JP4375432B2 - Fuel injection characteristic detection device and engine control system - Google Patents

Description

  The present invention relates to a fuel injection characteristic detection device that detects a fuel injection characteristic when fuel is injected and supplied to a target engine, and an engine control system in which the fuel injection characteristic detection device is mounted.

  As is well known, for example, in an engine (particularly an internal combustion engine) used as a power source of an automobile or the like, fuel injected and supplied by an appropriate fuel injection valve (for example, an injector) is ignited and burned in a combustion chamber in a predetermined cylinder. Thus, torque is generated on a predetermined output shaft (crank shaft). In recent years, in diesel engines for automobiles, etc., sub-injection with a smaller injection amount (usually minute amount) than the main injection before or after performing main injection for generating output torque in one combustion cycle The so-called multi-stage injection method has been adopted. For example, today, noise during fuel combustion and an increase in NOx emission amount are regarded as problems, and for the improvement, pilot injection and pre-injection may be performed with a small injection amount before main injection. In addition, after the main injection, after-injection (injection timing is during fuel combustion close to the main injection) or activation of the exhaust temperature is performed for the purpose of activating diffusion combustion and thus reducing PM emission. In some cases, post-injection (the injection timing is after the end of combustion, which is greatly retarded with respect to the main injection), for the purpose of activating the catalyst by supplying a reducing component, or the like. In recent engine control, the fuel is supplied to the engine in one or any combination of these various injections in an injection mode (injection pattern) more suitable for various situations.

Conventionally, when the above-described multistage injection is performed by controlling the injection operation of the fuel injection valve, the injection is performed according to the engine operating state according to the engine operating state according to the map or formula in which the injection pattern (adapted value) for each engine operating state is written. Control devices for setting patterns are widely used. This device refers to the maps, formulas, etc. by holding the optimum patterns (adapted values) obtained by experiments for each engine operating state assumed in advance as a map, formulas, etc. (for example, stored in ROM). Meanwhile, an injection pattern corresponding to the engine operating state is set. In addition, for example, a device such as the device described in Patent Document 1 that switches the injection pattern while observing the engine operating conditions has been proposed.
JP 2005-264810 A

  In this way, by using a map or a mathematical formula in which an appropriate value is written, an injection mode (injection pattern) suitable for each engine operating state is applied in the case of multistage injection as well as in the case of single stage injection (main injection only). ), It becomes possible to supply fuel to the engine. However, when multi-stage injection is performed using such a device, the control over the target engine operating state is compared to the case of single-stage injection due to the effect of continuous injection at short intervals. It has been confirmed by the inventor that the error becomes larger. For example, each of the continuously injected (particularly a small amount of sub-injection other than the main injection) is affected in various ways by the injection before and after the injection. One of them relates to the injection characteristics of fuel injection valves (for example, injectors), and particularly to individual differences.

  That is, for example, when mass-producing and selling each element of the engine control system, the fuel injection valve is usually included, for example, between engines or between cylinders in the case of a multi-cylinder engine. There will be some individual differences in the characteristics of the various control components. However, for mass production (for example, all cylinders mass-produced and mounted on a vehicle), it was considered in the current production system to obtain a suitable value (optimum injection pattern) that also considered individual differences. In some cases, it takes too much time and is not in line with the situation. Therefore, it is difficult to perform control in which all the influences due to individual differences are taken into account even when a map or mathematical expression in which an adaptive value is written is used.

  Moreover, when performing the above-described multi-stage injection, unlike the case of single-stage injection, in addition to the normal injection characteristics, the injection characteristics related to multi-stage injection (multiple continuous injections) (effects between injections, etc.) The inventors have confirmed that it is affected by individual differences. Therefore, in order to obtain the target engine operating state with high accuracy through the multistage injection, it is necessary to consider the injection characteristics of the multistage injection in addition to the injection characteristics of the single stage injection. For this reason, in the conventional apparatus including the apparatus described in Patent Document 1 described above, it is difficult to control the engine operating state with high accuracy, particularly when applied to multistage injection control.

  In addition, when the injection control is performed with high accuracy, the characteristic change caused by the secular change of the control component cannot be ignored. In this regard, in the conventional apparatus including the apparatus described in Patent Document 1 described above, even if the optimum value is obtained with high accuracy in the initial stage, the influence of the subsequent characteristic change cannot be known. For this reason, the deviation from the optimum value is concerned over time. In this case, a configuration is also conceivable in which an appropriate value of a deterioration coefficient (a coefficient related to the degree of deterioration over time) is obtained in advance by an experimental value or the like, and this is stored as a map or a mathematical expression. However, since there is the above-mentioned individual difference for each part with respect to the change in characteristics over time, it is still difficult to completely eliminate the influence.

  The present invention has been made in view of such circumstances, and has as its main object to provide a fuel injection characteristic detection device and an engine control system capable of acquiring an injection characteristic from time to time, including characteristic changes over time. To do.

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

According to the first aspect of the present invention, as a fuel injection characteristic detecting device for detecting the fuel injection characteristic when fuel is injected and supplied to the target engine, the fuel combustion of the target engine is performed by a predetermined fuel injection valve. This is applied to a fuel supply system that injects and supplies fuel into a cylinder or to its intake passage or exhaust passage. By sequentially detecting the pressure of fuel supplied to the fuel injection valve, the fuel pressure associated with the injection operation of the fuel injection valve is detected. A pulsation pattern detection means for detecting a pulsation pattern, and an undetected pattern derivation means for deriving an undetected portion of the pattern based on the pulsation pattern detected by the pulsation pattern detection means and its regularity , The undetected pattern deriving means is a multistage fuel injection performed during one combustion cycle in a predetermined cylinder of the engine. Based on the pulsation pattern by only the specific injection detected by the pulsation pattern detection means and the regularity thereof, the pulsation by the specific injection that follows and the pulsation by the subsequent injection Among the pulsation patterns of the part that interferes with each other, the pulsation pattern only by the specific injection is derived as the undetected part, and based on the undetected part of the pulsation pattern derived by the undetected pattern deriving means, From the pulsation pattern related to the multistage fuel injection performed in one combustion cycle in the predetermined cylinder of the engine, the pulsation pattern related only to the fuel injection after the nth stage corresponding to the predetermined stage after the second stage of the multistage fuel injection. comprising a pulsation pattern extraction means for extracting, characterized in Rukoto.

  When detecting the pulsation pattern of fuel pressure (transition of fuel pressure) accompanying the injection operation of the fuel injection valve, it is not always possible to detect with high accuracy in all of the portions. In this regard, with the apparatus according to claim 1, it is possible to derive other undetected parts from the detected part (detected part) with high accuracy by providing the undetected pattern deriving means. . As a result, it is possible to grasp the injection characteristics from time to time, including changes in characteristics over time.

In the experiments of the inventors, when a pulsation pattern (waveform of fuel pressure) related to multistage fuel injection is detected, the pulsation pattern related to the front injection and the pulsation pattern related to the rear injection interfere with each other in the detection result. There were many cases. However, in the apparatus according to the first aspect , by providing the undetected pattern deriving unit, it is possible to derive a pulsation pattern based on only the pre-stage injection for the interference portion even in such a case. And it becomes possible to perform various signal processing with the pulsation pattern, and to acquire a more detailed injection characteristic.

