FUEL INJECTION CONTROL DEVICE

Abstract

A fuel injection control device is provided that is capable of ensuring the accuracy of anomaly diagnosis with less process load. According to the present invention, the fuel injection control device acquires, as a first sample value, a drive voltage at a first predetermined time, at which a first predetermined time has elapsed since the energy supply to a fuel injection valve is stopped, and acquires, as a second sample value, a drive voltage measured at a second predetermined time, at which a second predetermined time has elapsed since the energy supply to the fuel injection valve is stopped.The fuel injection control device then calculates a noise determination value using the first and second samples, compares the noise determination value with a noise determination threshold to determine whether the noise determination value meets a noise determination condition or not, and performs an abnormality diagnosis in a case where the noise determination value meets the noise determination condition.

Description

Technical field

[0001] The present invention relates to a fuel injection control device that controls a fuel injection valve of an internal combustion engine. State of the art

[0002] Previously, a method for detecting an abnormality in voltage information used as a basis for correcting the fuel injection quantity of a fuel injector involved comparing a voltage difference between a downstream voltage and an upstream voltage of the fuel injector and a threshold value at a predetermined time after the end of a voltage supply control period. An abnormality determination for the voltage information was then performed based on the result of this comparison. Such an abnormality determination method can improve the accuracy of an abnormality diagnosis by capturing as many samples of the voltage difference as possible from the end of the voltage supply control period until the predetermined time.

[0003] PTL 1 subsequently discloses a technology for acquiring a value of a monitoring voltage derived as a counter-electromotive force several times after stopping the energy supply to an electromagnetic actuator, for generating an interpolation line passing through a predetermined estimated residence period, using a sample belonging to a period outside the estimated residence period, among several samples, and for determining whether a valve body is seated or not, based on a comparison between the several samples belonging to the estimated residence period and the interpolation line, to accurately determine whether the valve body contained in the fuel injector is seated or not. List of literature on patent literature

[0004] PTL 1: JP 2016-211452 A Summary of the invention: Technical problem

[0005] The state-of-the-art method, which involves acquiring as many samples as possible, presents the problem that computational loads are high and cannot be reduced. Conversely, if the number of samples is reduced, there is a possibility that the voltage information will be incorrectly identified if a sample is inadvertently acquired at the same time as a noise event. Therefore, it is necessary to eliminate such factors that could lead to a false diagnosis.

[0006] The present invention was developed in light of the above points, and one object of the present invention is to provide a fuel injection control device that is capable of ensuring the accuracy of an abnormality diagnosis with less process load. Solution to the problem

[0007] A fuel injection control device of the present invention, which solves the above problem, is a fuel injection control device that controls a fuel injection valve of an internal combustion engine, wherein the fuel injection control device comprises: an input voltage processing unit that detects a drive voltage of the fuel injector; and an abnormality diagnostic unit that performs an abnormality diagnosis of a drive circuit of the fuel injector based on the drive voltage, wherein The input voltage processing unit acquires a drive voltage as a first sample at a first predetermined time, at which a first predetermined time has elapsed from the time at which the energy supply to the fuel injector is stopped; acquires a drive voltage as a second sample, measured at a second predetermined time, at which a second predetermined time, longer than the first predetermined time, has elapsed from the time at which the energy supply to the fuel injector is stopped; calculates a noise determination value using the first and second samples; and compares the noise determination value with a noise determination threshold to determine whether the noise determination value meets a noise determination condition. The abnormality diagnosis unit performs the abnormality diagnosis in a case where the noise determination value meets the noise determination condition. Advantageous effects of the invention

[0008] According to the present invention, it is possible to obtain a fuel injection control device capable of ensuring the accuracy of anomaly diagnosis with less process load. Further features relating to the present invention will become apparent from the description in this document and the accompanying drawings. Problems, configurations, and effects that differ from those described above are further clarified by the following description of embodiments. Brief description of the drawings [ Fig. 1] Fig. Figure 1 is a diagram illustrating a basic configuration of an internal combustion engine comprising a fuel injection control device according to a first embodiment. [ Fig. 2] Fig. 2 is a block diagram to describe a configuration of the fuel injection control device that is in Fig. 1 is illustrated. [ Fig. 3] Fig. Figure 3 is a flowchart for describing the contents of a diagnostic procedure for a valve closing detection circuit for a fuel injector. [ Fig. 4] Fig. Figure 4 is a time diagram to describe a first calculation example of a noise determination value. [ Fig. 5] Fig. Figure 5 is a time diagram to describe a second calculation example of the noise determination value. [ Fig. 6] Fig. Figure 6 is a time diagram to describe a third calculation example of the noise determination value. [ Fig. 7] Fig. Figure 7 is a state diagram of a valve closing detection circuit and a graph illustrating a change in the drive voltage when the valve is closed. [ Fig. 8] Fig. Figure 8 is a state diagram of the valve closing detection circuit and a graph illustrating a change in the drive voltage when the valve is closed. [ Fig. 9] Fig. Figure 9 is a flowchart for describing the contents of a procedure for shifting the acquisition time for a sampled value. [ Fig. 10] Fig. Figure 10 is a diagram to describe a state in which the acquisition time for the sample value and an ignition time overlap. [ Fig. 11] Fig. Figure 11 is a diagram to describe a state in which the acquisition time for the sampled value is shifted. Description of the embodiments

[0009] The present embodiment is described below with reference to the accompanying drawings. Functionally identical elements in the accompanying drawings may be designated by the same reference numerals. Although the accompanying drawings further illustrate embodiments and implementation examples that comply with the principles of this disclosure, they serve only to aid understanding of this disclosure and are not intended to interpret it in a limited way. The illustrations in this description are also to be understood as merely exemplary and are not intended to limit the claims or application examples of this disclosure in any way.

