JP2012002178A - Fuel injection state detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection state detection device capable of detecting highly accurately the actual injection state.SOLUTION: The device includes a pressure waveform obtaining means S10 for obtaining a pressure waveform W representing the fuel pressure change occurring in a fuel supply path accompanying fuel injection based on the value sensed by a fuel pressure sensor, a pulsation model memory means storing pulsation models prepared by modelling pulsations in the pressure waveforms W generated accompanying movement of a valve element of a fuel injection valve to the valve closing position into a plurality of kinds of patterns, a pulsation model selecting means S40 for selecting a pulsation model M closest to the actual pulsation appeared in a pressure waveform W-PC out of the plurality of kinds of the pulsation models, a pulsation offsetting means S50 for calculating a pulsation offsetting waveform W-PC-M by subtracting the selected pulsation model M from the pressure waveform W-PC, and an injection state estimating means S60 for estimating the fuel injection ratio waveform (fuel injection state) based on the pulsation offsetting waveform W-PC-M.

Description

  The present invention relates to a fuel injection state detection device that detects a pressure waveform representing a change in fuel pressure that occurs in a fuel supply path with fuel injection by a fuel pressure sensor and estimates a fuel injection state based on the detected pressure waveform.

  In order to accurately control the output torque and the emission state of the internal combustion engine, it is important to accurately control the injection state such as the injection amount of fuel injected from the injection hole of the fuel injection valve and the injection start timing. Therefore, in Patent Documents 1 and 2, the actual injection state (injection start timing, injection amount, etc.) is detected by a fuel pressure sensor that detects a change in fuel pressure caused by injection in the fuel supply path up to the nozzle hole. ) Is disclosed. If the actual injection state can be detected in this way, the injection state can be accurately controlled based on the detection result.

  For example, in Patent Document 2, a pressure waveform detected by a fuel pressure sensor is acquired, change points P1, P2, and P3 (see FIG. 2C) appearing in the pressure waveform are detected, and these change points P1, Based on the appearance times and pressure values of P2 and P3, the actual injection state (injection start time R1, injection end time R4, injection amount Q, etc.) is calculated.

JP 2010-3004 A JP 2009-57924 A

  However, the pressure waveform detected by the fuel pressure sensor does not reflect the injection state as it is, and pulsations that occur independently of the injection state appear in the pressure waveform. It became clear.

  First, the structure of the fuel injection valve used in the above test will be described below with reference to FIG. 3 which is an enlarged view of FIG. The valve body 12 of the fuel injection valve 10 has a seat surface 12a. When the seat surface 12a is seated on the seating surface 11e of the body 11 (see FIG. 1), the high-pressure passage 11a is closed and the nozzle hole 11b. Is closed and the injection rate becomes zero. On the other hand, when the seat surface 12a is separated from the seating surface 11e (see FIG. 3), the high-pressure passage 11a is opened and the nozzle hole 11b is opened.

  When the valve body 12 is opened to the full lift position (see FIG. 3A), the flow passage area of the high pressure passage 11a is minimized at the injection hole 11b, and the flow rate of the injected fuel is at the injection hole 11b. The throttle hole is in a throttled state. After the start of the valve closing operation, the nozzle hole throttle state continues until the stroke amount (lift-up amount) of the valve body 12 reaches a predetermined amount (see FIG. 3B). On the other hand, when the stroke amount of the valve body 12 becomes less than a predetermined amount, the flow passage area of the high pressure passage 11a is minimized at the portion of the seat surface 12a, and the seat throttle state in which the flow rate is restricted by the seat surface 12a (FIG. 3C). )reference).

  That is, when the valve body 12 in the full lift position starts to move toward the valve closing position, the state is shifted from the nozzle hole throttle state to the seat throttle state, and at this transition time R3 (see FIG. 2B), the actual injection is performed. The rate (amount injected per unit time) begins to decline. The injection rate becomes zero at the time point R4 when the valve body 12 reaches the valve closing position.

  In view of this point, it was initially assumed that the pressure waveform starts to rise when the transition is made from the nozzle hole throttle state to the sheet throttle state. However, it was found that in the actually tested pressure waveform, a pulsation (see the one-dot chain line B in FIG. 2C) in which the pressure slightly increases immediately before the transition to the sheet throttle state occurs. The present inventor considered the mechanism of the occurrence of pulsation B as follows.

