JP5813531B2 - Fuel spray detection device - Google Patents

Description

  The present invention relates to a fuel spray detection device that detects the occurrence of fuel spray in a fuel injection valve.

  2. Description of the Related Art Conventionally, there is a common rail type fuel injection system that detects an abnormal fuel leakage (see, for example, Patent Document 1). In the one described in Patent Document 1, the discharge amount QT of the fuel pump, the internal leak amount QI of the injector (fuel injection valve), the switching leak amount QS accompanying the switching of the injector, the fuel amount QP corresponding to the change in the common rail pressure, The target fuel injection amount QF is calculated. Then, the fuel leakage amount QL = QT− (QI + QS + QP + QF) is calculated, and when the fuel leakage amount QL is equal to or greater than a predetermined value, it is determined that an abnormal fuel leakage has occurred.

JP 9-177586 A

  By the way, in the thing of patent document 1, even when the fuel is discharged in an injector, it determines with the abnormal fuel leak having arisen. If it is determined that an abnormal fuel leak has occurred, a fail-safe process is generally executed.

  Here, even if the fuel is temporarily ejected in the injector, it may recover to a normal state thereafter. However, in the device described in Patent Document 1, it is not possible to distinguish between the case where the fuel is blown off in the injector and the case where the fuel pipe does not recover naturally, such as a crack in the fuel pipe. For this reason, there is a possibility that the fail-safe process is excessively performed regardless of the type of abnormal fuel leakage.

  The present invention has been made to solve these problems, and an object of the present invention is to provide a fuel spray detection device capable of distinguishing and detecting fuel spray from a fuel injection valve among abnormal fuel leaks. It is to provide.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

The first invention is applied to a fuel injection system (50) in which fuel supplied from a pressure accumulating vessel (12) is injected by a plurality of fuel injection valves (20), and detection of the fuel injection in the fuel injection valves is detected. A plurality of fuel pressures for sequentially detecting the fuel pressure in each fuel passage (14, 22, 25) from the pressure accumulating container to the injection holes (20f) of the plurality of fuel injection valves. Based on the fuel pressure sequentially detected by the sensors (20a, 200a) and the plurality of fuel pressure sensors, the fuel pressure decreases in the plurality of fuel passages, and a specific fuel passage among the plurality of fuel passages Detection means (30) for detecting that the fuel is blown out when the fuel pressure in the fuel passage is lowered before the fuel pressure in the other fuel passages. Characterized in that it comprises a and.

  According to the above configuration, the fuel pressure in each fuel passage from the pressure accumulation container to the injection holes of the plurality of fuel injection valves is sequentially detected by the fuel pressure sensor. For this reason, the fluctuation of the fuel pressure at the injection hole can be accurately detected before the fluctuation of the fuel pressure in the pressure accumulating vessel is attenuated.

  Here, when fuel is blown out in a specific fuel injection valve, the fuel pressure in the fuel passage corresponding to the specific fuel injection valve is reduced. Along with this, the fuel pressure in the pressure accumulating vessel decreases, and as a result, the fuel pressure in the fuel passage corresponding to the other fuel injection valves also decreases. At this time, the fuel pressure in the fuel passage corresponding to the other fuel injection valve decreases with a delay from the fuel pressure in the fuel passage corresponding to the specific fuel injection valve. Note that when fuel leaks from the pressure accumulating container or the fuel pipe from the pump to the pressure accumulating container, the fuel pressure decreases substantially simultaneously in each fuel passage corresponding to the plurality of fuel injection valves.

  In this regard, when the fuel pressure is reduced in the plurality of fuel passages, and the fuel pressure in a specific fuel passage among the plurality of fuel passages is lowered before the fuel pressure in the other fuel passages, the fuel injection It is detected that release has occurred. Therefore, it is possible to distinguish and detect the fuel injection from the fuel injection valve among abnormal fuel leaks.

The schematic diagram which shows a fuel-injection system. Sectional drawing which shows the injector of FIG. 1 typically. The flowchart which shows the process sequence of fuel-injection control. The flowchart which shows the process sequence of abnormal fuel leak detection. The time chart which shows the relationship between the waveform of the detection pressure at the time of single stage injection execution, and the waveform of an injection rate. The time chart which shows the relationship between the waveform of the detection pressure at the time of multistage injection execution, and the waveform of an injection rate.

  Hereinafter, an embodiment will be described with reference to the drawings. In this embodiment, for example, a common rail type fuel injection system for a four-wheeled vehicle engine (internal combustion engine) is embodied. This system is used when high-pressure fuel (for example, light oil having an injection pressure of “1000 atm” or higher) is directly injected into a combustion chamber (cylinder) of a diesel engine.

  First, an outline of a common rail fuel injection system will be described with reference to FIG. In this embodiment, a multi-cylinder (for example, inline 4-cylinder) 4-stroke, reciprocating diesel engine is assumed. In this engine, a cylinder discrimination sensor (electromagnetic pickup) provided on the camshaft of the intake / exhaust valve sequentially discriminates the target cylinder at that time, and intake, compression, combustion, and exhaust for each of the four cylinders # 1 to # 4 are performed. One combustion cycle by the four strokes is executed at a period of “720 ° CA”. Specifically, one combustion cycle is sequentially executed in the order of cylinders # 1, # 3, # 4, and # 2, with a shift of “180 ° CA” between the cylinders.

  As shown in the figure, the fuel injection system 50 is roughly configured by each device that an ECU 30 (electronic control unit) takes in sensor outputs from various sensors and constitutes a fuel supply system based on the respective sensor outputs. It is comprised so that the drive of may be controlled. The ECU 30 adjusts the current supply amount to the intake adjustment valve 11c and controls the fuel discharge amount of the fuel pump 11 to a desired value, thereby feedback-controlling the fuel pressure in the common rail 12 (pressure accumulator) to the target value (for example, PID control). Then, based on the fuel pressure, the fuel injection amount to the predetermined cylinder of the target engine, and consequently the output of the engine (the rotational speed and torque of the output shaft) are controlled to a desired magnitude.

