JP2012026339A - Fuel injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device capable of accurately controlling an actual injection state.SOLUTION: The fuel injection control device includes a parameter acquisition means 33a acquiring the parameter (for instance, injection end time R4) of an injection rate waveform showing the variation of an injection rate based on the detection value of a fuel pressure sensor, a learning means 33b storing as learning values the injection command signal (for instance, energization period Tq) outputted to a fuel injection valve and the parameter R4 corresponding to the signal, a memory 32 (storage means) stored with a model waveform M3 showing that the parameter R4 varies periodically with a variation of the injection command signal Tq, and an interpolation means 33c calculating the injection command signal Tq situated between the learning values and the value of the parameter R4 situated at the signal by interpolating the learning values using the model waveform M3.

Description

  The present invention relates to a fuel injection control device that detects a change in fuel pressure caused by injecting fuel from a fuel injection valve of an internal combustion engine with a fuel pressure sensor and controls 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 fuel injection valve and the injection start timing.

  Therefore, in Patent Documents 1 and 2 and the like, a fuel pressure sensor detects a change in fuel pressure caused by injection in the fuel supply path from the discharge opening of the common rail to the injection hole of the fuel injection valve. The pressure waveform detected by the fuel pressure sensor (pressure waveform) has a high correlation with the injection rate waveform representing the change in the injection rate. Therefore, the injection rate waveform can be estimated based on the pressure waveform. It is possible to grasp the injection state.

  According to this, the relationship between the injection command signal output to the fuel injection valve and the actual injection state (injection rate waveform) can be learned, and if the injection command signal from the next time is set based on this learning value, The injection state can be accurately controlled to a desired state.

JP 2010-3004 A JP 2009-57924 A

  Regarding the learning, the present inventor has considered storing and updating the value of the injection end timing (parameter of the injection rate waveform) corresponding to the energization period (injection command signal) to the fuel injection valve as the learning value. Then, it was found that the relationship between the energization period and the injection end timing is not a simple proportional relationship, but periodically changes as illustrated by the solid line in FIG. Therefore, for example, if the learning values G1 to G5 of the learning regions A1 to A5 are linearly interpolated as indicated by the one-dot chain line in FIG. 4A, the relationship deviated from the actual energization period-injection end timing relationship Therefore, the energization period is set based on this, and the injection end timing cannot be controlled accurately.

  Incidentally, the present inventor considered as follows why the relationship between the energization period and the injection end timing periodically changes as indicated by the solid line in FIG. For example, in the case of the fuel injection valve 10 illustrated in FIG. 1, a high-pressure passage 11 a that circulates fuel to the injection hole 11 b and a branch passage that diverges from the high-pressure passage 11 a and circulates fuel to the fuel pressure sensor 20. 11e is formed. The pulsation of the fuel pressure change generated in the nozzle hole 11b due to the fuel injection propagates through the high-pressure passage 11a, but a part of the pulsation resonates in the branch passage 11e. It is considered that the relationship between the energization period and the injection end timing changes periodically due to this resonance.

  Further, as illustrated in FIG. 5, even in a fuel injection valve in which the fuel pressure sensor 200 is attached in the vicinity of the high-pressure passage 11a and the branch passage 11e is abolished, for example, pulsation resonance occurs in the large-diameter passage 11f to which the filter 17 is attached. Due to the occurrence of this, the relationship between the energization period and the injection end timing changes periodically.

  Further, such a periodic change does not appear only in the relationship between the energization period and the injection end timing illustrated in FIG. 4, for example, the relationship between the energization period and the injection amount (area of the injection rate waveform). If there is a relationship between the injection command signal and the parameter of the injection rate waveform, such as the relationship between the energization start timing and the injection start timing (injection rate increase start timing).

  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 control device designed to accurately control the fuel injection state.

  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 fuel injection valve that injects fuel to be burned in an internal combustion engine from an injection hole, and fuel that is generated in a fuel supply path from the injection hole to the injection hole as fuel is injected from the injection hole It is assumed that the present invention is applied to a fuel injection system including a fuel pressure sensor that detects a change in pressure.