In this case, the pattern start point (base point) of the pulsation pattern (detection pattern) used by the undetected pattern deriving means is important. Therefore, in the apparatus according to claim 1 , it is effective that the pulsation pattern (detection pattern) used by the undetected pattern deriving means has a predetermined timing as a pattern start point (base point). . More specifically, an injection start timing of the specific injection, an injection end timing of the specific injection, a timing when a predetermined condition is satisfied after the completion of the injection of the specific injection, and the like are set as a pattern start point (base point) of the detection pattern. ) Is effective.
In the experiments of the inventors, when a pulsation pattern (waveform of fuel pressure) related to multistage fuel injection is detected, the pulsation pattern related to the front injection and the pulsation pattern related to the rear injection interfere with each other in the detection result. There were many cases. Due to this interference, it becomes difficult to identify a steep pressure fluctuation (fuel pressure drop accompanying the start of fuel injection) at the injection start timing of the subsequent injection, and it is difficult to know the injection start timing from the pulsation pattern. In this regard, in the apparatus according to the first aspect, by providing the pulsation pattern extraction means, it is possible to obtain a pulsation pattern from which the influence of the interference from the preceding injection is removed. Specifically, for example, the undetected pattern deriving means derives the interference portion as an undetected portion of the pulsation pattern and uses it for comparison with the pulsation pattern related to the multistage fuel injection, appropriate calculation, etc. From the pulsation pattern related to the multistage fuel injection, it is possible to extract the pulsation pattern related only to the fuel injection after the nth stage. As a result, the pulsation pattern relating only to the fuel injection after the nth stage is obtained with high accuracy, and as a result, the injection timing and the like relating to the nth stage injection can be detected with high accuracy.

In the invention described in claim 2, in the apparatus according to the claim 1, wherein the regularity of the pulsation pattern used by undetected pattern deriving means, at least one of the amplitude and period of the pattern, over time It is characterized by the accompanying rate of change or rate of change accompanying propagation.

  Generally, the wave has a smaller amplitude and a longer period as the propagation distance becomes longer and time elapses due to the release of energy. According to the inventors' experiments and the like, the rate of change at that time (amplitude decay rate and period expansion rate) is substantially constant. That is, as in the apparatus according to the third aspect, by utilizing such regularity, the undetected part can be derived more easily and accurately. In addition, it has been confirmed by experiments of the inventors that the expansion rate of the period is substantially “0” in most injection modes. Therefore, in order to simplify the arithmetic processing, it is effective to derive the undetected portion assuming that the cycle is constant (assuming that “cycle = constant”). It is also effective to calculate the amplitude attenuation rate as an amplitude ratio between adjacent local maximum points and local minimum points.

According to a third aspect of the present invention, the undetected pattern deriving means in the apparatus according to the first or second aspect is used, and at least one of a node, a maximum point, and a minimum point for an undetected portion of the pulsation pattern. It is effective to derive an undetected portion of the pulsation pattern by obtaining one as a reference point and performing at least one of interpolation and extrapolation based on the reference point. This makes it possible to derive the undetected part with high accuracy and efficiency. The nodes, maximum points, and minimum points of the pulsation pattern (pressure waveform) are detected based on the time differential value of the fuel pressure (maximum point, minimum point = differential value “0”, node = maximum differential value). It is also effective.

  In order to derive (estimate) an undetected portion with high accuracy, it is desirable to obtain more accurate pulsation pattern regularity. In general, a wave like the pulsation pattern includes a local minimum point, a node (first node), a local maximum point, and a node (second node). The inventors' experiments have confirmed that the undetected portion can be derived (estimated) with high accuracy if three or more of these four can be detected. Therefore, it is desirable that the pulsation pattern used by the undetected pattern deriving means is a pattern of “3/4” period or more (more preferably “1” period or more).

According to a fourth aspect of the present invention, in the apparatus according to any one of the first to third aspects, the pulsation pattern comprises a pressure waveform that alternately vibrates from the reference level to the large side and the small side. The standard level tendency is included in the regularity of the pulsation pattern used by the undetected pattern deriving means.

The reference level corresponds to the pressure value of the node portion. Therefore, in deriving an undetected portion, it is important to know the tendency of the reference level. In this regard, with the apparatus according to the fourth aspect, the tendency of the reference level in the undetected portion can be estimated from the tendency of the reference level in the detected portion. This makes it possible to derive the undetected part more easily and accurately.

According to the inventors' experiment and the like, the tendency of the reference level changes depending on the amount of fuel leakage of the fuel supply system and the pumping amount (fuel discharge amount) of the fuel pump that supplies fuel to the fuel injection valve. To do. For example, it was confirmed that the reference level tends to decrease as the amount of fuel leak increases (the slope of pressure decrease (the amount of decrease in fuel pressure per unit time) increases). For example, when the pumping timing of the fuel pump and the injection timing overlap, the pumping amount of the fuel pump increases. It was confirmed that the reference level tends to increase as the pumping amount of the fuel pump at the time of injection increases (the slope of pressure increase (the amount of increase in fuel pressure per unit time) increases). Therefore, in the apparatus according to claim 5 , as in the invention according to claim 5 , the undetected pattern deriving unit is configured to provide fuel leakage with respect to the fuel supply system and fuel with respect to the fuel injection valve. It is effective to detect the tendency of the reference level based on at least one of the pumping amount of the fuel pump that supplies the fuel. In this way, the undetected part can be derived more easily and accurately.

According to a sixth aspect of the present invention, in the apparatus according to any one of the first to fifth aspects, the fuel supply system accumulates and holds the fuel to be supplied to the fuel injection valve, and the common rail. One or more fuels for detecting the pressure of the fuel flowing in the fuel passage at a predetermined location located downstream of the fuel discharge port of the common rail in the fuel passage to the fuel injection port of the fuel injection valve A common rail fuel injection system including a pressure sensor, wherein the pulsation pattern detection means sequentially detects the pressure of the fuel supplied to the fuel injection valve based on at least one output of the fuel pressure sensor. It is characterized by being.

In general, the common rail fuel injection system including the device described in Patent Document 1 controls the injection pressure of the fuel injection valve only by a rail pressure sensor that measures the pressure in the common rail (rail pressure). Therefore, in such a device, the pressure fluctuation (pulsation pattern) accompanying the injection operation attenuates before reaching the common rail from the fuel injection port (injection hole) of the fuel injection valve, and does not appear as the fluctuation of the rail pressure. On the other hand, the apparatus according to claim 6 includes a fuel pressure sensor that measures the injection pressure at a position closer to the fuel injection port than the rail pressure sensor (the sensor provided in the vicinity of the common rail). Therefore, this pressure sensor can accurately capture the pressure fluctuation (pulsation pattern) before it attenuates. Therefore, according to such an apparatus, it becomes possible to detect with high accuracy a pulsation pattern (swelling characteristic) indicating an injection characteristic at a time including a characteristic change with time.

Incidentally, although the pressure fluctuation (pulsation pattern) is considerably attenuated, it is possible to detect a certain pressure fluctuation mode (pulsation characteristic) even by the pressure in the common rail (rail pressure). Specifically, for example, by calculating the slope of pressure transition (time differential value of pressure), it is possible to estimate the injection rate related to the predetermined injection based on the differential value. However, in this configuration, the pressure value before attenuation is estimated as a differential value, and it is difficult to detect the transition of the injection rate, and thus the injection amount corresponding to the integral value of the injection rate, with high accuracy. On the other hand, in the apparatus according to the sixth aspect , the pressure value before attenuation can be directly measured by the fuel pressure sensor. For this reason, for example, when determining the transition of the injection rate and the injection amount relating to the predetermined injection, the configuration via the differential value is obtained by directly determining the transition of the injection rate, and hence the injection amount, from the pressure measurement value. These injection characteristics can be detected with higher accuracy.

  When the pressure of the fuel supplied to the fuel injection valve is sequentially detected, the sensor output of the fuel pressure sensor is sequentially acquired at intervals that are short enough to draw the locus of the pressure transition waveform with the sensor output. It is effective to do. More specifically, it is effective to sequentially acquire the sensor output of the fuel pressure sensor at intervals shorter than “50 μsec”.

  The pulsation pattern can usually be detected as a pressure transition waveform. In order to accurately detect such a pressure transition waveform with high accuracy, as described above, the sensor output of the fuel pressure sensor is sequentially acquired at intervals that are short enough to grasp the pressure transition waveform. Is beneficial. According to the inventors' experiments and the like, the configuration in which the sensor output is sequentially acquired at intervals shorter than “50 μsec” is particularly effective in accurately grasping the above-described pulsation pattern and thus the tendency of pressure fluctuation. However, in order to obtain the pulsation pattern with high accuracy, a configuration in which sensor outputs are sequentially acquired at shorter intervals is more preferable. Therefore, it is usually desirable to set the acquisition interval of the sensor output (fuel pressure signal) to a shorter interval while taking into account inconveniences due to an increase in the number of acquisitions of sensor outputs, for example, inconveniences such as an increase in calculation load.