[0010] In the present embodiment, the description has been sufficiently detailed for the person skilled in the art to implement the present disclosure. However, it should be understood that other implementations and modes are also possible, and changes in the configurations and structures, as well as the exchange of various elements, may be possible without deviating from the scope and spirit of the technical idea of ​​the present disclosure. Therefore, the following description is not to be interpreted as being limited only to the foregoing. [First embodiment]

[0011] Fig. Figure 1 illustrates a basic configuration of an internal combustion engine comprising a fuel injection control device according to a first embodiment of the present invention.

[0012] An internal combustion engine 101 of the present embodiment is a drive machine mounted on a vehicle, such as an automobile or a hybrid automobile, and comprises a piston 102, an inlet valve 103, and an exhaust valve 104 in a cylinder. As an example, the internal combustion engine 101 can be an internal combustion engine comprising a plurality of cylinders, for example, four cylinders (#1 to #4), wherein Fig. 1 merely illustrates one of the many cylinders.

[0013] Each cylinder of the internal combustion engine 101 is equipped with a fuel injector 105 that injects fuel directly into a combustion chamber in the cylinder, and a cylinder head is fitted with a spark plug 106 and an ignition coil 107. Furthermore, a water temperature sensor 108 for the coolant is provided in a water jacket of the cylinder. Additionally, a crank angle sensor 11, which measures the crankshaft angle of the internal combustion engine 101, is attached to a crankcase of the internal combustion engine 101.

[0014] An engine control unit (ECU) 109 is designed as a control unit that controls the internal combustion engine 101. The ECU 109 is implemented, for example, by a microcomputer comprising a central processing unit (CPU) and memory, such as random access memory (RAM) or read-only memory (ROM). The crankshaft angle sensor 11 and an accelerator pedal position sensor 12, which measures the pedal position of an accelerator pedal actuated by a driver, are also connected to the ECU 109. Detection signals from the crankshaft angle sensor 11 and the accelerator pedal position sensor 12 are further input into a fuel injection control device 109A of the ECU 109.

[0015] An inlet pipe 110 for introducing air drawn into the internal combustion engine 101 is located upstream of the inlet valve 103, and an exhaust pipe 111, which expels air from the cylinder, is located downstream of the exhaust valve 104. Furthermore, a three-way catalytic converter 112 for cleaning the exhaust gas and an oxygen sensor 113 are provided in the exhaust pipe 111. Additionally, a collector 115, a throttle valve 119, and an air flow meter 120 are provided in the inlet pipe 110.

[0016] The air drawn into the internal combustion engine 101 is introduced into the intake pipe 110 via the air flow meter 120, the throttle valve 119, and the collector 115, and then fed to a combustion chamber 121 via the intake valve 103. An output signal from the air flow meter 120 is also supplied to the fuel injection control device 109A of the ECU 109.

[0017] The fuel used in the internal combustion engine 101 is conveyed by a low-pressure fuel pump 124 from a fuel tank 123 to a high-pressure fuel pump 125, which is provided in the internal combustion engine 101. The high-pressure fuel pump 125 increases the pressure of the fuel introduced into it by power transmitted from an exhaust camshaft (not illustrated) of an exhaust cam 128. Specifically, the pressure of the fuel introduced into the high-pressure fuel pump 125 is increased by moving a piston provided in the high-pressure fuel pump 125 up and down. An on / off valve provided in an intake port is further controlled by a solenoid such that the pressure of the fuel expelled from the high-pressure fuel pump 125 reaches a desired pressure, based on a control command value from the ECU 109.The fuel, now under increased pressure, is also conveyed through a high-pressure fuel line 129 to the fuel injector 105, and the fuel injector 105 injects the fuel into the combustion chamber 121 based on a command from the fuel injection control device 109A, which is provided in the ECU 109.

[0018] The internal combustion engine 101 is further equipped with a fuel pressure sensor 13, which measures the pressure in the high-pressure fuel line 129 to control the high-pressure fuel pump 125. The fuel injection control device 109A of the ECU 109 is configured to perform feedback control such that the fuel pressure in the high-pressure fuel line 129 reaches a desired pressure, based on an output from the fuel pressure sensor 13. As described above, the internal combustion engine 101 includes the spark plug 106 and the ignition coil 107, and the ECU 109 performs control to excite the ignition coil 107 and control to ignite the spark plug 106 based on the output of the fuel pressure sensor 13.Accordingly, the intake air and fuel in the combustion chamber 121 are burned by a spark released by the spark plug 106, and the piston 102 is pushed downwards by the pressure.

