JP2011007203A - Fuel injection state detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve control accuracy of a fuel injection system by newly providing a fuel injection state detector detecting an injection state of fuel actually injected from a fuel injection valve.SOLUTION: A common rail type fuel injection system includes a fuel pressure sensor 20a arranged on a side close to an injection hole with respect to a common rail 12 in an internal fuel passage 25 leading from the common rail 12 to the injection hole of an injector 20 and detecting fuel pressure fluctuated with fuel injection from the injection hole. An ECU 30 estimates injection start timing and injection completion timing based on the fluctuation waveform of the pressure detected by the fuel pressure sensor 20a, produced with the fuel injection. The ECU 30 estimates the amount of fuel injected based on a pressure difference in the detected pressure between the detected pressure before injection is started and detected pressure after injection is completed. Then, the ECU 30 calculates the transitional waveform of a fuel injection rate based on the estimated injection start timing, the estimated injection complete timing, and the estimated amount of fuel injected.

Description

  The present invention relates to a fuel injection state detection device that detects an injection state of fuel injected from a fuel injection valve.

  2. Description of the Related Art Conventionally, there is known a common rail type fuel injection system in which fuel used for combustion of an engine (internal combustion engine) is stored in a common rail (pressure accumulating container) in a high pressure state, and fuel distributed from the common rail is injected from a fuel injection valve. This type of conventional system detects the pressure of fuel accumulated by a fuel pressure sensor (rail pressure sensor) attached to a common rail, and based on the detection result, a fuel pump, a fuel injection valve, etc. for supplying fuel to the common rail, In general, driving of various components constituting the fuel supply system is controlled (see Patent Document 1).

JP 2006-200378 A

  According to the knowledge of the present inventors, if the injection state (for example, injection amount or injection rate) of the fuel actually injected from the fuel injection valve can be detected, the detected value controls the fuel injection system with high accuracy. This is an important parameter. For example, if operation command values for various components (for example, fuel injection valves) of the fuel injection system are calculated or corrected based on the detected amount, these components can be controlled with high accuracy.

  On the other hand, none of the various fuel injection systems that have been proposed in the past has a means for detecting the injection state of the fuel actually injected from the fuel injection valve. There is room for improvement to control accuracy.

  The present invention has been made to solve the above-described problems, and its object is to provide a new fuel injection state detection device that detects the injection state of fuel actually injected from a fuel injection valve. The purpose is to improve the control accuracy of the fuel injection system.

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

The first configuration is a fuel injection state detection device applied to a fuel injection system that injects fuel accumulated in a pressure accumulator from a fuel injection valve, and includes the following configurations (a) to (d). And That is,
(A) Fuel that is arranged on the side closer to the injection hole with respect to the pressure accumulation container in the fuel passage from the pressure accumulation container to the injection hole of the fuel injection valve, and fluctuates with fuel injection from the injection hole A fuel pressure sensor for detecting the pressure of
(B) first injection amount estimation means for estimating a fuel injection amount based on a fluctuation waveform caused by fuel injection out of the pressure detected by the fuel pressure sensor;
(C) second injection amount estimation means for estimating a fuel injection amount based on a pressure difference between a detected pressure before the start of injection and a detected pressure after the end of injection among the detected pressures;
(D) injection amount calculating means for calculating a fuel injection amount based on both estimation results by the first and second injection amount estimating means;
It is characterized by providing.

  By the way, the pressure of the fuel in the injection hole of the fuel injection valve varies as the fuel is injected. However, in the apparatus described in Patent Document 1, the fuel pressure sensor (rail pressure sensor) is attached to the pressure accumulating container because it aims to detect the fuel pressure in the pressure accumulating container. Therefore, the pressure fluctuation caused by the injection is attenuated in the pressure accumulating container. Therefore, it is difficult for such a conventional apparatus to accurately detect the pressure fluctuation.

  On the other hand, in this configuration, as shown in the configuration (a), the fuel pressure sensor is disposed on the side closer to the injection hole with respect to the pressure accumulation container, so that the pressure fluctuation at the injection hole is attenuated in the pressure accumulation container. Can be detected. Therefore, since the actual change in the injection amount can be accurately detected as the fluctuation waveform of the detected pressure, the fuel injection amount can be estimated based on the detected fluctuation waveform (first injection amount estimation means: configuration (b)).

  Specifically, the fuel injection amount is estimated based on the appearance times of the change points P1 and P3 exemplified in FIG. 5C and the maximum pressure drop amount Pβ (maximum drop amount). The change point P1 is a pressure decrease start point that appears in the fluctuation waveform as the injection starts, and the change point P3 is a pressure increase end point that appears in the fluctuation waveform as the injection ends. To explain a more specific estimation example, the fluctuation waveform of the detected pressure and the change (transition) of the injection rate (injection amount per unit time) have a correlation as shown in FIGS. 5B and 5C. The change in the injection rate can be estimated based on the change points P1 and P3 appearing in the fluctuation waveform, the maximum drop amount Pβ, and the like. And the area S shown by the oblique line in FIG.5 (b) is equivalent to the injection quantity. Estimating the fuel injection amount by calculating the area S in this way can be given as a specific example of estimation according to the first injection amount estimation means.

  Here, the detected value of the detected pressure includes a detection variation, and the detection variation appears more prominently as the injection amount increases. In particular, it has been found that the variation in the maximum drop amount Pβ is larger. In order to reduce the influence on the estimation result due to the detection variation, the present inventors, in addition to the injection amount estimation method by the first injection amount estimation unit, include the second injection amount estimation unit (configuration (c Recalling that the injection quantity is estimated by the method of)). That is, since the pressure difference between the detected pressure before the start of injection and the detected pressure after the end of injection has a correlation with the actual injection amount, the fuel injection amount can be estimated based on the pressure difference.

  In this configuration, since the fuel injection amount is calculated based on both estimation results by the first and second injection amount estimation units (configuration (d)), the estimation result of the first injection amount estimation unit is provided. As compared with the case where the injection amount is calculated based on this, the influence of detection variation can be reduced, and the injection amount can be detected with high accuracy.

  As described above, according to this configuration, since the fuel pressure sensor is disposed on the side closer to the injection hole with respect to the pressure accumulating vessel, a change in the injection amount of the actually injected fuel (injection state) is detected as a fluctuation waveform of the detected pressure. In addition, it is possible to detect the injection amount with high accuracy and to provide a new fuel injection state detection device that has not been available so far. Therefore, if the fuel injection system is controlled using the detection result, the fuel injection system can be controlled with high accuracy.

  In the second configuration, the injection rate calculating means for calculating the transition waveform of the fuel injection rate based on the fluctuation waveform of the detected pressure and the integral value of the transition waveform (for example, the area of the shaded portion S in FIG. 5) are calculated. Injection rate correcting means for correcting the transition waveform so that the fuel injection amount is close to the fuel injection amount calculated by the injection amount calculating means.