In view of the position of the fuel pressure sensor, for example, the following configuration is effective.
A configuration in which at least one of the fuel pressure sensors (a part or all of the fuel pressure sensors if any) is provided in or near the fuel injection valve.
A configuration in which at least one of the fuel pressure sensors (a part or all of the fuel pressure sensors, if any) is provided at a fuel intake port of the fuel injection valve.
-At least one of the fuel pressure sensors (a part or all of the fuel pressure sensors, if any) is connected to the fuel discharge side of the common rail, the fuel injection port of the fuel injection valve is more than the common rail. The structure provided in the position near.
It is effective to adopt a structure such as.

  In addition to the fuel pressure sensor, it is also effective to further include a rail pressure sensor that measures the pressure in the common rail. With such a configuration, in addition to the pressure measurement value by the fuel pressure sensor, the pressure in the common rail (rail pressure) can be acquired, and the fuel pressure can be detected with higher accuracy. .

More specifically, in the apparatus according to any one of claims 1 to 6 , the pulsation pattern extraction means is replaced with the undetected pattern derivation means as in the invention according to claim 7. The pulsation pattern related to the fuel injection with the number of stages smaller than the n stages is obtained based on the undetected portion of the pulsation pattern derived by the above, and the pulsation pattern related to the fuel injection with the number of stages smaller than the n stages and the multistage fuel By comparing (for example, subtraction or division) with the pulsation pattern related to injection, the pulsation pattern related only to the fuel injection after the nth stage is extracted, so that the extraction process can be performed more easily and accurately. Can be realized.

In the apparatus according to any one of claims 1 to 7, it is effective to use the pulsation pattern extracted by the pulsation pattern extraction means for correcting the fuel injection characteristic.

That is, as in the invention described in claim 8 , based on a pulsation pattern relating to only fuel injection after the nth stage extracted by the pulsation pattern extraction means, a command signal (for example, injection timing and injection) for the fuel injection valve. By adopting a configuration including correction means for correcting the time-related command signal), fuel injection control with higher accuracy becomes possible.

Further, as in the ninth aspect of the invention, when the nth stage injection corresponding to a predetermined stage after the second stage is executed by the fuel injection valve, the pulsation pattern extracting means performs the nth stage injection. It is also effective to include a means for extracting a pulsation pattern related to only the injection of the first and determining the injection end timing of the n-th stage injection based on the extracted pulsation pattern.

  If a direct-acting injector, which is currently in the development stage, will be put into practical use in the future and the calculation speed will increase, it will be possible to simultaneously perform pulsation pattern extraction by the pulsation pattern extraction means while detecting the fuel pressure from time to time. become. Then, the injection end timing is determined on the basis of the pulsation pattern detected with high synchronism (in real time), and the injection is ended at the injection end timing through the high-speed operation of the linear motion injector. Highly accurate fuel injection becomes possible.

By the way, depending on the type of business, application, etc., in the case where this device is used for engine control in a larger unit instead of the unit of the fuel injection property detection device, not only the fuel injection property detection device but also other related devices. There are cases where it is handled as an engine control system constructed to include (for example, various devices related to control of sensors, actuators, etc.). The apparatus according to any one of claims 1 to 9 is also assumed to be used by being incorporated in an engine control system as one of the applications. The invention according to claim 10 corresponds to such an application, that is, as the engine control system, the fuel injection characteristic detection device according to any one of claims 1 to 9 and the fuel injection characteristic detection. The present invention relates to a fuel supply system including a fuel pressure sensor that detects the pressure of fuel supplied to the fuel injection valve and the fuel injection valve, and an engine based on the operation of the fuel supply system. Engine control means for performing predetermined control (for example, torque control or rotation speed control of the engine output shaft). The device according to any one of claims 1 to 9 is particularly useful when incorporated into an engine control system.

  Hereinafter, an embodiment embodying a fuel injection characteristic detection device and an engine control system according to the present invention will be described with reference to the drawings. In addition, the apparatus of this embodiment is mounted in the common rail type fuel injection system (high pressure injection fuel supply system) which targets the engine (internal combustion engine) for 4 wheels, for example. That is, this apparatus also supplies high-pressure fuel (for example, light oil having an injection pressure of “1000 atm” or more) directly to the combustion chamber in the engine cylinder of the diesel engine (direct injection) as in the apparatus described in Patent Document 1 above. Used).

  First, an outline of a common rail fuel injection control system (vehicle engine system) according to the present embodiment will be described with reference to FIG. As an engine of the present embodiment, a multi-cylinder (for example, in-line four-cylinder) engine for a four-wheel automobile is assumed. Specifically, it is a 4-stroke reciprocating diesel engine (internal combustion engine). 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 of the four strokes is executed in the order of cylinders # 1, # 3, # 4, and # 2 with a “720 ° CA” period, specifically, for example, by shifting “180 ° CA” between the cylinders. The injector 20 in the figure is an injector for cylinders # 1, # 2, # 3, and # 4 from the fuel tank 10 side.

  As shown in FIG. 1, in this system, an ECU (electronic control unit) 30 mainly captures sensor outputs (detection results) from various sensors and configures a fuel supply system based on these sensor outputs. It is comprised so that the drive of each apparatus to control may be controlled. The ECU 30 adjusts the amount of current supplied to the intake adjustment valve 11c and controls the fuel discharge amount of the fuel pump 11 to a desired value, so that the fuel pressure in the common rail 12 (the fuel at the time measured by the fuel pressure sensor 20a) The pressure is controlled to a target value (target fuel pressure) by feedback control (for example, PID control). Based on the fuel pressure, the fuel injection amount to the predetermined cylinder of the target engine, and thus 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 the order of the fuel tank 10, the fuel pump 11, the common rail 12, and the injector 20 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.

  Here, the fuel tank 10 is a tank (container) for storing fuel (light oil) of the target engine. The fuel pump 11 includes a high-pressure pump 11a and a low-pressure pump 11b, and is configured so that 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 adjusted by a suction control valve (SCV) 11c provided on the fuel suction side of the fuel pump 11. It has become. 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 can be controlled to a 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 feeds it to the pressurizing chamber by reciprocating predetermined plungers (for example, three plungers) in the axial direction by eccentric cams (eccentric cams) (not shown). The fuel is 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 “½” with respect to one rotation of the crankshaft 41. It has become. 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 by the fuel pump 11 from the fuel tank 10 through the fuel filter 10b 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 and stores the fuel in a high pressure state through the pipe 14 (high pressure fuel passage) provided for each cylinder. To each fuel injection valve). The fuel discharge ports of these injectors 20 (# 1) to (# 4) are connected to a pipe 18 for returning excess fuel to the fuel tank 10, respectively. FIG. 2 shows a detailed structure of the injector 20. The four injectors 20 (# 1) to (# 4) basically 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 engine fuel for combustion (fuel in the fuel tank 10), and transmission of driving power during fuel injection is transmitted through the hydraulic chamber Cd (command chamber). Done.

  As shown in FIG. 2, this injector 20 is an internal valve opening type fuel injection valve, and is configured as a so-called normally closed type fuel injection valve that is closed when not energized. High pressure fuel is sent from the common rail 12 to the injector 20. Further, a fuel pressure sensor 20a (see also FIG. 1) is provided at the fuel intake port of the injector 20, and the fuel pressure (inlet pressure) at the fuel intake port can be detected at any time. Yes. Specifically, the output of the fuel pressure sensor 20a can detect (measure) the pulsation pattern 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. It has become.