[0019] The exhaust gas produced by combustion is expelled through the exhaust valve 104 into the exhaust pipe 111, cleaned by the catalytic action of the three-way catalyst 112, and released to the outside. The oxygen concentration of the exhaust gas is also measured by the oxygen sensor 113, which is located upstream of the three-way catalyst 112. An output signal from the oxygen sensor 113 is fed to the fuel injection control device 109A of the ECU 109.

[0020] The control of the ECU 109 is explained in more detail below. The ECU 109 calculates the required torque of the internal combustion engine 101 based on a signal from the accelerator pedal position sensor 12 and determines whether the internal combustion engine 101 is idling or not. The ECU 109 also has a function for calculating the rotational speed (hereinafter referred to as engine speed) of the internal combustion engine 101 based on a signal from the crankshaft position sensor 11 and for determining whether the three-way catalytic converter 112 is warmed up or not, based on the coolant temperature of the internal combustion engine 101 obtained from the water temperature sensor 108, the time elapsed since the start of the internal combustion engine 101, and similar factors.

[0021] Furthermore, the ECU 109 calculates an intake air quantity necessary for the internal combustion engine 101, based on the required torque of the internal combustion engine 101 described above, and the like, and outputs an opening degree signal corresponding to the intake air quantity to the throttle valve 119, and the fuel injection control device 109A calculates a fuel quantity corresponding to the intake air quantity, outputs a fuel injection signal corresponding to the fuel quantity to the fuel injector 105 and furthermore an ignition signal to the ignition coil 107.

[0022] Next, a configuration of the fuel injection control device 109A of the ECU 109, which is in Fig. 1 is illustrated by reference to a block diagram of Fig. 2 described.

[0023] The fuel injection control device 109A comprises a drive IC 200, an engine state detection unit 201, a pulse signal calculation unit 202, a drive waveform command unit 203, a drive voltage input unit 207, an input voltage processing unit 204, an abnormality diagnostic unit 212, and a fuel injection quantity correction unit 213. The drive IC 200 acts as a drive control unit that controls the entire fuel injection control device 109A. The engine state detection unit 201 collects various types of information, such as the engine speed of the internal combustion engine 101, the intake air volume, the coolant temperature, the fuel pressure, and any fault conditions of the internal combustion engine, and supplies this information to each unit.

[0024] The pulse signal calculation unit 202 further calculates a pulse width Wp of an injection pulse Sp, which defines a fuel injection period of the fuel injector 105 based on various types of information received from the engine state sensing unit 201, and outputs the injection pulse Sp with the pulse width Wp. The drive waveform command unit 203 calculates a command value Swf, which relates to a waveform of a drive current Id supplied to open or maintain an open state of the fuel injector 105, and outputs the command value Swf to the drive IC 200. The drive IC 200 can thereby appropriately set a stroke amount and valve closing time of a valve body and precisely control the fuel injection quantity by controlling the waveform of the drive current Id through the drive waveform command unit 203.

[0025] The drive voltage input unit 207 is connected to a high-voltage (Hi) and a low-voltage (Low) side of the fuel injector 105 and supplies a drive voltage to the fuel injector 105. The drive voltage input unit 207 is switched on or off according to a control signal from the drive IC 200 to switch the supply of the drive current Id to the fuel injector 105. For this purpose, the drive IC 200 switches the drive voltage input unit 207 on or off based on the injection pulse Sp, which is calculated by the pulse signal calculation unit 202, and the command value Swf of the drive current waveform, which is calculated by the drive waveform command unit 203. It then applies an increased voltage Vboost or a battery voltage Vbat to the fuel injector 105 to control the drive current Id supplied to the fuel injector 105.The drive voltage input unit 207 is a drive circuit of the fuel injection valve 105 and includes a valve closing detection circuit that detects the closing of the fuel injection valve 105.

[0026] The fuel injection quantity correction unit 213 further determines a correction to the fuel injection quantity to be carried out in the internal combustion engine 101 and generates a signal to perform the correction. The fuel injection quantity correction unit 213 generates this signal to correct the fuel injection quantity based on information regarding a drive signal for the fuel injector 105 from the drive voltage input unit 207 and information regarding an engine state from the engine state detection unit 201.

[0027] The input voltage processing unit 204 also detects the drive voltage of the fuel injector 105. After the energy supply to the fuel injector 105 is stopped, the input voltage processing unit 204 detects a voltage value, generated as a counter-electromotive force (hereinafter also referred to as a voltage difference of the drive voltage), a predetermined number of times from the drive voltage input unit 207 at a predetermined detection time. The input voltage processing unit 204 then sets the detection time for detecting the voltage difference (diagnostic differential voltage) of the drive voltage of the fuel injector 105 as a sample value and a sample count, which is the number of detections.

[0028] The sampled value of the voltage difference represents a voltage difference (INJ_L - INJ_H) between a drive voltage (INJ_H) of the fuel injector 105 on the high side and a drive voltage (INJ_L) of the fuel injector 105 on the low side at a predetermined time p (interruption), at which a predetermined time tp has elapsed since an end time tp0 (a time at which the injection pulse changes from an on state to an off state) of a voltage supply control period. The acquisition time for the sampled value is set based on a value calculated according to an operating state of the internal combustion engine 101.

