JP5293765B2 - Fuel injection state estimation device - Google Patents

Abstract

A first curve obtaining unit receives a fuel injection pressure curve and a fuel non-injection pressure curve related to the fuel injection states of a fuel injector (10-1). A transmission time calculation unit calculates the transmission time required till a change in the fuel pressure, based on the phase difference between both the pressure curves. A detecting unit detects the fuel injection state in the fuel injector (10-3), based on a fuel non-injection curve received by a second curve obtaining unit, and the calculated transmission time. The fuel injection pressure curve obtained by the first curve obtaining unit, represents the relationship between a change of pressure due to fuel injection by the first fuel injector, which is detected by the first fuel pressure sensor (22), and the detection time. The fuel non-injection pressure curve represents a relationship between a change of pressure due to fuel injection by the first fuel injector, which is detected by the second fuel pressure sensor (20), and a detection time. A transmission time calculation unit calculates the transmission time required till a change in the fuel pressure, based on the phase difference between both the pressure curves. The second curve obtaining unit receives the fuel non-injection curve that represents the relationship between a change of pressure due to fuel injection by the third fuel injector, which is detected by the first fuel pressure sensor or the second fuel pressure sensor, and the pick-up timing. A detecting unit detects the fuel injection state in the third fuel injector, based on the fuel non-injection curve received by the second curve obtaining unit, and the calculated transmission time.

Description

  The present invention relates to a fuel injection state estimation device for estimating an injection state such as a fuel injection start timing, an injection end timing, and an injection abnormality occurrence in a multi-cylinder internal combustion engine.

  In Patent Documents 1 to 3 and the like, a pressure change (injection cylinder waveform) caused by fuel injection is detected by detecting the pressure of the fuel supplied to the fuel injection valve with a fuel pressure sensor. An invention for calculating the fuel injection state based on this is disclosed. Specific examples of the injection state include an injection start timing, an injection end timing, an injection abnormality, and the like described below.

  That is, paying attention to the fact that there is a high correlation between the pressure drop start time and the injection start time that occur as a result of the start of injection, the injection start time (injection state) is calculated based on the pressure drop start time detected from the injection cylinder waveform. In addition, paying attention to the fact that the correlation between the pressure rise end time and the injection end time generated with the end of injection is high, the injection end time (injection state) is calculated based on the pressure rise end time detected from the injection cylinder waveform. Then, by performing feedback control of the operation of the fuel injection valve based on the injection state calculated in this way, the injection control can be performed with high accuracy so that the injection state becomes a desired state.

  In addition, when the pressure drop start timing and the pressure rise end timing described above are greatly deviated from the expected timing from the time when the command signal is output to the fuel injection valve, an abnormality in which the injection cannot be started or an abnormality in which the injection cannot be ended It can be diagnosed as a state (injection state).

JP 2009-103063 A JP 2010-3004 A JP 2010-223184 A

  However, when the above-described conventional technology is applied to a multi-cylinder engine, a fuel pressure sensor is provided for each of the plurality of fuel injection valves, and a lot of fuel pressure sensors are required.

  Therefore, the present inventor has a specific fuel injection valve not equipped with a fuel pressure sensor (hereinafter referred to as “sensorless injection valve”) and another fuel injection valve equipped with a fuel pressure sensor (hereinafter referred to as “sensor-equipped injection valve”). In a multi-cylinder engine, estimation of the injection state at the sensorless injection valve based on the detection value of the fuel pressure sensor of the injection valve with sensor was studied as follows.

  That is, when fuel injection is started by the sensorless injection valve, the pulsation of the fuel pressure drop generated by the sensorless injection valve propagates to the sensored injection valve through the common rail (accumulated pressure distribution container). Therefore, when the time required for propagation (propagation time) has elapsed from the injection start timing at the sensorless injection valve, the pressure waveform detected by the fuel pressure sensor (non-injection cylinder waveform) has a change point at the start of pressure drop. appear. Similarly, when the fuel injection at the sensorless injection valve is terminated, the change point of the pressure increase end appears in the non-injection cylinder waveform when the propagation time has elapsed from the injection end timing at the sensorless injection valve. . Therefore, the injection state at the sensorless injection valve can be estimated based on the non-injection cylinder waveform, and the number of fuel pressure sensors can be reduced.

  However, the propagation time changes when physical quantities that affect the speed of sound in the fuel, such as the properties and temperature of the fuel being used, change. Therefore, the inventors of the present invention cannot accurately estimate the injection state at the sensorless injection valve from the non-injection cylinder waveform as described above based on a predetermined propagation time set in advance. It became clear by examination.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to enable accurate estimation of the fuel injection state in the fuel injection valve targeted for reduction in reducing the number of fuel pressure sensors. Another object of the present invention is to provide a fuel injection state estimating device.

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

  In the first aspect of the invention, the first fuel injection valve provided in the first cylinder of the internal combustion engine, the second fuel injection valve provided in the second cylinder, and the third fuel injection valve provided in the third cylinder. A pressure accumulation container for distributing the accumulated high-pressure fuel to each of the first fuel injection valve, the second fuel injection valve, and the third fuel injection valve; and a first accumulator provided in the first fuel injection valve It is assumed that the present invention is applied to a fuel injection system including a first fuel pressure sensor and a second fuel pressure sensor provided in the second fuel injection valve.

  An injection cylinder waveform representing a relationship between a pressure change detected by the first fuel pressure sensor at the time of fuel injection at the first fuel injection valve and a detection time thereof, and at the time of fuel injection at the first fuel injection valve A first waveform acquisition means for acquiring a non-injection cylinder waveform representing a relationship between a pressure change detected by the second fuel pressure sensor and a detection time thereof; and the injection cylinder acquired by the first waveform acquisition means Based on the phase difference between the waveform and the non-injection cylinder waveform, a propagation time for calculating the propagation time required for the fuel pressure change generated in the first fuel injection valve to propagate to the second fuel injection valve through the pressure accumulation distribution container is calculated. Non-injection air for estimation representing the relationship between the time calculation means, the pressure change detected by the first fuel pressure sensor or the second fuel pressure sensor at the time of fuel injection by the third fuel injection valve, and the detection time Based on the second waveform acquisition means for acquiring a waveform, the non-injection cylinder waveform for estimation acquired by the second waveform acquisition means, and the propagation time calculated by the propagation time calculation means, the third fuel Estimating means for estimating the fuel injection state at the injection valve.

  In short, at the time of fuel injection at the first fuel injection valve, an injection cylinder waveform by the first fuel pressure sensor and a non-injection cylinder waveform by the second fuel pressure sensor are acquired. Based on the phase difference between the two waveforms, the propagation time required for the fuel pressure change to propagate from the first fuel injection valve to the second fuel injection valve is calculated. Then, at the time of fuel injection at the third fuel injection valve, an estimation non-injection cylinder waveform by the first fuel pressure sensor or the second fuel pressure sensor is acquired, and based on the estimation non-injection cylinder waveform and the propagation time, the third A fuel injection state (for example, injection start timing, injection end timing, etc.) at the fuel injection valve is estimated.

  For this reason, even if the fuel property or fuel temperature actually used changes and the propagation time changes, the actual propagation time is detected by two fuel pressure sensors, and the detected value (propagation time) is used for estimation. Since the injection state at the third fuel injection valve (sensorless injection valve) is estimated from the non-injection cylinder waveform, the injection state can be accurately estimated. As described above, according to the above-described invention, the injection state at the third fuel injection valve can be accurately estimated without requiring the mounting of the fuel pressure sensor on the third fuel injection valve.

  Specific examples of the “injection state” estimated by the estimation means include time and time described below. That is, the fuel injection start timing from the third fuel injection valve, the fuel injection end timing, the injection period (corresponding to the injection amount) calculated from these start timing and end timing, and the injection rate (injection amount per unit time) are The time when the maximum is reached, the time when the valve closing operation is started, the time when the injection rate starts to decrease, the time from when the start of injection is commanded until the time when each time is reached, the time when the end of injection is commanded, Time to reach, etc.

  Specific examples of the “phase difference” include the amount of time shift described below. That is, the pressure drop start time P1 in the injection cylinder waveform generated when the injection at the first fuel injection valve starts, and the pressure drop start time in the non-injection cylinder waveform generated when the injection starts at the first fuel injection valve The amount of deviation from P1u (see FIG. 6). Further, the pressure rise end time P5 in the injection cylinder waveform generated when the injection at the first fuel injection valve is ended, and the pressure increase end in the non-injection cylinder waveform generated when the injection at the first fuel injection valve is ended. This is the amount of deviation from time P5u (see FIG. 6).