  According to this, in addition to the injection amount (injection state) of the actually injected fuel, the transition waveform of the actual injection rate can also be detected as the injection state. In addition, since the transition waveform of the injection rate is corrected so as to approach the fuel injection amount calculated by the injection amount calculation means, the injection rate transition waveform (injection state) can be detected with high accuracy.

  In the third configuration, the first and second injection amount estimation means include the fuel pressure sensor detected when a fuel pumping period from a fuel pump to the pressure accumulating container does not overlap with an injection period from the injection hole. The estimation is performed based on the detected pressure.

  Here, when the pressure fluctuation caused by fuel injection is detected by the fuel pressure sensor, the fluctuation waveform of the detected pressure when the fuel pumping period overlaps with the injection period is the fluctuation waveform when the fuel pumping period does not overlap This is a waveform with the fuel pumping amount added. That is, for the detected pressure (fluctuation waveform) used for estimating the fuel injection amount, the added amount of the fuel pumping amount becomes a disturbance, and thus when the fuel injection amount is estimated by the first and second injection amount estimating means, Estimating the fuel injection amount based on the detected pressure including a disturbance can be a cause of deterioration in estimation accuracy. In addition, as described above, the variation in the maximum drop amount Pβ is large in the detection variation included in the detection value of the detected pressure, as described above, but the added amount of the fuel pumping amount has a great influence on the maximum drop amount Pβ. There is a particular concern about the deterioration of estimation accuracy.

  On the other hand, in the third configuration, the estimation is performed based on the detected pressure detected when the fuel pumping period does not overlap with the injection period, so that the component (disturbance) due to fuel pumping is not added. The estimation can be executed based on the pressure, and as a result, the estimation accuracy can be improved.

  The fourth configuration is applied to a fuel injection system of a multi-cylinder internal combustion engine including a plurality of the fuel injection valves, and the fuel pressure sensor is provided for each of the plurality of fuel injection valves. Pressure-feeding fluctuation waveform acquisition means is provided for acquiring a fluctuation waveform that appears in the detected pressure of the fuel pressure sensor corresponding to a non-injection cylinder among multi-cylinders in which injection is sequentially performed, and that is caused by fuel pumping from the fuel pump to the pressure accumulating vessel. The first and second injection amount estimation means change the fuel pressure sensor corresponding to the injection cylinder when estimating the fuel injection amount in the injection cylinder when the fuel pumping period overlaps with the injection period. The estimation is performed based on a fluctuation waveform obtained by subtracting a fluctuation waveform component acquired by the pumping fluctuation waveform acquisition means from a waveform.

  According to this, a fluctuation waveform (fuel pumping component as a disturbance) generated by fuel pumping is acquired from the detected pressure of the fuel pressure sensor corresponding to the non-injection cylinder, and the fuel pumping is performed from the fluctuation waveform of the fuel pressure sensor corresponding to the injection cylinder. Since the estimation is performed based on the fluctuation waveform obtained by subtracting the components, the first and second injection amount estimation means estimate the fuel injection amount even when the fuel pumping period overlaps the injection period. Can do.

  In the fifth configuration, the detected pressure of the fuel pressure sensor detected at the time when the start of injection is commanded by the injection command signal commanding fuel injection (for example, at the time t1 in FIG. 5A), The detected pressure before the start of the injection used by the injection amount estimating means is used. Further, in the sixth configuration, the detected pressure of the fuel pressure sensor detected at the time when the start of injection is commanded by the injection command signal related to the next injection (for example, at time t3 in FIG. 5A), The detected pressure after the end of the injection used by the injection amount estimating means is used.

  Since the pulsation of the detected pressure is small at each of these time points t1 and t3, the values of the detected pressure before the start of injection and the detected pressure after the end of injection used for the estimation by the second injection amount estimating means can be obtained with high accuracy. it can. Therefore, the pressure difference used for the estimation by the detected second injection amount estimating means can be acquired with high accuracy, and the estimation by the second injection amount estimating means can be accurately performed.

The seventh configuration is applied to a fuel injection system capable of performing multi-stage injection in which multiple injections are performed from the same fuel injection valve per combustion cycle,
The first injection amount estimation means estimates a fuel injection amount for each injection stage of the multi-stage injection based on a fluctuation waveform that varies with each injection;
The second injection amount estimation means is configured to perform one combustion cycle based on a pressure difference between a detected pressure before the start of injection related to the first injection stage and a detected pressure after the end of injection related to the last injection stage of the multistage injection. Per unit of fuel injection,
The total amount of injection amounts related to the injection other than the main injection with the largest injection amount among the multi-stage injections among the injection amounts estimated by the first injection amount estimation means (for example, Q1 + Q2 + Q4 in FIG. 7), Main injection amount estimating means for estimating the injection amount (for example, Q3 in FIG. 7) related to the main injection by subtracting from the fuel injection amount per combustion cycle estimated by the second injection amount estimating means;
The injection amount calculation means is based on the injection amount related to the main injection among the injection amounts estimated by the first injection amount estimation means and the injection amount estimated by the main injection amount estimation means. A main injection amount related to the main injection is calculated.

  By the way, when calculating the injection amount of each injection stage when performing multi-stage injection, both estimations by the first and second injection quantity estimating means are performed for each of the plurality of injection stages and based on both estimation results. If an attempt is made to calculate the fuel injection amount, the estimation process becomes complicated and the processing load required for both estimations is large. Specifically, it is necessary to acquire the pressure difference used for the estimation of the second injection amount estimating means for each of the plurality of injection stages, and the processing of the injection amount calculating means based on both estimation results is performed for each of the injection stages. Will be required. Accordingly, the seventh configuration is a configuration for simplifying the estimation process and reducing the processing load by simply calculating the injection amount when multistage injection is performed.

  That is, in the seventh configuration, the fuel injection amount is estimated for each injection stage by the first injection amount estimating means. Since the injection amount is small in the injection other than the main injection, the error amount due to the estimation error is small with respect to the entire injection amount. Therefore, for the injection other than the main injection, the estimation result by the first injection amount estimation unit is regarded as a true value without performing the estimation by the second injection amount estimation unit. On the other hand, for the main injection, the main injection amount is calculated based on the estimation result by the main injection amount estimation unit using the estimation result of the second injection amount estimation unit and the estimation result by the first injection amount estimation unit. That is, the main injection amount estimating means calculates the total fuel injection amount related to the injection other than the main injection estimated by the first injection amount estimating means, and the fuel injection amount per combustion cycle estimated by the second injection amount estimating means. By subtracting from, the injection amount related to the main injection is estimated.