  Various devices constituting the fuel supply system are arranged in order of the fuel tank 10, the fuel pump 11 (pump), the common rail 12, and the injector 20 (fuel injection valve) from the upstream side of the fuel. Of these, the fuel tank 10 and the fuel pump 11 are connected by a pipe 10a via a fuel filter 10b.

  The fuel pump 11 has a high-pressure pump 11a and a low-pressure pump 11b that are driven by a drive shaft 11d. The fuel pumped up from the fuel tank 10 by the low pressure pump 11b is pressurized and discharged by the high pressure pump 11a. The amount of fuel pumped to the high-pressure pump 11a, and hence the amount of fuel discharged from the fuel pump 11, is metered by a suction control valve (SCV) 11c provided on the fuel suction side of the fuel pump 11. That is, in the fuel pump 11, the fuel discharge from the pump 11 is adjusted by adjusting the drive current amount (and consequently the valve opening) of the intake adjustment valve 11 c (for example, a normally-on type adjustment valve that opens when not energized). The amount is controlled to the desired value.

  Of the two pumps constituting the fuel pump 11, the low-pressure pump 11b is configured as a trochoid feed pump, for example. On the other hand, the high-pressure pump 11a is composed of, for example, a plunger pump, and fuel sent to the pressurizing chamber by reciprocating predetermined plungers (for example, three plungers) in the axial direction by eccentric cams (not shown). Are sequentially pumped at a predetermined timing. Both pumps are driven by the drive shaft 11d. Incidentally, the drive shaft 11d is interlocked with the crankshaft 41, which is the output shaft of the target engine, and rotates, for example, at a ratio of "1/1" or "1/2" with respect to one rotation of the crankshaft 41. That is, the low pressure pump 11b and the high pressure pump 11a are driven by the output of the target engine.

  The fuel pumped up from the fuel tank 10 through the fuel filter 10 b by the fuel pump 11 is pressurized and supplied (pressure-fed) to the common rail 12. The common rail 12 stores the fuel pumped from the fuel pump 11 in a high pressure state. The common rail 12 distributes and supplies the stored fuel to the injectors 20 of the cylinders # 1 to # 4 through the high-pressure pipe 14 provided for each cylinder. The fuel discharge ports 21 of these injectors 20 (# 1) to (# 4) are connected to a pipe 18 for returning excess fuel to the fuel tank 10, respectively. In addition, an orifice 12 a (fuel pulsation reducing means) is provided between the common rail 12 and the high-pressure pipe 14 to attenuate the pressure pulsation of fuel propagating from the common rail 12 to the high-pressure pipe 14.

  FIG. 2 shows a detailed structure of the injector 20. The four injectors 20 (# 1) to (# 4) have the same structure (for example, the structure shown in FIG. 2). Each of the injectors 20 is a hydraulically driven fuel injection valve that uses combustion fuel (fuel in the fuel tank 10). During fuel injection, driving power is transmitted through the hydraulic chamber Cd (control chamber). As shown in the figure, the injector 20 is configured as a normally closed type fuel injection valve that is in a closed state when not energized.

  High-pressure fuel pumped from the common rail 12 flows into the fuel inlet 22 formed in the housing 20 e of the injector 20. A part of the high-pressure fuel that flows in flows into the hydraulic chamber Cd, and the other flows toward the injection hole 20f. A leak hole 24 that is opened and closed by the control valve 23 is formed in the hydraulic chamber Cd. When the leak hole 24 is opened by the control valve 23, the fuel in the hydraulic chamber Cd is returned to the fuel tank 10 from the leak hole 24 through the fuel discharge port 21.

  When fuel is injected from the injector 20, the control valve 23 is operated according to the energized state (energized / non-energized) for the solenoid 20b constituting the two-way solenoid valve. As a result, the degree of sealing of the hydraulic chamber Cd, and consequently the pressure in the hydraulic chamber Cd (corresponding to the back pressure of the needle valve 20c) is increased or decreased. As the pressure increases or decreases, the needle valve 20c reciprocates (up and down) in the housing 20e according to or against the extension force of the spring 20d (coil spring). Thereby, the internal fuel passage 25 to the injection hole 20f is opened and closed. Specifically, the needle valve 20c is seated or separated from the valve seat portion based on the reciprocating motion.

  Here, drive control of the needle valve 20c is performed through on / off control. That is, a pulse signal (energization signal) for instructing on / off is sent from the ECU 30 to the drive portion (the above-described two-way electromagnetic valve) of the needle valve 20c. Then, the needle valve 20c is lifted up based on the ON signal (or OFF signal), and the injection hole 20f is opened. On the other hand, the needle valve 20c is lifted down based on the off signal (or on signal), and the injection hole 20f is closed.

  Incidentally, the pressure increasing process of the hydraulic chamber Cd is performed by supplying fuel from the common rail 12. On the other hand, the pressure reducing process of the hydraulic chamber Cd is performed by opening the leak hole 24 by operating the control valve 23 by energizing the solenoid 20b. As a result, the fuel in the hydraulic chamber Cd is returned to the fuel tank 10 through the pipe 18 (FIG. 1) connecting the injector 20 and the fuel tank 10. That is, by adjusting the fuel pressure in the hydraulic chamber Cd by the opening / closing operation of the control valve 23, the operation of the needle valve 20c that opens and closes the injection hole 20f is controlled.

  In the non-driving state of the injector 20, the needle valve 20c is displaced toward the valve closing side by a constantly applied force toward the valve closing side (extension force by the spring 20d). On the other hand, in the driving state, when the driving force is applied as described above, the needle valve 20c is displaced toward the valve opening side against the extension force of the spring 20d. At this time, the lift amount of the needle valve 20c changes substantially symmetrically between the non-driven state and the driven state.