  When the fuel is injected from the injector 20, the degree of sealing of the hydraulic chamber Cd and the pressure of the hydraulic chamber Cd (the back of the needle 20c) are determined according to the energized state (energized / non-energized) of the solenoid 20b constituting the two-way solenoid valve. (Corresponding to pressure) is increased or decreased. As the pressure increases or decreases, the needle 20c reciprocates (up and down) in the valve cylinder (inside the housing 20e) in accordance with or against the extension force of the spring 20d (coil spring). The number of the fuel supply passages is opened and closed in the middle (specifically, a tapered seat surface on which the needle 20c is seated or separated based on reciprocation). Here, the drive control of the needle 20c is performed through so-called PWM (Pulse Width Modulation) control. That is, a pulse signal (energization signal) is sent from the ECU 30 to the drive unit (the two-way electromagnetic valve) of the needle 20c. The lift amount (the degree of separation from the seat surface) of the needle 20c is variably controlled based on the pulse width (corresponding to the energization time). In this control, the lift amount increases as the energization time increases. As the amount increases, the injection rate (the amount of fuel injected per unit time) increases. 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 decompression process of the hydraulic chamber Cd is performed by returning the fuel in the hydraulic chamber Cd to the fuel tank 10 through the pipe 18 (FIG. 1) connecting the injector 20 and the fuel tank 10.

  In this way, the injector 20 opens and closes the injector 20 by opening and closing (opening / closing) the fuel supply passage to the injection hole 20f based on a predetermined reciprocation within the valve body (housing 20e). A needle 20c for closing the valve is provided. In the non-driving state, the needle 20c is displaced to the valve closing side by a force constantly applied to the valve closing side (extension force by the spring 20d), and in the driving state, a driving force is applied. The needle 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 20c changes substantially symmetrically between the non-driven state and the driven state.

  In the present embodiment, a fuel pressure sensor 20a is provided in the vicinity of the injectors 20 (# 1) to (# 4), particularly the fuel intake port. Based on the output of the fuel pressure sensor 20a, the pulsation pattern (swell characteristic) of the fuel pressure accompanying the injection operation of the injector 20 can be detected with high accuracy for a predetermined injection (in detail). 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, on the outer peripheral side of the crankshaft 41 that is the output shaft of the target engine, a crank angle sensor 42 (for example, an electromagnetic pickup) that outputs a crank angle signal at every predetermined crank angle (for example, in a cycle of 30 ° CA) is provided on the crankshaft. 41 is provided for detecting the rotational angle position, rotational speed (engine rotational speed), and the like. In addition, an accelerator sensor 44 that outputs an electric signal corresponding to the state (displacement amount) of the pedal to the accelerator pedal (driving operation unit) detects an operation amount (depression amount) of the accelerator pedal by the driver. Is provided.

  In such a system, the ECU 30 is a part that functions as the fuel injection characteristic detection device of the present embodiment and performs engine control mainly as an electronic control unit. The ECU 30 (engine control ECU) includes a well-known microcomputer (not shown), grasps the operating state of the target engine and the user's request based on the detection signals of the various sensors, and according to the above, By operating various actuators such as the intake adjustment valve 11c and the injector 20, various controls related to the engine are performed in an optimum manner according to the situation at that time. The microcomputer mounted on the ECU 30 basically includes a CPU (basic processing device) that performs various calculations, and a RAM (main memory that temporarily stores data and calculation results during the calculation) ( Random Access Memory (ROM), ROM (program only memory) as program memory, EEPROM (electrically rewritable non-volatile memory) as data storage memory, backup RAM (on-vehicle battery etc. even after main power supply of ECU 30 is stopped) Memory that is constantly powered by a backup power supply), signal processing devices such as A / D converters and clock generation circuits, various arithmetic devices such as input / output ports for inputting / outputting signals to / from the outside, A storage device, a signal processing device, a communication device, a power supply circuit, and the like are included. The ROM stores various programs related to engine control including a program related to the fuel injection control, a control map, and the like, and the data storage memory (for example, EEPROM) includes design data of the target engine. Various 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. In this way, by variably setting the fuel injection amount of the injector 20, the indicated torque (generated torque) generated through fuel combustion in each cylinder (combustion chamber), and in fact, actually 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 (drive amount) is output to the injector 20. Thus, that is, based on the drive amount (for example, valve opening time) of the injector 20, the output torque of the target engine is controlled to the target value. In the present embodiment, a portion that performs such control (specifically, a program installed in the ECU 30) corresponds to “engine control means”.

  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, with reference to FIG. 3, a basic processing procedure of the fuel injection control according to the present embodiment will be described. Note that the values of various parameters used in the processing of FIG. 3 are stored as needed in a storage device such as a RAM, EEPROM, or backup RAM mounted in the ECU 30 and updated as necessary. The series of processes shown in these drawings is basically executed in sequence at a frequency of once per combustion cycle for each cylinder of the target engine by the ECU 30 executing a program stored in the ROM. The That is, with this program, fuel is supplied to all the cylinders except the idle cylinder in one combustion cycle.

  As shown in FIG. 3, in this series of processing, first, in step S11, predetermined parameters, for example, the engine speed at that time (actual value measured by the crank angle sensor 42) and fuel pressure (actual value measured by the fuel pressure sensor 20a) are shown. Furthermore, the accelerator operation amount (actual value measured by the accelerator sensor 44) by the driver at that time is read. In the subsequent step S12, an injection pattern is set based on the various parameters read in step S11 (calculating the required torque including the loss due to the external load as necessary). For example, in the case of single-stage injection, the injection amount (injection time) of the injection, and in the case of multi-stage injection pattern, the total injection amount (total injection time) of each injection that contributes to torque is the output shaft. It is variably set according to the torque to be generated on the (crankshaft 41) (required torque, corresponding to the engine load at that time). Based on the injection pattern, a command value (command signal) for the injector 20 is set. As a result, the pilot injection, pre-injection, after-injection, post-injection and the like described above are appropriately performed together with the main injection in accordance with the vehicle conditions and the like.

  The injection pattern is acquired based on a predetermined map (an injection control map, which may be a mathematical expression) stored in the ROM and a correction coefficient, for example. Specifically, for example, an optimal injection pattern (adapted value) is obtained in advance for the assumed range of the predetermined parameter (step S11) by experiments or the like and written in the map. Incidentally, this injection pattern is determined by parameters such as the number of injection stages (the number of injections in one combustion cycle) and the injection timing (injection timing) and injection time (corresponding to the injection amount) of each injection. Thus, the map shows the relationship between these parameters and the optimum injection pattern. Then, the injection pattern acquired in this map is corrected based on a correction coefficient (for example, stored in an EEPROM in the ECU 30) that is separately updated (described later in detail) (for example, “set value = value on map / correction”). By performing the calculation “coefficient”, an injection pattern to be injected at that time, and thus a command signal for the injector 20 corresponding to the injection pattern is obtained. 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 some elements of these injection patterns may be used. You may make it use the map produced collectively (for example, all).

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

  In the present embodiment, the correction coefficient (strictly, a predetermined coefficient among a plurality of kinds of coefficients) used in step S12 in FIG. 3 is updated sequentially. FIG. 4 is a flowchart showing a series of processes relating to the update of the correction coefficient. The series of processes shown in FIG. 4 are executed sequentially at predetermined processing intervals (for example, at “20 μsec” intervals) by executing a program stored in the ROM by the ECU 30. Also, the values of various parameters used in the processing of FIG. 4 are stored at any time in a storage device such as a RAM, EEPROM, or backup RAM mounted on the ECU 30 and updated as necessary.

  As shown in FIG. 4, in this series of processes, first, in step S21, it is necessary to record fuel pressure data (sometimes fuel pressure) based on whether or not multi-stage injection is performed in any cylinder. Judge whether there is. Specifically, if it is before the start of fuel pressure data recording, it is determined whether or not multi-stage injection is performed within a predetermined time. If it is determined that multi-stage injection is performed, it is determined that recording is necessary, and the following steps Proceed to S22. In addition, if it is after the start of fuel pressure data recording, it is determined whether or not the recording is completed. If it is determined that the recording is not yet completed (recording is in progress), it is still necessary to record. Then, the process proceeds to step S22. On the other hand, if it is determined in step S21 that multi-stage injection is not performed (no recording is required), the series of processes in FIG. 4 is terminated. That is, in the series of processes in FIG. 4, the processes after step S22 are executed only when it is determined in step S21 that recording is necessary.