  Further, the pressure drop end time P2 (see FIG. 2 (c)) in the injection cylinder waveform generated when the injection rate (injection amount per unit time) at the first fuel injection valve is maximized, This is the amount of deviation from the pressure drop end time in the non-injection cylinder waveform caused by the maximum injection rate at one fuel injection valve. Further, the pressure increase start time P3 (see FIG. 2C) in the injection cylinder waveform generated when the injection rate at the first fuel injection valve starts to decrease, and the injection rate at the first fuel injection valve Is the amount of deviation from the pressure rise start time in the non-injection cylinder waveform caused by the start of the decrease.

  According to a second aspect of the present invention, a fuel path length from the first fuel injection valve to the second fuel injection valve through the pressure accumulation distribution container is a first path length, and the pressure accumulation from the third fuel injection valve. In the case where the fuel path length from the distribution container to the first fuel injection valve or the second fuel injection valve is the second path length, the first path length and the second path length are the same. It is characterized by being.

  In the following description, the waveform representing the relationship between the change in the pressure of the fuel generated in the third fuel injection valve at the time of fuel injection by the third fuel injection valve and the detection time is referred to as “estimation target waveform”. . Since the fuel pressure sensor is not mounted on the third fuel injection valve, the estimation target waveform (see FIG. 6B) cannot be directly detected.

  Here, if the fuel path length is different, the propagation time of the fuel pressure change is different. Accordingly, the fuel path length (first path length) from the first fuel injection valve to the second fuel injection valve and the first or second from the third fuel injection valve (sensorless injection valve) to be estimated. If the fuel path length up to the fuel injection valve (second path length) is different, the phase difference between the injection cylinder waveform and the non-injection cylinder waveform used for calculating the propagation time is the same as the estimation non-injection cylinder waveform. It differs from the phase difference from the estimation target waveform. Therefore, in this case, when estimating the injection state at the third fuel injection valve (sensorless injection valve) from the non-injection cylinder waveform for estimation using the propagation time calculated by the propagation time calculation means, the estimation accuracy is There is concern about getting worse.

  In the above invention in view of this point, since the first fuel path length and the second fuel path length are the same (see FIGS. 5 and 13), there is a concern that “the estimation accuracy is deteriorated” as described above. Can be eliminated.

  According to a third aspect of the present invention, a fuel path length from the first fuel injection valve to the second fuel injection valve through the pressure accumulation distribution container is defined as a first path length, and the pressure accumulation from the third fuel injection valve. In the case where the fuel path length from the distribution container to the first fuel injection valve or the second fuel injection valve is a second path length, and the first path length and the second path length are different, Storage means for storing, as path length information, a difference between the first path length and the second path length or a physical quantity correlated with the difference, and the estimation means includes the propagation time and the path length information. Based on the above, the estimation is performed.

  As described above, if the first path length is different from the second path length, the phase difference between the injection cylinder waveform and the non-injection cylinder waveform used for calculating the propagation time, the estimation non-injection cylinder waveform, and the estimation are estimated. Since the phase difference from the target waveform is different, there is a concern that the estimation accuracy of the injection state in the injection valve without sensor is deteriorated.

  In the above invention in view of this point, a difference between the first path length and the second path length or a physical quantity correlated with the difference is stored in advance as path length information, and the propagation time and the path length are stored. The estimation is performed based on the information. Therefore, for example, since the injection start time estimated based on the propagation time can be corrected according to the difference between the first path length and the second path length, the above-mentioned “estimation accuracy is degraded”. Can eliminate concerns. A specific example of the “physical quantity correlated with the difference” includes a deviation amount (corresponding to the correction value) between the propagation time in the first path length and the propagation time in the second path length. .

  In a fourth aspect of the invention, a first fuel injection valve provided in the first cylinder of the internal combustion engine, a second fuel injection valve provided in the second cylinder, a third fuel injection valve provided in the third cylinder, And the fourth fuel injection valve provided in the fourth cylinder, and the high pressure accumulated in each of the first fuel injection valve, the second fuel injection valve, the third fuel injection valve, and the fourth fuel injection valve It is assumed that the present invention is applied to a fuel injection system including a pressure accumulation container for distributing fuel and a fuel pressure sensor provided in the first fuel injection valve.

  Then, a pressure change detected by the fuel pressure sensor at the time of fuel injection at the second fuel injection valve is acquired as a second injection waveform, and detected by the fuel pressure sensor at the time of fuel injection by the third fuel injection valve. Waveform acquisition means is provided for acquiring a pressure change as a third injection waveform and acquiring a pressure change detected by the fuel pressure sensor as a fourth injection waveform when fuel is injected by the fourth fuel injection valve.

  Further, a second injection response time is calculated which is a time from when the second fuel injection valve is commanded to start or end the injection until the second injection waveform changes according to the command. Response time calculation unit for injection and response at the time of third injection which is a time from when the start or end of injection is commanded to the third fuel injection valve to when the waveform at the time of third injection changes according to the command The time from the time when the third injection response time calculating means for calculating the time and the fourth fuel injection valve are commanded to start or end the injection to the time when the fourth injection waveform changes according to the command. And a fourth injection response time calculating means for calculating a fourth injection response time.

  Further, based on the comparison of the second injection time response time, the third injection time response time, and the fourth injection time response time, the second fuel injection valve, the third fuel injection valve, and the fourth fuel injection An abnormality diagnosis means for diagnosing whether or not an abnormality has occurred in the fuel injection state at the valve is provided.

  The above invention uses the detection result of the fuel pressure sensor provided in the first fuel injection valve for abnormality diagnosis of the second to fourth fuel injection valves, so that the fuel pressure sensor is mounted on the second to fourth fuel injection valves. Is intended to be unnecessary. In addition, as a specific example of the abnormality, the valve body that opens and closes the nozzle hole of the fuel injection valve is in an abnormal state of poor sliding due to foreign matter biting or the like, or an actuator that opens the valve body May have deteriorated over time. When such an abnormality occurs, a response delay from the start of injection to the fuel injection valve until the start of injection, or a delay in response from the end of injection to the end of injection becomes longer. Abnormal fuel injection condition.

  Therefore, when such an abnormality occurs, the response time during injection becomes longer. However, since the propagation time changes when the fuel property, temperature, etc. change as described above, the response time at the time of the second injection and the response time at the time of the third injection may also become longer in this case. However, when the propagation time changes due to the fuel property or temperature, any of the second to fourth response times during injection should be longer. Therefore, if each of the second to fourth response times at the time of injection is compared and the difference is small, the abnormality should not occur even if the response time is long. On the other hand, if only one of the response times is significantly different from the other response times, the abnormality should have occurred in the fuel injection valve when the greatly different response time is detected.

  According to the above-mentioned invention in view of this point, it is diagnosed whether or not an abnormality has occurred in the fuel injection state in the second to fourth fuel injection valves based on the comparison of the response times during the second to fourth injections. Therefore, even if the fuel property or fuel temperature actually used changes and the propagation time changes, it is possible to accurately diagnose the presence or absence of abnormality in the second to fourth fuel injection valves. Therefore, it is possible to accurately diagnose the injection state (abnormality presence / absence) of these fuel injection valves without requiring the fuel pressure sensors to be mounted on the second to fourth fuel injection valves.