  Then, based on the detection value of the fuel pressure sensor, parameter acquisition means for acquiring a parameter of an injection rate waveform representing a change in injection rate, an injection command signal output to the fuel injection valve, and the parameter corresponding to the signal Corresponding to the injection command signal and its signal, learning means for storing the value as a learning value, storage means for storing a model waveform representing that the parameter periodically changes as the injection command signal changes Interpolating means for interpolating the learning value using the model waveform to calculate the parameter value.

  The inventor has obtained the knowledge that “when the injection command signal changes, the parameter of the injection rate waveform changes periodically”. Therefore, in the above invention, a model waveform representing that the parameter periodically changes with a change in the injection command signal is acquired in advance by a test or the like and stored in the storage means. The injection command signal and the parameter value located between the learning values are calculated by interpolating the learning value using the stored model waveform. Therefore, since the relationship between the injection command signal located between the learning values and the parameter can be calculated with high accuracy, if the injection command signal is set based on the calculation result, the actual injection state is accurately set to a desired state. Can be controlled.

  According to a second aspect of the present invention, the storage means stores a plurality of types of the model waveforms set in different waveforms according to the supply pressure of the fuel supplied to the fuel injection valve, and the interpolation means The interpolation is performed using the model waveform corresponding to the supply pressure.

  The inventor has conducted various tests on the fact that “the change in the parameter accompanying the change in the injection command signal changes in a different pattern depending on the supply pressure of the fuel supplied to the fuel injection valve”. I found it. In the above invention in view of this point, since the interpolation is performed using the model waveform corresponding to the supply pressure, the relationship between the injection command signal and the parameter between the learning values can be calculated with higher accuracy.

  According to a third aspect of the present invention, the storage means stores a plurality of types of model waveforms set in different waveforms according to fuel temperature, and the interpolation means stores the model waveform according to the fuel temperature. The interpolation is performed using the above.

  The present inventor has found the fact that “a change in the parameter accompanying a change in the injection command signal changes in a different pattern depending on the fuel temperature” by performing various tests. In the above invention in view of this point, since the interpolation is performed using the model waveform corresponding to the fuel temperature, the relationship between the injection command signal and the parameter between the learning values can be calculated with higher accuracy.

  In the invention according to claim 4, the fuel injection valve is configured to have a valve body that opens and closes the nozzle hole, and a body in which the valve body is housed and the fuel pressure sensor is attached. The body is formed with the injection hole, a high-pressure passage through which fuel flows to the injection hole, and a branch passage branched from the high-pressure passage and through which fuel flows to the fuel pressure sensor.

  In the case of such a fuel injection valve, the pulsation of the fuel pressure change generated in the nozzle hole due to fuel injection propagates through the high-pressure passage, but part of the pulsation resonates in the branch passage, and this resonance Therefore, the periodic change of the injection rate waveform parameter with respect to the change of the injection command signal becomes remarkable. Therefore, if the above inventions such as interpolation using a model waveform are applied to the fuel injection valve in which such a periodic change is noticeable, the relationship between the injection command signal and the parameter between the learning values can be accurately determined. The above-described effect that it can be calculated is remarkably exhibited.

  According to a fifth aspect of the present invention, the parameters include an injection end timing at which the fuel injection ends and the injection rate becomes zero, a timing at which the injection rate starts to decrease with the end of fuel injection, and an injection rate with the end of fuel injection. Is at least one of the slopes of decrease.

  The resonance that occurs in the above-described branch passage or the like occurs after the pulsation of the fuel pressure change generated in the nozzle hole due to fuel injection is propagated to the resonance location. Therefore, the portion of the injection rate waveform in which the injection rate decreases with the end of injection from parameters related to the waveform immediately after the start of injection (for example, the injection start time, the maximum injection rate arrival time, the injection rate increase slope, etc.) With respect to the waveform parameters (for example, the injection end timing, the injection rate lowering start timing, and the injection rate lowering slope), the periodic change in the injection rate waveform parameter with respect to the change in the injection command signal appears more markedly. Therefore, according to the above-described invention to which the parameter in which such a periodic change is remarkably applied is applied, the above-described effect that the relationship between the injection command signal between the learning values and the parameter can be calculated with high accuracy is remarkably exhibited. The