  In step S22, the fuel pressure at that time is measured by the fuel pressure sensor 20a, and the measured data is stored in a predetermined storage device (a first storage device, for example, a RAM in the ECU 30). In the subsequent step S23, it is determined whether or not a recording completion condition is satisfied. Thus, until it is determined in step S23 that the condition for completion of recording is satisfied, the series of processes shown in FIG. (Fuel pressure data) continues to be recorded. Here, as the condition for the completion of the recording, it is desirable to set a condition indicating that desired data has been obtained (data acquisition completion timing). For example, the recording is started slightly before the start of the target injection in step S21, and the recording is ended on the condition that the injection has ended and the fluctuation of the fuel pressure has sufficiently attenuated.

  If it is determined in step S23 that the condition for completion of recording is satisfied, in the following step S24, based on the pulsation pattern detected through the processing in step S22 and its regularity (attenuation rate of amplitude, etc.). Then, an undetected portion of the same pattern is derived (estimated). Specifically, in multi-stage injection, the pulsation pattern related to the pre-stage injection and the pulsation pattern related to the post-stage injection interfere with each other, causing a steep pressure fluctuation at the injection start timing of the post-stage injection (fuel pressure drop accompanying the start of fuel injection). Often difficult to identify. Therefore, for the preceding injection (specific injection), based on the pulsation pattern by only the preceding injection detected through the process of step S22 and its regularity, the pulsation pattern that follows it, that is, the pulsation by the preceding injection and the subsequent pulsation About the pulsation pattern of the part which the pulsation by injection interferes, the pulsation pattern only by the preceding stage injection is derived (estimated). As the specific injection, any injection that is not the final stage can be set.

  The pulsation pattern (pressure waveform) estimation process will be described below with reference to FIGS. 5 is a flowchart showing details of the processing contents of step S24 in FIG. 4, and FIG. 6 is a flowchart showing details of the processing contents of step S35 in FIG. FIG. 7 is a timing chart showing an estimation mode of the pressure waveform. Here, based on the pulsation pattern of the portion detected (actually measured) through the processing of step S22 in the pressure waveform shown in FIG. 7, that is, the actually measured portion indicated by the solid line L11 in the drawing (period until timing t16). A case will be described in which the pulsation pattern of the subsequent portion, that is, the undetected portion indicated by the broken line L12 in the drawing (corresponding to the interference portion, the period after timing t16) is estimated. Incidentally, this pulsation pattern is a pressure waveform that oscillates alternately on the large side and the small side at the reference pressure P0 (reference level) indicated by a one-dot chain line TR1 (corresponding to a pulsation tendency) in the drawing.

  The process of FIG. 5 is executed by executing the process of the previous step S24 in the series of processes shown in FIG. First, in the process of FIG. 5, in steps S31 to S34, based on the fuel pressure data detected (actually measured) through the process of step S22, that is, the pressure waveform actual measurement part (solid line L11 in FIG. 7), Desired data necessary for estimating the detection portion (broken line L12 in FIG. 7) is obtained.

  First, in step S31, the waveform data relating to the first node (base point) after the end of injection (timing t12), that is, the timing t13 and the fuel pressure P0 (FIG. 7) at that time, as the base point data of the pressure waveform actual measurement part (solid line L11). To get. Next, in subsequent step S32, a timing t16 (FIG. 7) corresponding to one cycle is acquired from the base point (timing t13). In a further subsequent step S33, the timing and the fuel pressure value at that time are acquired for the minimum point and the maximum point during one cycle (periods t13 to t16) from the base point. That is, the timing t14 and the fuel pressure P1 (FIG. 7) are acquired as waveform data related to the local minimum point, and the timing t15 and the fuel pressure P2 (FIG. 7) are acquired as waveform data related to the local maximum point.

  In the subsequent step S34, a change rate K0 (amplitude attenuation rate) corresponding to the regularity of the pressure waveform is calculated based on the data acquired in these steps S31 to S33. Specifically, the ratio between the amplitude ΔP1 (= | P0−P1 |, FIG. 7) of the minimum point (timing t14) and the amplitude ΔP2 (= | P0−P2 |, FIG. 7) of the maximum point (timing t15). Then, the change rate K0 (= ΔP2 / ΔP1) is obtained.

  In subsequent step S35, a portion after timing t16, that is, a pressure waveform undetected portion (broken line L12 in FIG. 7) is estimated based on the data acquired in steps S31 to S34. FIG. 6 is a flowchart showing details of the estimation calculation process. The process of FIG. 6 is repeatedly executed until a desired pulsation pattern is obtained (until a predetermined estimation completion condition is satisfied). Here, the estimation calculation process will be described by taking as an example the case of acquiring data in the second period from the base point.

  As shown in FIG. 6, in this series of processing, waveform data is obtained in the order of a minimum point, a node (first node), a maximum point, and a node (second node).

  That is, first in step S41, waveform data relating to the next extreme point (minimum point in the second cycle) is acquired. Specifically, based on the amplitude ΔP2 of the immediately previous extreme point (maximum point at timing t15) and the rate of change K0 calculated in step S34 in FIG. 5, the amplitude ΔP3 of the minimum point in the second period as a multiplication value of these two values. (= ΔP2 × K0) is calculated. Then, the fuel pressure P3 at the minimum point (= P0−ΔP3, FIG. 7) is calculated as a pressure value smaller than the fuel pressure P0 by the amplitude ΔP3. On the other hand, the timing t17 (FIG. 7) of the minimum point in the second cycle is calculated based on the timing t16 (calculated in step S32) and the cycle T0 (= difference between the timing t16 and the timing t13). To do. Specifically, a time obtained by adding (adding) a quarter cycle (= T0 / 4) to the timing t16 is set as a timing t17 (= t16 + (T0 / 4)).

  In the subsequent step S42, waveform data relating to the next section (first section in the second cycle) is acquired. Specifically, the fuel pressure in this first node is equal to the fuel pressure P0 (FIG. 7). Further, the timing t18 (FIG. 7) of the first node is a time (= t16 +) obtained by adding (adding) a half cycle (= T0 / 2) to the timing t16 (calculated in step S32). (T0 / 2)).

  In the subsequent step S43, waveform data relating to the next extreme point (maximum point in the second cycle) is acquired. Specifically, based on the amplitude ΔP3 of the immediately preceding extreme point (minimum point at timing t17) and the change rate K0 calculated in step S34 in FIG. 5, the amplitude ΔP4 of the maximum point in the second cycle as a multiplication value of these two values. (= ΔP3 × K0) is calculated. Then, the fuel pressure P4 (= P0 + ΔP4, FIG. 7) at the maximum point is calculated as a pressure value larger than the fuel pressure P0 by the amplitude ΔP4. On the other hand, the timing t19 (FIG. 7) of the maximum point in the second cycle is calculated based on the timing t16 (calculated in step S32) and the cycle T0. Specifically, a time obtained by adding (adding) a three-quarter cycle (= (3/4) × T0) to the timing t16 is defined as a timing t19 (= t16 + (3/4) × T0).

  In subsequent step S44, waveform data relating to the next section (second section in the second period) is acquired. Specifically, the fuel pressure in this second node is equal to the fuel pressure P0 (FIG. 7). The timing t20 (FIG. 7) of the second node is calculated as a time (= t16 + T0) obtained by adding (adding) one cycle (= T0) to the timing t16 (calculated in step S32).