  A fuel pressure sensor 20a (see also FIG. 1) for detecting the fuel pressure is attached to the injector 20. Specifically, the fuel inlet 22 formed in the housing 20e and the high-pressure pipe 14 are connected by a jig 20j, and the fuel pressure sensor 20a is attached to the jig 20j. By attaching the fuel pressure sensor 20a to the fuel inlet 22 of the injector 20 in this way, it is possible to detect the fuel pressure (inlet pressure) in the fuel inlet 22 at any time. Specifically, the output of the fuel pressure sensor 20a can detect (measure) the fluctuation of the fuel pressure accompanying the injection operation of the injector 20, the fuel pressure level (stable pressure), the fuel injection pressure, and the like.

  The fuel pressure sensor 20a is provided for each of the plurality of injectors 20 (# 1) to (# 4). Based on the output of the fuel pressure sensor 20a, the waveform of the fuel pressure accompanying the injection operation of the injector 20 can be detected with high accuracy for a predetermined injection (details will be described later).

  A vehicle (not shown) (for example, a four-wheel passenger car or a truck) is provided with various sensors for vehicle control in addition to the above sensors. For example, a crank angle sensor 42 (for example, an electromagnetic pickup) that outputs a crank angle signal at every predetermined crank angle (for example, at a cycle of 30 ° CA) is provided on the outer peripheral side of the crankshaft 41 that is the output shaft of the target engine. . The crank angle sensor 42 detects the rotation angle position, rotation speed (engine rotation speed), and the like of the crankshaft 41. The accelerator pedal of the vehicle is provided with an accelerator sensor 44 that outputs an electrical signal corresponding to the state (displacement amount) of the accelerator pedal. The accelerator sensor 44 detects the amount of operation (depression amount) of the accelerator pedal by the driver.

  In such a system, the part that performs engine control is the ECU 30. The ECU 30 includes a known microcomputer, and grasps the operating state of the target engine and the user's request based on the detection signals of the various sensors. Then, by operating various actuators such as the suction adjusting valve 11c and the injector 20 in accordance with them, various controls relating to the engine are performed in an optimum manner according to the situation at that time.

  The microcomputer mounted on the ECU 30 includes a CPU (basic processing unit) that performs various calculations, a RAM as a main memory that temporarily stores data during the calculation, calculation results, and the like, and a ROM as a program memory. And a nonvolatile memory for storing data, a backup RAM, and the like. The ROM stores various programs and control maps related to engine control including a program related to fuel injection control, and the nonvolatile memory for storing data includes various data including design data of the target engine. Control data and the like are stored in advance.

  In the present embodiment, the ECU 30 satisfies the torque (required torque) to be generated on the output shaft (crankshaft 41) at that time, based on various sensor outputs (detection signals) input at any time, and thus satisfies the required torque. The fuel injection amount for calculating is calculated. Thus, by variably setting the fuel injection amount of the injector 20, torque (generated torque) generated through fuel combustion in each cylinder (combustion chamber), and eventually output to the output shaft (crankshaft 41). The shaft torque (output torque) is controlled (matched to the required torque).

  That is, the ECU 30 calculates a fuel injection amount in accordance with, for example, the engine operating state from time to time or the accelerator pedal operation amount by the driver, and injects fuel at that fuel injection amount in synchronization with a desired injection timing. An instructing injection control signal (injection command signal) is output to the injector 20. Thereby, based on the drive amount (for example, valve opening period) of the injector 20, the output torque of the target engine is controlled to the target value.

  As is well known, in a diesel engine, the intake throttle valve (throttle valve) provided in the intake passage of the engine is maintained in a substantially fully open state for the purpose of increasing the amount of fresh air and reducing pumping loss during steady operation. Is done. Therefore, control of the fuel injection amount is mainly used as combustion control during steady operation (particularly combustion control related to torque adjustment).

  Hereinafter, a basic processing procedure of the fuel injection control will be described with reference to FIG. Note that the values of various parameters used in this control are stored as needed in a storage device such as a RAM, a non-volatile memory, or a backup RAM mounted on the ECU 30, and updated as necessary.

  As shown in the figure, in this series of processing, first, in step S11, predetermined parameters, for example, the engine speed at that time (actually measured value by the crank angle sensor 42) and fuel pressure (actually measured value by the fuel pressure sensor 20a), Further, the accelerator operation amount (actual value measured by the accelerator sensor 44) by the driver at that time is read.

  In subsequent step S12, an injection pattern is set based on the various parameters read in step S11. For example, in the case of single-stage injection, the injection amount Q (injection time) of the injection, and in the case of the injection pattern of multi-stage injection, the total injection amount Q (total injection time) of each injection that contributes to torque is described above. It is variably set according to the torque to be generated on the output shaft (crankshaft 41) (requested torque calculated from the accelerator operation amount or the like).

  This injection pattern is acquired based on, for example, a predetermined map (an injection control map, which may be a mathematical expression) stored in the ROM and a correction coefficient. Specifically, for example, an optimal injection pattern (adapted value) is obtained in advance for a range of the predetermined parameter (step S11) that is assumed, and is written in the injection control map.

  This injection pattern is determined by parameters such as the number of injection stages (the number of injections in one combustion cycle), the injection timing (injection timing) and the injection time (corresponding to the injection amount) of each injection. Thus, the injection control map shows the relationship between these parameters and the optimal injection pattern.

  Then, the injection pattern acquired in the map for injection control is corrected based on a separately updated correction coefficient (for example, stored in a nonvolatile memory in the ECU 30) (for example, “set value = value on map / correction”). "Coefficient" is calculated). As a result, an injection command signal for the injector 20 corresponding to the injection pattern of the fuel to be injected at that time, and corresponding to the injection pattern is obtained. The correction coefficient is sequentially updated during operation of the internal combustion engine by a separate process.

  It should be noted that, for the setting of the injection pattern (step S12), each map provided separately for each element of the injection pattern (the number of injection stages, etc.) may be used, or each element of these injection patterns may be used. Several (for example, all) maps created together may be used.