  That is, when the valve body 12 moves from the full lift position toward the valve closing position, the volume of the valve body housing chamber 11f that houses the valve body 12 in the high-pressure passage 11a decreases. Then, the fuel pressure in the high pressure passage 11a slightly increases by the volume reduction, and this increase becomes the pulsation B and appears in the pressure waveform. In short, when the valve body 12 starts moving toward the valve closing position, the pulsation in which the pressure slightly increases at the time point P3a despite the injection hole throttle state due to the volume reduction of the valve body accommodating chamber 11f. B is produced. Thereafter, the pressure starts to increase at time P3 due to the shift to the sheet squeezed state. Incidentally, the pressure rises as it is even after the valve body 12 reaches the valve closing position.

  Based on the above considerations, the pressure increase after the point P3 in the pressure waveform represents a decrease in the injection rate, but the pulsation B occurs even though the injection rate has not changed. It can be said that the waveform is due to the influence other than Therefore, the methods of Patent Documents 1 and 2 that calculate the injection rate based on the pressure waveform in the state where the pulsation B is included cannot detect the actual injection rate (injection state) with high accuracy.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel injection state detection device capable of detecting an actual injection state with high accuracy.

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

  According to the first aspect of the present invention, a valve body that opens and closes the nozzle hole is opened, thereby a fuel injection valve that injects fuel to be burned in the internal combustion engine from the nozzle hole, and fuel supply up to the nozzle hole It is assumed that the present invention is applied to a fuel injection system including a fuel pressure sensor that detects a fuel pressure in a path.

  Then, based on the detected value of the fuel pressure sensor, a pressure waveform acquisition means for acquiring a pressure waveform representing a change in fuel pressure that occurs in the fuel supply path due to fuel injection, and the valve body toward the valve closing position. A pulsation model storage means in which a pulsation model obtained by modeling pulsations in the pressure waveform caused by movement into a plurality of types of patterns is stored in advance, and the plurality of types of pulsation models in the pressure waveform. A pulsation model selecting means for selecting a pulsation model similar to the actual pulsation that appears; Injection state estimating means for estimating a fuel injection state from the nozzle hole based on a waveform.

  In short, in the above invention, the pulsation in the pressure waveform generated when the valve body moves toward the valve closing position is modeled and stored in a plurality of types of patterns. Then, a pulsation model similar to the actual pulsation is selected, and the pulsation elimination waveform is calculated by subtracting the selected pulsation model from the pressure waveform. Therefore, pulsation due to effects other than injection is removed from the pressure waveform, and thus the correlation between the corrected pressure waveform (pulsation canceling waveform) and the injection state can be increased. Since the injection state is estimated based on the pulsation extinguishing waveform having a high correlation, the injection state can be detected with high accuracy.

  The invention according to claim 2 is characterized in that the pulsation model selection means selects the pulsation model based on a supply pressure of fuel supplied to the fuel injection valve.

  As described above, the pulsation is a phenomenon in which the fuel pressure slightly increases due to the volume of the valve body accommodating chamber 11f being reduced. The inventors have found that the shape of the pulsation generated in this way is different if the pressure (supply pressure) of the fuel supplied to the fuel injection valve at that time is different. According to the above invention in view of this knowledge, since the pulsation model is selected based on the supply pressure, a pulsation model similar to the actual pulsation can be selected with high accuracy. Therefore, the calculation accuracy of the pulsation canceling waveform can be improved, and the estimation accuracy of the fuel injection state can be improved.

  According to a third aspect of the present invention, the fuel injection valve is provided in each cylinder of a multi-cylinder internal combustion engine, and the fuel pressure sensor is provided for each of the plurality of fuel injection valves. Is characterized in that the selection is performed by regarding the pressure detected by the fuel pressure sensor corresponding to the fuel injection valve that is not injecting among the plurality of fuel pressure sensors as the supply pressure.

  It can be said that the pressure detected by the non-injection cylinder fuel pressure sensor represents the supply pressure. Therefore, according to the invention, for example, it is unnecessary to provide a dedicated fuel pressure sensor for detecting the supply pressure in a distribution container that accumulates fuel supplied from a fuel pump and distributes and supplies the fuel to a plurality of fuel injection valves.