  In this way, data for the second period from the base point can be acquired. Further, the data in the third period and thereafter are similarly processed, that is, the third period is based on the second period data, the fourth period is based on the third period data, and so on. It can be calculated in order by repeatedly executing steps S41 to S44). In addition, it has been confirmed by experiments of the inventors that the period of the pressure waveform is substantially constant (≈period T0). Therefore, if data of each point (minimum point, first node, maximum point, second node) can be obtained, a pulsation pattern can be acquired by interpolating between the data.

  In step S24 of FIG. 4, the pressure waveform (pulsation pattern) is thus estimated. In the subsequent step S25, the injection characteristic of the target injection is based on the pulsation pattern of the pre-stage injection estimated in step S24 and the pulsation pattern of the multi-stage injection (target injection) detected through the processing of the previous step S22. Is acquired (detected). Hereinafter, with reference to FIG. 8 to FIG. 11, a description will be given of how the injection characteristic is detected in the process of step S25. In these drawings, (a) is a timing chart showing a command signal (energization pulse) for the injector 20, and (b) is a timing chart showing a pulsation pattern of fuel pressure in fuel injection based on the command signal. .

  FIG. 8 is a timing chart showing the fuel pressure data of the target injection acquired in the previous step S22. That is, in this fuel pressure data, the pulsation pattern is a pattern as indicated by the solid line L2b in FIG. 8B with respect to the energization pulse indicated by the solid line L2a in FIG. 8A. That is, of the two injections shown in the figure, in the vicinity of the injection start timing of the latter-stage injection (second-stage injection), the pulsation pattern of the latter-stage injection and the pulsation pattern of the first-stage injection (pre-stage injection) interfere with each other. Therefore, it is difficult to recognize each pulsation pattern of these injections independently.

  FIG. 9 is a timing chart showing the pulsation pattern (estimated data) estimated in the previous step S24, that is, the pulsation pattern of the pre-stage injection of the target injection (FIG. 8). In this estimated data, the pulsation pattern is a pattern as shown by a solid line L1b in FIG. 9B with respect to the energized pulse shown by the solid line L1a in FIG. 9A.

  In step S25 of FIG. 4, the estimated data is subtracted from the fuel pressure data of the target injection by comparing the fuel pressure data of the target injection (solid line L2b in FIG. 8) with the estimated data (solid line L1b in FIG. 9). A pulsation pattern relating only to the second-stage fuel injection of the target injection is extracted as a waveform obtained by subtracting each part.

  FIG. 10 shows the fuel pressure data (solid lines L2a, L2b) of the target injection in a state where the pulsation pattern related to the first stage injection (previous stage injection) of the target injection and the pulsation pattern of the estimated data corresponding thereto are matched. The estimated data (broken lines L1a and L1b) are superimposed on each other.

  In step S25 of FIG. 4, the estimated data is subtracted from the fuel pressure data of the target injection (corresponding portions are respectively subtracted) in the state shown in FIG. By doing so, as shown in FIG. 11, the pulsation pattern (solid line L2c) relating only to the second stage fuel injection (subsequent injection, solid line L2c) of the target injection is extracted. Then, based on the extracted pulsation pattern (solid line L2c), the injection characteristics (injection start timing, injection time, etc.) of the second stage injection are obtained, and when the error in the injection characteristics is large (or the error is small). In all subsequent cases (including the case), in the subsequent step S26, a correction coefficient for compensating for the error is calculated and updated. Note that the correction coefficient updated here is, for example, one of the correction coefficients used in step S12 in FIG.

  The processing in FIG. 4 ends with the processing in step S26. In the present embodiment, the correction coefficient related to the fuel injection control is sequentially updated by sequentially executing the process of FIG. 4, and the fuel of the fuel is injected under the injection condition in which the correction coefficient is reflected by the process of FIG. 3. The injection is executed sequentially. As a result, the characteristic change caused by the secular change or the like of the control component can be accurately compensated, and the injection control accuracy can be maintained high.

  As described above, according to the fuel injection characteristic detection device and the engine control system according to the present embodiment, the following excellent effects can be obtained.

  (1) Fuel applied when a fuel is injected into and supplied to the target engine by being applied to a cylinder that is a part that performs fuel combustion of the target engine by a predetermined fuel injection valve (injector 20). As a fuel injection characteristic detecting device (engine control ECU 30) for detecting injection characteristics, a program for detecting a pulsation pattern of fuel pressure accompanying an injection operation of the injector 20 by sequentially detecting the pressure of the fuel supplied to the injector 20 (Pulsation pattern detection means, step S22 in FIG. 4), and based on the pulsation pattern detected in step S22 (solid line L11 in FIG. 7) and its regularity, the undetected portion of the same pattern (broken line in FIG. 7) L12) and a program (undetected pattern deriving means, step S24 in FIG. 4). . As a result, it is possible to grasp the injection characteristics from time to time, including changes in characteristics over time.

  (2) In step S24 of FIG. 4, a predetermined stage that is not the final stage (for example, the front stage injection of the second stage injection) among the multistage fuel injections performed in one combustion cycle in the predetermined cylinder of the target engine is specified. Regarding the injection, based on the pulsation pattern of only the specific injection detected through step S22 of FIG. 4 and the regularity thereof, the pulsation of the portion where the pulsation of the specific injection that follows and the pulsation of the subsequent stage interfere with each other Among the patterns, a pulsation pattern (broken line L12 in FIG. 7) by only the specific injection is derived. With such a configuration, it is possible to obtain more detailed injection characteristics by performing various signal processing based on the derived pulsation pattern based only on the preceding stage injection.

  (3) The pattern start point (base point) of the pulsation pattern (detection pattern) used in step S24 of FIG. 4 is set to a predetermined condition (for example, the first node) after the end of the specific injection (for example, the front stage injection of the second stage injection). ) Is satisfied (step S31 in FIG. 5). This makes it possible to derive the undetected portion (broken line L12 in FIG. 7) with higher accuracy based on a detection pattern in a more stable state of pressure fluctuation, that is, a detection pattern with higher reliability. .

  (4) The regularity of the pulsation pattern used in step S24 in FIG. 4 is defined as the rate of change (amplitude decay rate) of the amplitude of the pattern with time. By doing so, the undetected portion (broken line L12 in FIG. 7) can be derived more easily and accurately.

  (5) The change rate K0 (attenuation rate of amplitude) was calculated as the amplitude ratio (= ΔP2 / ΔP1) between adjacent local maximum points and local minimum points (step S34 in FIG. 5). By doing so, the undetected portion (broken line L12 in FIG. 7) can be derived more easily and accurately.

  (6) Assuming that the period T0 is constant (assuming that "period = constant"), the undetected part (broken line L12 in FIG. 7) was derived. By doing so, it is possible to simplify the arithmetic processing.

  (7) In step S24 of FIG. 4, for the undetected portion of the pulsation pattern of the specific injection (for example, the first stage), the node, maximum point and minimum point are obtained as reference points, and interpolation is performed based on the reference point. By performing extrapolation, an undetected portion of the pulsation pattern is derived. By doing so, it is possible to efficiently derive the undetected portion (broken line L12 in FIG. 7) with high accuracy.

  (8) The pulsation pattern (detection pattern) used in step S24 of FIG. 4 is a pattern having a period of “1” or more. By doing so, it becomes possible to derive the undetected portion (broken line L12 in FIG. 7) with higher accuracy.

  (9) Regarding the pulsation pattern (pressure waveform) that alternately vibrates from the fuel pressure P0 (reference level) to the large side and the small side, the tendency of the fuel pressure P0 is used for derivation (estimation) of the undetected portion. I made it. As a result, the undetected portion (broken line L12 in FIG. 7) can be derived more easily and accurately.