  The injection pattern thus set, and thus the command value (injection command signal) corresponding to the injection pattern, is used in the subsequent step S13. That is, in step S13, the command value is output to the injector 20, and the drive of the injector 20 is controlled. Then, with the drive control of the injector 20, the series of processes in FIG.

  Next, a processing procedure for detecting abnormal fuel leakage in the fuel injection system 50 will be described with reference to FIG. The series of processes shown in FIG. 4 is executed for each predetermined crank angle (specifically, every 180 ° CA).

  First, in step S21, the detected pressure (output value) from the fuel pressure sensor 20a is taken in by 180 ° CA. This intake process is executed for each of the plurality of fuel pressure sensors 20a. Hereinafter, the capturing process in step S21 will be described in detail with reference to FIG.

  FIG. 5A shows the injection command signal (pulse signal) output to the injector 20 in step S13 of FIG. 3, and the solenoid 20b is activated by the ON signal of this command signal to release the injection hole 20f. Is done. That is, the start of injection is commanded by the on timing t1 of the injection command signal, and the end of injection is commanded by the off timing t2. Therefore, the injection amount Q is controlled by controlling the release time Tq of the injection hole 20f according to the ON period (injection command period) of the command signal. FIG. 5B shows a change (injection rate waveform) of the fuel injection rate from the injection hole 20f caused by the injection command, and the solid line in FIG. 5C shows the fuel pressure sensor 20a generated by the change of the injection rate. The change in detected pressure due to (detected pressure waveform) is shown.

  Then, the ECU 30 sequentially detects the output value of the fuel pressure sensor 20a by a subroutine process different from the process of FIG. In the subroutine processing, the output value of the fuel pressure sensor 20a is sequentially acquired at intervals that are short enough to draw a pressure waveform (pressure transition) based on the output (interval shorter than the processing cycle of FIG. 4). . Specifically, sensor outputs are sequentially acquired at intervals shorter than 50 μsec (more desirably, less than 20 μsec). And ECU30 memorize | stores for the predetermined period (180 degreeCA minutes or more) of the sensor output acquired sequentially in RAM etc. which were mounted.

  Since the change in the detected pressure by the fuel pressure sensor 20a and the change in the injection rate have a correlation described below, the waveform of the injection rate can be estimated from the waveform of the detected pressure. That is, first, as shown in FIG. 5 (a), after the time point t1 when the injection start command is made, the injection rate starts increasing at the time point R1, and the injection is started. On the other hand, the detected pressure starts decreasing at the change point P1 as the injection rate starts increasing at the time point R1. Thereafter, as the injection rate reaches the maximum injection rate at the time point R2, the decrease in the detected pressure stops at the change point P2. Next, as the injection rate starts decreasing at the time point R2, the detected pressure starts increasing at the change point P2. Thereafter, as the injection rate becomes zero at the time point R3 and the actual injection is finished, the increase in the detected pressure stops at the change point P3.

  As described above, by detecting the change points P1 and P3 in the waveform of the pressure detected by the fuel pressure sensor 20a, the injection rate increase start time R1 (actual injection start time) and decrease end time R3 (actual injection end time) are calculated. (Estimated). Further, the change in the injection rate can be estimated from the change in the detected pressure based on the correlation between the change in the detected pressure and the change in the injection rate described below.

  That is, there is a correlation between the pressure decrease rate Pα from the detected pressure change point P1 to P2 and the injection rate increase rate Rα from the injection rate change point R1 to R2. There is a correlation between the pressure increase rate Pγ from the change points P2 to P3 and the injection rate decrease rate Rγ from the change points R2 to R3. There is a correlation between the pressure drop amount Pβ (maximum drop amount) from the change points P1 to P2 and the injection rate increase amount Rβ from the change points R1 to R2. Therefore, the injection rate increase rate Rα, the injection rate decrease rate Rγ, and the injection rate increase amount Rβ are detected by detecting the pressure decrease rate Pα, the pressure increase rate Pγ, and the pressure decrease amount Pβ from the waveform of the pressure detected by the fuel pressure sensor 20a. Can be calculated (estimated). Accordingly, it is possible to calculate (estimate) the waveform of the fuel injection rate (transition of the fuel injection rate) shown in FIG.

  Note that the integral value of the injection rate from the start to the end of actual injection (the area of the portion indicated by the hatched symbol S) corresponds to the injection amount. The integral value of the pressure and the integral value S of the injection rate in the portion corresponding to the change in the injection rate from the start to the end of the actual injection (the change points P1 to P3) in the fluctuation waveform of the detected pressure have a correlation. Therefore, the injection rate integrated value S corresponding to the injection amount Q can be calculated (estimated) based on calculating the pressure integrated value from the waveform of the detected pressure by the fuel pressure sensor 20a.

  Returning to the description of FIG. 4, processing contents after step S <b> 21 will be described. In the processing after step S21, the waveform of the detected pressure by the fuel pressure sensor 20a corresponding to the injection cylinder and the cylinder that performs the next injection among the plurality of cylinders in which injection and non-injection are sequentially executed is used. During the period in which fuel is being pumped from the high pressure pump 11a to the common rail 12, the pressure detected by the fuel pressure sensor 20a includes a pressure increase due to the fuel pumping of the high pressure pump 11a. However, in the series of processes shown in FIG. 4, the result of the process is not affected by this fuel pumping. Therefore, in the following description, fuel pumping is not considered.

  In step S22 following step S21 described above, fuel is injected by the plurality of injectors 20 based on the waveform of the detected pressure acquired in step S21 in a state where no abnormal fuel leakage has occurred in the fuel injection system 50 in advance. In a non-period, it is determined whether or not the deviations of the plurality of detected pressures respectively corresponding to the plurality of injectors 20 are smaller than a predetermined value. Specifically, based on the detected pressure acquired in a state where no abnormal fuel leakage has occurred in the fuel injection system 50 in advance, the deviation of the detected pressure from each other at a predetermined time when no fuel is injected in all the injectors 20. It is determined whether (the absolute value of the difference) is smaller than a predetermined value. Various known methods can be used to determine whether or not the fuel injection system 50 is in an abnormal fuel leak state. When it is determined in step S22 that the deviations of the plurality of detected pressures are not smaller than the predetermined value (S22: NO), the process proceeds to step S23.