  As described above, according to the seventh configuration, the detected pressure before the start of injection related to the first injection stage and the detection after the end of injection related to the last injection stage are detected for the pressure difference used for the estimation by the second injection amount estimating means. Since only the pressure difference with the pressure needs to be acquired, the acquisition process can be simplified and the processing load can be reduced. Further, since the processing by the injection amount calculation means for calculating the fuel injection amount based on both estimation results of the first and second injection amount estimation means has only to be executed for the main injection, the processing by the injection amount calculation means Simplification and reduction of processing burden can be achieved. Moreover, for the main injection, the injection amount is calculated based on both estimation results in the same manner as in the first configuration, so that the injection amount (injection state) can be detected with high accuracy.

  In the eighth configuration, the injection rate calculating means calculates a transition waveform of the main injection rate related to the main injection based on a fluctuation waveform that varies with the main injection, and the injection rate correcting means includes the main injection rate. The transition of the main injection rate so that the main injection amount calculated as the integral value of the transition waveform (for example, the area indicated by the hatched portion S3 in FIG. 7) approaches the main injection amount calculated by the injection amount calculating means. It is characterized by correcting the waveform.

  According to this, in addition to the calculation of the main injection amount, it is possible to newly provide a fuel injection state detection device having a function of calculating a transition waveform of the main injection rate. In addition, since the transition waveform of the main injection rate is corrected so as to approach the main injection amount calculated by the injection amount calculation means, a highly accurate transition waveform can be acquired.

  In the ninth configuration, the fuel pressure sensor detected at the time when the start of injection related to the first injection stage is instructed by an injection command signal instructing multistage injection of fuel (for example, at time t10 in FIG. 6A). The detected pressure is the detected pressure before the injection start used by the second injection amount estimating means. In the tenth configuration, the detected pressure of the fuel pressure sensor detected at the time when the start of injection related to the first injection stage is commanded by the injection command signal related to the next multi-stage injection is sent to the second injection amount estimating means. The detected pressure after the end of the injection is used.

  Since the pulsation of the detected pressure is small at each time point t10, the values of the detected pressure before the start of injection and the detected pressure after the end of injection used for estimation by the second injection amount estimating means can be obtained with high accuracy. Therefore, the pressure difference used for the estimation by the detected second injection amount estimating means can be acquired with high accuracy, and the estimation by the second injection amount estimating means can be accurately performed.

In invention of Claim 1,
The pressure of the fuel that is arranged on the side closer to the injection hole with respect to the pressure accumulation container in the fuel passage from the pressure accumulation container to the injection hole of the fuel injection valve, and fluctuates with fuel injection from the injection hole A fuel pressure sensor for detecting
An injection start / end timing estimation means for estimating an injection start timing and an injection end timing based on a fluctuation waveform generated with fuel injection out of the pressure detected by the fuel pressure sensor;
Injection amount estimating means for estimating a fuel injection amount based on a pressure difference between a detected pressure before the start of injection and a detected pressure after the end of injection among the detected pressures;
Injection rate calculation means for calculating a transition waveform of the fuel injection rate based on the injection start time estimated by the injection start end time estimation means, the injection end timing, and the fuel injection amount estimated by the injection amount estimation means;
It is characterized by providing.

  According to this, since the fuel pressure sensor is arranged on the side closer to the injection hole with respect to the pressure accumulating container, the pressure fluctuation in the injection hole can be detected before being attenuated in the pressure accumulating container. Therefore, since the actual change in the injection amount can be accurately detected as the fluctuation waveform of the detected pressure, the injection start timing and the injection end timing can be estimated based on the detected fluctuation waveform (injection start / end timing estimation means).

  Here, a transition waveform of the fuel injection rate can be calculated based on the maximum drop amount Pβ in addition to the estimation result (injection start / end timing). However, as described above, since the maximum drop amount Pβ has a large detection variation, the above method cannot accurately calculate the injection rate transition waveform. Therefore, the present inventors, when calculating the injection rate estimation waveform, estimate the fuel injection amount based on the pressure difference between the detected pressure before the start of injection and the detected pressure after the end of injection (injection amount estimating means), and the estimation Recalling that the injection rate transition waveform is calculated (injection rate calculating means) based on the result and the previously estimated injection start / end timing. According to this, since the influence on the transition waveform calculation result by the detection variation of the maximum drop amount Pβ can be reduced, the injection rate transition waveform (injection state) can be detected with high accuracy.

  As described above, according to the present invention, since the fuel pressure sensor is arranged on the side closer to the injection hole with respect to the pressure accumulating vessel, a change (injection state) in the amount of fuel actually injected is detected as a fluctuation waveform of the detected pressure In addition, the injection rate transition waveform (injection state) can be detected with high accuracy, and a fuel injection state detection device that has never been available can be newly provided. Therefore, if the fuel injection system is controlled using the detection result, the fuel injection system can be controlled with high accuracy.

In invention of Claim 2,
Applied to a fuel injection system capable of performing multi-stage injection in which multiple injections are performed from the same fuel injection valve per combustion cycle;
The injection start / end timing estimation means estimates an injection start timing and an injection end timing for the main injection having the largest injection amount in the multi-stage injection;
The injection amount estimating means is based on a pressure difference between a detected pressure before the start of injection related to the first injection stage and a detected pressure after the end of injection related to the last injection stage of the multistage injection. Estimate the fuel injection amount,
A non-main injection amount estimating means for estimating a fuel injection amount based on a fluctuation waveform of the detected pressure that fluctuates with each injection for each injection stage other than the main injection;
By subtracting the total amount of each injection amount estimated by the non-main injection amount estimation means (for example, Q1 + Q2 + Q4 in FIG. 7) from the fuel injection amount per combustion cycle estimated by the injection amount estimation means, A main injection amount estimating means for estimating an injection amount related to the main injection (for example, Q3 in FIG. 7);
The fuel injection rate calculation means is a fuel injection related to the main injection based on the injection start timing estimated by the injection start / end timing estimation means, the injection end timing, and the main injection amount estimated by the main injection amount estimation means. A rate transition waveform is calculated.

  Here, since the injection amount (Q1, Q2, Q4) other than the main injection amount is smaller than the entire injection amount per combustion cycle, the estimation error of the total amount (Q1 + Q2 + Q4) gives the estimation result of the main injection amount. The impact is small. Further, since the fuel injection amount per combustion cycle is estimated based on the pressure difference without using the maximum drop amount Pβ having a large detection variation, the fuel injection amount per combustion cycle is estimated based on the fluctuation waveform. The estimation accuracy can be increased compared to the case. Therefore, the main injection amount (Q3) estimated by subtracting the total amount (Q1 + Q2 + Q4) of each injection amount from the fuel injection amount per combustion cycle estimated in this way is estimated with high accuracy.

  Therefore, since the main injection rate transition waveform is calculated based on the main injection amount, the injection start timing, and the injection end timing estimated with high accuracy in this way, the main injection rate transition waveform (injection state) is detected with high accuracy. Can do.