[0029] The number of samples is preset and stored in a memory of the ECU 109. In the present embodiment, the number of samples is set to two as the minimum number of measurements. That is, the number of samples is set such that voltage differences, measured at a first predetermined time p1, at which a first predetermined time tp1 has elapsed since an end time tp0 (a time at which the energy supply to the fuel injector 105 is stopped) of the voltage supply control period, and at a second predetermined time p2, at which a second predetermined time tp2, which is longer than the first predetermined time tp1, has elapsed since the end time tp0 of the voltage supply control period, are recorded as sample values ​​V1 and V2.The first predetermined time tp1 and the second predetermined time tp2 are set according to the operating state of the internal combustion engine 101.

[0030] The input voltage processing unit 204 measures the voltage difference at the set acquisition time and records this difference as the sampled value. Furthermore, the input voltage processing unit 204 calculates a noise determination value using information regarding the acquired sampled voltage difference. This noise determination value serves to determine the noise reduction or the presence or absence of noise in the sampled value.

[0031] The input voltage processing unit 204 uses the first sample V1, measured at the first predetermined time p1, and the second sample V2, measured at the second predetermined time p2, to calculate a value such as an average, difference, ratio, or predicted value as the noise determination value. The input voltage processing unit 204 then acquires a noise determination threshold and compares it to the noise determination value to determine whether the noise determination value meets a noise determination condition.

[0032] The input voltage processing unit 204 determines, based on a comparison between the noise detection threshold and the noise detection value, whether noise is mixed into the sampled value. If the noise detection value is determined not to meet the noise detection condition, the input voltage processing unit 204 determines that noise is mixed in and performs adjustment processing to change the acquisition time setting for the next sampled value.

[0033] In the setting processing, for example in a case where an ignition timing obtained from the engine state detection unit 201 and a voltage detection timing obtained from the input voltage processing unit 204 overlap, the input voltage processing unit 204 performs processing to change the setting of the detection timing for the first sample V1 or the setting of the detection timing for the second sample V2 such that the voltage detection timing differs from the ignition timing.

[0034] The input voltage processing unit 204 subsequently determines, based on the result of the determination of whether or not noise is present, whether or not the state of the valve closing detection circuit of the fuel injector 105 should be diagnosed. If the input voltage processing unit 204 determines that the state of the valve closing detection circuit of the fuel injector 105 should be diagnosed, the abnormality diagnostic unit 212 performs an abnormality diagnosis using the first sample value V1 and the second sample value V2. Conversely, if the input voltage processing unit 204 determines that the state of the valve closing detection circuit of the fuel injector 105 should not be diagnosed, the abnormality diagnosis in the abnormality diagnostic unit 212 is skipped and not performed.

[0035] During abnormality diagnostics, the abnormality diagnostic unit 212 compares both the first sample value V1 and the second sample value V2 with a diagnostic upper threshold Vth_d1, which represents a high_input threshold, and a diagnostic lower threshold Vth_d2, which represents a low_input threshold. If both the first sample value V1 and the second sample value V2 are greater than the diagnostic upper threshold Vth_d1 or less than the diagnostic lower threshold Vth_d2, it is determined that the valve closing detection circuit of the fuel injector 105 has failed. The diagnostic upper threshold Vth_d1 and the diagnostic lower threshold Vth_d2 are set based on values ​​calculated according to the operating state of the internal combustion engine 101.

[0036] Fig. Figure 3 is a flowchart for describing the contents of a diagnostic procedure for a valve closing detection circuit for a fuel injector.

[0037] The fuel injection control device 109A performs the continuous task C_n of managing the flow that is in Fig. 3 is illustrated in a predetermined programming cycle.

[0038] The input voltage processing unit 204 of the fuel injection control device 109A first records as the first sample value V1 a drive voltage at the first predetermined time p1, at which the first predetermined time tp1 has elapsed since the end time t0 of the voltage supply control period, and records as the second sample value V2 a drive voltage at the second predetermined time p2, at which the second predetermined time tp2, which is longer than the first predetermined time, has elapsed since the end time of the voltage supply control period (S301).

[0039] The input voltage processing unit 204 then calculates a noise determination value Va, which is a diagnostic determination voltage after noise processing, using the first sample V1 and the second sample V2 (S302). For example, in a first calculation example, to remove the noise from the sample, an average value of the first sample V1 and the second sample V2 is obtained and set as a noise determination value Va1.

[0040] In a second calculation example, to determine the presence or absence of noise in the sample, a second sample is predicted from the first sample V1, and a difference or ratio between a predicted value V2' of the second sample and an actually measured value V2 of the actually measured second sample is obtained and defined as a noise determination value Va2. In a third calculation example, to further determine the presence or absence of noise in the sample, a difference or ratio between the first sample V1 and the second sample V2 is obtained and defined as a noise determination value Va3.

[0041] The input voltage processing unit 204 then receives a noise determination threshold Vth_n (S303). The input voltage processing unit 204 calculates the noise determination threshold Vth_n based on the motor operating state. For this purpose, the input voltage processing unit 204 includes, for example, a calculation table defined according to a motor load, and calculates the noise determination threshold Vth_n with reference to this calculation table.