The figure which shows the outline of the fuel-injection system with which the fuel-injection-state estimation apparatus concerning 1st Embodiment of this invention is applied. The figure which shows the change of the injection rate and fuel pressure corresponding to an injection command signal. The block diagram which shows the outline | summarys, such as a setting of the injection command signal with respect to an injection valve with a sensor (# 2, # 3) in 1st Embodiment. The figure which shows the fuel pressure waveform Wa at the time of injection, the fuel pressure waveform Wu at the time of non-injection, and the injection waveform Wb. The figure which shows the propagation path along which a pressure change propagates from a predetermined injection valve to another injection valve. The figure explaining the method of calculating propagation time based on the waveform at the time of injection and the waveform at the time of non-injection in a 1st embodiment. The figure explaining the method of estimating the injection state of a sensorless injection valve based on the calculated propagation time and the non-injection waveform in the first embodiment. The block diagram which shows the outline | summarys, such as a setting of the injection command signal with respect to a sensorless injection valve (# 1, # 4) in 1st Embodiment. The flowchart which shows the calculation procedure of propagation time in 1st Embodiment. The flowchart which shows the calculation procedure of the injection rate parameter concerning a sensorless injection valve in 1st Embodiment. The figure which shows the propagation path in 2nd Embodiment of this invention. The figure which shows the propagation path in 3rd Embodiment of this invention. The figure which shows the propagation path in 4th Embodiment of this invention. The figure which shows the propagation path in 5th Embodiment of this invention. The flowchart which shows the abnormality diagnosis procedure of an injection valve in 5th Embodiment.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. The fuel injection state estimation device described below is mounted on a vehicle engine (internal combustion engine), and compresses the engine by injecting high-pressure fuel into a plurality of cylinders # 1 to # 4. A diesel engine that burns by self-ignition is assumed.

(First embodiment)
FIG. 1 is a schematic diagram showing a fuel injection valve 10 mounted on each cylinder of the engine, a fuel pressure sensor 22 mounted on each fuel injection valve 10, an ECU 30 as an electronic control device mounted on a vehicle, and the like. is there.

  First, an engine fuel injection system including the fuel injection valve 10 will be described. The fuel in the fuel tank 40 is pumped and stored in the common rail 42 (pressure accumulating container) by the fuel pump 41, and distributed and supplied to the fuel injection valves 10 (# 1 to # 4) of each cylinder. The plurality of fuel injection valves 10 (# 1 to # 4) sequentially inject fuel in a preset order. In this embodiment, it is assumed that injection is performed in the order of # 1 → # 3 → # 4 → # 2.

  In addition, since the plunger pump is used for the fuel pump 41, fuel is pumped in synchronism with the reciprocating motion of the plunger. Since the fuel pump 41 is driven by the crankshaft using the engine output as a driving source, the fuel is pumped from the fuel pump 41 a predetermined number of times during one combustion cycle.

  The fuel injection valve 10 includes a body 11, a needle-shaped valve body 12, an actuator 13, and the like described below. The body 11 forms a high-pressure passage 11a inside and a nozzle hole 11b for injecting fuel. The valve body 12 is accommodated in the body 11 and opens and closes the nozzle hole 11b.

  A back pressure chamber 11c for applying a back pressure to the valve body 12 is formed in the body 11, and the high pressure passage 11a and the low pressure passage 11d are connected to the back pressure chamber 11c. The communication state between the high pressure passage 11a and the low pressure passage 11d and the back pressure chamber 11c is switched by the control valve 14, and the actuator 13 such as an electromagnetic coil or a piezoelectric element is energized to push the control valve 14 downward in FIG. As a result, the back pressure chamber 11c communicates with the low pressure passage 11d and the fuel pressure in the back pressure chamber 11c decreases. As a result, the back pressure applied to the valve body 12 is lowered and the valve body 12 is lifted up (opening operation). Thereby, the seat surface 12a of the valve body 12 is separated from the seat surface of the body 11, and fuel is injected from the injection hole 11b.

  On the other hand, when the power supply to the actuator 13 is turned off and the control valve 14 is operated upward in FIG. 1, the back pressure chamber 11c communicates with the high pressure passage 11a and the fuel pressure in the back pressure chamber 11c increases. As a result, the back pressure applied to the valve body 12 increases and the valve body 12 is lifted down (closed valve operation). Thereby, the seat surface 12a of the valve body 12 is seated on the seat surface of the body 11, and the fuel injection from the injection hole 11b is stopped.

  Therefore, the ECU 30 controls the energization of the actuator 13 so that the opening / closing operation of the valve body 12 is controlled. Thereby, the high-pressure fuel supplied from the common rail 42 to the high-pressure passage 11 a is injected from the injection hole 11 b according to the opening / closing operation of the valve body 12.

  The fuel pressure sensors 22 are not mounted on all the fuel injection valves 10, but are mounted on at least two fuel injection valves 10. In short, the number of fuel pressure sensors 22 mounted is less than the number of fuel injection valves 10 and two or more. In the present embodiment, the fuel pressure sensor 22 is mounted on the # 2 and # 3 fuel injection valves 10 (sensorless injection valves), and the fuel pressure sensor 22 is mounted on the # 1 and # 4 fuel injection valves 10 (sensor injection valves). Is not installed.

  The sensor device 20 is mounted on each fuel injection valve 10 and includes a stem 21 (distortion body), a fuel pressure sensor 22, a fuel temperature sensor 23, a mold IC 24, and the like described below. The stem 21 is attached to the body 11, and the diaphragm portion 21a formed on the stem 21 is elastically deformed by receiving the pressure of the high-pressure fuel flowing through the high-pressure passage 11a. A fuel pressure sensor 22 constituted by a pressure sensor element is attached to the diaphragm portion 21a, and outputs a pressure detection signal to the ECU 30 in accordance with the amount of elastic deformation generated in the diaphragm portion 21a.

  Moreover, the fuel temperature sensor 23 comprised by the temperature sensor element is attached to the diaphragm part 21a. The temperature detected by the fuel temperature sensor 23 can be regarded as the temperature of the fuel in the branch passage. That is, it can be said that the sensor device 20 has a function of a fuel temperature sensor. However, this fuel temperature sensor 23 may be abolished in the implementation of the present invention.

  The mold IC 24 is formed by resin molding electronic components such as an amplification circuit that amplifies the detection signal output from the fuel pressure sensor 22 and the fuel temperature sensor 23 and a transmission circuit that transmits the detection signal. It is mounted on the injection valve 10. The mold IC 24 is electrically connected to the ECU 30, and the amplified detection signal is transmitted to the ECU 30.

  The ECU 30 calculates a target injection state (for example, the number of injection stages, the injection start timing, the injection end timing, the injection amount, etc.) based on the operation amount of the accelerator pedal, the engine load, the engine rotational speed NE, and the like. For example, the optimal injection state corresponding to the engine load and the engine speed is stored as an injection state map. Based on the current engine load and engine speed, the target injection state is calculated with reference to the injection state map. Then, the injection command signals t1, t2, and Tq (see FIG. 2A) corresponding to the calculated target injection state are set based on the injection rate parameters td, te, Rα, Rβ, and Rmax described in detail later, and the fuel By outputting to the injection valve 10, the operation of the fuel injection valve 10 is controlled.

  Next, an injection control method when fuel is injected from the sensor-equipped injection valve 10 (# 2, # 3) will be described below with reference to FIGS.

  For example, when fuel is injected by the # 2 cylinder fuel injection valve 10 (# 2), the fuel pressure generated by the injection based on the detected value of the fuel pressure sensor 22 (# 2) mounted on the sensor-equipped injection valve 10 Is detected as a fuel pressure waveform (see FIG. 2C). Then, the injection state is detected by calculating an injection rate waveform (see FIG. 2B) representing a change in the fuel injection amount per unit time based on the detected fuel pressure waveform. Then, while learning the injection rate parameters Rα, Rβ, and Rmax that specify the detected injection rate waveform (injection state), the correlation between the injection command signals (pulse-on timing t1, pulse-off timing t2, and pulse-on period Tq) and the injection state. The injection rate parameters td and te for specifying

  Specifically, in the fuel pressure waveform, a descending approximation line that approximates a descending waveform from the inflection point P1 at which the fuel pressure drop starts at the start of injection to the inflection point P2 at which the descent ends by a least square method or the like. Lα is calculated. Then, a time (a crossing time LBα between Lα and Bα) that is the reference value Bα in the descending approximate straight line Lα is calculated. Focusing on the fact that the intersection time LBα and the injection start time R1 are highly correlated, the injection start time R1 is calculated based on the intersection time LBα. For example, a timing that is a predetermined delay time Cα before the intersection timing LBα may be calculated as the injection start timing R1.

  In addition, a rising approximation line Lβ is calculated by approximating the rising waveform from the inflection point P3 where the fuel pressure rises at the end of injection to the inflection point P5 where the descent ends from the fuel pressure waveform by a least square method or the like. To do. Then, a time (intersection time LBβ between Lβ and Bβ) that is the reference value Bβ in the rising approximate straight line Lβ is calculated. Focusing on the fact that the intersection timing LBβ and the injection end timing R4 are highly correlated, the injection end timing R4 is calculated based on the intersection timing LBβ. For example, a timing that is a predetermined delay time Cβ before the intersection timing LBβ may be calculated as the injection end timing R4.