  In step S23, among the detected pressures that have been taken in this time in step S21, during a period in which fuel is not injected by the plurality of injectors 20, the decreasing speeds of the plurality of detected pressures respectively corresponding to the plurality of injectors 20 are higher than a predetermined speed. Judge whether it is large or not. For example, the amount of change in the detected pressure during this period, and the slope obtained by dividing this amount of change by this period are used as the change speed of the detected pressure. The predetermined speed is set to a value that can detect that an abnormal fuel leak has occurred in the fuel injection system 50. In this determination, when it is determined that the decreasing speeds of the plurality of detected pressures respectively corresponding to the plurality of injectors 20 are not greater than the predetermined speed (S23: NO), this series of processes is temporarily ended (END). . On the other hand, in this determination, if it is determined that the decrease speeds of the plurality of detected pressures respectively corresponding to the plurality of injectors 20 are greater than the predetermined speed (S23: YES), the process proceeds to step S24.

  In step S24, it is detected that an abnormal fuel leak has occurred in the fuel injection system 50. In this case, since the type of abnormal fuel leakage is unknown, it is detected that some abnormal fuel leakage has occurred.

  In a succeeding step S25, a process for warning the driver is executed. Specifically, a warning lamp (not shown) is turned on. Then, this series of processing is temporarily ended (END).

  On the other hand, in the determination of step S22, if the deviation of the plurality of detected pressures respectively corresponding to the plurality of injectors 20 is smaller than a predetermined value in a state where no abnormal fuel leakage has occurred in the fuel injection system 50 in advance. If it is determined (S22: YES), the process proceeds to step 26.

  Here, FIG. 6 shows the relationship between the waveform of the detected pressure and the waveform of the injection rate when the multistage injection is executed. In the example shown in FIG. 6, pilot injection, pre-injection, main injection, and after-injection are sequentially performed during one combustion cycle, and symbols P11, P21, P31, and P41 in FIG. The reference points P13, P23, P33, and P43 indicate the change points that appear in the waveform as the injection ends in each injection stage. In FIG. 6 (c), the solid line is the detected pressure in the normal state, the alternate long and short dash line L1 is the detected pressure corresponding to the specific injector 20 (injector 20 of the injection cylinder) in which the fuel is blown out, and the alternate long and two short dashes line L2 The detected pressure corresponding to another injector 20 (cylinder that performs injection next to the injection cylinder) when fuel is blown out by a specific injector 20 is shown. Note that areas S1, S2, S3, and S4 indicated by hatching in FIG. 6B correspond to the injection amounts Q1, Q2, Q3, and Q4 of the respective injection stages.

  As shown in the figure, when fuel is blown out in a specific injector 20, as shown by a one-dot chain line L1, in the fuel inlet 22 (in the fuel passage) corresponding to the specific injector 20 The fuel pressure decreases. Along with this, the fuel pressure in the common rail 12 decreases, and as indicated by the two-dot chain line L2, the fuel pressure in the fuel inlet 22 corresponding to the other injectors 20 also decreases. At this time, the fuel pressure in the fuel inlet 22 corresponding to the other injectors 20 decreases later than the fuel pressure in the fuel inlet 22 corresponding to the specific injector 20. When fuel leaks from the common rail 12 or the fuel pipe from the pump 11 to the common rail 12, the fuel pressure at each fuel inlet 22 corresponding to the plurality of injectors 20 decreases substantially simultaneously.

  Returning to FIG. 4, in step S <b> 26, the rate of decrease in the detected pressure by the fuel pressure sensor 20 a corresponding to the injection cylinder and the cylinder to be injected next is calculated. Specifically, the waveform of the detected pressure in the period of 180 ° CA shown in FIG. 6 is approximated to a straight line of a linear function by the least square method or the like, and the inclination of the straight line is defined as a decrease rate of the detected pressure. For example, in a normal state, the waveform of the detected pressure indicated by the solid line is approximated to a straight line indicated by the broken line L3, and the slope of this straight line is defined as the decrease rate of the detected pressure. Even in the state where fuel is blown off in a specific injector 20, the waveform of the detected pressure is similarly approximated to a straight line, and the slope of this straight line is used as the decrease rate of the detected pressure. In the example shown in FIG. 6, as indicated by the alternate long and short dash line L <b> 1, a straight line approximating the waveform of the detected pressure substantially coincides with the alternate long and short dash line L <b> 1 in a state where fuel is blown out in the specific injector 20. For this reason, in the following description, a one-dot chain line L1 is used as a straight line approximating the waveform of the detected pressure for convenience. Similarly, for the detected pressure corresponding to the cylinder that performs injection next to the injection cylinder, a two-dot chain line L2 is used as a straight line that approximates the waveform of the detected pressure for convenience.

  In the subsequent step S27, the fuel pressure Pt (predetermined pressure) corresponding to the injection cylinder at the intermediate point of 180 ° CA is calculated based on the approximate straight line calculated in step S26. For example, as shown in FIG. 6, on the basis of the approximate straight line indicated by the alternate long and short dash line L1, in the period of 180 ° CA from 90 ° CA before compression top dead center (TDC) to after 90 ° CA, injection at TDC A fuel pressure Pt corresponding to the cylinder is calculated.