  According to a third aspect of the present invention, the fuel pressure sensor is attached to the fuel injection valve. Therefore, the attachment position of the fuel pressure sensor is closer to the injection hole of the fuel injection valve than the case where the fuel pressure sensor is attached to the pipe connecting the pressure accumulating container and the fuel injection valve. Therefore, the pressure fluctuation at the injection hole can be detected more accurately as compared with the case where the pressure fluctuation after the pressure fluctuation at the injection hole is attenuated by the pipe is detected.

  As described above, when the fuel pressure sensor is attached to the fuel injection valve, the invention according to claim 4 is attached to the fuel inlet of the fuel injection valve, and the invention according to claim 5 is characterized in that the fuel injection sensor is installed inside the fuel injection valve. A fuel pressure is detected in the internal fuel passage from the fuel inlet of the fuel injection valve to the injection hole.

  In the case where the fuel pressure sensor is attached to the fuel inlet as described above, the fuel pressure sensor attachment structure can be simplified as compared with the case where the fuel pressure sensor is attached inside the fuel injection valve. On the other hand, when installed inside the fuel injection valve, the fuel pressure sensor is installed closer to the injection hole of the fuel injection valve than when installed at the fuel inlet, so that the pressure fluctuation at the injection hole is more accurately detected. Can be detected.

  In a sixth aspect of the present invention, the fuel passage from the pressure accumulator vessel to the fuel inlet of the fuel injection valve is provided with an orifice for attenuating the pressure pulsation of the fuel in the pressure accumulator vessel, and the fuel pressure sensor It is arrange | positioned in the fuel flow downstream of an orifice, It is characterized by the above-mentioned. Here, when a fuel pressure sensor is arranged on the upstream side of the orifice, the pressure fluctuation after the pressure fluctuation at the injection hole is attenuated by the orifice is detected. On the other hand, according to the invention described in claim 6, since the fuel pressure sensor is arranged on the downstream side of the orifice, the pressure fluctuation in the state before being attenuated by the orifice can be detected, and the pressure fluctuation in the injection hole can be detected. It can be detected more accurately.

The block diagram which shows the outline of the fuel-injection system to which the fuel-injection-state detection apparatus which concerns on 1st Embodiment was applied. 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 1st Embodiment. The flowchart which shows the process sequence of fuel injection amount detection and fuel injection rate estimation which concern on 1st Embodiment. The time chart at the time of single stage injection execution which shows the relationship between the fluctuation waveform of the detected pressure by the fuel pressure sensor of FIG. 1, and an injection rate transition waveform. The figure which shows the correction example of the injection rate transition waveform shown in FIG. The time chart at the time of multistage injection execution which shows the relationship between the fluctuation waveform of the detected pressure by the fuel pressure sensor of FIG. 1, and an injection rate transition waveform. The time chart explaining the process which calculates the injection rate transition waveform at the time of a pump overlap regarding 3rd Embodiment.

  Hereinafter, embodiments embodying a fuel injection device and a fuel injection system will be described with reference to the drawings. In addition, the apparatus of each following embodiment is mounted in the common rail type fuel-injection system which targets the engine (internal combustion engine) for four-wheeled motor vehicles, for example, and high pressure is directly applied to the combustion chamber in the engine cylinder of a diesel engine. It is used when fuel (for example, light oil having an injection pressure of “1000 atm” or more) is supplied by injection (direct injection supply).

(First embodiment)
First, an outline of a common rail fuel injection system (vehicle engine system) according to the present embodiment will be described with reference to FIG. In this embodiment, a multi-cylinder (for example, in-line four-cylinder) four-stroke, reciprocating diesel engine (internal combustion 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 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.

  As shown in FIG. 1, this system is roughly divided into an ECU (fuel injection control means) 30 that is an electronic control unit, which takes in sensor outputs from various sensors, and a fuel supply system based on these sensor outputs. It is comprised so that the drive of each apparatus which comprises may be controlled. The ECU 30 controls the fuel pressure (measured by the fuel pressure sensor 20a) in the common rail 12 (pressure accumulating container) by adjusting the amount of current supplied to the intake regulating valve 11c and controlling the fuel discharge amount of the fuel pump 11 to a desired value. Feedback control (for example, PID control) to a target value (target fuel pressure). 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 order of the fuel tank 10, the fuel pump 11, 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 driven by a drive shaft 11d, and 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. It is configured. The amount of fuel pumped to the high-pressure pump 11a, and thus 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 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 the fuel sent to the pressurizing chamber is obtained by reciprocating predetermined plungers (for example, three plungers) in the axial direction by eccentric cams (not shown). The pump is configured to sequentially pump 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 (suppressed) to the common rail 12. The common rail 12 stores the fuel pumped from the fuel pump 11 in a high pressure state and distributes and supplies the fuel to the injectors 20 of the cylinders # 1 to # 4 through the high pressure pipes 14 provided for the respective cylinders. . 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 the fuel flowing 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) 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 (control chamber). Done. As shown in FIG. 2, the injector 20 is configured as a normally closed type fuel injection valve that is in a closed state when not energized.

  The high pressure fuel sent from the common rail 12 flows into the fuel inlet 22 formed in the housing 20e of the injector 20, a part of the high pressure fuel that flows in flows into the hydraulic chamber Cd, and the other flows into the injection hole 20f. It flows toward. 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 passes through the fuel discharge port 21 from the leak hole 24. Returned to the fuel tank 10.

  When fuel is injected from the injector 20, the control valve 23 is operated in accordance with the energized state (energized / non-energized) with respect to the solenoid 20b constituting the two-way solenoid valve. The pressure of 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). ) Is opened and closed in the middle thereof (specifically, a tapered seat surface on which the needle valve 20c is seated or separated 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. When the pulse is turned on (or off), the needle valve 20c is lifted up to open the injection hole 20f, and when the pulse is turned off (or on), the needle valve 20c is lifted down to close the injection hole 20f.

  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 opening the leak hole 24 by operating the control valve 23 by energizing the solenoid 20b. Thereby, 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, the operation of the needle valve 20c that opens and closes the injection hole 20f is controlled by adjusting the fuel pressure in the hydraulic chamber Cd by the opening and closing operation of the control valve 23.

  In this way, the injector 20 opens and closes the injector 20 by opening and closing (opening / closing) the fuel supply passage 25 to the injection hole 20f based on a predetermined reciprocation within the valve body (housing 20e). And a needle valve 20c for closing the valve. In the non-driving state, the needle valve 20c is displaced to the closing side by a force constantly applied to the valve closing side (extension force by the spring 20d), and in the driving state, driving force is applied. As a result, 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) at the fuel inlet 22 at any time. Specifically, the output of the fuel pressure sensor 20a can detect (measure) the fluctuation waveform 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 fluctuation 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, 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. Further, an accelerator sensor 44 that outputs an electric signal corresponding to the state (displacement amount) of the accelerator pedal is provided to detect the amount of operation (depression amount) of the accelerator pedal by the driver.