  (10) The common rail 12 for accumulating and holding the fuel supplied to the injector 20 and the fuel discharge port of the common rail 12 among the fuel passage (pipe 14) from the common rail 12 to the fuel injection port (injection hole 20f) of the injector 20 A common rail fuel injection system including a fuel pressure sensor (fuel pressure sensor 20a) for detecting the pressure of the fuel flowing in the fuel passage at a predetermined position located on the fuel downstream side from the vicinity thereof is applied. Specifically, the fuel pressure sensor 20a for detecting the fuel pressure is more specifically positioned in the pipe 14 connected to the fuel discharge side of the common rail 12 closer to the fuel injection port of the injector 20 than the common rail 12. Is attached to the fuel intake port of the injector 20. In step S22 of FIG. 4, the pressure of the fuel supplied to the injector 20 is sequentially detected based on the output of the fuel pressure sensor 20a. By doing so, it becomes possible to detect with high accuracy a pulsation pattern (swelling characteristic) showing an ejection characteristic including a characteristic change with time.

  (11) In step S22 of FIG. 4, the sensor output of the fuel pressure sensor 20a is sequentially acquired at intervals shorter than “50 μsec”, specifically at intervals of “20 μsec”. Thereby, the pulsation pattern mentioned above and by extension, the tendency of pressure fluctuation can be grasped more accurately.

  (12) Based on the undetected portion (estimated data) of the pulsation pattern derived in step S24 in FIG. 4, multistage fuel injection (for example, FIG. 8 to FIG. 8) performed in one combustion cycle in a predetermined cylinder of the target engine. From the pulsation pattern related to the second stage injection shown in FIG. 11, only after the nth stage fuel injection corresponding to the predetermined stage after the second stage of the multistage fuel injection (for example, only the second stage injection shown in FIG. 11) ) Pulsation pattern extraction program (pulsation pattern extraction means, step S25 in FIG. 4). As a result, the pulsation pattern relating only to the fuel injection after the nth stage is obtained with high accuracy, and as a result, the injection timing and the like relating to the nth stage injection can be detected with high accuracy.

  (13) In step S25 of FIG. 4, based on the undetected portion of the pulsation pattern derived in step S24 of FIG. 4, a pulsation pattern related to fuel injection with a number of stages (for example, a single stage) smaller than n stages is obtained. The nth and subsequent stages are obtained by comparing (subtracting) the pulsation pattern relating to the fuel injection with the number of stages smaller than the n stage and the pulsation pattern relating to the n-stage multistage fuel injection (for example, two-stage injection). The pulsation pattern related to only fuel injection is extracted. In this way, the extraction process can be realized more easily and accurately.

  (14) Based on the pulsation pattern related to only the nth and subsequent fuel injections extracted in step S25 of FIG. 4, the command signal for the injector 20 (for example, the command signal related to the injection timing and injection time) is corrected. The program (correction means, step S12 in FIG. 3 and step S26 in FIG. 4) is provided. By doing so, fuel injection control with higher accuracy becomes possible.

  (15) A program (engine control means) for performing predetermined control on the target engine based on the operation of the fuel supply system shown in FIG. In addition to the ECU 30, various sensors (such as the fuel pressure sensor 20a) and an actuator (see FIG. 1) are further provided. In such a configuration, the fuel injection control mode is improved as described above, so that more reliable engine control can be performed.

  The above embodiment may be modified as follows.

  -According to the experiment of the inventor and the like, the tendency of the fuel pressure P0 (reference level) indicates that the fuel leakage amount of the fuel supply system (FIG. Varies depending on (fuel discharge amount). FIGS. 12A and 12B schematically show the experimental results as timing charts. For example, it is confirmed that the reference level indicated by the alternate long and short dash line TR2 in FIG. 12A tends to decrease as the fuel leak amount increases (the pressure decrease gradient (the amount of decrease in fuel pressure per unit time) increases). It was done. For example, when the pumping timing of the fuel pump 11 and the injection timing of the injector 20 overlap, the pumping amount of the fuel pump 11 increases. Then, as the pumping amount of the fuel pump 11 at the time of injection increases, the reference level indicated by the alternate long and short dash line TR3 in FIG. 12B tends to increase (inclination of pressure increase (increase amount of fuel pressure per unit time)). Is increased).

  From these experimental results, when the tendency of the reference level (dashed lines TR1 to TR3) is expressed by a relational expression such as “y = Ax + B” (y: fuel pressure, x: time), the fuel supply system ( The slope A and intercept B in the relational expression “y = Ax + B” are variably set based on the fuel leak amount in FIG. 1), the pumping amount of the fuel pump 11 that supplies fuel to the injector 20, the time, and the like. It is also effective to have a configuration including a program. More specifically, for example, the slope A and the intercept B are defined by the function of each parameter, and the tendency of the reference level is determined based on the function prior to step S31 in FIG. Or, prior to step S31 in FIG. 5, the tendency of the reference level is calculated from the fuel pressure data before the base point (timing t13). By doing so, the undetected portion (broken line L12 in FIG. 7) can be derived more easily and accurately.

  ・ Detection of node, maximum point, and minimum point of the above pulsation pattern (pressure waveform) based on the time differential value of fuel pressure (maximum point, minimum point = differential value “0”, node = maximum differential value) Etc. are also effective.

  In the above embodiment, assuming that an adaptation map (used in step S12 in FIG. 3) in which an adaptation value has been determined in advance by experiment or the like is adopted, a correction coefficient for correcting the injection characteristics based on the adaptation map is set. Updated. However, the present invention is not limited to this. For example, a value after correction (a value reflecting the correction coefficient) may be stored in the EEPROM or the like instead of the correction coefficient. As such a configuration, if sufficient reliability is obtained for the corrected value, it is possible to adopt a configuration that does not require the adaptation map, that is, a so-called adaptation-less configuration.

  A piezo drive injector may be used instead of the electromagnetic drive injector 20 illustrated in FIG. It is also possible to use a fuel injection valve that does not cause a pressure leak, for example, a direct acting injector (for example, a direct acting piezo injector that has been developed in recent years) that does not involve a hydraulic chamber (command chamber Cd) for transmitting driving power. it can. When a direct acting injector is used, the injection rate can be easily controlled.

  -And, for example, if a linear motion injector, which is currently in the development stage, will be put into practical use in the future and the calculation speed will increase, extraction of the undetected part (broken line L12 in FIG. 7) while detecting the fuel pressure from time to time Can also do this at the same time. Then, the injection end timing is determined on the basis of the pulsation pattern detected with high synchronism (in real time), and the injection is ended at the injection end timing through the high-speed operation of the linear motion injector. Highly accurate fuel injection becomes possible. That is, for example, when the nth stage (for example, the second stage injection in the second stage injection) corresponding to a predetermined stage after the second stage is executed by the injector 20, the n is performed in step S25 of FIG. A program for extracting a pulsation pattern related only to the injection at the stage (for example, the second stage) and determining the injection end timing of the injection at the n-th stage based on the extracted pulsation pattern at step S13 in FIG. It is also effective to have a configuration comprising

  The pattern start point (base point) of the pulsation pattern (detection pattern) used in step S24 in FIG. 4 is set to a predetermined condition (for example, the first node) after the end of the specific injection (for example, the front stage injection of the second stage injection). Satisfied timing. However, the present invention is not limited to this, and it is effective to use, for example, the injection start timing of specific injection or the injection end timing of specific injection as the pattern start point (base point) of the detection pattern.

  In the above embodiment, the fuel pressure sensor 20a (fuel pressure sensor) for detecting the fuel pressure is attached to the fuel intake port of the injector 20. However, the present invention is not limited to this, and the fuel pressure sensor 20a may be provided inside the injector 20 (for example, in the vicinity of the injection hole 20f in FIG. 2). Further, the number of such fuel pressure sensors is arbitrary. For example, two or more sensors may be provided for the fuel flow path of one cylinder. In the above embodiment, the fuel pressure sensor 20a is provided for each cylinder. However, this sensor is provided only for some cylinders (for example, one cylinder), and the estimated values based on the sensor output for other cylinders. May be used.