The figure which shows the outline of the fuel-injection system with which the fuel-injection control apparatus concerning one Embodiment of this invention is applied. The functional block diagram which shows a state when ECU shown in FIG. 1 is functioning to set an injection command signal. (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 the fuel injection rate caused by the injection command signal, and (c) is detected by the fuel pressure sensor shown in FIG. The figure which shows the pressure waveform based on a value. (A) shows the command map M2 used by the injection command signal setting means of FIG. 3, and (b) to (d) show the model waveform M3 used by the interpolation means of FIG. The figure which shows the modification of the fuel injection valve to which this invention is applied.

  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 accumulator) by a high pressure pump 41 (fuel pump), 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.

  As shown in FIG. 2, the ECU 30 has means (target injection state calculation means 31) for calculating a 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 timing, the injection end timing, the injection amount, etc.) corresponding to the engine load and the engine rotation speed is stored in the memory 32 in advance as the injection state map M1. Then, based on the current engine load and engine speed, the target injection state is calculated with reference to the injection state map M1.

  Further, the ECU 30 has means (injection command signal setting means 33) for setting the injection command signals t1, t2, and Tq based on the calculated target injection state. For example, the injection command signal corresponding to the target injection state is set to the command map M2 and stored in the memory 32 in advance. Then, based on the calculated target injection state, an injection command signal is set with reference to the command map M2. 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 will be described in detail later, the fuel injection rate waveform is calculated based on the pressure waveform detected by the fuel pressure sensor 20, the injection state is detected, and the detected injection state (parameter of the injection rate waveform) and the output injection command are output. The correlation between the signals (pulse-on timing t1, pulse-off timing t2, and energization period Tq) is learned, and the injection command signal stored in the command map M2 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.

  However, when there is no learning value of the injection command signal corresponding to the target injection state, it is necessary to calculate an injection command signal corresponding to the target injection state by interpolating a plurality of existing learning values. This interpolation method will be described in detail later.

  Next, the hardware configuration of the fuel pressure sensor 20 will be described with reference to FIG. 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 electronic components such as an amplification circuit that amplifies the pressure detection signal output from the pressure sensor element 22 and a transmission circuit that transmits the pressure detection signal. 10 is installed. 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. The amplified pressure detection signal is transmitted to the ECU 30 and received by a receiving circuit included in the ECU 30. This communication process for transmission / reception is performed for each fuel pressure sensor 20 of each cylinder.

  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) have a correlation, and the change in the injection rate (actual injection state) can be detected from the change in the fuel pressure. Then, the injection command signal in the command map M2 described above 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 detection waveform that is a waveform of the pressure detected by the fuel pressure sensor 20 mounted on the fuel injection valve 10 during fuel injection, and an injection rate waveform that represents a change in the fuel injection rate applied to the fuel injection valve 10 The correlation will be described with reference to FIG.

  FIG. 3A 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 energization period of the command signal (injection command period Tq).

  FIG. 3B shows a change (injection rate waveform) of the fuel injection rate from the injection hole 11b caused by the injection command, and FIG. 3C is provided in the fuel injection valve 10 during fuel injection. The change (pressure waveform) of the detected pressure which arises with the change of the injection rate detected by the fuel pressure sensor 20 is shown.

  Since the pressure waveform and the injection rate waveform have a correlation described below, the injection rate waveform can be estimated (detected) from the detected pressure waveform. That is, first, as shown in FIG. 3A, after the time point t1 when the injection start command is made, the injection rate starts increasing at the time point R1, and the injection is started. On the other hand, the detected pressure starts decreasing at the change point P1 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, when the delay time C3 elapses after 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.

  As explained above, the correlation between the pressure waveform and the injection rate waveform is high. The injection rate waveform includes an injection start time (R1 appearance time), an injection end time (R4 appearance time), an injection amount (area of a halftone dot portion in FIG. 3B), a maximum injection rate Rh, and an injection. Since the rate increase speed Rα and the injection rate decrease speed Rβ are represented, the injection state can be detected by estimating the injection rate waveform from the pressure waveform.