  In such a system, the ECU 30 is a part that functions as the fuel injection control means 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 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. An EEPROM as a data storage memory, a backup RAM (a memory that is constantly powered by a backup power source such as an in-vehicle battery after the main power supply of the ECU 30 is stopped), and the like. 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. 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. 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.

  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. In the series of processes shown in these drawings, a program stored in the ROM is basically executed by the ECU 30.

  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 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) (required torque calculated from the accelerator operation amount or the like, which corresponds to the engine load at that time).

  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. More specifically, for example, an optimum injection pattern (adapted value) is obtained in advance for the assumed range of the predetermined parameter (step S11) and 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 injection control map is corrected based on a separately updated correction coefficient (for example, stored in the EEPROM in the ECU 30) (for example, “set value = value on the map / correction coefficient”). To obtain an injection command signal for the injector 20 corresponding to the injection pattern to be injected at that time. The correction coefficient (strictly, a predetermined coefficient among a plurality of types of coefficients) 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 (the number of injection stages, etc.) of the injection pattern may be used, or several elements of these injection patterns may be used. Alternatively (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 (command signal output means), the drive of the injector 20 is controlled based on the command value (injection command signal) (specifically, the injection command signal is output to the injector 20). Then, with the drive control of the injector 20, the series of processes in FIG.

  Next, the process of detecting the fuel injection amount from the injector 20 and estimating the fuel injection rate will be described with reference to FIG. A series of processes shown in FIG. 4 is executed at a predetermined cycle (for example, a calculation cycle performed by the CPU described above) or at predetermined crank angles. In addition, ECU30 which performs this process is corresponded to a fuel-injection state detection apparatus.

  First, in step S21, the output value (detected pressure) of the fuel pressure sensor 20a is captured. 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 output to the injector 20 in step S13 of FIG. 3, and when the command signal is turned on, the solenoid 20b is activated to open the injection hole 20f. That is, the injection start is commanded by the pulse-on timing t1 of the injection command signal, and the injection end is commanded by the pulse-off timing t2. Therefore, the injection amount Q is controlled by controlling the valve opening time Tq of the injection hole 20f by the pulse-on period (injection command period) of the command signal. FIG. 5 (b) shows a change (transition) in the fuel injection rate from the injection hole 20f caused by the injection command, and FIG. 5 (c) shows an output value of the fuel pressure sensor 20a (a change caused by the change in the injection rate). (Detection pressure) change (fluctuation waveform) is shown.

  The ECU 30 detects the output value of the fuel pressure sensor 20a by a subroutine process different from the process of FIG. 4. In the subroutine process, the output value of the fuel pressure sensor 20a is detected, and the locus of the pressure transition waveform by the sensor output is detected. Data are sequentially acquired at intervals (an interval shorter than the processing cycle of FIG. 4) as short as the (trajectory illustrated in FIG. 5C) is drawn. Specifically, sensor outputs are sequentially acquired at intervals shorter than 50 μsec (more desirably 20 μsec).

  Since the fluctuation of the detected pressure of the fuel pressure sensor 20a and the change of the injection rate have a correlation described below, the transition waveform of the injection rate can be estimated from the fluctuation 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 of 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 ends, the increase in the detected pressure stops at the change point P3.

  As described above, by detecting the change points P1 and P3 among the fluctuations in the detected pressure 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 estimated. can do. Further, based on the correlation between the change in the detected pressure and the change in the injection rate described below, the change in the injection rate can be estimated from the change in the detected pressure.

  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 obtained by detecting the pressure decrease rate Pα, the pressure increase rate rate Pγ, and the pressure decrease rate Pβ from the fluctuation of the detected pressure by the fuel pressure sensor 20a. Can be estimated. As described above, various states R1, R3, Rα, Rβ, and Rγ of the injection rate can be estimated. Therefore, the change (transition waveform) of the fuel injection rate shown in FIG. 5B can be estimated.

  Further, 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 estimated by calculating the pressure integrated value from the fluctuation of the detected pressure by the fuel pressure sensor 20a.

  Returning to the description of FIG. 4, the processing contents in steps S22 to S28 after step S21 are different between when multistage injection is performed and when single stage injection is performed. Hereinafter, first, the processing content when the single-stage injection is executed will be described with reference to FIG. 5, and then the processing content when the multi-stage injection is executed will be described with reference to FIG. In subsequent steps S22 to S28, the fluctuation waveform of the fuel pressure sensor 20a corresponding to the injection cylinder among the multiple cylinders in which injection and non-injection are sequentially executed is used.

  Further, as described above, since the plunger pump is adopted as the high-pressure pump 11a, the pulsation due to the pumping is generated in the pressure of the fuel pumped from the high-pressure pump 11a to the common rail 12. In the present embodiment, among the fluctuation waveforms acquired for each of the plurality of fuel pressure sensors 20a, the fluctuation waveforms acquired when the fuel pumping period from the high pressure pump 11a to the common rail 12 does not overlap with the injection period from the injection hole 20f. The subsequent steps S22 to S28 are executed.

<When single-stage injection is performed>
In step S22 following step S21 described above, the appearance times of the change points P1 and P3 are detected from the fluctuation waveform acquired in step S21. Specifically, the first-order differential value of the fluctuation waveform is calculated, and the occurrence of the change point P1 is detected when the differential value first exceeds the threshold after the pulse-on timing t1 of the injection command. It is. Further, after the appearance of the change point P1, when the differential value becomes a stable state that fluctuates within the threshold value, the change point P3 appears when the differential value finally falls below the threshold value before the stable state. Is preferably detected.

  In subsequent step S23, the pressure decrease amount Pβ is detected from the fluctuation waveform acquired in step S21. Specifically, the pressure drop amount Pβ is detected by subtracting the detected pressure at the time of the change point P1 from the peak value of the detected pressure at the change points P1 to P3 of the fluctuation waveform.

  In subsequent step S24 (injection rate calculating means), the injection rate increase start time R1 (actual injection start time) and decrease end time R3 (actual injection end time) are estimated based on the detection results P1 and P2 in step S22. Further, the injection rate increase amount Rβ is estimated based on the detection result Pβ in step S23. Then, a transition waveform of the injection rate as shown in FIG. 5B is calculated based on at least these estimated values R1, R3, and Rβ. In addition to these estimated values R1, R3, and Rβ, values such as R2, Rα, and Rγ are estimated as described above, and these estimated values R2, Rα, and Rγ are used for calculating the injection rate transition waveform. It may be.