[0042] The input voltage processing unit 204 then determines, using the noise determination threshold Vth_n, whether the noise determination value Va meets the noise determination condition or not (S304). For example, the noise determination value Va is compared with the noise determination threshold Vth_n. Subsequently, if the noise determination value Va lies outside a range of the noise determination threshold Vth_n, it is determined that the noise determination condition is not met (NO in S304). Subsequently, if the noise determination value Va lies within the range of the noise determination threshold Vth_n, it is determined that the noise determination condition is met (YES in S304).

[0043] The noise determination condition determination processing in step S304 is described with reference to Fig. 4 to Fig. 6 described.

[0044] Fig. Figure 4 is a time diagram to describe the first calculation example of the noise determination value.

[0045] The noise figure is calculated for each continuous task C_n. In the first calculation example, the average value Va1 of the first sample V1 and the second sample V2 is obtained as the noise figure Va. (Va1=(V1+V2) / 2).

[0046] As in Fig. As shown in section 4(3), if the average value Va1 lies within a range between an upper noise determination threshold Vth_n1 and a lower noise determination threshold Vth_n2 (a range of an average value determination threshold), the noise determination condition is determined to be satisfied (YES in S304). Conversely, if the average value Va1 does not lie within the range between the upper noise determination threshold Vth_n1 and the lower noise determination threshold Vth_n2, the noise determination condition is determined to be not satisfied (NO in S304).

[0047] For example, in the Fig. 4(2) illustrated the example where the second sample value V2 is smaller than a preset differential voltage lower limit V_min. Therefore, for example, in a comparative example where one condition of the abnormality diagnosis is that both the first sample value V1 and the second sample value V2 lie between a differential voltage upper limit V_max and the differential voltage lower limit V_min, it is determined that the abnormality diagnosis cannot be performed.

[0048] On the other hand, in the present embodiment, using the noise determination value of the first calculation example, the second sample value V2 is smaller than the differential voltage lower limit V_min, but the average value Va1 is equally within the range between the noise determination upper limit threshold Vth_n1 and the noise determination lower limit threshold Vth_n2, thus determining that the abnormality diagnosis can be carried out.

[0049] In the first calculation example, the first sample V1 and the second sample V2 are averaged, and noise contained in the first sample V1 and the second sample V2 can be removed.

[0050] Fig. Figure 5 is a time diagram to describe the second calculation example of the noise determination value.

[0051] In the second calculation example for the noise determination value, the predicted value V2' of the second sample is obtained from the first sample V1. The predicted value V2' of the second sample can be obtained by referring to a table-based characteristic map that was previously defined based on the first sample V1 and the engine operating condition, such as the engine load.

[0052] The difference or ratio between the predicted value V2' of the second sample and the actually measured value V2 of the second sample is then obtained as the noise determination value Va2. For example, if the noise determination value Va2 is a difference δ between the predicted value V2' and the measured value V2, and the difference δ is less than a threshold δth, the noise determination condition is determined to be met (YES in S304). Conversely, if the difference δ is greater than the threshold δth, the sample is determined to contain noise and the noise determination condition is not met (NO in S304).

[0053] For example, in the Fig. 5(1) illustrated example where the measured value V2 of the second sample is between the differential voltage upper limit V_max and the differential voltage lower limit V_min, and a differential value δ1, which is the noise determination value Va2, is smaller than the threshold δth. Therefore, it is determined that the noise determination condition is satisfied (JA in S304).

[0054] On the other hand, it contains in the Fig. In the example illustrated in Section 5(2), the measured value V2 of the second sample contains noise, and a difference δ2 is greater than the threshold δth, thus determining that the sample contains noise and the noise determination condition is not met (NO in S304). Therefore, in a case where the processing eventually proceeds to an abnormality diagnosis skip (S308), the abnormality diagnosis is not performed in this task, and it is possible to prevent the input voltage processing unit 204 from incorrectly determining that an output of the valve closing detection circuit is abnormal. In a case where the noise determination value Va2 is a ratio value, for example, if the ratio between the predicted value V2' and the actually measured value of the second sample V2 is within a threshold range of 90% to 110%, the noise determination condition is determined to be met (YES in S304).

[0055] Fig. Figure 6 is a time diagram to describe the third calculation example of the noise determination value.

[0056] In the third calculation example of the noise determination value, the difference or ratio between the first sample value V1 and the second sample value V2 is defined as the noise determination value Va3.

[0057] For example, in a case where the difference 5 between the first sample V1 and the second sample V2 is the noise determination value Va3, if the difference 5 is within the range of the threshold δth, it is determined that the noise determination condition is met (YES in S304), and processing proceeds to abnormality diagnosis (S305). On the other hand, if the difference 5 is outside the range of the threshold δth, it is determined that the sample contains noise and the noise determination condition is not met (NO in S304).

[0058] For example, in the Fig. 6 (1) illustrated example the first sample V1 and the second sample V2 exist between the differential voltage upper limit V_max and the differential voltage lower limit V_min, and a differential value δ3, which is the noise determination value Va3, lies within the range of the threshold δth. Therefore, it is determined that the noise determination condition is satisfied (JA in S304).