  In the subsequent step S28, based on the approximate straight line calculated in step S26, a delay period Tr until the fuel pressure corresponding to the cylinder that performs the injection after the injection cylinder becomes the fuel pressure Pt is calculated. For example, as shown in FIG. 6, the time point at which the fuel pressure becomes equal to the fuel pressure Pt is calculated based on the approximate straight line indicated by the two-dot chain line L2. Then, a delay period Tr is calculated from the time when the fuel pressure corresponding to the injection cylinder becomes the fuel pressure Pt to the time when the fuel pressure corresponding to the cylinder that performs the injection next to the injection cylinder becomes equal to the fuel pressure Pt. In contrast to the example shown in FIG. 6, when the fuel injection is occurring in the injector 20 of the cylinder that performs the next injection, the delay period Tr becomes a negative value. In addition, when no fuel is blown out in the injection cylinder and the cylinder that performs the next injection, the absolute value of the delay period Tr becomes small.

  In the subsequent step S29, it is determined whether or not the detected pressure decreasing speeds corresponding to the injection cylinder calculated in step S26 and the cylinder that performs the next injection are respectively greater than a predetermined speed. The predetermined speed is set to a value that can detect that an abnormal fuel leak has occurred in the fuel injection system 50. In this determination, if it is determined that at least one of the detected pressure decreasing speeds is not greater than the predetermined speed (S29: NO), the process proceeds to step S41, and the first counter and the second counter are reset to A series of processing is once ended (END). That is, since it is considered that no abnormal fuel leakage has occurred in the fuel injection system 50 or that the abnormal fuel leakage has been restored to the normal state, the detection of the abnormal fuel leakage is reset. On the other hand, in this determination, when it is determined that both of the detected pressure decreasing speeds are larger than the predetermined speed (S29: YES), the process proceeds to step S30.

  In step S30, it is determined whether or not the absolute value of the delay period Tr calculated in step S28 is longer than a predetermined period. This predetermined period is set to a value capable of detecting that fuel is blown out in the specific injector 20. In this determination, if it is determined that the absolute value of the delay period Tr is longer than the predetermined period (S30: YES), the process proceeds to step 31.

  In step S31, it is detected that any of the injectors 20 is spraying fuel. In particular, when the delay period Tr is a positive value, that is, when the fuel pressure corresponding to the injection cylinder has dropped before the fuel pressure corresponding to the cylinder that performs the next injection, the injector corresponding to the injection cylinder At 20, it is detected that fuel has been blown out.

  In the subsequent step S32, a first counter that counts the number of times of detection of fuel ejection is incremented. In a succeeding step S33, it is determined whether or not the value of the first counter is larger than a predetermined count. This predetermined count is set to a value, for example, “4”, for which it can be determined that the state where it is detected that the fuel has been blown out has continued longer than the determination period. In this determination, when it is determined that the value of the first counter is greater than the predetermined count (S33: YES), the process proceeds to step S34. In step S34, the first fail-safe process corresponding to the fuel injection is executed. On the other hand, in this determination, when it is determined that the value of the first counter is not greater than the predetermined count (S33: NO), the process proceeds to step S35.

  In the subsequent step S35, the second counter that counts the number of times of detecting abnormal fuel leakage other than the fuel injection is reset. That is, when it is detected that an abnormal fuel leak has occurred in the fuel injection system 50 (S29: YES), it is detected that the fuel has been blown out (S30: YES). It is determined that no abnormal fuel leakage other than release has occurred. Thereafter, this series of processing is temporarily terminated (END).

  On the other hand, if it is determined in step S30 that the absolute value of the delay period Tr is not longer than the predetermined period (S30: NO), the process proceeds to step 36. In step S36, it is detected in the fuel injection system 50 that an abnormal fuel leakage other than the fuel injection is occurring.

  In a succeeding step S37, a second counter that counts the number of times of detecting abnormal fuel leakage other than fuel injection is incremented. In a succeeding step S38, it is determined whether or not the value of the second counter is larger than a predetermined count. This predetermined count is a value that can be used to determine that the state in which an abnormal fuel leak other than the fuel spraying has occurred is longer than the determination period, and the value of the first counter. It is set to a value larger than a predetermined count for determining, for example, “8”. In this determination, when it is determined that the value of the second counter is greater than the predetermined count (S38: YES), the process proceeds to step S39. In step S39, a second fail-safe process corresponding to an abnormal fuel leak other than fuel injection is executed. On the other hand, in this determination, if it is determined that the value of the second counter is not greater than the predetermined count (S38: NO), the process proceeds to step S40.

  In the subsequent step S40, the first counter that counts the number of times the fuel is blown off is reset. That is, when it is detected that an abnormal fuel leak has occurred in the fuel injection system 50 (S29: YES), it has been detected that an abnormal fuel leak other than the fuel spraying has occurred (S30: NO), it is determined that no fuel spraying has occurred. Thereafter, this series of processing is temporarily terminated (END).

  The fuel pressure sensor 20a and the ECU 30 constitute a fuel spray detection device, the ECU 30 constitutes a detection means, the process of S34 corresponds to the process as the first failsafe means, and the process of S39 is the second failsafe means. It corresponds to the processing as.

  The embodiment described in detail above has the following advantages.

  The fuel pressure sensor 20a sequentially detects the fuel pressure in the fuel passage from the common rail 12 to the injection hole 20f of the injector 20, specifically, the fuel inflow port 22. For this reason, the fluctuation of the fuel pressure in the injection hole 20f can be accurately detected before the fluctuation of the fuel pressure in the common rail 12 is attenuated.

  The fuel pressure is reduced in the plurality of fuel passages (fuel inlets 22), and the fuel pressure in a specific fuel passage among the plurality of fuel passages is lowered before the fuel pressure in the other fuel passages. , It is detected that any one of the injectors 20 is spraying fuel. Therefore, it is possible to distinguish and detect the fuel injection in the injector 20 among the abnormal fuel leaks in the fuel injection system 50.

  -When the fuel pressure in a specific fuel passage among a plurality of fuel passages is lowered before the fuel pressure in other fuel passages, fuel injection occurs in the injector 20 corresponding to the specific fuel passage. Is detected. Therefore, when it is detected that any of the injectors 20 is sprayed with fuel, it is possible to identify the injector 20 with which fuel is further sprayed.

