output diagnosis drive signal Tdig is not monitored in the fuel injection cutoff setting state. In this way, the diagnosis drive signal Tdig is applied only to the fuel injection valve 109 of the selected cylinder and not to the remaining fuel injection valves 109; thus, it is possible to diagnose the normality of the fuel injection cutoff function at an early stage.

[0098] <<Schritt S26> > Finally, in step S26, it is determined that the fuel injection shutdown function is normal, and starting of the internal combustion engine is permitted, since it is determined in step S22 that the diagnostic monitoring current Idig was supplied to at least one fuel injector 109, and in step S25 it is determined that the diagnostic monitoring current was not supplied to the selected fuel injector 109. The internal combustion engine is thereby started by activating the starter motor.

[0099] <<Schritt S27> > In step S27, starting of the engine is prohibited because it is determined in step S25 that the setting of the fuel injection cut-off function is abnormal.

[0100] In this way, the fuel injection control system for the internal combustion engine is constituted by the internal combustion engine control device 101 including the fuel injection valve drive circuit 111, which applies a drive current to each of the fuel injection valves 109 and controls the internal combustion engine. Furthermore, the control section 102 includes: a function that sends the drive signal Tdig corresponding to each of the fuel injection valves to the fuel injection valve drive circuit 111 in the state of placing the fuel injection cutoff cancellation state before starting the internal combustion engine; a function that detects whether the drive current Idig based on the drive signal Tdig has been supplied to each of the fuel injection valves 109 by an operation of the fuel injection valve drive circuit 111;a function that sets the fuel injection valve drive circuit 111 to the fuel injection cut-off set state and that sends the drive signal Tdig to the fuel injection valve drive circuit 111 when, in the fuel injection cut-off cancellation state, the supply of the drive current Idig based on the drive signal Tdig to at least one fuel injection valve 109 is detected; and a function that prohibits the engine from starting when, in the fuel injection cut-off set state, it is detected whether the drive current Idig based on the drive signal Tdig has been supplied to the fuel injection valve 109 and the supply of the drive current Idig based on the drive signal Tdig is detected.

[0101] <<Schritt S28> > In step S28, it is determined that the control component constituting one of the fuel injection valves 109 or the ECU 101 is abnormal, and starting of the engine is prohibited because it is determined in step S22 that the diagnosis monitor current Idig is not observed in any of the fuel injection valves 109 and that the fuel injection cutoff function is not normal.

[0102] In the present embodiment, it is noted that it is possible to shorten the diagnosis time because the normality of the fuel injection cutoff function is diagnosed for the cylinder in which the diagnosis monitor current Idig is first detected in the fuel injection cutoff cancellation state. Third embodiment

[0103] While a third embodiment of the present invention will be described with reference to Fig. 13, the present embodiment differs from the first embodiment in that it is diagnosed whether the fuel injection cut-off function operates normally at a time of executing an idle stop in the middle of driving the engine.

[0104] <<Schritt S30> > In step S30, while the engine is being driven, ordinary self-diagnosis is performed to control components constituting each fuel injection valve 109 and the ECU 101. Upon determining that the self-diagnosis is over, the processing proceeds to step S31.

[0105] <<Schritt S31> > In step S31, a self-diagnosis result is confirmed to determine whether there is a failure in any of the fuel injection valves 109 during engine drive. If it is determined in step S31a that there is no failure in that the fuel injection valve 109 of the first cylinder is not operating, the processing proceeds to step S32a. On the other hand, if it is determined in step S31a that there is a failure in that the fuel injection valve 109 of the first cylinder is not operating, it is determined in step S31b whether there is a failure in that the fuel injection valve 109 of the third cylinder is not operating. If it is determined that there is no failure in step S31b, the processing proceeds to step S32b.Similar determinations are then made in steps S31c and S31d for the fuel injectors 109 of the fourth cylinder and the second cylinder. If it is determined in either control step that no fault exists, processing proceeds to step S32c or S32d.

[0106] Therefore, if it is first determined, for example, in step S31a that there is no failure in the fuel injection valve 109 of the first cylinder, the control components constituting the fuel injection valve 109 and the ECU 101 can operate normally, and the subsequent control steps, that is, steps S22b to S22d, can be omitted. If it is determined in step S31a that there is a failure, the processing proceeds to step S31b, and the same determination is made in step S31b. The following steps S31c and S31d are executed similarly.