[0059] On the other hand, in the Fig. In the example illustrated in Section 6(2), the second sample V2 is smaller than the differential voltage lower limit V_min, and a difference δ4 is large and lies outside the range of the threshold δth. Therefore, it is determined that the sample contains noise and the noise determination condition is not met (NO in S304). Therefore, in a case where the processing eventually proceeds to an abnormality diagnosis skip (S308), the abnormality diagnosis is not performed in this task, and it is possible to prevent the input voltage processing unit 204 from erroneously determining that an output of the valve closing detection circuit is abnormal.

[0060] In a case where the noise determination value Va3 is also a ratio value, for example in a case where the noise determination value Va3 lies within a threshold range of 90% to 110% with respect to the second sample V2 which contains no noise, it is determined that the noise determination condition is met (JA in S304).

[0061] The description then returns to page 304 and the subsequent steps in the flow of Fig. 3 back.

[0062] In a case where it is determined that the noise determination condition is not met (NO in S304), the input voltage processing unit 204 subsequently performs processing to measure the number n of times in which it is determined that the noise determination condition is not met (S305). In S305, each time a negative determination (NO) is made in S304, a counter is incremented by 1, and 1 is added to the number n of times (n + 1).

[0063] Subsequently, the number n of times in which it is determined that the noise determination condition is not met, as measured in S305, is compared with a preset abnormality diagnosis execution determination threshold nth (the number of times) and it is determined whether the number n of times in which it is determined that the noise determination condition is not met is equal to or greater than the abnormality diagnosis execution determination threshold nth or not (S306).

[0064] In this case, the input voltage processing unit 204 determines that the noise determination condition is not met in a case where the number n of times it is determined that it is less than the abnormality diagnosis execution determination threshold nth (NO in S306), that the abnormality diagnosis cannot be performed.

[0065] On the other hand, in a case where the number n of times in which it is determined that the noise determination condition is not met is equal to or greater than the abnormality diagnosis execution determination threshold nth (JA in S306), the input voltage processing unit 204 determines that the abnormality diagnosis can be performed.

[0066] In a case where it is determined that the noise determination condition is met (YES in S304), the input voltage processing unit 204 then performs processing to reset the number n of times in which it is determined that the noise determination condition is not met to 0 (S307). Then the input voltage processing unit 204 determines that the abnormality diagnosis can be performed.

[0067] In a case where the input voltage processing unit 204 determines that the abnormality diagnosis can be performed, the abnormality diagnosis unit 212 of the fuel injection control device 109A also performs the abnormality diagnosis to diagnose the presence or absence of an abnormality in the valve closing detection circuit of the fuel injector 105 (S309). On the other hand, in a case where the input voltage processing unit 204 determines that the abnormality diagnosis cannot be performed, the abnormality diagnosis is skipped and not performed in this routine (S308).

[0068] During the abnormality diagnosis (S309), a comparison of the sampled value with a diagnostic threshold determines whether an abnormality has occurred in the valve closing detection circuit. Specifically, if both the first sampled value V1 and the second sampled value V2 are greater than the preset upper diagnostic threshold or less than the preset lower diagnostic threshold, it is determined that an abnormality has occurred in the valve closing detection circuit.

[0069] Fig. Figure 7 shows a state diagram of the valve closing detection circuit and a graph illustrating a change in the drive voltage when the valve is closed. More precisely illustrated Fig. 7(1) a state of the valve closing detection circuit in a case where there is a disconnection or a GND short circuit in a wiring INJ_H connected to a high side of the fuel injector 105, or in a case where there is a VCC short circuit in a wiring INJ_L, and Fig. Figure 7(2) represents a diagram showing a change in the drive voltage in the state of Fig. 7(1) illustrates.

[0070] In a case where the disconnection or GND short circuit occurs in the INJ_H wiring connected to the high side of fuel injector 105, or in a case where the VCC short circuit occurs in the INJ_L wiring, as in Fig. As illustrated in Figure 7(1), an INJ drive voltage is set to the high side, which is not lower than the diagnostic upper limit threshold Vth_d1, as shown in Figure 7(1). Fig. 7(2) illustrates this. Therefore, if both the first sample value V1 and the second sample value V2 are greater than the diagnostic upper limit threshold Vth_d1, it is determined that an abnormality has occurred in the valve closing detection circuit.

[0071] Fig. Figure 8 shows a state diagram of the valve closing detection circuit and a graph illustrating a change in the drive voltage when the valve is closed. More precisely, it illustrates... Fig. 8(1) a state of the valve closing detection circuit in a case where there is a disconnection or a GND short circuit in the INJ_L wiring connected to the low side of the fuel injector 105, or in a case where there is a VCC short circuit in the INJ_H wiring, and Fig. Figure 8(2) represents a diagram showing a change in the drive voltage in the state of Fig. 8(1) illustrates.

[0072] In a case where the disconnection or GND short circuit occurs in the INJ_L wiring connected to the low side of fuel injector 105, or in a case where the VCC short circuit occurs in the INJ_H wiring, as in Fig. As illustrated in Figure 8(1), the INJ drive voltage is fixed on the low side, which is not higher than the diagnostic lower limit threshold Vth_d2, as shown in Figure 8(1). Fig. 8(2) illustrates this. Therefore, if both the first sample value V1 and the second sample value V2 are less than the diagnostic lower limit threshold Vth_d2, it is determined that an abnormality has occurred in the valve closing detection circuit.