  According to a fourth aspect of the present invention, the pulsation canceling means associates the phase of the pressure waveform and the phase of the pulsation model based on the time point when the injection end command signal is output to the fuel injection valve, and The pulsation elimination waveform is calculated by subtracting the pulsation model from the pressure waveform.

  When calculating the pulsation elimination waveform by subtracting the pulsation model from the pressure waveform, the accuracy of the pulsation elimination waveform will be improved if the above calculation is not performed in a state where the phase of the pressure waveform and the phase of the pulsation model are accurately correlated and combined. It will decline. In view of this problem, the present inventor has conceived the above invention by paying attention to the fact that there is a high correlation between the time when the injection end command signal is output and the time when pulsation appears. That is, since the phase of the pressure waveform and the phase of the pulsation model are associated based on the output time point of the injection end command signal, the calculation accuracy of the pulsation canceling waveform can be improved, and the estimation accuracy of the fuel injection state can be improved.

The figure which shows the outline of the fuel-injection system with which the fuel-injection state detection apparatus concerning one Embodiment of this invention is applied. (A) is an injection command signal to the fuel injection valve shown in FIG. 1, (b) is an injection rate waveform representing a change in fuel injection rate caused by the injection command signal, and (c) is detected by a fuel pressure sensor shown in FIG. The time chart which shows the pressure waveform showing the change of the detected pressure made. (A) shows the state in which a valve body exists in a full lift position, (b) shows a nozzle hole throttle state, (c) is sectional drawing which shows a sheet | seat throttle state. (A) shows an injection pressure waveform W and a non-injection pressure waveform PC, (b) shows a waveform W-PC obtained by subtracting a non-injection pressure waveform PC from an injection pressure waveform W, (c ) Is a diagram showing a waveform W-PC-M obtained by subtracting the pulsation model M from the waveform W-PC. The flowchart which shows the process sequence which calculates the waveform W-PC-M shown in FIG.4 (c), and calculates an injection rate waveform.

  Hereinafter, an embodiment embodying a fuel injection state detection device according to the present invention will be described with reference to the drawings. The fuel injection state detection device according to the present embodiment is mounted on a vehicle engine (internal combustion engine), and compression auto-ignition is performed by injecting high-pressure fuel into a plurality of cylinders # 1 to # 4. It assumes a diesel engine that burns.

  FIG. 1 is a schematic diagram showing a fuel injection valve 10 mounted on each cylinder of the engine, a fuel pressure sensor 20 mounted on each fuel injection valve 10, an ECU 30 that is 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 high pressure pump 41, and is 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. Since the plunger pump is used as the high-pressure pump 41, the fuel is intermittently pumped in synchronism with the reciprocating movement of the plunger.

  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 decreases and the valve body 12 opens. 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 rises and the valve body 12 is closed.

  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. For example, the ECU 30 calculates a target injection state such as an injection start timing, an injection end timing, and an injection amount based on the rotation speed of the engine output shaft, the engine load, and the like, and sends an injection command signal to the actuator 13 so that the calculated target injection state is obtained. Is output to control the operation of the fuel injection valve 10.

  The ECU 30 calculates the target injection state based on the engine load and engine speed calculated from the accelerator operation amount and the like. For example, the optimal injection state (the number of injection stages, the injection start time, the injection end time, the injection amount, etc.) 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, injection command signals t1, t2, and Tq are set based on the calculated target injection state. For example, an injection command signal corresponding to the target injection state is stored as a command map, and the injection command signal is set with reference to the command map based on the calculated target injection state. Thus, the injection command signal corresponding to the engine load and the engine rotation speed is set and output from the ECU 30 to the fuel injection valve 10.

  Here, the actual injection state with respect to the injection command signal changes due to deterioration of the fuel injection valve 10 such as wear of the injection hole 11b. Therefore, as described in detail later, the fuel injection rate waveform is calculated based on the pressure waveform detected by the fuel pressure sensor 20 to detect the injection state, and the detected injection state and the injection command signal (pulse on timing t1, pulse off timing t2). And the correlation with the pulse-on period Tq), and the injection command signal stored in the command map is corrected based on the learning result. Thus, the fuel injection state can be controlled with high accuracy so that the actual injection state matches the target injection state.