  In the above embodiment, the regularity of the pulsation pattern used in step S24 of FIG. 4 is the change rate (amplitude attenuation rate) of the amplitude of the pattern with time. However, instead of (or together with), the rate of change with the passage of time of the cycle (cycle extension rate) may be used. In addition, as the rate of change of the amplitude and period, a rate of change accompanying propagation may be used instead of the rate of change accompanying time. Note that the rate of change (for example, the rate of attenuation of the amplitude) accompanying propagation (propagation of the pressure waveform) can be easily calculated, for example, by providing two or more sensors for the fuel flow path.

  In the above-described embodiment, the configuration in which the sensor output of the fuel pressure sensor 20a is sequentially acquired at “20 μsec” intervals (cycles) is described, but this acquisition interval is appropriately set within a range in which the above-described tendency of pressure fluctuation can be captured. Can be changed. However, according to the inventors' experiment, an interval shorter than “50 μsec” is effective.

  It is also effective to provide a rail pressure sensor that measures the pressure in the common rail 12 in addition to the fuel pressure sensor 20a. With such a configuration, in addition to the pressure measurement value by the fuel pressure sensor 20a, the pressure in the common rail 12 (rail pressure) can be acquired, and the fuel pressure can be detected with higher accuracy. Become.

  In the above embodiment, the subtraction is performed when extracting the pulsation pattern. However, even when the subtraction is performed, a waveform similar to the waveform shown in FIG. 11 can be obtained. However, the calculation mode can be arbitrarily set according to the type of the estimated data.

  -The type and system configuration of the engine to be controlled can be changed as appropriate according to the application.

  For example, in the above embodiment, the case where the present invention is applied to a diesel engine is mentioned as an example. However, the present invention is basically applied to a spark ignition type gasoline engine (particularly a direct injection engine). be able to. The apparatus and system according to the present invention are not limited to a fuel injection valve that directly injects fuel into a cylinder, but also a fuel injection valve that injects fuel into an intake passage or an exhaust passage of an engine. It can be used for the control of etc. Further, the target fuel injection valve is not limited to the injector illustrated in FIG. 2 and is arbitrary. When such a configuration change is made for the above-described embodiment, the details of the various processes (programs) described above may be changed (design change) as appropriate in accordance with the actual configuration. preferable.

  In the embodiment and the modification, it is assumed that various kinds of software (programs) are used. However, similar functions may be realized by hardware such as a dedicated circuit.

1 is a configuration diagram illustrating an outline of a fuel injection characteristic detection device and an engine control system according to an embodiment of the present invention. The internal side view which shows typically the internal structure of the fuel injection valve used for the system. The flowchart which shows the basic procedure of the fuel-injection control process which concerns on this embodiment. 7 is a flowchart showing a series of processes related to the correction coefficient update process of the embodiment. The flowchart which shows the processing content of the pressure waveform estimation process in the correction coefficient update process. The flowchart which shows the processing content of the pressure waveform estimation calculation used for the same pressure waveform estimation process. The timing chart which shows the one aspect | mode of the same pressure waveform estimation process. (A) And (b) is a timing chart which shows the detection aspect of the injection characteristic which concerns on this embodiment, respectively. (A) And (b) is a timing chart which shows the detection aspect of the injection characteristic which concerns on this embodiment, respectively. (A) And (b) is a timing chart which shows the detection aspect of the injection characteristic which concerns on this embodiment, respectively. (A) And (b) is a timing chart which shows the detection aspect of the injection characteristic which concerns on this embodiment, respectively. (A) And (b) is a timing chart which shows the modification of a pressure waveform estimation aspect, respectively.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Fuel pump, 12 ... Common rail, 14 ... Piping, 20 ... Injector, 20a ... Fuel pressure sensor, 20f ... Injection hole, 30 ... ECU (electronic control unit).

Claims (10)

It is applied to a fuel supply system that injects and supplies fuel into a cylinder that is a part that performs fuel combustion of a target engine or its intake passage or exhaust passage by a predetermined fuel injection valve,
Pulsation pattern detection means for detecting a pulsation pattern of fuel pressure accompanying an injection operation of the fuel injection valve by sequentially detecting the pressure of the fuel supplied to the fuel injection valve;
An undetected pattern deriving unit for deriving an undetected portion of the pattern based on the pulsation pattern detected by the pulsation pattern detection unit and its regularity ,
The undetected pattern deriving means is detected by the pulsation pattern detecting means for a specific injection at a predetermined stage which is not the final stage among the multistage fuel injections performed during one combustion cycle in a predetermined cylinder of the engine. Based on the pulsation pattern by only the specific injection and its regularity, the pulsation pattern by only the specific injection is selected from the pulsation pattern of the portion where the pulsation by the specific injection and the pulsation by the subsequent stage interfere thereafter , Derived as the undetected part,
Based on the undetected portion of the pulsation pattern derived by the undetected pattern deriving means, the pulsation pattern related to the multistage fuel injection performed in one combustion cycle in the predetermined cylinder of the engine is used to perform two stages of the multistage fuel injection. fuel injection characteristic sensing device according to claim Rukoto comprises a pulsation pattern extraction means for extracting a pulsating pattern of only the n-th stage after the fuel injection corresponding to a predetermined stage subsequent eye. The regularity of the pulsation pattern used by the undetected pattern deriving means includes a rate of change with time or a rate of change with propagation of at least one of the amplitude and period of the pattern . Fuel injection characteristic detection device. The undetected pattern deriving means obtains at least one of a node, a maximum point, and a minimum point as a reference point for an undetected portion of the pulsation pattern, and performs at least one of interpolation and extrapolation based on the reference point. 3. The fuel injection characteristic detecting device according to claim 1 , wherein an undetected portion of the pulsation pattern is derived by performing . The pulsation pattern is composed of a pressure waveform that alternately vibrates from the reference level to the large side and the small side, and the regularity of the pulsation pattern used by the undetected pattern deriving means includes the tendency of the reference level. fuel injection characteristic sensing device according to any one of claims 1 to 3 to be. The undetected pattern deriving unit detects the tendency of the reference level based on at least one of a fuel leak amount of the fuel supply system and a pumping amount of a fuel pump that supplies fuel to the fuel injection valve. The fuel injection characteristic detecting device according to claim 4 , wherein The fuel supply system accumulates and holds fuel to be supplied to the fuel injection valve, and a fuel passage from the common rail to the fuel injection port of the fuel injection valve, fuel downstream from the vicinity of the fuel discharge port of the common rail A common rail fuel injection system comprising one or more fuel pressure sensors for detecting the pressure of the fuel flowing in the fuel passage at a predetermined position located on the side,
The said pulsation pattern detection means detects sequentially the pressure of the fuel supplied to the said fuel injection valve based on the at least 1 output of the said fuel pressure sensor. Fuel injection characteristic detection device. The pulsation pattern extraction means obtains a pulsation pattern related to fuel injection having a number of stages smaller than the n stages based on the undetected portion of the pulsation pattern derived by the undetected pattern derivation means, and more than the n stages. The pulsation pattern relating only to the fuel injection after the nth stage is extracted by comparing the pulsation pattern relating to the fuel injection with a small number of stages and the pulsation pattern relating to the multistage fuel injection . The fuel injection characteristic detection device according to any one of the above. The correction means which correct | amends the command signal with respect to the said fuel injection valve based on the pulsation pattern which concerns on only the fuel injection after the n-th stage extracted by the said pulsation pattern extraction means. The fuel injection characteristic detection device according to the description. When the fuel injection valve is performing an n-th stage injection corresponding to a predetermined stage after the second stage, the pulsation pattern extracting means extracts a pulsation pattern related only to the n-th stage injection, and The fuel injection characteristic detecting device according to any one of claims 1 to 7, further comprising means for determining an injection end timing of the n-th stage injection based on the extracted pulsation pattern .   The fuel injection characteristic detection device according to any one of claims 1 to 9,
  As a target for application of the fuel injection characteristic detection device, a fuel supply system including the fuel injection valve and a fuel pressure sensor that detects a pressure of fuel supplied to the fuel injection valve;
  Engine control means for performing predetermined control on the engine based on the operation of the fuel supply system;
An engine control system comprising:

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