  In subsequent step S25 (first injection amount estimating means), the area S is calculated by integrating the injection rate transition waveform calculated in step S24 in the interval from R1 to R3. Then, the area S is set as a first estimated value of the injection amount.

  In subsequent step S26 (second injection amount estimating means), a pressure difference ΔP between the detected pressure before the start of injection and the detected pressure after the end of injection is calculated based on the fluctuation waveform of the detected pressure acquired in step S21. Specifically, a pressure difference ΔP between the detected pressure at the injection start command time t1 based on the injection command signal and the detected pressure at the injection start command time t3 based on the injection command signal related to the next injection is detected. Then, an injection amount (second estimated value) is calculated based on the pressure difference ΔP. Specifically, the injection amount is calculated by multiplying the pressure difference ΔP by a predetermined coefficient K.

  In subsequent step S27 (injection amount calculating means), an injection amount finally used for control is calculated based on the first estimated value calculated in step S25 and the second estimated value calculated in step S26. Specifically, the difference between the first estimated value and the second estimated value is regarded as an estimation error of the first estimated value, and the first estimated value is corrected according to the difference. For example, a correction amount is calculated by multiplying the difference by a predetermined coefficient (preferably a value smaller than 1), and the correction is performed by adding the correction amount to a first estimated value. Moreover, it is good also considering the average value of a 1st and 2nd estimated value as the injection amount as a final detection result.

  In subsequent step S28 (injection rate correcting means), the transition waveform of the injection rate calculated in step S24 is corrected based on the injection amount calculated in step S27. Specifically, the injection rate transition waveform calculated in step S24 is corrected so that the area S (first estimated value) calculated in step S24 matches the injection amount calculated in step S27. As described above, the detected pressure value has a particularly large variation in the maximum drop amount Pβ. Therefore, it is desirable to correct the transition waveform so as to match the corrected injection amount by correcting the injection rate increase amount Rβ. For example, when the injection rate transition waveform calculated as indicated by the solid line L1 in FIG. 6 is corrected so that the injection amount increases, it is desirable to correct the injection rate increase amount Rβ as indicated by the dotted line L2.

  In addition, as shown by the alternate long and short dash line L3, the transition waveform may be corrected to match the corrected injection amount by correcting the holding time of the injection rate peak value R2, or the injection rate increase amount Rβ and the peak value may be corrected. The transition waveform may be corrected so as to match the corrected injection amount by correcting both the holding times of R2. However, since the detection accuracy is higher at the detected pressure change points P1 and P3 than the maximum drop amount Pβ, it is desirable not to correct the actual injection start timing R1 and the actual injection end timing R3.

  As described above, the series of processes in FIG. 4 is completed, and the fuel injection amount corrected in step S27 and the injection rate transition waveform corrected in step S28 are the above-described injection control map used in step S11 in FIG. Is used for updating (learning).

<When performing multi-stage injection>
The fluctuation waveform of the detected pressure at the time of single-stage injection is in the form shown in FIG. 5 (c), while that in multi-stage injection is in the form shown in FIG. 7 (c). In the example shown in FIG. 7, 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. , P12, P22, P32, and P42 indicate pressure drop peak points for each injection stage, and P13, P23, P33, and P43 change with the end of injection in each injection stage. Indicates the change point that appears in the waveform. In addition, areas S1, S2, S3, and S4 indicated by oblique lines in FIG. 7B correspond to the injection amounts Q1, Q2, Q3, and Q4 of the respective injection stages.

  In the case of multi-stage injection shown in FIG. 7, in step S22, the appearance timing of the change points P11, P13, P21, P23, P31, P33, P41, and P43 for each injection stage is determined from the fluctuation waveform acquired in step S21. The detection is performed in the same manner as in the case of single stage injection. In subsequent step S23, pressure drop amounts Pβ1, Pβ2, Pβ3, and Pβ4 for each injection stage are detected from the fluctuation waveform acquired in step S21 by the same method as in the case of single stage injection. In subsequent step S24, a transition waveform of the injection rate as shown in FIG. 7B is calculated for each injection stage based on the detection results in steps S22 and S23.

  In the following step S25, the injection amount related to each injection stage is calculated by calculating the areas S1 to S4 related to each injection stage based on the injection rate transition waveform calculated in step S24 by the same method as in the case of single stage injection. Q1 to Q4 are estimated. Of these estimated injection amounts Q1 to Q4, the main injection amount Q3 corresponds to the first estimated value.

  In subsequent step S26, a pressure difference ΔP between the detected pressure before the start of injection and the detected pressure after the end of injection is calculated based on the fluctuation waveform of the detected pressure acquired in step S21. Specifically, a pressure difference ΔP between the detected pressure at the pilot injection start command time t11 based on the injection command signal and the detected pressure at the injection start command time t51 based on the injection command signal related to the next injection is detected. Then, a total injection amount injected per combustion cycle is calculated based on the pressure difference ΔP. Specifically, the total injection amount is calculated by multiplying the pressure difference ΔP by a predetermined coefficient K.

  Further, in step S26 (main injection amount estimating means), the total amount Q1 + Q2 + Q4 of the injection amount related to the injection other than the main injection estimated in step S25 is subtracted from the total injection amount calculated based on the pressure difference ΔP as described above. Thus, the injection amount Q3 related to the main injection is estimated. The main injection amount Q3 estimated in this way corresponds to the second estimated value.

  In subsequent step S27, based on the first estimated value calculated in step S25 and the second estimated value calculated in step S26, the main injection amount finally used for control is the same as in the case of single-stage injection. Calculate by the method. In the subsequent step S28, the transition waveform of the portion related to the main injection in the transition waveform of the injection rate calculated in step S24 is based on the main injection amount calculated in step S27, and the same method as in the case of single-stage injection. Correct with.

  As described above, according to the present embodiment, since the fuel pressure sensor 20a is disposed on the side closer to the injection hole 20f with respect to the common rail 12, the pressure fluctuation in the injection hole 20f is detected before the common rail 12 attenuates. Can do. Therefore, since the actual change in the injection amount can be accurately detected as the fluctuation waveform of the detected pressure, the fuel injection amount can be estimated based on the detected fluctuation waveform (first injection amount estimation means: S25), before and after the start of injection. The fuel injection amount can be estimated based on the pressure difference ΔP of the detected pressure (second injection amount estimating means: S26).

  According to the present embodiment, the injection amount Q is estimated by two different methods S25 and S26 as described above, and the injection amount is calculated based on the obtained first and second estimated values. Therefore, compared with the case where the injection amount is calculated based on one of the estimation results, the influence of the detection variation of the maximum drop amount Pβ which is a concern when the injection amount is large can be reduced. Therefore, the injection amount can be detected with high accuracy, and as a result, the injection rate transition waveform based on the injection amount detected with high accuracy can be detected with high accuracy.