  Next, paying attention to the fact that the slope of the descending approximate line Lα and the slope of the injection rate increase are highly correlated, the slope of the straight line Rα indicating the increase in the injection rate waveform shown in FIG. Calculation is based on the slope of Lα. For example, the slope of Rα may be calculated by multiplying the slope of Lα by a predetermined coefficient. Similarly, since the slope of the rising approximate line Lβ and the slope of the injection rate decrease are highly correlated, the slope of the straight line Rβ indicating the decrease in injection in the injection rate waveform is calculated based on the slope of the rising approximate line Lβ.

  Next, based on the straight lines Rα and Rβ of the injection rate waveform, a timing (valve closing operation start timing R23) at which the valve body 12 starts lift-down in response to the command to end injection is calculated. Specifically, the intersection of both straight lines Rα and Rβ is calculated, and the intersection timing is calculated as the valve closing operation start timing R23. Further, a delay time (injection start delay time td) with respect to the injection start command timing t1 of the injection start timing R1 is calculated. Further, a delay time (valve closing start delay time te) with respect to the injection end command timing t2 of the valve closing operation start timing R23 is calculated.

  Further, the pressure corresponding to the intersection of the descending approximate straight line Lα and the ascending approximate straight line Lβ is calculated as the intersection pressure Pαβ, and a pressure difference ΔPγ between the reference pressure Pbase and the intersection pressure Pαβ, which will be described in detail later, is calculated. Focusing on the fact that the correlation with the maximum injection rate Rmax is high, the maximum injection rate Rmax is calculated based on the pressure difference ΔPγ. Specifically, the maximum injection rate Rmax is calculated by multiplying the pressure difference ΔPγ by the correlation coefficient Cγ. However, in the case of the small injection in which the pressure difference ΔPγ is less than the predetermined value ΔPγth, Rmax = ΔPγ × Cγ is set as described above, while in the case of the large injection in which ΔPγ ≧ ΔPγth, it is set in advance. The value (set value Rγ) is calculated as the maximum injection rate Rmax.

  Note that the “small injection” is assumed to be an injection in which the valve body 12 starts to be lifted down before the injection rate reaches Rγ, and fuel is throttled at the seat surface 12a to limit the injection amount. The injection rate when the engine is running is the maximum injection rate Rmax. On the other hand, the “large injection” is assumed to be an injection in which the valve body 12 starts to lift down after the injection rate reaches Rγ, and the injection amount is limited by the fuel being throttled at the injection hole 11b. The injection rate when the engine is running is the maximum injection rate Rmax. In short, when the injection command period Tq is sufficiently long and the valve opening state is continued even after reaching the maximum injection rate, the injection rate waveform shown in FIG. On the other hand, in the case of small injection that starts the valve closing operation before reaching the maximum injection rate, the injection rate waveform is a triangle.

  The set value Rγ which is the maximum injection rate Rmax at the time of large injection changes as the fuel injection valve 10 changes over time. For example, when aged deterioration such as deposits or the like deposits on the nozzle holes 11b and the injection amount decreases, the pressure drop amount ΔP shown in FIG. 2C decreases. Further, when the aging deterioration such that the seat surface 12a wears and the injection amount increases, the pressure drop amount ΔP increases. Note that the pressure drop amount ΔP is the amount of decrease in the detected pressure caused by the increase in the injection rate. For example, the pressure drop amount from the reference pressure Pbase to the inflection point P2 or the change from the inflection point P1. It is the amount of pressure drop to the bend point P2.

  Therefore, in the present embodiment, focusing on the fact that the maximum injection rate Rmax (set value Rγ) and the pressure drop amount ΔP during large injection are highly correlated, learning is performed by calculating the set value Rγ from the detection result of the pressure drop amount ΔP. To do. That is, the learned value of the maximum injection rate Rmax at the time of large injection corresponds to the learned value of the set value Rγ based on the pressure drop amount ΔP.

  As described above, the injection rate parameters td, te, Rα, Rβ, and Rmax can be calculated from the fuel pressure waveform. Based on the learned values of the injection rate parameters td, te, Rα, Rβ, and Rmax, an injection rate waveform (see FIG. 2B) corresponding to the injection command signal (see FIG. 2A) is calculated. be able to. Since the area of the injection rate waveform calculated in this way (see halftone dot hatching in FIG. 2B) corresponds to the injection amount, the injection amount can also be calculated based on the injection rate parameter.

  FIG. 3 is a block diagram showing an outline of learning of these injection rate parameters and setting of an injection command signal to be output to the fuel injection valves 10 of the # 2 and # 3 cylinders. Each means 31 and 32 functioning by the ECU 30 is shown in FIG. , 33 will be described below. The injection rate parameter calculation means 31 calculates injection rate parameters td, te, Rα, Rβ, Rmax based on the fuel pressure waveform detected by the fuel pressure sensor 22.

  The learning means 32 learns by updating the calculated injection rate parameter in the memory of the ECU 30. Since the injection rate parameter varies depending on the supply fuel pressure (pressure in the common rail 42) at that time, the injection rate parameter can be learned in association with the supply fuel pressure or a reference pressure Pbase (see FIG. 2C) described later. desirable. In the example of FIG. 3, the injection rate parameter value corresponding to the fuel pressure is stored in the injection rate parameter map M.

  The setting means 33 acquires an injection rate parameter (learned value) corresponding to the current fuel pressure from the injection rate parameter map M. And based on the acquired injection rate parameter, the injection command signals t1, t2, and Tq corresponding to the target injection state are set. The fuel pressure sensor 22 detects the fuel pressure waveform when the fuel injection valve 10 is operated in accordance with the injection command signal set in this way. Based on the detected fuel pressure waveform, the injection rate parameter calculation means 31 calculates the injection rate parameter td, te, Rα, Rβ, Rmax are calculated.

  In short, an actual injection state (that is, injection rate parameters td, te, Rα, Rβ, Rmax) with respect to the injection command signal is detected and learned, and an injection command signal corresponding to the target injection state is set based on the learned value. . Therefore, the injection command signal is feedback-controlled based on the actual injection state, and the fuel injection state can be controlled with high accuracy so that the actual injection state coincides with the target injection state even when the above-described aging deterioration proceeds. In particular, feedback control is performed so as to set the injection command period Tq based on the injection rate parameter so that the actual injection amount becomes the target injection amount, so that the actual injection amount is compensated to become the target injection amount.

  In the following description, a cylinder that is injecting fuel from the fuel injection valve 10 is an injection cylinder (front cylinder), and a cylinder that is not injecting fuel when the injection cylinder is injecting fuel is a non-injection cylinder (back cylinder). The fuel pressure sensor 22 corresponding to the injection cylinder is referred to as an injection fuel pressure sensor, and the fuel pressure sensor 22 corresponding to the non-injection cylinder is referred to as a non-injection fuel pressure sensor.

  The fuel pressure waveform Wa during injection, which is the fuel pressure waveform detected by the fuel pressure sensor during injection (see FIG. 4A), does not represent only the influence due to the injection, but is caused by the influence other than the injection exemplified below. It also includes waveform components. That is, when the fuel pump 41 that pumps the fuel in the fuel tank 40 to the common rail 42 pumps the fuel intermittently like a plunger pump, if pump pumping is performed during fuel injection, the pump pumping period The fuel pressure waveform Wa during the injection is a waveform in which the pressure is increased as a whole. That is, the injection fuel pressure waveform Wa (see FIG. 4 (a)) represents the injection waveform Wb (see FIG. 4 (c)), which is the fuel pressure waveform representing the fuel pressure change due to injection, and the fuel pressure increase due to pumping. It can be said that the fuel pressure waveform (see the solid line Wu ′ in FIG. 4B) is included.

  Even if such pump pumping is not performed during fuel injection, immediately after the fuel is injected, the fuel pressure in the entire injection system is reduced by that amount. Therefore, the fuel pressure waveform Wa at the time of injection becomes a waveform in which the pressure is lowered as a whole. That is, the injection fuel pressure waveform Wa includes a component of an injection waveform Wb that represents a change in fuel pressure due to injection and a component of a fuel pressure waveform that represents a decrease in the fuel pressure in the entire injection system (see the dotted line Wu in FIG. 4B). It can be said that is included.