[0107] In this way, if it is first determined that no fault exists, the subsequent control steps in step S31 can be omitted, and it is advantageously possible to shorten the diagnosis time. Furthermore, if it is determined that a fault exists in all steps S31a to S31d, it is determined that the control components constituting the fuel injection valves 109 and the ECU 101 cannot operate normally, and the processing proceeds to step S38, where engine start-up is prohibited.

[0108] <<Schritt S32> > In step S32, the cylinder for which no failure is first determined in any one of steps S32a to S32d is selected, since no failure can be determined in step S31 in any of steps S31a to S31d. Since the control steps in steps S31 and S32 correspond to the fuel injection cutoff cancellation state according to the second embodiment, it is not necessary to perform the monitoring of the diagnostic monitoring current Idig again at the time of canceling the fuel injection cutoff function.

[0109] Therefore, if it is first determined in step S32a that there is no fault in the fuel injection valve 109 of the first cylinder, the execution of the following control steps, i.e., steps S32b to S32d, can be omitted. Upon selection of one of the cylinders, processing proceeds to step S33.

[0110] <<Schritt S33> > In step S22, when it is determined that a state is a state where an idle stop is executed based on information such as the pressing position of an accelerator pedal, an engine speed, and a pressing position of a brake pedal, an idle stop is executed. At this time, the engine drive is stopped, and the engine does not rotate. After the idle stop is executed, the processing proceeds to step S34.

[0111] <<Schritt S34> > Since step S34 is identical with steps SS11 and S12 of Fig.3, the description of step S34 is omitted. Note that in this case, the diagnosis drive signal is applied only to the fuel injection valve 109 of the selected cylinder, and the application of the diagnosis drive signals Tdig to the remaining fuel injection valves 109 can be omitted because the rotation of the engine is stopped. Upon setting the fuel injection cutoff function and outputting the diagnosis drive signal, processing proceeds to step S35.

[0112] <<Schritt S35> > In step S35, it is determined whether the diagnostic drive current set / outputted in step S34 based on the diagnostic drive signal Tdig has been supplied to the fuel injection valve 109 of the selected cylinder. If the diagnostic monitor current Idig is observed in the control step, it is determined that the fuel injection cutoff function is not operating normally, and processing proceeds to step S37, where engine startup is prohibited. On the other hand, if the diagnostic monitor current Idig is not observed, it is determined that the fuel injection cutoff function is operating normally, and processing proceeds to step S36, where engine startup is permitted.

[0113] <<Schritt S36> > Finally, in step 36, it is determined that the fuel injection shutoff function is normal, and engine start-up is permitted because it is determined in step S35 that the diagnostic monitoring current was not supplied to the fuel injector 109 selected in step S35. The engine is then started by activating the starter motor.

[0114] <<Schritt S37> > In step S37, starting of the engine is prohibited because it is determined in step S35 that the setting of the fuel injection cut-off function is abnormal.

[0115] <<Schritt S38> > In step S38, it is determined that the control component constituting one of the fuel injection valves 109 or the ECU 101 is abnormal, and starting of the engine is prohibited because it is determined in step S22 that errors occur in all of the fuel injection valves 109.

[0116] According to the present embodiment, the diagnosis of whether the fuel injection cutoff function is operating normally is performed when the idle stop is performed. This makes it possible to diagnose whether the fuel injection cutoff function is operating normally after the engine is started. Furthermore, a combination of the self-diagnosis performed during normal operation and a diagnosis result of the fuel injection cutoff function makes it possible to omit the control step of canceling the fuel injection cutoff function and diagnose whether the fuel injection cutoff function is operating normally at an early stage.

[0117] Note that the ECU 101 uses the high-voltage generation section 107 and supplies the drive current to each of the fuel injection valves 109 according to the current profile in the first, second, and third embodiments. For this reason, in the current profile used at the time of diagnosis, a peak current is set to have a current value achievable only by the battery voltage from the battery power supply 110. Since it is unnecessary to open each fuel injection valve 109 when diagnosing the fuel injection cutoff function, it is unnecessary to set the peak current to have a peak current value required to open the fuel injection valve 109 during normal operation.

[0118] Furthermore, if the diagnosis is performed before the DC / DC converter constituting the high-voltage generation section 107 completes the boost during engine start-up, a predetermined drive current waveform will not be achieved, possibly resulting in an incorrect diagnosis. Considering the above aspects, the peak current is set to the peak current value that can be achieved by the battery voltage without using the voltage from the high-voltage generation section 107. This makes it possible to perform the diagnosis even when the DC / DC converter is not operating before engine start-up and the boost voltage is not achieved. It is also possible to prevent malfunction of the fuel injection valves 109 due to the excessively high peak current value.