  Further, according to the present embodiment, using the fluctuation waveform acquired when the fuel pumping period from the high-pressure pump 11a to the common rail 12 does not overlap with the injection period from the injection hole 20f, the steps S22 to S22 in FIG. Since the process of S28 is executed, the injection rate transition waveform can be estimated based on the detected pressure to which the component (disturbance) due to fuel pumping is not added, and as a result, the estimation accuracy can be improved.

  Further, according to the present embodiment, the pressure difference ΔP between the detected pressure at the injection start command time t1 and the detected pressure at the injection start command time t3 related to the next injection is used in the second injection amount estimating means S26. It is used as. At these time points t1 and t3, since the pulsation of the detected pressure is small and stable, the pressure difference ΔP used in the second injection amount estimating means S26 can be obtained with high accuracy, and eventually by the second injection amount estimating means S26. Estimation can be performed with high accuracy.

  Further, in this embodiment, since the fuel pressure sensor 20a is attached to the injector 20, the attachment position of the fuel pressure sensor 20a is injected as compared with the case where the fuel pressure sensor 20a is attached to the high-pressure pipe 14 that connects the common rail 12 and the injector 20. The position is close to the hole 20f. 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.

(Second Embodiment)
In the first embodiment, the injection amount Q is estimated by two different methods S25 and S26, and the injection rate transition waveform is calculated using the injection amount calculated based on the obtained first and second estimated values. Calculated. On the other hand, in this embodiment, one estimation is abolished and the transition waveform of the injection rate is calculated based on the other estimated value. Hereinafter, it will be described more specifically by dividing into single-stage injection and multi-stage injection.

<When single-stage injection is performed>
In the present embodiment, first, by executing the same processing (injection start / end timing estimation means) as steps S21 and S22 shown in FIG. 4, the appearance times (injection start timing R1 and injection end timing R3) of the change points P1 and P3 are obtained. ). Next, the fuel injection amount Q is estimated based on the pressure difference ΔP shown in FIG. 5 by executing the same processing (injection amount estimation means) as step S26 shown in FIG.

  Next, a transition waveform of the fuel injection rate is calculated based on the injection start timing R1, the injection end timing R3, and the fuel injection amount Q obtained by the above processing (injection rate calculating means). For example, the injection rate is calculated by dividing the injection amount Q by the injection period from R1 to R3, and the transition waveform is calculated so that the injection rate during the injection period changes with the injection rate obtained by the division. Is given as a specific example. The transition waveform in this case is a rectangular waveform that changes at the injection rate by the division from the injection start timing R1 to the injection end timing R3.

  Another specific example is calculating the transition waveform so that the injection rate obtained by the division has a peak value. The transition waveform in this case is a waveform similar to FIG. 5B in which the injection rate by the division changes to the peak value from the injection start timing R1 to the injection end timing R3.

<When performing multi-stage injection>
When multi-stage injection is performed, the injection start timing and the injection end timing for each injection stage are estimated by executing the same processing as steps S21 and S22 of FIG. Next, by performing the same process as step S26 shown in FIG. 4, the total injection quantity injected per combustion cycle is calculated based on the pressure difference ΔP shown in FIG. 7C.

  Next, processing similar to steps S23 and S24 in FIG. 4 is executed for each injection stage other than the main injection, thereby calculating an injection rate transition waveform relating to each injection stage other than the main injection. Next, based on these transition waveforms, areas S1, S2, and S4 related to the injection stages other than the main injection are calculated. That is, each injection amount Q1, Q2, Q4 other than the main injection is calculated (non-main injection amount estimating means). Next, the injection amount Q3 related to the main injection is estimated by subtracting the total amount Q1 + Q2 + Q4 of these calculated values from the total injection amount calculated based on the pressure difference ΔP (main injection amount estimating means).

  Next, based on the main injection start timing, the main injection end timing, and the main injection amount Q3 obtained by the above-described processing, a transition waveform of the main fuel injection rate is calculated by the same method as in the case of single stage injection. As described above, the present embodiment also exhibits the same effects as those of the first embodiment.

(Third embodiment)
In the first embodiment, steps S22 to S28 in FIG. 4 are performed using the fluctuation waveform acquired when the fuel pumping period from the high pressure pump 11a to the common rail 12 does not overlap with the injection period from the injection hole 20f. Processing is being executed. On the other hand, in the present embodiment, in addition to calculating the injection rate transition waveform at the time of non-overlap, the injection rate transition waveform can be calculated even at the time of overlap.

  Hereinafter, the process which calculates the injection rate transition waveform at the time of the pump overlap implement | achieved by this embodiment is demonstrated using FIG. FIG. 8A shows the transition of the injection command signal for the injector 20, FIG. 8B shows the transition of the injection rate, and FIG. 8C shows the transition of the detected pressure of the fuel pressure sensor 20a for the injection cylinder (variation during injection pumping). (D) shows the transition of the detected pressure of the fuel pressure sensor 20a for the non-injection cylinder (fluctuation waveform during non-injection pumping), and (e) shows the pressure value corresponding to the pump pumping component. ing.

  In addition, in (c) and (d), the fluctuation waveform shown by the alternate long and short dash lines L11 and L13 is the transition of the fuel pressure when there is no influence of the pumping component (when the pumping component is zero). The fluctuation waveform L10 at the time of injection pumping in (c) is a waveform when the fuel injection by the injector 20 and the fuel pumping by the fuel pump 11 are performed in duplicate. This is a waveform in which a decreasing component (a component indicated by a one-dot chain line L11) and a rising component (a component that increases in conjunction with the pumping component shown in (e)) generated by fuel pumping are combined. On the other hand, the fluctuation waveform at the time of non-injection pumping indicated by the solid line L12 in (d) rises in conjunction with the rising component (pushing component shown in (e)) that occurs with fuel pumping because the injector 20 is not injecting. This is a waveform in a state where only the component that appears) appears.

  In the present embodiment, first, a fluctuation waveform (that is, a waveform indicated by a solid line L12) as a pump pressure component that appears in the detected pressure of the fuel pressure sensor 20a corresponding to the non-injection cylinder is acquired (pressure fluctuation fluctuation acquisition means). Next, a fluctuation waveform (a waveform shown by a clogged solid line L10) of the detected pressure of the fuel pressure sensor 20a corresponding to the injection cylinder when the fuel pumping period overlaps with the injection period is acquired.

  Next, the fluctuation waveform shown by the solid line L11 is calculated by subtracting the fluctuation waveform L12 (pump pumping component) of the fuel pressure sensor 20a corresponding to the non-injection cylinder from the obtained fluctuation waveform L10. When there are a plurality of fuel pressure sensors 20a corresponding to the non-injection cylinders, an average value is calculated for the fluctuation waveform of each fuel pressure sensor 20a corresponding to the non-injection cylinder, and the waveform based on the average value is calculated from the fluctuation waveform L10. The fluctuation waveform L11 may be calculated by subtraction. And the process of step S22-S28 of FIG. 4 is performed using the fluctuation waveform L11 calculated in this way. As described above, the injection rate transition waveform (see FIG. 8B) when the pumps overlap can be calculated.