  Therefore, in this embodiment, focusing on the fact that the non-injection fuel pressure waveform Wu ′ (Wu) detected by the non-injection cylinder sensor represents a change in the fuel pressure in the common rail (the fuel pressure in the entire injection system), the injection cylinder A process of calculating the injection waveform Wb by subtracting the non-injection fuel pressure waveform Wu ′ (Wu) from the non-injection cylinder sensor from the injection fuel pressure waveform Wa detected by the sensor is performed. The fuel pressure waveform shown in FIG. 2C is the injection waveform Wb.

  Further, when performing multi-stage injection, the pulsation Wc (see FIG. 2C) of the fuel pressure waveform applied to the previous stage injection is superimposed on the fuel pressure waveform Wa. In particular, when the interval with the pre-stage injection is short, the fuel pressure waveform Wa is greatly affected by the pulsation Wc. Therefore, it is desirable to calculate the injection waveform Wb by performing a process (undulation process) of subtracting the pulsation Wc from the fuel pressure waveform Wa in addition to the non-injection fuel pressure waveform Wu ′ (Wu).

  The injection control method for the sensor-equipped injection valve 10 (# 2, # 3) has been described above with reference to FIGS. 2 to 4. Next, the sensor-less injection valve 10 (# 1, # 4) will be described. The injection control method will be described with reference to FIGS.

  FIG. 5 is a schematic diagram showing a path through which fuel is supplied from the common rail 42 to each fuel injection valve 10 through the high-pressure pipe 42b. For example, when fuel injection is started by the sensorless injection valve 10 (# 1), the pulsation of the fuel pressure drop generated by the sensorless injection valve 10 (# 1) propagates to the common rail 42 through the high-pressure pipe 42b (# 1). After that, it further propagates to each injection valve through the other high-pressure pipes 42b (# 2 to # 4). Among these, a propagation path propagating to the injection valve with sensor 10 (# 2) is indicated by a symbol K12 in FIG. That is, the propagation path K12 is a path such as the sensorless injection valve 10 (# 1) → the high pressure pipe 42b (# 1) → the common rail 42 → the high pressure pipe 42b (# 2) → the sensor-equipped injection valve 10 (# 2). .

  Similarly, the symbol K23 in FIG. 5 indicates the injection valve with sensor 10 (# 2) → the high pressure pipe 42b (# 2) → the common rail 42 → the high pressure pipe 42b (# 3) → the injection valve 10 with sensor (# 3). Represents the route. In FIG. 5, a symbol K43 indicates a route such as the sensorless injection valve 10 (# 4) → the high pressure pipe 42b (# 4) → the common rail 42 → the high pressure pipe 42b (# 3) → the injection valve 10 with sensor (# 3). Represents.

  The lengths of the high-pressure pipes 42b (# 1 to # 4) connected to the injection valves 10 (# 1 to # 4) are all the same. These high-pressure pipes 42b (# 1 to # 4) are connected to the common rail 42 at the same pitch. In other words, in the common rail 42, the interval L12 between the connecting portion of the high pressure pipe 42b (# 1) and the connecting portion of the high pressure pipe 42b (# 2), and the connecting portion of the high pressure pipe 42b (# 2) and the high pressure pipe 42b ( The distance L23 between the connecting portions of # 3) is the same as the distance L34 between the connecting portion of the high-pressure pipe 42b (# 3) and the connecting portion of the high-pressure pipe 42b (# 4). Accordingly, the lengths of the paths K12, K23, and K43 described above are all the same.

  Incidentally, the injection valve with sensor 10 (# 2) corresponds to the first fuel injection valve, the injection valve with sensor 10 (# 3) corresponds to the second fuel injection valve, and the injection valve 10 without sensor (# 1). This corresponds to the third fuel injection valve. The fuel pressure sensor 22 (# 2) mounted on the sensor-equipped injection valve 10 (# 2) corresponds to a first fuel pressure sensor, and the fuel pressure sensor 22 (mounted on the sensor-equipped injection valve 10 (# 3)) ( # 3) corresponds to the second fuel pressure sensor. The path length of the path K23 corresponds to the first path length, and the path length of the path K12 corresponds to the second path length.

  FIGS. 6A to 6C show an injection command signal, an injection fuel pressure waveform Wa (# 2), and a non-injection fuel pressure waveform Wu (#) when fuel is injected by the injection valve with sensor 10 (# 2). 3). In this case, the pulsation of the fuel pressure change shown in the fuel pressure waveform Wa (# 2) at the time of injection is detected by the fuel pressure sensor 22 of the sensor-equipped injection valve 10 (# 3) through the path 23.

  FIG. 6 also shows the relationship between the output time of the injection command signal, the detection time of the fuel pressure waveform Wa (# 2) during injection, and the detection time of the fuel pressure waveform Wu (# 3) during non-injection. That is, the inflection point P1 of the fuel pressure waveform Wa (# 2) at the time of injection appears at the time when the predetermined time C1 (C1 = td + Cα) has elapsed from the output time of the injection start command timing t1. Further, an inflection point P5 of the fuel pressure waveform Wa (# 2) at the time of injection appears at a time when a predetermined time C2 (C2 = teu + Cβu, or C2 = te + Cβu ′) has elapsed from the output time of the injection end command timing t2.

  And the inflection point of the non-injection fuel pressure waveform Wu (# 3) at the time when the time required for the fuel pressure change to propagate through the path K23 (propagation time tw) elapses from the appearance time of the inflection point P1. P1u appears. Further, the inflection point P5u of the non-injection fuel pressure waveform Wu (# 3) appears at the time when the propagation time tw has elapsed from the appearance time of the inflection point P5. The time difference between the appearance time of the inflection point P1 and the appearance time of the inflection point P1u, or the time difference between the appearance time of the inflection point P5 and the appearance time of the inflection point P5u corresponds to the “phase difference”. Incidentally, each of the waveforms Wa and Wu shown in FIGS. 4A and 4B has been corrected to eliminate the phase difference, thereby improving the accuracy of the above-described reverse processing.

  7A to 7C show an injection command signal, an injection fuel pressure waveform Wa (# 1), and a non-injection fuel pressure waveform Wu (#) when fuel is injected by the sensorless injection valve 10 (# 1). 2). In this case, the pulsation of the fuel pressure change shown in the fuel pressure waveform Wa (# 1) at the time of injection is detected by the fuel pressure sensor 22 of the sensor-equipped injection valve 10 (# 2) through the path 12. However, the injection fuel pressure waveform Wa (# 1) in this case cannot be detected.

  In FIG. 7, as in FIG. 6, the inflection point P1 of the fuel pressure waveform Wa (# 1) during injection is expected to appear at the time when the predetermined time C1 has elapsed from the output time of the injection start command timing t1. In addition, it is expected that the inflection point P5 of the fuel pressure waveform Wa (# 1) during injection will appear at the time when the predetermined time C2 has elapsed from the output time of the injection end command timing t2.

  The inflection point of the non-injection fuel pressure waveform Wu (# 2) is obtained at the time when the time required for the fuel pressure change to propagate through the path K12 (propagation time tw) elapses from the appearance time of the inflection point P1. P1u is expected to appear. Further, it is expected that the inflection point P5u of the non-injection fuel pressure waveform Wu (# 2) appears at the time when the propagation time tw has elapsed from the appearance time of the inflection point P5. Here, since the route lengths of the route 23 and the route 12 are the same, the propagation time tw shown in FIG. 6 and the propagation time tw shown in FIG. 7 can be regarded as the same.

  In view of the above points, in the present embodiment, the propagation time tw shown in FIG. 6 is measured at the time of injection at the sensor-equipped injection valve 10 (# 2 or # 3). Then, at the time of injection at the sensorless injection valve 10 (# 1 or # 4), the appearance time of the inflection points P1u and P5u of the non-injection fuel pressure waveform Wu (# 2 or # 3) is detected, and from the detection time It is estimated that the time that has gone back the measured propagation time tw is the appearance time of the inflection points P1 and P5 applied to the sensorless injection valve 10. Based on this estimated time, an injection start time R1 and an injection end time R4 are calculated. For example, the injection start time R1 may be calculated as a time that is a predetermined delay time Cα before the estimated inflection point P1 appearance time. Further, a timing that is a predetermined delay time Cβu (see FIG. 2) from the estimated time of appearance of the inflection point P5 may be calculated as the injection end timing R4.