[0119] As described so far, the present invention is characterized by preventing the starting of the internal combustion engine when, in the case of sending the drive prohibition signal associated with the fuel injection valve to the fuel injection valve drive circuit before starting the internal combustion engine and sending the diagnosis drive signal associated with the fuel injection valve to the fuel injection valve drive circuit, the supply of the diagnosis monitoring current based on the diagnosis drive signal to the fuel injection valve is detected.

[0120] According to the present invention characterized as described above, by sending the diagnosis drive signal associated with each of the fuel injection valves to the fuel injection valve drive circuit in the state of sending the drive prohibition signal associated with the fuel injection valve to the fuel injection valve drive circuit to actuate the fuel injection cut-off function, and by monitoring whether the diagnosis monitor current based on the diagnosis drive signal is transmitted to the fuel injection valve, it is possible to ensure a diagnosis as to whether the fuel injection cut-off function operates normally.

[0121] The present invention is not limited to the embodiments described above, but includes various modifications. For example, the embodiments described above have been described in detail in order to facilitate understanding of the present invention, and the present invention is not always limited to the invention having all the configurations described above. Moreover, the configuration of a specific embodiment may be partially replaced with the configuration of the other embodiment, or the configuration of the other embodiment may be added to the configuration of the specific embodiment. Furthermore, additions, omissions, and substitutions of the other configurations may be made for a means in the configuration of each embodiment. Description of reference symbols 101 ECU 102 Tax Section 103 Fuel injection shutdown function section 106 Control IC circuit 107 High-voltage generation section 108a, 108b Fuel injection valve control section 109 Fuel injection valve 111 Fuel injection valve control section 112 Fuel injector operation monitoring section