  Next, the hardware configuration of the fuel pressure sensor 20 will be described. The fuel pressure sensor 20 includes a stem 21 (distortion body), a pressure sensor element 22, a mold IC 23, 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. The pressure sensor element 22 is attached to the diaphragm portion 21a, and outputs a pressure detection signal in accordance with the amount of elastic deformation generated in the diaphragm portion 21a.

  The mold IC 23 is formed by resin molding an electronic component such as an amplifier circuit that amplifies the pressure detection signal output from the pressure sensor element 22, and is mounted on the fuel injection valve 10 together with the stem 21. A connector 15 is provided on the upper portion of the body 11, and the mold IC 23, the actuator 13, and the ECU 30 are electrically connected by a harness 16 connected to the connector 15.

  Here, the fuel pressure (fuel pressure) in the high-pressure passage 11a decreases with the start of fuel injection from the nozzle hole 11b, and the fuel pressure increases with the end of injection. That is, it can be said that the change in the fuel pressure and the change in the injection rate (injection amount injected per unit time) are correlated, and the change in the injection rate (actual injection state) can be detected from the change in the fuel pressure. Then, the above-described injection command signal is corrected so that the detected actual injection state becomes the target injection state. Thereby, the injection state can be controlled with high accuracy.

  Next, a pressure waveform representing a change in fuel pressure detected by a fuel pressure sensor 20 mounted on the fuel injection valve 10 during fuel injection, and an injection rate waveform representing a change in the fuel injection rate applied to the fuel injection valve 10. The correlation will be described with reference to FIG.

  FIG. 2A shows an injection command signal output from the ECU 30 to the actuator 13 of the fuel injection valve 10. When the command signal is turned on, the actuator 13 is energized to open the nozzle hole 11b. 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 of the nozzle hole 11b according to the pulse-on period (injection command period Tq) of the command signal.

  FIG. 2 (b) shows a change in fuel injection rate (injection rate waveform) from the nozzle hole 11b caused by the injection command, and FIG. 2 (c) is provided in the fuel injection valve 10 during fuel injection. The change of the detection pressure (pressure waveform at the time of injection) which arises with the change of the injection rate detected by the fuel pressure sensor 20 is shown. Since the injection pressure waveform and the injection rate waveform have the correlation described below, the injection rate waveform can be estimated (detected) from the detected injection pressure waveform.

  That is, first, as shown in FIG. 2 (a), after the time t1 when the injection start command is given, the injection rate starts to rise and the injection is started when the injection rate is R1. On the other hand, the detected pressure starts decreasing at the change point P1 when the delay time C1 elapses after the injection rate starts increasing at the time 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 R3, the detected pressure starts increasing at the change point P3. Thereafter, as the injection rate becomes zero at the time point R4 and the actual injection ends, the increase in the detected pressure stops at the change point P5.

  Incidentally, the pulsation of the portion indicated by the alternate long and short dash line A in the pressure waveform at the time of injection compensates for the fuel decrease in the high pressure passage 11a caused by the fuel injection, and immediately after reaching the maximum injection rate, from the common rail 42 to the high pressure passage 11a. This is caused by the fuel being supplied. Further, as described above, the pulsation of the portion indicated by the alternate long and short dash line B in the pressure waveform during injection is that the valve body 12 moves toward the valve closing position during the period of the injection hole throttle state of FIG. As a result, the volume of the valve body accommodating chamber 11f is reduced.

  As explained above, the pressure waveform during injection and the injection rate waveform are highly correlated. The injection rate waveform shows the injection start time (R1 appearance time), the injection end time (R4 appearance time), and the injection amount (area of the halftone dot portion in FIG. 2B). The injection state can be detected by converting the injection pressure waveform into the injection rate waveform.

  Incidentally, the pressure (distributed supply pressure PC) of the fuel distributed and supplied from the common rail 42 to the fuel injection valve 10 changes every moment. For example, the solid line in FIG. 4A indicates the pressure waveform W corresponding to the injection cylinder, whereas the dotted line in FIG. 4A indicates the distributed supply pressure PC detected at the same time as the pressure waveform W. Shows changes. The change in the distribution supply pressure PC is detected by using the fuel pressure sensor 20 corresponding to the fuel injection valve 10 that is not injecting. Therefore, for example, when the fuel is injected from the fuel injection valve 10 (# 1) of the # 1 cylinder and the injection is stopped from the fuel injection valve 10 (# 2) of the # 2 cylinder, the fuel pressure sensor of the # 1 cylinder The pressure detected by 20 corresponds to the pressure waveform W during injection, and the pressure detected by the fuel pressure sensor 20 of the # 2 cylinder (back cylinder) corresponds to the pressure waveform during non-injection indicating the change in the distribution supply pressure PC.