  6 and 7 show the non-injection waveform Wu when the pump is not pumped, corresponding to the symbol Wu in FIG. 4B. For the injection waveform Wu ′, the propagation time tw can be calculated, the appearance times of the inflection points P1u and P5u can be calculated, and the injection start timing R1 and the injection end timing R4 can be calculated in the same manner as described above.

  FIG. 8 shows calculation of propagation time tw, calculation of injection rate parameters td, te, learning, and fuel injection valve 10 for # 1, # 4 cylinders for sensorless injector 10 (# 1 or # 4). FIG. 2 is a block diagram showing an outline of setting of an injection command signal to be output to, and each means 34, 31a, 32a, 33a functioning by the ECU 30 will be described below.

  The propagation time calculation means 34 obtains the fuel pressure waveform Wa during injection and the fuel pressure waveform Wu during non-injection shown in FIGS. 6B and 6C at the time of fuel injection by the injection valve 10 with sensor (# 2 or # 3). . Then, the appearance time of the inflection point P1 and the inflection point P1u is detected from these waveforms Wa and Wu, and the propagation time tw is calculated (tw = P1u−P1). In this embodiment, P1u-P1 and P5u-P5 are considered to be the same, and detection of the appearance time of P5u-P5 is not performed.

  The injection rate parameter calculation means 31a acquires the non-injection fuel pressure waveform Wu (estimated non-injection cylinder waveform) shown in FIG. 7C when fuel is injected from the sensorless injection valve 10 (# 1 or # 4). . Further, the propagation time tw calculated by the propagation time calculating means 34 is acquired. Then, the appearance times of the inflection points P1u and P5u are detected from the waveform Wu, and the timings before the propagation time tw and the predetermined delay times Cα and Cβu from the detection time are set as the injection start timing R1 and the injection end timing R4. Calculate as Then, the time from the injection start command timing t1 to the injection start timing R1 is calculated as the injection start delay time td (injection rate parameter). Further, the time from the injection end command timing t2 to the injection end timing R4 is calculated as the injection end delay time teu (injection rate parameter) shown in FIG.

  Note that the time before the propagation time tw and the predetermined delay time Cβu ′ (see FIG. 2) from the appearance time of P5u is calculated as the valve closing operation start timing R23, and the valve closing operation start timing R23 from the injection end command timing t2. May be calculated as the valve closing start delay time te (injection rate parameter).

  In the learning means 32a, the injection rate parameters td and teu (or te) calculated by the injection rate parameter calculation means 31a are stored in the memory of the ECU 30 and learned. Since the injection rate parameter varies depending on the supply fuel pressure (pressure in the common rail 42) at that time, the injection rate parameter can be learned in association with the supply fuel pressure or a reference pressure Pbase (see FIG. 2C) described later. desirable. Further, learning may be performed in association with the fuel temperature based on the detection value of the fuel temperature sensor 23. In the example of FIG. 8, the injection rate parameter value corresponding to the fuel pressure is stored in the injection rate parameter map M.

  The setting means 33a acquires an injection rate parameter (learned value) corresponding to the current fuel pressure from the injection rate parameter map M. And based on the acquired injection rate parameter, the injection command signals t1, t2, and Tq corresponding to the target injection state are set. The fuel pressure sensor 22 detects the fuel pressure waveform when the fuel injection valve 10 is operated in accordance with the injection command signal set in this way. Based on the detected fuel pressure waveform, the injection rate parameter calculation means 31a uses the injection rate parameter td, teu (or te) is calculated.

  In short, an actual injection state (that is, injection rate parameters td, te) with respect to the injection command signal is detected and learned, and an injection command signal corresponding to the target injection state is set based on the learned value. Therefore, the injection command signal is feedback-controlled based on the actual injection state, and the fuel injection state can be controlled with high accuracy so that the actual injection state coincides with the target injection state even when the above-described aging deterioration proceeds. In particular, since the injection amount changes according to the injection command period Tq (that is, t1 and t2), the injection command period Tq is set based on the injection rate parameters td and te so that the actual injection amount becomes the target injection amount. By performing feedback control, compensation is performed so that the actual injection amount becomes the target injection amount.

  Next, the procedure for calculating the propagation time tw by the propagation time calculating means 34 will be described with reference to the flowchart of FIG. The process shown in FIG. 9 is executed each time fuel injection is performed once in the sensor-equipped injection valve 10 (# 2, # 3) by the microcomputer of the ECU 30.

  First, in step S10 (first waveform acquisition means) shown in FIG. 9, the fuel pressure waveform Wa during injection and the fuel pressure waveform Wu during non-injection are acquired from the two fuel pressure sensors 22, respectively. An injection waveform Wb (Wb = Wa−Wu) may be used instead of the fuel pressure waveform Wa during injection. Further, the non-injection fuel pressure waveform Wu may be a waveform at the time of pumping or a waveform at the time of non-pumping.

  In the subsequent step S11, the appearance time of the inflection point P1 (hereinafter referred to as the descent start time P1) is detected from the acquired injection waveform Wb (or Wa). In the subsequent step S12, the appearance time of the inflection point P1u (hereinafter referred to as the descent start time P1u) is detected from the acquired non-injection fuel pressure waveform Wu (or Wu ′). In the subsequent step S13 (propagation time calculation means), the propagation time tw (tw = P1u−P1) is calculated based on the detected descent start timings P1 and P1u. Since the propagation time tw varies depending on the properties and temperature of the fuel, it is desirable that the propagation time tw calculated at a predetermined cycle is sequentially updated and learned.

  Next, the procedure for calculating the injection rate parameters td and teu for the sensorless injection valve 10 (# 1, # 4) by the injection rate parameter calculation means 31a will be described with reference to the flowchart of FIG. Note that the process shown in FIG. 10 is executed each time fuel is injected into the sensorless injector 10 (# 1, # 4) by the microcomputer of the ECU 30.

  First, in step S20 (second waveform acquisition means) shown in FIG. 10, the non-injection fuel pressure waveform Wu (or Wu ′) is acquired from the fuel pressure sensor selected from the two fuel pressure sensors 22 as follows. That is, the path length between the selected fuel pressure sensor 22 and the fuel injection valve 10 that has commanded injection is the same as the path length of the two fuel pressure sensors 22 used in the process of FIG. 9 (that is, the path length of the path K23). Thus, the fuel pressure sensor 22 is selected. In the example of FIG. 5, when fuel is injected in the # 1 cylinder, the fuel pressure sensor 22 for the # 2 cylinder is selected and the path length of the path K12 is set. Further, when fuel is injected in the # 4 cylinder, the # 3 cylinder fuel pressure sensor 22 is selected to set the path length of the path K43.

  As shown in FIG. 5, in the case of a four-cylinder engine and four cylinders (fuel injection valves 10) arranged in a row, two injection valves 10 ( The fuel pressure sensor 22 may be mounted on # 2, # 3). When fuel is injected from the two sensorless injection valves 10 (# 1, # 4) located at both ends, the detected value of the fuel pressure sensor 22 of the sensor-equipped injection valve located next to the injected injection valve (during non-injection) If the waveform is acquired by step S20 of FIG. 10 and the injection rate parameter calculation means 31a of FIG. 8, the path length can be made the same as described above.

  In the subsequent step S21, the appearance time of the inflection point P1u (fall start time P1u) and the appearance time of the inflection point P5u (rise end time P5u) from the non-injection fuel pressure waveform Wu (or Wu ′) acquired in step S20. ) Is detected. In the subsequent step S22 (estimating means), the injection start timing R1 and the injection end timing R4 are determined based on the descent start timing P1u and the rise end timing P5u detected in step S21 and the propagation time tw calculated in the process of FIG. Estimate (R1 = P1u-tw-Cα, R4 = P5u-tw-Cβ).

  In the subsequent step S23, the injection start delay time td is calculated based on the injection start timing R1 and the injection start command timing t1 calculated in step S22 (td = R1-t1). Further, the injection end delay time teu is calculated based on the injection end timing R4 and the injection end command timing t2 calculated in step S22 (teu = R4-t2). In subsequent step S24, the injection rate parameters td and teu calculated in step S23 are stored in a map Ma (see FIG. 8) for learning.