Claims

[1] An internal combustion engine control device comprising a fuel injection valve control circuit which applies a control current to each of the fuel injection valves and controls an internal combustion engine, the internal combustion engine control device comprising: a control section that prohibits the starting of the internal combustion engine when it detects the supply of the drive current based on a drive signal associated with each of the fuel injection valves to the fuel injection valve drive circuit in a case of sending a drive prohibition signal associated with each of the fuel injection valves to the fuel injection valve drive circuit before starting the internal combustion engine and sending the drive signal associated with each of the fuel injection valves to the fuel injection valve drive circuit. [2] An internal combustion engine control device according to claim 1, wherein a current value of the drive current applied to each of the fuel injection valves based on the drive signal from the fuel injection valve drive circuit is set to a level at which the fuel injection valve is not allowed to open. [3] Internal combustion engine control device according to claim 2, wherein the control section, after sending the drive prohibition signal, sends a drive prohibition cancellation signal associated with each of the fuel injection valves to the fuel injection valve drive circuit, and the current value of the drive current sent to each of the fuel injection valves in a case where the control section sends the drive signal associated with the fuel injection valve to the fuel injection valve drive circuit is set to the strength at which each of the fuel injection valves is not allowed to open. [4] An internal combustion engine control device according to claim 1, wherein the control section sends the drive signal, in which the current conducting time is set to be shorter than an injection-disabled time for which each of the fuel injection valves is not allowed to be opened, to the fuel injection valve drive circuit. [5] An internal combustion engine control device according to claim 1, wherein the control section prohibits the starting of the internal combustion engine when detecting the supply of the drive current based on the drive signal to one of the plurality of fuel injection valves in a case where the control section outputs a plurality of the drive signals corresponding to the plurality of fuel injection valves in a sequential order at predetermined intervals in a state where the control section sends the drive prohibition signal corresponding to each of the fuel injection valves to the fuel injection valve drive circuit. [6] An internal combustion engine control device according to claim 1, wherein the control section detects the drive current based on the drive signal from a current detecting section that detects a current passed through an exciting coil of each of the fuel injection valves. [7] The internal combustion engine control device according to claim 3, wherein the control section sends the drive prohibition cancellation signal to the fuel injection valve drive circuit after sending the drive prohibition signal to the fuel injection valve drive circuit before starting the internal combustion engine. [8] Internal combustion engine control device according to claim 3, wherein a power supply of each of the fuel injection valves is switchable by the fuel injection valve drive circuit between a battery power supply and a high-voltage power supply that generates a high voltage by boosting a voltage from the battery power supply, and In a case where the control section sends the drive prohibition cancellation signal associated with each of the fuel injection valves to the fuel injection valve drive circuit before starting the engine, and where the control section sends the drive signal associated with each of the fuel injection valves to the fuel injection valve drive circuit, the control section does not supply the drive current to be supplied from the fuel injection valve drive circuit to each of the fuel injection valves from the battery power supply via the high-voltage power supply. [9] Internal combustion engine control device with a fuel injection valve control circuit which controls fuel injection valves and controls an internal combustion engine, the fuel injection valve control circuit comprising: a tax section with a function which, in a state in which the fuel injection valve control circuit is set to a fuel injection cut-off state before starting the internal combustion engine, sends a control signal belonging to each of the fuel injection valves to the fuel injection valve control circuit, a function that detects whether a drive current based on the drive signal has been supplied to each of the fuel injection valves by actuating the fuel injection valve drive circuit, and a function that prevents the engine from starting when the supply of the drive current based on the drive signal to each of the fuel injection valves is detected in the fuel injection cut-off setting state. [10] Internal combustion engine control device according to claim 9, wherein the control section contains a function that cancels the fuel injection cut-off setting state and causes the fuel injection valve drive circuit to enter a fuel injection cut-off cancellation state when the control section detects no conduction of the drive current based on the drive signal in the fuel injection cut-off setting state, a function that sends the drive signal in the fuel injection cut-off cancellation state to the fuel injection valve drive circuit and detects whether or not the drive current based on the drive signal has been supplied to each of the fuel injection valves, and a function that allows the engine to be started when the control section detects the supply of the drive current based on the drive signal to one of the fuel injection valves in the fuel injection cut-off cancellation state. [11] An internal combustion engine control device according to claim 9, wherein the control section includes: a function that cancels the fuel injection cut-off setting state and causes the fuel injection valve drive circuit to enter a fuel injection cut-off cancellation state when the control section detects no conduction of the drive current based on the drive signal in the fuel injection cut-off setting state, a function that sends the drive signal in the fuel injection cut-off cancellation state to the fuel injection valve drive circuit and detects whether or not the drive current based on the drive signal has been supplied to each of the fuel injection valves, a function that allows the engine to be started when the control section detects the supply of the drive current based on the drive signal to one of the fuel injection valves in the fuel injection cut-off cancellation state, and a function that prevents the engine from starting when the control section does not detect that the drive current based on the drive signal is supplied to one of the fuel injection valves in the fuel injection cut-off cancellation state. [12] Internal combustion engine control device with a fuel injection valve control circuit which controls fuel injection valves and controls an internal combustion engine, the internal combustion engine control device comprising: a tax section with a function that, in a state in which the fuel injection valve drive circuit is placed in a fuel injection cut-off cancellation state before starting the internal combustion engine, sends a drive signal belonging to each of the fuel injection valves to the fuel injection valve drive circuit, a function that detects whether or not a drive current based on the control signal has been supplied to each of the fuel injection valves by actuating the fuel injection valve drive circuit, a function that sets the fuel injection valve drive circuit to a fuel injection cut-off setting state and that sends the drive signal to the fuel injection valve drive circuit when the control section detects, in the fuel injection cut-off cancellation state, the supply of the drive current based on the drive signal to at least one of the fuel injection valves, and a function that prohibits the starting of the internal combustion engine when the control section detects, in the fuel injection cut-off setting state, whether or not the drive current based on the drive signal has been supplied to each of the fuel injection valves, and detects the supply of the drive current based on the drive signal. [13] An internal combustion engine control device according to any one of claims 10 to 12, wherein the control section sends the drive signal, in which the current conduction time is set to be shorter than the injection-disabled time for which each of the fuel injection valves is not allowed to be opened, to the fuel injection valve drive circuit. [14] Internal combustion engine control device according to one of claims 10 to 12, wherein the tax section in the fuel injection cut-off setting state and the fuel injection cut-off cancellation state, sends the drive signal, in which the current-carrying time of the drive signal is set to be shorter than the injection-disabled time for which each of the fuel injection valves is not allowed to open, to the fuel injection valve drive circuit. [15] An internal combustion engine control device according to claim 14, wherein the control section sets an interval length for at least continuous drive signals to be applied to one of the fuel injection valves in such a manner that the drive signal to be applied to the other fuel injection valves is present between the at least continuous drive signals.

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