  The reason why the non-injection pressure waveform illustrated in FIG. 4A is a waveform that gradually decreases with the start of injection is that the distribution is performed by the amount distributed from the common rail 42 to the fuel injection valve 10 of the injection cylinder. This is because the supply pressure PC decreases. Incidentally, when the pumping by the high-pressure pump 41 is performed during fuel injection, the distribution supply pressure PC increases even during fuel injection.

  In short, since the injection pressure waveform W is affected by the change of the distribution supply pressure PC (non-injection pressure waveform), if the non-injection pressure waveform is subtracted from the injection pressure waveform W, the injection pressure waveform W Thus, the influence of the change in the distribution supply pressure PC is removed. The solid line in FIG. 4B shows the pressure waveform W-PC at the time of injection after the correction to be subtracted in this way. In addition, the pressure waveform W at the time of injection illustrated in FIG. 2C is a waveform when it is assumed that the distribution supply pressure PC has not changed. The subtracted waveform W-PC and the pressure waveform W at the time of injection W Are assumed to have the same waveform.

  Next, a procedure for calculating the injection rate waveform shown in FIG. 2B based on the detection value (pressure waveform W during injection) of the fuel pressure sensor 20 will be described.

  FIG. 5 is a flowchart showing a procedure for calculating the injection rate waveform by the microcomputer of the ECU 30. This process is repeatedly executed at a predetermined cycle after being started up when the ignition switch is turned on.

  First, in step S10 (pressure waveform acquisition means) shown in FIG. 5, the pressure waveform W (FIG. 4A) detected by the fuel pressure sensor 20 corresponding to the fuel injection valve 10 of the cylinder # 1 during fuel injection. (See the solid line inside.) In the subsequent step S20, the aforementioned non-injection pressure waveform PC detected by the fuel pressure sensor 20 corresponding to the fuel injection valve 10 of the cylinder # 2 that has not injected is acquired (see the broken line in FIG. 4A). . In subsequent step S30, the non-injection pressure waveform PC acquired in step S20 is subtracted from the injection pressure waveform W acquired in step S10 to correct the injection pressure waveform W (see the solid line in FIG. 4B). ). Thereby, the waveform component (change in supply pressure PC) of the non-injection cylinder (back cylinder) included in the injection pressure waveform W is removed from the injection pressure waveform.

  Here, the pulsation B described above is modeled in advance into a plurality of types of patterns as exemplified by the symbols M1, M2, and M3 in FIG. These pulsation models M1 to M3 have different pulsation shapes. Specifically, the pulsation height (amplitude) indicating the pressure increase amount and the pulsation length (period) indicating the pressure increase period are different. Has been modeled. These plural types of pulsation models M1 to M3 are stored in advance in a nonvolatile memory such as an EEPROM included in the ECU 30 (pulsation model storage means).

  In step S40 (pulsation model selection means) in FIG. 5, the pulsation model (optimal pulsation model M) closest to the actual pulsation B appearing in the corrected injection pressure waveform W-PC is selected from a plurality of types of pulsation models. Select from M1 to M3. Specifically, the relationship between the supply pressure PC and the optimum pulsation model is stored in advance in the ECU 30 in the form of a map or the like. Then, referring to the map based on the supply pressure PC acquired in step S20, the optimum pulsation model M whose shape is most similar to the waveform shape of the actual pulsation B is selected. The shape of the pulsation model changes according to the supply pressure PC. For example, the pulsation height of the pulsation model increases as the supply pressure PC increases, and the pulsation length of the pulsation model increases as the supply pressure PC increases. Therefore, the optimal pulsation model M can be selected based on the supply pressure PC.

  For example, the relationship between the supply pressure PC and the optimum pulsation model is set so that the pulsation model that minimizes the amount of deviation between the pulsation models M1 to M3 and the pulsation B (the sum of the pressure differences at each time) is selected. This is suitable for selecting the most similar optimal pulsation model M. Alternatively, the relationship between the supply pressure PC and the optimum pulsation model may be set such that at least one of the amplitude difference and the frequency difference between the pulsation models M1 to M3 and the pulsation B is selected. Good.