  As described above, according to the present embodiment, the actual propagation time tw is detected by the two fuel pressure sensors 22 when fuel is injected from the sensor-equipped injection valve 10. At the time of fuel injection by the sensorless injector 10, the sensorless injector 10 is based on the non-injection fuel pressure waveform Wu (estimated non-injection cylinder waveform) acquired at the time of injection and the detected propagation time tw. The injection rate parameters such as the injection start delay time td, the valve closing start delay time te, and the injection end delay time teu are calculated. Therefore, even if the fuel property or fuel temperature actually used changes and the propagation time tw changes, the injection rate parameter (injection state) applied to the sensorless injection valve 10 based on the actually detected propagation time tw. Therefore, the injection rate parameter can be calculated accurately.

  Also, the length of the path K23 of the two fuel pressure sensors 22 for detecting the fuel pressure waveform Wa during injection and the fuel pressure waveform Wu during non-injection used for detecting the propagation time tw, and the fuel pressure sensor 22 used for calculating the injection state at the sensorless injection valve. The length of the path K12 from the sensorless injection valve to the sensorless injection valve is set to be the same. Therefore, the propagation time tw detected in the path K23 can be made the same as the propagation time when the injection is performed with the sensorless injection valve, so that the accuracy of the injection state calculation with the sensorless injection valve can be improved.

(Second Embodiment)
In the first embodiment, a 4-cylinder engine is targeted. In the present embodiment shown in FIG. 11, two fuel pressure sensors 22 are mounted for a 6-cylinder engine. In the example of FIG. 11, the length of the path K34 of the two fuel pressure sensors 22 that detects the fuel pressure waveform Wa during injection and the fuel pressure waveform Wu during non-injection used for detecting the propagation time tw, and the injection state calculation at the sensorless injection valve. The lengths of the paths K13, K24, K53, K64 from the fuel pressure sensor 22 to be used to the sensorless injection valve are not the same. However, the lengths of the paths K13, K24, K53, K64 are all set to be the same.

  In this embodiment, the lengths of the high-pressure pipes 42b (# 1 to # 6) connected to the injection valves 10 (# 1 to # 6) are all the same as in the first embodiment. is there. These high-pressure pipes 42b (# 1 to # 6) are connected to the common rail 42 at the same pitch.

  Further, in the present embodiment, the injection start timing R1 and the injection end timing R4 are calculated using the propagation time tw calculated in the process of FIG. 9 (R1 = P1u−tw × Cw−Cα, R4 = P5u−tw ×). Cw−Cβ) is calculated by multiplying the propagation time tw by a predetermined coefficient Cw (path length information) stored in advance in the memory (storage means) of the ECU 30. The coefficient Cw may use a ratio (for example, the length of the route K13 / the length of the route K34) representing a difference (difference) in the route length, or may be set based on a test result performed in advance. The value may be used.

  Also in the present embodiment, the injection rate parameter (injection state) applied to the sensorless injection valve 10 is calculated based on the actually detected propagation time tw in the same manner as in the first embodiment. Can be accurate. The lengths of the paths K13, K24, K53, and K64 from the fuel pressure sensor 22 used for calculating the injection state at the sensorless injection valve to the sensorless injection valve are all set to be the same. Therefore, the coefficient Cw used for calculating the injection state in the sensorless injection valve can be made the same for all the sensorless injection valves. Therefore, the calculation variation of the injection state which occurs between the sensorless injection valves can be suppressed. Moreover, the trouble of setting the coefficient Cw corresponding to each path length based on the execution of a test or the like can be reduced.

(Third embodiment)
In the present embodiment shown in FIG. 12, the length of the path 13 and the path 64 among the paths K13, K23, K54, and K64 from the fuel pressure sensor 22 to the sensorless injection valve used for calculating the injection state at the sensorless injection valve. Is different from the length of the path K34 of the two fuel pressure sensors 22 that detect the fuel pressure waveform Wa during injection and the fuel pressure waveform Wu during non-injection used for detecting the propagation time tw. However, the route 23 and the route 54 are set to be the same as the length of the route K34.

  And about the sensorless injection valve 10 (# 1, # 6) concerning the path | route 13 and the path | route 64, when calculating an injection state using the propagation time tw similarly to the said 2nd Embodiment, propagation time tw Is multiplied by a predetermined coefficient Cw. On the other hand, for the sensorless injection valve 10 (# 2, # 5) on the path 23 and the path 53, the injection state is calculated without using the coefficient Cw, as in the first embodiment.

  As described above, according to the present embodiment, for the sensorless injectors 10 (# 2, # 5) on the path 23 and the path 53, the lengths of the path 23 and the path 54 are the same as the length of the path K34. Therefore, the injection state can be calculated without using the coefficient Cw, and the calculation accuracy of the injection state for the sensorless injection valve 10 (# 2, # 5) can be improved.

(Fourth embodiment)
In the first to third embodiments, an in-line engine in which a plurality of cylinders (fuel injection valves 10) are arranged in a row is targeted, whereas in the present embodiment shown in FIG. 13, two common rails 42 are provided. It is intended for V-type engines or horizontally opposed engines. Two fuel pressure sensors 22 are mounted for each common rail 42.

  In the example of FIG. 13, the engine is an 8-cylinder engine, and four fuel injection valves 10 and two fuel pressure sensors 22 are mounted on one common rail 42. Similarly to the first embodiment, the lengths of the paths K12, K43, K56, K87 from the fuel pressure sensor 22 used for calculating the injection state at the sensorless injection valve to the sensorless injection valve and the propagation time tw are detected. The lengths of the paths K23 and K67 of the two fuel pressure sensors 22 that detect the fuel pressure waveform Wa during injection and the fuel pressure waveform Wu during non-injection used in the above are set to be the same.

  Therefore, also in the present embodiment, the injection rate parameter (injection state) applied to the sensorless injection valve 10 is calculated based on the actually detected propagation time tw in the same manner as in the first embodiment. Can be calculated accurately. The lengths of the paths K23 and K67 when detecting the propagation time tw and the lengths of the paths K12, K43, K56, and K87 from the fuel pressure sensor 22 used for calculating the injection state at the sensorless injection valve to the sensorless injection valve Are set to be the same. Therefore, the propagation time tw detected in the paths K23 and K67 can be made the same as the propagation time when the injection is performed with the sensorless injection valve, so that the accuracy of the injection state calculation with the sensorless injection valve can be improved.

(Fifth embodiment)
In each of the above embodiments, at least two fuel pressure sensors 22 are mounted. In the present embodiment, one fuel pressure sensor 22 may be provided as shown in FIG. The hardware configuration of the fuel injection system in this embodiment is the same as that of the first embodiment shown in FIG. 5 except that the # 3 cylinder fuel pressure sensor is eliminated.

  In the present embodiment, the response time tv (see FIG. 7) from the injection start command timing t1 to the sensorless injection valve until the detection waveform of the fuel pressure sensor 22 changes in accordance with the command is detected. Alternatively, the response time tv from the injection end command timing t2 to the sensorless injection valve to the change in the detection waveform of the fuel pressure sensor 22 accompanying the command is detected. Then, by comparing the response times tv12, tv32, tv42 when the injection is performed by each sensorless injection valve 10 (# 1, # 3, # 4), whether or not an abnormality has occurred in the sensorless injection valve 10 is determined. Diagnose.

  Hereinafter, the diagnosis procedure will be described with reference to the flowchart of FIG. Note that the process shown in FIG. 15 is repeatedly executed at a predetermined cycle by a microcomputer included in the ECU 30.

  First, in step S30 of FIG. 15, at the time of fuel injection from the # 1 cylinder sensorless injection valve 10 (corresponding to the second fuel injection valve), the sensorless injection valve 10 to # 2 cylinder sensored injection valve 10 ( The pressure change (that is, the non-injection waveform Wu shown in FIG. 7C) that has propagated to the first fuel injection valve is acquired. Then, the descent start timing P1u or the rise end timing P5u appearing in the non-injection waveform Wu (corresponding to the second injection waveform) is detected. Then, the time from the injection start command timing t1 to the descent start timing P1u or the time from the injection end command timing t2 to the rise end timing P5u is calculated as a response time t12 (corresponding to the second injection response time).