[0073] If, during processing of S304, it is determined that the noise determination condition is not met (NO in S304), and the number n of times the noise determination condition is not met is less than the abnormality diagnosis execution determination threshold nth (NO in S306), the abnormality diagnosis determination is skipped and not performed in this continuous task (S308). The input voltage processing unit 204 then determines that the noise determination value Va is outside the range of the noise determination threshold Vth_n and that noise is mixed into the sample, and performs the adjustment processing to change the setting of the acquisition time for the sample to be acquired next.

[0074] The input voltage processing unit 204 increases or decreases at least one of the first predetermined time tp1 and the second predetermined time tp2 set in the current continuous task C_n, and changes the acquisition time setting to an acquisition time that differs from the acquisition time for the sample value determined to be mixed with noise. In subsequent cycles, the sample value is also acquired at the acquisition time after the setting change.

[0075] The input voltage processing unit 204 compares the voltage acquisition time with the ignition time at the time of determining the abnormality diagnostic skip (S306) and performs processing to shift the voltage acquisition time to the time of the next voltage acquisition if a difference between the voltage acquisition time and the ignition time is within a predetermined range. For example, if the acquisition time (first predetermined time p1) for the first sample V1 or the acquisition time (second predetermined time p2) for the second sample V2 overlaps with an ignition time p3, the input voltage processing unit 204 modifies the setting of the acquisition time for the first sample V1 or the setting of the acquisition time for the second sample V2 so that it differs from the ignition time in subsequent cycles.

[0076] Fig. Figure 9 shows a flowchart to describe the contents of a procedure for shifting the acquisition time for the sampled value.

[0077] The input voltage processing unit 204 first performs a processing operation to calculate the elapsed time tp3' since the end time tp0 of the voltage supply control period (when the injection pulse changes from an on state to an off state) by using an elapsed time tp3 from the continuous task C_n until the ignition time p3. Here, the input voltage processing unit 204 calculates the elapsed time tp3' from the end time tp0 of the voltage supply control period until the ignition time p3 by calculating an elapsed time from the continuous task C_n until the end time tp0 of the voltage supply control period, and by subtracting the calculated elapsed time from the elapsed time tp3 from the continuous task C_n until the ignition time p3 (S901).

[0078] The input voltage processing unit 204 further calculates a first displacement determination value λ1, which is a time difference between the ignition time p3 and the first predetermined time p1, which is the acquisition time for the first sample value V1, and a second displacement determination value λ2, which is a time difference between the ignition time p3 and the second predetermined time p2, which represents the acquisition time for the second sample value (S902).

[0079] The first displacement value λ1 is calculated by subtracting the first predetermined time tp1 from the elapsed time tp3' (λ1 = |tp3' - tp1|). The second displacement value λ2 is calculated by subtracting the second predetermined time tp2 from the elapsed time tp3' (λ2 = |tp3' - tp2|).

[0080] The input voltage processing unit 204 then determines whether the first displacement determination value λ1 and the second displacement determination value λ2 each lie within a threshold range between a preset upper determination limit and a preset lower determination limit (S903). The upper determination limit and the lower determination limit are set the same for each predetermined time point in an injection pulse.

[0081] In a case where the first displacement determination value λ1 and / or the second displacement determination value λ2 are within the threshold range, it is determined that the voltage detection time overlaps the ignition time p3, and the voltage detection time is changed (S905). When the voltage detection time is changed, the predetermined time for the displacement determination value λ that lies within the threshold range is increased or decreased. On the other hand, in a case where neither the first displacement determination value λ1 nor the second displacement determination value λ2 are within the threshold range, it is determined that the voltage detection time does not overlap the ignition time p3, and the voltage detection time setting is not changed (S904).

[0082] Fig. Figure 10 shows a diagram to describe a state in which the acquisition time for the sampled value overlaps the ignition time, and Fig. Figure 11 is a diagram to describe a state in which the acquisition time for the sampled value is shifted from the ignition time.

[0083] The input voltage processing unit 204 calculates the first displacement determination value λ1 and the second displacement determination value λ2 in the continuous task C_n and determines whether the first displacement determination value λ1 and the second displacement determination value λ2 are each within the threshold range between the upper determination limit and the lower determination limit in the next continuous task C_n+1 or not.

[0084] In the Fig. In the 10 illustrated example, in the continuous task C_n, the difference between the first predetermined time p1 and the ignition time p3 is large, while the difference between the second predetermined time p2 and the ignition time p3 is small. Therefore, in the continuous task C_n+1, it is determined that the first shift determination value λ1 is greater than the upper determination limit, and that the first predetermined time p1 and the ignition time p3 do not overlap. Consequently, no shift determination flag is set for the first predetermined time p1, and it is determined that the first predetermined time p1, which is the acquisition time for the first sample value V1, is not shifted.

[0085] On the other hand, in the continuous task C_n+1, it is determined that the second shift determination value λ2 lies within the threshold range between the upper determination limit and the determination threshold, and that the second predetermined time p2 and the ignition time p3 overlap. Therefore, a shift determination flag is set for the second predetermined time p2, and it is determined that the second predetermined time p2, which is the acquisition time for the second sample value V2, is shifted. For example, this is achieved by adjusting the second predetermined time p2 such that the second predetermined time tp2 is increased.