  Note that the pressure P0 before the start of injection (see FIG. 2C) may be used as the supply pressure PC used for the selection, but the supply pressure PC after time t2 when the injection end command signal is output is used. Is desirable. For example, the supply pressure PC during the period T20 in which the pulsation M appears (see FIG. 4B) may be used. Specifically, the average of the supply pressure PC during the period T20 may be used. It should be noted that the time point at which a predetermined time T10 (see FIG. 2 (a)) has elapsed from the time point t2 when the injection end command signal is output may be set as the start time point t3 of the period T20. Alternatively, the supply pressure PC at the time t2 may be used as the supply pressure PC used for the selection, or the supply pressure PC at the time t3 may be used.

  In the subsequent step S50 (pulsation canceling means), a process (pulsation canceling process) for subtracting the pulsation model M selected in step S40 from the pressure waveform W-PC calculated in step S30 is performed, as shown in FIG. A pulsation elimination waveform W-PC-M is calculated. The influence of the pulsation B is removed from the pulsation elimination waveform W-PC-M calculated in this way.

  In performing this pulsation canceling process, if the above process is not performed in a state where the phase of the pressure waveform W-PC and the phase of the pulsation model M are accurately associated and matched, the pulsation canceling waveform W-PC-M Accuracy will be reduced. Therefore, in the present embodiment, the phase of the pressure waveform and the phase of the pulsation model are associated based on the output time point of the injection end command signal. For example, the start time point of the pulsation model M may be associated with the time point t3. Thereby, the calculation accuracy of the pulsation elimination waveform W-PC-M can be improved.

  In subsequent step S60 (injection state estimating means), the injection rate waveform shown in FIG. 2B is estimated based on the pulsation elimination waveform W-PC-M calculated in step S50. For example, various change points P1, P2, P3, and P5 appearing in the pulsation elimination waveform W-PC-M, slopes Pα and Pβ, and pressure drop amounts from P1 to P2, and various change points R1 and R1 of the injection rate waveform. Correlations with R2, R3, R4, gradients Rα, Rβ, and maximum injection rate Rh are stored in advance in ECU 30, and an injection rate waveform is estimated from pulsation elimination waveform W-PC-M based on the correlation. Incidentally, in the example of FIG. 2B, the injection rate waveform is estimated in a trapezoidal shape. However, when the injection command period Tq is short and the injection amount is small, the injection rate waveform has a triangular shape.

  As described above, according to the present embodiment, the pulsation B in the pressure waveform generated when the valve body 12 moves toward the valve closing position (sitting position on the seating surface 11e) is modeled into a plurality of types of patterns. To remember. Then, a pulsation model M most similar to the actual pulsation B is selected from a plurality of types of pulsation models M1 to M3, and the selected pulsation model M is subtracted from the pressure waveform W-PC to eliminate the pulsation elimination waveform W-PC-. M is calculated. Therefore, since the pulsation B due to the influence other than the injection is removed from the pressure waveform W, the correlation between the corrected pressure waveform (pulsation canceling waveform) and the actual change in the injection rate can be enhanced. Since the injection rate waveform is estimated based on the pulsation elimination waveform W-PC-M having a high correlation, the injection rate waveform (injection state) can be detected with high accuracy.

  Further, since the pulsation model M most similar to the actual pulsation B is selected based on the supply pressure PC at that time, the pulsation model M most similar to the actual pulsation B can be selected with high accuracy. Therefore, the calculation accuracy of the pulsation elimination waveform W-PC-M can be improved, and the estimation accuracy of the fuel injection state can be improved.

  In addition, paying attention to the fact that the waveform (non-injection pressure waveform) detected at the same time as the injection pressure waveform W by the fuel pressure sensor 20 of the non-injection cylinder represents a change in the distribution supply pressure PC, it is used for the selection. Since the supply pressure PC is acquired based on the non-injection pressure waveform, it is unnecessary to provide a dedicated fuel pressure sensor for detecting the supply pressure on the common rail 42.