  Next, in step S31, the non-injection waveform Wu (corresponding to the third injection waveform) is acquired during fuel injection from the sensorless injection valve 10 (corresponding to the third fuel injection valve) of the # 3 cylinder. Then, the descent start timing P1u or the rise end timing P5u at which the non-injection waveform Wu appears is detected, and the response time t32 (corresponding to the third injection response time) is calculated in the same manner as in step S30. Next, in step S32, the non-injection waveform Wu (corresponding to the fourth injection waveform) is acquired during fuel injection from the sensorless injection valve 10 (corresponding to the fourth fuel injection valve) of the # 4 cylinder. Then, the descent start timing P1u or the rise end timing P5u at which the non-injection waveform Wu appears is detected, and the response time t42 (corresponding to the third injection response time) is calculated in the same manner as in step S30.

  Here, the pressure change propagation paths K12 and K32 for the response time t12 and the response time t32 have the same path length. On the other hand, the length of the propagation path K42 for the response time t42 is longer than the propagation paths K12 and K32. Therefore, in the next step S33, the response time t42 is corrected based on the difference in length. For example, the response time t42 is multiplied by a predetermined coefficient Cw (path length information) stored in advance in the memory (storage means) of the ECU 30. For the coefficient Cw, a ratio (for example, the length of the route K12 / the length of the route K42) representing a difference (difference) in the route length may be used, or set based on a test result performed in advance. The value may be used.

  Next, in step S34, the three response times t12, t32, and t42 calculated in steps S30, S31, and S33 are compared. Then, it is determined whether any one response time has a value significantly different from the other two response times. For example, an average of three response times is calculated, and a deviation from the average is calculated for each of the three response times t12, t32, and t42. If the deviation is larger than a predetermined value, it is determined that the corresponding response time is significantly different from the other two.

  If any of the three response times has a deviation equal to or greater than a predetermined value (S34: YES), the process proceeds to step S35, and the valve body 12 is selected for the injection valve corresponding to the response time. Diagnose that there is an abnormality that makes the responsiveness worse. On the other hand, if none of the response times has a deviation greater than or equal to the predetermined value (S34: NO), the process proceeds to step S36, and the responsiveness of the valve body 12 is normal for all the injection valves. Diagnose it.

  Each of the steps S30, S31, S32 corresponds to a second injection time response time calculation means, a third injection time response time calculation means, and a fourth injection time response time calculation means, and also corresponds to a waveform acquisition means. To do.

  As described above, according to the present embodiment, the fuel injection at any of the sensorless injection valves 10 (# 1, # 3, # 4) is performed by detecting and comparing the response times t12, t32, t42. Diagnose whether the condition is abnormal. Therefore, even if the fuel property or fuel temperature actually used changes and the propagation time changes, the presence or absence of abnormality in the sensorless injector 10 (# 1, # 3, # 4) can be accurately diagnosed. Therefore, by mounting the fuel pressure sensor 22 on at least one fuel injection valve 10 without mounting the fuel pressure sensor 22 on all the fuel injection valves 10, the injection state (abnormality presence / absence) of the sensorless injection valve can be accurately determined. Can be diagnosed.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows. Moreover, you may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  The propagation time calculated by the propagation time calculation unit 34 in FIG. 8 is learned in association with the temperature of the fuel, and the injection rate parameter calculation unit 31a calculates the injection rate parameter based on the learned value. Good.

  10 (# 2) ... 1st fuel injection valve, 10 (# 3) ... 2nd fuel injection valve, 10 (# 1) ... 3rd fuel injection valve, 22 (# 2) ... 1st fuel pressure sensor, 22 (# 3) ... second fuel pressure sensor, 42 ... common rail (accumulation distribution container), S10 ... first waveform acquisition means, S13, 34 ... propagation time calculation means, S20 ... second waveform acquisition means, S22, 31a ... Estimating means, S30 ... second injection response time calculating means (waveform acquiring means), S31 ... third injection response time calculating means (waveform acquiring means), S32 ... fourth injection response time calculating means (waveform acquiring means) , S34 ... abnormality diagnosis means.

Claims (4)

A first fuel injection valve provided in the first cylinder of the internal combustion engine, a second fuel injection valve provided in the second cylinder, and a third fuel injection valve provided in the third cylinder;
A pressure accumulation and distribution container for distributing the accumulated high-pressure fuel to each of the first fuel injection valve, the second fuel injection valve, and the third fuel injection valve;
A first fuel pressure sensor provided in the first fuel injection valve, and a second fuel pressure sensor provided in the second fuel injection valve;
Applied to a fuel injection system comprising:
An injection cylinder waveform representing a relationship between a change in pressure detected by the first fuel pressure sensor at the time of fuel injection at the first fuel injection valve and a detection time thereof, and the first time at the time of fuel injection at the first fuel injection valve. A first waveform acquisition means for acquiring a non-injection cylinder waveform representing a relationship between a pressure change detected by the two fuel pressure sensors and a detection time thereof;
Based on the phase difference between the injection cylinder waveform acquired by the first waveform acquisition means and the non-injection cylinder waveform, the fuel pressure change generated in the first fuel injection valve is transmitted through the pressure accumulation distribution container to the second fuel injection. Propagation time calculation means for calculating the propagation time required to propagate to the valve;
A second non-injection cylinder waveform for estimation representing a relationship between a change in pressure detected by the first fuel pressure sensor or the second fuel pressure sensor and a detection time at the time of fuel injection by the third fuel injection valve; Waveform acquisition means;
Estimation means for estimating a fuel injection state at the third fuel injection valve based on the estimation non-injection cylinder waveform acquired by the second waveform acquisition means and the propagation time calculated by the propagation time calculation means. When,
A fuel injection state estimation device comprising: The fuel path length from the first fuel injection valve to the second fuel injection valve through the pressure accumulation distribution container is defined as a first path length, and the first fuel injection from the third fuel injection valve through the pressure accumulation distribution container is performed. In the case where the fuel path length up to the valve or the second fuel injection valve is the second path length,
The fuel injection state estimation device according to claim 1, wherein the first path length and the second path length are the same. The fuel path length from the first fuel injection valve to the second fuel injection valve through the pressure accumulation distribution container is defined as a first path length, and the first fuel injection from the third fuel injection valve through the pressure accumulation distribution container is performed. A fuel path length up to the valve or the second fuel injection valve is a second path length, and the first path length and the second path length are different,
Storage means for storing a difference between the first path length and the second path length, or a physical quantity correlated with the difference as path length information;
The fuel injection state estimation apparatus according to claim 1, wherein the estimation unit performs the estimation based on the propagation time and the path length information. The first fuel injection valve provided in the first cylinder of the internal combustion engine, the second fuel injection valve provided in the second cylinder, the third fuel injection valve provided in the third cylinder, and the fourth cylinder. A fourth fuel injection valve;
An accumulator distribution container for distributing the accumulated high-pressure fuel to each of the first fuel injection valve, the second fuel injection valve, the third fuel injection valve, and the fourth fuel injection valve;
A fuel pressure sensor provided in the first fuel injection valve;
Applied to a fuel injection system comprising:
A pressure change detected by the fuel pressure sensor at the time of fuel injection at the second fuel injection valve is acquired as a second injection waveform, and a pressure change detected by the fuel pressure sensor at the time of fuel injection by the third fuel injection valve. Waveform acquisition means for acquiring a change in pressure detected by the fuel pressure sensor at the time of fuel injection at the fourth fuel injection valve as a waveform at the time of fourth injection,
Second injection time for calculating a second injection response time, which is the time from when the second fuel injection valve is commanded to start or end of injection to when the second injection waveform changes according to the command. Response time calculation means;
Third injection time for calculating a third injection time response time, which is a time from when the third fuel injection valve is commanded to start or end of injection to when a change occurs in the third time injection waveform in accordance with the command. Response time calculation means;
At the time of the fourth injection for calculating the response time at the time of the fourth injection, which is the time from when the fourth fuel injection valve is commanded to start or end the injection to when the fourth injection waveform changes according to the command. Response time calculation means;
Based on the comparison of the second injection time response time, the third injection time response time, and the fourth injection time response time, the second fuel injection valve, the third fuel injection valve, and the fourth fuel injection valve An abnormality diagnosis means for diagnosing whether an abnormality has occurred in the fuel injection state;
A fuel injection state estimation device comprising:

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