  The fuel pressure in the other fuel passages after the speed at which the fuel pressure decreases in each of the plurality of fuel passages is faster than a predetermined speed, and the fuel pressure in the specific fuel passage among the plurality of fuel passages becomes the fuel pressure Pt. When the absolute value of the delay period Tr until the fuel pressure Pt reaches the fuel pressure Pt is longer than the predetermined period, it is detected that the fuel is blown out. According to such a configuration, it can be detected by a simple configuration that the fuel pressure in a specific fuel passage among the plurality of fuel passages is lowered before the fuel pressure in the other fuel passages.

  -In the state in which no abnormal fuel leakage has occurred in the fuel injection system 50 in advance and the fuel is not injected by the plurality of injectors 20, the deviation of the fuel pressure in the plurality of fuel passages is smaller than a predetermined value On the condition that the determination is made, detection of the occurrence of fuel spray is permitted. That is, in the state where no abnormal fuel leakage has occurred in the fuel injection system 50 in advance, if there is a deviation of a predetermined value or more between the fuel pressures in the plurality of fuel passages, fuel injection has occurred. Detection is prohibited. For this reason, it is possible to suppress erroneous detection of fuel spraying, and it is possible to improve the accuracy of detecting fuel spraying.

  The first fail-safe process is executed when the state where it is detected that fuel has been blown out continues for longer than the determination period. On the other hand, the first fail-safe process is not executed when the state where it is detected that the fuel is blown out does not continue longer than the determination period. Therefore, even if the fuel is temporarily ejected in the injector 20, the first fail-safe process can be prevented from being executed when the normal state is restored within the determination period. As a result, excessive execution of the first failsafe process can be suppressed.

  When the speed at which the fuel pressure decreases in each of the plurality of fuel passages is faster than a predetermined speed, it is considered that abnormal fuel leakage has occurred in the fuel injection system 50. Here, the absolute value of the delay period Tr from when the fuel pressure in the specific fuel passage among the plurality of fuel passages becomes the fuel pressure Pt to when the fuel pressure in the other fuel passage becomes the fuel pressure Pt is greater than the predetermined period. If it is too long, it is presumed that the fuel is blown out as described above. On the other hand, the absolute value of the delay period Tr from when the fuel pressure in the specific fuel passage among the plurality of fuel passages becomes the fuel pressure Pt to when the fuel pressure in the other fuel passage becomes the fuel pressure Pt is larger than the predetermined period. If it is short, it is presumed that an abnormal fuel leakage other than the spraying of fuel has occurred. Therefore, according to the abnormal fuel leakage detection of the present embodiment, it is detected that the abnormal fuel leakage other than the fuel injection is generated in the fuel injection system 50 in distinction from the fuel injection in the injector 20. Can do.

  The second fail-safe process is executed when the state where it is detected that an abnormal fuel leak other than the spraying of fuel has continued for longer than the determination period. On the other hand, the second fail-safe process is not executed when the state in which it is detected that an abnormal fuel leakage other than the fuel injection is not continued for longer than the determination period. Therefore, it is possible to prevent the second fail-safe process from being executed until it is determined that an abnormal fuel leak other than the spraying of fuel has occurred. As a result, it is possible to suppress the second failsafe process from being performed excessively.

  The first fail-safe process is executed when the fuel is blown off, and the second fail-safe process is executed when an abnormal fuel leak other than the fuel is blown off. Therefore, an appropriate fail-safe process can be executed according to the type of abnormal fuel leakage.

  Since the fuel pressure sensor 20a is attached to the injector 20, the attachment position of the fuel pressure sensor 20a is closer to the injection hole 20f than the case where the fuel pressure sensor 20a is attached to the high-pressure pipe 14 connecting the common rail 12 and the injector 20. Become. Therefore, the pressure fluctuation at the injection hole 20f can be detected more accurately as compared with the case where the pressure fluctuation after the pressure fluctuation at the injection hole 20f is attenuated by the high-pressure pipe 14 is detected.

(Other embodiments)
The embodiment described above can be implemented with the following modifications.

  -The process of step S32 of FIG. 4, S33 can also be abbreviate | omitted. Even in this case, among the abnormal fuel leaks in the fuel injection system 50, it is possible to distinguish and detect the fuel spray in the injector 20. An appropriate fail-safe process can be executed according to the type of abnormal fuel leakage.

  -The process of step S37 of FIG. 4, S38 can also be abbreviate | omitted. Even in this case, among the abnormal fuel leaks in the fuel injection system 50, it is possible to distinguish and detect an abnormal fuel leak other than the fuel spraying in the injector 20. An appropriate fail-safe process can be executed according to the type of abnormal fuel leakage.

  -The process of step S22-S25 of FIG. 4 can also be abbreviate | omitted.

  In the above embodiment, as shown in FIG. 6, the fact that the fuel pressure in a specific fuel passage among the plurality of fuel passages has decreased before the fuel pressure in the other fuel passages, Among them, the absolute value of the delay period Tr from when the fuel pressure in the specific fuel passage becomes the fuel pressure Pt until the fuel pressure in the other fuel passage becomes the fuel pressure Pt is detected by being longer than the predetermined period. However, as shown in the figure, the compression top dead center (TDC) indicates that the fuel pressure in the specific fuel passage among the plurality of fuel passages is lowered before the fuel pressure in the other fuel passages. It is also possible to detect based on the pressure deviation Pr between the fuel pressure in a specific fuel passage and the fuel pressure in another fuel passage.

  In the above embodiment, when it is determined in step S29 in FIG. 4 that both of the detected pressure reduction speeds corresponding to the injection cylinder and the cylinder to be injected next are larger than the predetermined speed, the fuel injection system 50 It was determined that abnormal fuel leakage occurred. However, it may be determined whether or not an abnormal fuel leak has occurred in the fuel injection system 50 by other known methods.