  Furthermore, according to the present embodiment, the waveform representing the change in the distribution supply pressure PC is corrected by subtracting it from the injection pressure waveform W, so that the influence due to the change in the distribution supply pressure PC is removed from the injection pressure waveform W. Therefore, since the correlation between the pulsation elimination waveform W-PC-M and the actual change in the injection rate can be increased, the improvement in the calculation accuracy of the injection rate waveform can be promoted.

(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.

  In the above embodiment, the optimum pulsation model M is selected based on the supply pressure PC. However, a matching process for calculating a deviation amount from the pressure waveform W-PC is performed for all of the plural types of pulsation models M1 to M3. Then, the pulsation model with the smallest deviation amount may be selected. The deviation amount may be calculated by, for example, the least square method.

  In the above embodiment, the distributed supply pressure PC is acquired based on the pressure waveform detected by the fuel pressure sensor 20 of the non-injection cylinder, but a fuel pressure sensor (not shown) is mounted on the common rail 42 and the fuel pressure sensor The distribution supply pressure PC may be acquired based on the pressure waveform detected by the above.

  In the above embodiment, correction is performed by subtracting the non-injection pressure waveform from the injection pressure waveform W, and subtracting the pulsation model M from the corrected injection pressure waveform W-PC. It may be abolished and a process of subtracting the pulsation model M from the injection pressure waveform W may be performed.

  In the above embodiment shown in FIG. 1, the fuel pressure sensor 20 is mounted on the fuel injection valve 10, but the fuel pressure sensor according to the present invention is located in the fuel path from the discharge port 42a of the common rail 42 to the injection hole 11b. Any fuel pressure sensor arranged to detect the fuel pressure may be used. Therefore, for example, a fuel pressure sensor may be mounted on the high-pressure pipe 42 b that connects the common rail 42 and the fuel injection valve 10. That is, the high-pressure pipe 42b connecting the common rail 42 and the fuel injection valve 10 and the high-pressure passage 11a in the body 11 correspond to the “fuel supply path”.

  DESCRIPTION OF SYMBOLS 10 ... Fuel injection valve, 11b ... Injection hole, 12 ... Valve body, 20 ... Fuel pressure sensor, 30 ... ECU (pulsation model storage means), 42 ... Common rail (distribution container), S10 ... Pressure waveform acquisition means, S40 ... Pulsation model Selection means, S50: Pulsation canceling means, S60: Injection state estimation means.

Claims (4)

A fuel injection valve that injects fuel to be burned in an internal combustion engine from the nozzle hole by opening a valve body that opens and closes the nozzle hole;
A fuel pressure sensor for detecting the fuel pressure in the fuel supply path leading to the nozzle hole;
Applied to the fuel injection system with
Pressure waveform acquisition means for acquiring a pressure waveform representing a change in fuel pressure generated in the fuel supply path due to fuel injection based on a detection value of the fuel pressure sensor;
A pulsation model storage means in which a pulsation model obtained by modeling pulsations in the pressure waveform generated when the valve body moves toward the valve closing position into a plurality of types of patterns is stored in advance;
A pulsation model selection means for selecting a pulsation model similar to an actual pulsation appearing in the pressure waveform from the plurality of types of pulsation models;
Pulsation canceling means for calculating a pulsation canceling waveform by subtracting the pulsation model selected by the pulsation model selecting means from the pressure waveform;
Injection state estimating means for estimating a fuel injection state from the nozzle hole based on the pulsation canceling waveform;
A fuel injection state detection device comprising:   2. The fuel injection state detection device according to claim 1, wherein the pulsation model selection unit selects the pulsation model based on a supply pressure of fuel supplied to the fuel injection valve. The fuel injection valve is provided in each cylinder of a multi-cylinder internal combustion engine, and the fuel pressure sensor is provided for each of the plurality of fuel injection valves,
The pulsation model selection means performs the selection by regarding a pressure detected by a fuel pressure sensor corresponding to a fuel injection valve that is not injecting among the plurality of fuel pressure sensors as the supply pressure. Item 3. The fuel injection state detection device according to Item 2.   The pulsation canceling unit associates the phase of the pressure waveform and the phase of the pulsation model based on the time point when the injection end command signal is output to the fuel injection valve, and subtracts the pulsation model from the pressure waveform in the associated state. The fuel injection state detection apparatus according to claim 1, wherein the pulsation canceling waveform is calculated.

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