[0086] In the Fig. In the illustrated example 11, the acquisition time for the second sample value V2 is further changed in the continuous task C_n to a second predetermined time p2', such that the difference between the second predetermined time p2 and the ignition time p3 is greater than that in the Fig. This is illustrated in example 10. Therefore, in the continuous task C_n+1, it is determined that the second shift determination value λ2 is greater than the upper determination limit, i.e., it lies outside the threshold range, and that the second predetermined time p2 and the ignition time p3 do not overlap. Therefore, the shift determination flag for the second predetermined time p2 is cleared, and it is determined that the second predetermined time p2 is not shifted.

[0087] In the fuel injection control device 109A of the present embodiment, the number of samples was set to two, and the first and second samples are used to determine whether or not to perform the abnormality diagnosis. Therefore, it is possible to ensure the accuracy of an abnormality diagnosis with less process load.

[0088] In the fuel injection control device 109A of the present embodiment, the noise determination value is calculated and compared with the noise determination threshold to determine whether the noise determination condition is met or not. If the noise determination condition is not met, the abnormality diagnosis is skipped and not performed. Therefore, the abnormality diagnosis is not performed in this case, and it is possible to prevent the input voltage processing unit 204 from erroneously determining that an output of the valve closing detection circuit is abnormal. In the above embodiment, a case where the number of samples is two, which is the minimum number, has been described as an example.However, the number of samples can also be three, and the accuracy of an abnormality diagnosis can be ensured with less process load, similar to a case where the number of samples is two.

[0089] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the embodiment described above, and various design changes can be made without departing from the spirit of the present invention as described in the claims. For example, the embodiment described above has only been described in such detail to present the present invention in an easily understandable manner, and the present invention is not necessarily limited to those embodiments that have all the described configurations. Furthermore, part of a configuration of one embodiment can be replaced by a configuration of another embodiment, and a configuration of one embodiment can be added to a configuration of another embodiment.Furthermore, a part of a configuration of each embodiment can be added to, deleted from, or replaced by another configuration. Reference symbol list 101 internal combustion engine 109A Fuel injection control device 201 Engine condition monitoring unit 202 Pulse signal calculation unit 202 Pulse signal calculation unit 203 Drive shaft shaping command unit 204 Input voltage processing unit 207 Drive voltage input unit 212 Abnormality Diagnostic Unit 213 Fuel injection quantity correction unit tp1 first predetermined time tp2 second predetermined time p1 first predetermined time p2 second predetermined time p3 Ignition timing V_max differential voltage limit V_min differential voltage lower limit V1 first sample value V2 second sample value Vth_d1 Diagnostic upper limit threshold (High_input threshold) Vth_d2 diagnostic lower limit threshold (low_input threshold) Vth_n1 Noise determination upper limit threshold Vth_n2 noise determination lower limit threshold C_n continuous task QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2016-211452 A

[0004]

Claims

[1] Fuel injection control device controlling a fuel injector of an internal combustion engine, the fuel injection control device comprising: an input voltage processing unit that detects a drive voltage of the fuel injector; and an abnormality diagnostic unit that performs an abnormality diagnosis of a drive circuit of the fuel injector based on the drive voltage, wherein The input voltage processing unit acquires a drive voltage as a first sample at a first predetermined time, at which a first predetermined time has elapsed from the time at which the energy supply to the fuel injector is stopped; acquires a drive voltage as a second sample, measured at a second predetermined time, at which a second predetermined time, longer than the first predetermined time, has elapsed from the time at which the energy supply to the fuel injector is stopped; calculates a noise determination value using the first and second samples; and compares the noise determination value with a noise determination threshold to determine whether the noise determination value meets a noise determination condition. The abnormality diagnosis unit performs the abnormality diagnosis in a case where the noise determination value meets the noise determination condition. [2] The fuel injection control device according to claim 1, wherein the input voltage processing unit calculates a predicted value of the second sample according to the first sample and sets a difference or ratio between the predicted value and an actually measured value of the second sample as the noise determination value. [3] The fuel injection control device according to claim 1, wherein the input voltage processing unit sets an average value of the first sample and the second sample as the noise determination value. [4] The fuel injection control device according to claim 1, wherein the input voltage processing unit sets a difference or ratio between the first sample value and the second sample value as the noise determination value. [5] The fuel injection control device according to claim 1, wherein the input voltage processing unit sets at least one of the first predetermined time and the second predetermined time according to an operating state of the internal combustion engine. [6] The fuel injection control device according to claim 5, wherein in a case where it is determined that the noise determination value does not meet the noise determination condition, the input voltage processing unit performs a setting processing of changing settings of acquisition times for the first sample value and the second sample value by increasing or decreasing at least one of the first predetermined time and the second predetermined time. [7] The fuel injection control device according to claim 6, wherein in a case where the detection time for the first sample value or the detection time for the second sample value overlaps an ignition timing of the internal combustion engine, the input voltage processing unit changes the setting of the detection time for the first sample value or the setting of the detection time for the second sample value so that it differs from the ignition timing of the internal combustion engine.

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