  In attaching the fuel pressure sensor 20 a to the injector 20, the fuel pressure sensor 20 a is attached to the fuel inlet 22 of the injector 20 in the above embodiment. However, as shown by the one-dot chain line in FIG. 2, a fuel pressure sensor 200a is assembled inside the housing 20e to detect the fuel pressure in the internal fuel passage 25 from the fuel inlet 22 to the injection hole 20f. May be.

  When the fuel pressure sensor 20a is attached to the fuel inlet 22 as described above, the structure of the attachment portion of the fuel pressure sensor 20a can be simplified compared to the case where the fuel pressure sensor 20a is attached to the inside of the housing 20e. On the other hand, in the case of mounting inside the housing 20e, the mounting position of the fuel pressure sensor 20a is closer to the injection hole 20f than in the case of mounting to the fuel inlet 22, so the pressure fluctuation at the injection hole 20f is more accurately detected. Can be detected.

  The fuel pressure sensor 20a may be attached to the high pressure pipe 14. In this case, it is desirable to attach the fuel pressure sensor 20a at a position separated from the common rail 12 by a certain distance.

  The number of fuel pressure sensors 20a is arbitrary, and for example, two or more sensors may be provided for the fuel flow path of one cylinder. In addition to the fuel pressure sensor 20a described in the above embodiment, a rail pressure sensor for measuring the pressure in the common rail 12 may be provided.

  A piezo drive injector may be used instead of the electromagnetic drive injector 20 illustrated in FIG. Further, a fuel injection valve that does not cause pressure leakage from the leak hole 24 or the like, for example, a direct acting injector (for example, a direct acting piezo injector) that does not involve the hydraulic chamber Cd for transmission of driving power can be used.

  -The type and system configuration of the engine to be controlled can be changed as appropriate according to the application. For example, although the case where it applied to the diesel engine was mentioned in the said embodiment, it can apply fundamentally similarly, for example also to a spark ignition type gasoline engine (especially direct injection engine) etc., for example. The fuel injection system of a direct injection type gasoline engine is equipped with a delivery pipe that stores fuel (gasoline) in a high-pressure state. The fuel is pumped from the fuel pump to the delivery pipe, and the high-pressure fuel in the delivery pipe is The fuel is distributed to a plurality of injectors 20 and injected into the engine combustion chamber. In such a system, the delivery pipe corresponds to a pressure accumulating vessel.

  DESCRIPTION OF SYMBOLS 12 ... Common rail, 14 ... High pressure piping, 20 ... Injector, 20a ... Fuel pressure sensor, 20f ... Injection hole, 30 ... ECU, 50 ... Fuel injection system, 200a ... Fuel pressure sensor.

Claims (7)

Applied to a fuel injection system (50) for sequentially injecting fuel supplied from a pressure accumulating vessel (12) by means of a plurality of fuel injection valves (20), and detecting the fuel injection in the fuel injection valve. A device,
A plurality of fuel pressure sensors (20a, 200a) for sequentially detecting the fuel pressure in each fuel passage (14, 22, 25) from the pressure accumulating container to the injection holes (20f) of the plurality of fuel injection valves;
Based on the fuel pressures sequentially detected by the plurality of fuel pressure sensors, the speed at which the fuel pressure decreases in the plurality of fuel passages is higher than a predetermined speed in a period in which injection is performed by one fuel injection valve. The fuel pressure in the specific fuel passage corresponding to the fuel injection valve in which the injection is performed quickly among the plurality of fuel passages becomes a predetermined pressure, and then the fuel pressure in the other fuel passages becomes the predetermined pressure. Detecting means (30) for detecting that the fuel is blown out when a period until the time is longer than a predetermined period ;
A fuel spray detection device comprising: It said detecting means, in a period in which the injection by one of said fuel injection valve is carried out faster than each of the rate at which the fuel pressure decreases in a plurality of said fuel passage predetermined speed, and the particular one of the plurality of said fuel passage When the period from when the fuel pressure in the fuel passage reaches a predetermined pressure until the fuel pressure in the other fuel passage reaches the predetermined pressure is longer than a predetermined period, the fuel pressure corresponding to the specific fuel passage The fuel spray detection device according to claim 1, wherein the fuel injection valve detects that the fuel spray has occurred. In the period when injection is performed by one fuel injection valve , the detection means detects that an abnormal fuel leak in each of the plurality of fuel passages has a speed at which the fuel pressure decreases is faster than a predetermined speed in the fuel injection system. Based on the fuel pressure sequentially detected by the plurality of fuel pressure sensors in a state where no fuel has occurred, the fuel pressure in the plurality of fuel passages in a period during which the fuel is not injected by the plurality of fuel injection valves. 3. The fuel spray detection device according to claim 1, wherein detection of occurrence of the fuel spray is permitted on condition that the mutual deviation is determined to be smaller than a predetermined value. 4. The first fail-safe process corresponding to the fuel spraying is executed on condition that the state in which the fuel spraying has been detected by the detecting means has continued for a longer period than the determination period. The fuel spray detection device according to any one of claims 1 to 3 , comprising one fail-safe means. It said detecting means, in a period in which the injection by one of said fuel injection valve is carried out faster than each of the rate at which the fuel pressure decreases in a plurality of said fuel passage predetermined speed, and the particular one of the plurality of said fuel passage When the fuel pressure in the other fuel passage becomes a predetermined pressure and the fuel pressure in the other fuel passages becomes shorter than the predetermined pressure, the fuel injection system The fuel according to any one of claims 1 to 4 , wherein an abnormal fuel leak is detected in which a speed at which the fuel pressure decreases in each of the plurality of fuel passages other than release is faster than a predetermined speed. Spray detection device. The state in which the abnormal fuel leakage outside release Spray has been detected to have occurred in the fuel by the detection means, on condition that continued longer than determination period, a said abnormal non release spouting of the fuel The fuel spray detection device according to claim 5 , further comprising second fail-safe means for executing a second fail-safe process corresponding to fuel leakage . The fuel pressure sensor is a fuel jetted release detector according to any one of claims 1 to 6 is attached to the fuel injection valve.

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