(Other embodiments)
The above embodiments may be implemented with the following modifications. Moreover, it is not limited to the description content of the said embodiment, You may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  In the first embodiment, the pressure difference ΔP between the injection start command times t1 and t11 and the injection start command times t3 and t51 related to the next injection is used in the estimation of the second injection amount estimating means S26. The pressure difference between the start point and end point of the injectable range Tb (injectable crank angle) exemplified in (1) may be used for the estimation. Or you may use for the said estimation the pressure difference between the present time of change point P1, P11 and the present time of change point P3, P43.

  In the first embodiment, as the fluctuation waveform used in steps S22 to S28 in FIG. 4, the fluctuation waveform acquired when the fuel pumping period does not overlap with the injection period is used. In the case where a pressure reducing valve is installed in the fuel supply path, the fluctuation waveform acquired when the pressure reducing valve is in operation and the fuel pressure is not reduced and when the pressure reducing valve is not in operation and when the fuel pressure does not overlap may be used. . According to this, since the estimation of the injection rate transition waveform can be performed based on the detected pressure to which the decompression component (disturbance) due to the decompression valve operation is not added, the estimation accuracy can be improved.

  -In attaching the fuel pressure sensor 20a to the injector 20, in the said embodiment, although the fuel pressure sensor 20a is attached to the fuel inflow port 22 of the injector 20, as shown to the dashed-dotted line 200a in FIG. The sensor 200a may be assembled to detect the fuel pressure in the internal fuel passage 25 from the fuel inlet 22 to the injection hole 20f.

  And when attaching to the fuel inflow port 22 as mentioned above, the attachment structure of the fuel pressure sensor 20a can be simplified compared with the case where it attaches 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.

  -Between the common rail 12 and the high voltage | pressure piping 14, you may provide the flow volume restriction | limiting means which restrict | limits the flow volume of the fuel which flows into the high voltage | pressure piping 14 from the common rail 12. FIG. This flow restricting means functions to close the flow path when an excessive fuel outflow occurs due to fuel leakage due to damage to the high-pressure pipe 14 or the injector 20, and for example, closes the flow path at an excessive flow rate. As a specific example, a valve element such as a ball that operates in a continuous manner is used. Note that a flow damper in which the orifice 12a (fuel pulsation reducing means) and the flow rate limiting means are integrated may be employed.

  In addition to the configuration in which the fuel pressure sensor 20a is disposed on the downstream side of the fuel flow of the orifice and the flow restriction means, the fuel pressure sensor 20a may be arranged on the downstream side of at least one of the orifice and the flow restriction means.

  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 a pressure leak from the leak hole 24 or the like, for example, a direct acting injector (for example, a direct acting piezo injector that has been developed in recent years) or the like that does not involve the hydraulic chamber Cd for transmitting driving power is used. You can also. When a direct acting injector is used, the injection rate can be easily controlled.

  -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 gasoline engine is equipped with a delivery pipe that stores fuel (gasoline) in a high-pressure state. 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. The apparatus and system are not limited to a fuel injection valve that directly injects fuel into a cylinder, but can also be applied to a fuel injection valve that injects fuel into an intake passage or an exhaust passage of an engine.

  DESCRIPTION OF SYMBOLS 12 ... Common rail (pressure accumulation container), 20 ... Injector (fuel injection valve), 20a, 200a ... Fuel pressure sensor, 20f ... Injection hole, S24 ... Injection rate calculation means, S25 ... First injection amount estimation means, S26 ... Second injection Amount estimation means, main injection amount estimation means, S27 ... injection amount calculation means, S28 ... injection rate correction means.

Claims (6)

A fuel injection state detection device applied to a fuel injection system that injects fuel accumulated in a pressure accumulator from a fuel injection valve,
The fuel passage from the pressure accumulating container to the injection hole of the fuel injection valve is disposed on the side closer to the injection hole with respect to the pressure accumulating container, and the fuel pressure that fluctuates with the fuel injection from the injection hole. A fuel pressure sensor to detect,
An injection start / end timing estimation means for estimating an injection start timing and an injection end timing based on a fluctuation waveform caused by fuel injection out of the pressure detected by the fuel pressure sensor;
An injection amount estimating means for estimating a fuel injection amount based on a pressure difference between a detected pressure before the start of injection and a detected pressure after the end of injection among the detected pressures;
An injection rate calculating means for calculating a transition waveform of a fuel injection rate based on the injection start timing, the injection end timing estimated by the injection start end timing estimating means, and the fuel injection amount estimated by the injection amount estimating means;
A fuel injection state detection device comprising: Applied to a fuel injection system capable of performing multi-stage injection in which multiple injections are performed from the same fuel injection valve per combustion cycle,
The injection start / end timing estimation means estimates an injection start timing and an injection end timing for the main injection having the largest injection amount in the multi-stage injection,
The injection amount estimation means is a fuel per combustion cycle based on a pressure difference between a detected pressure before the start of injection related to the first injection stage and a detected pressure after the end of injection related to the last injection stage of the multistage injection. Estimate the injection amount,
Non-main injection amount estimation means for estimating the fuel injection amount based on the fluctuation waveform of the detected pressure that fluctuates with each injection for each injection stage other than the main injection,
An injection amount related to the main injection is estimated by subtracting the total amount of each injection amount estimated by the non-main injection amount estimation unit from the fuel injection amount per combustion cycle estimated by the injection amount estimation unit. Main injection amount estimating means for
The injection rate calculating means is a fuel injection rate related to the main injection based on the injection start timing estimated by the injection start / end timing estimating means, the injection end timing, and the main injection amount estimated by the main injection amount estimating means. The fuel injection state detection device according to claim 1, wherein a transition waveform is calculated.   The fuel injection state detection device according to claim 1, wherein the fuel pressure sensor is attached to the fuel injection valve.   The fuel injection state detection device according to claim 3, wherein the fuel pressure sensor is attached to a fuel inlet of the fuel injection valve.   The fuel pressure sensor is attached to the inside of the fuel injection valve, and is configured to detect a fuel pressure in an internal fuel passage from the fuel inlet of the fuel injection valve to the injection hole. The fuel injection state detection device according to claim 3. The fuel passage from the pressure accumulating vessel to the fuel inlet of the fuel injection valve is provided with an orifice that attenuates the pressure pulsation of the fuel in the common rail,
6. The fuel injection state detection device according to claim 1, wherein the fuel pressure sensor is disposed on the downstream side of the fuel flow of the orifice.

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