  The injection rate waveform estimation method will be described in more detail. If parameters such as the injection start timing R1, the maximum injection rate arrival timing R2, the injection rate decrease start timing R3, the injection end timing R4, and the injection amount are specified, A trapezoidal injection rate waveform can be identified. That is, the injection rate waveform can be calculated by calculating the various parameters from the pressure waveform.

  For example, when the change points P1 and P2 appear in the detected pressure waveform are detected, the delay times C1 and C3 are subtracted from the detected timing, and the injection start timing R1 and the injection rate decrease start are detected. Time R3 is calculated. Further, the pressure decrease rate Pα and the increase rate Pβ are detected, and the detected values are converted by a predetermined conversion value to calculate the injection rate increase rate Rα and the injection rate decrease rate Rβ. Further, the maximum pressure drop amount P1-P2 is detected, and the detected value is converted with a predetermined conversion value to calculate the maximum injection rate Rh. Further, the injection end timing R4 is calculated based on the injection rate decrease start timing R3 and the injection rate decrease speed Rβ calculated as described above.

  The injection command signal setting means 33 has means (parameter acquisition means 33a) for calculating and acquiring parameters of the injection rate waveform based on the pressure waveform thus detected, as shown in FIG. Further, the learning means 33b included in the injection command signal setting means 33 associates the calculated parameter with the injection command signal corresponding to the pressure waveform used for calculating the parameter of the injection rate waveform. Then, the associated injection command signal and the learned value that is a parameter are stored in the command map M2 and updated.

  FIG. 4A shows an example of the command map M2, which is an example when the injection command signal is the energization period Tq and the parameter of the injection rate waveform is the injection end timing R4. The energization period Tq constituting the map M2 is divided into a plurality of learning areas A1 to A5, and the learning values G1 to G5 (that is, the injection end timing R4 corresponding to the energization period of the learning area) are obtained for each learning area A1 to A5. It is remembered. For example, when the calculated parameter corresponds to the learning region A3, the injection command signal associated with the parameter is stored as the learning value of the learning region A3.

  Here, as the energization period Tq is longer, the injection end timing R4 is not simply delayed, and the Tq-R4 characteristic changes while periodically pulsating, as illustrated by the solid line in FIG. Therefore, for example, if the learning values G1 to G5 of the learning regions A1 to A5 are linearly interpolated as indicated by the alternate long and short dash line in FIG. 4A, the injection command signal setting means 33 performs the actual energization period-injection. The energization period Tq is set based on the relationship deviating from the relationship of the end timing, and the injection end timing R4 cannot be accurately controlled.

  Therefore, in the present embodiment, a model waveform M3 (see FIGS. 4B, 4C, and 4D) indicating that the injection end timing R4 changes in pulsation with the change in the energization period Tq is acquired in advance by a test or the like. The data is stored in advance in the memory 32 (storage means). Note that the actual pulsation change waveform varies depending on the pressure (supply pressure) of the fuel supplied from the common rail 42 to the fuel injection valve 10 and the fuel temperature. Therefore, in the present embodiment, a plurality of types of model waveforms M3 set in different waveforms according to the supply pressure and the fuel temperature are stored in the memory 32.

  For example, the model waveform M3 is set as shown in FIG. 4C so that the pulsation period T10 becomes longer as the fuel temperature is higher. Further, the model waveform M3 is set as shown in FIG. 4D so that the pulsation period T10 is shortened as the supply pressure is increased. Incidentally, the present inventor considered the relationship between the fuel temperature and supply pressure and the pulsation cycle T10 as follows.

  In the fuel supply path including the high-pressure passage 11a and the branch passage 11e, the following relational expressions (1) and (2) are established for the acoustic velocity and bulk modulus of the fuel.

a = √ (K / ρ) (1)
K = Kc + α × P + β × T (2)
a: sound velocity in the supply path, K: bulk modulus of fuel, ρ: density of fuel, Kc: constant (determined by the type of fuel), α: constant (positive value), β: constant (negative value) , P: fuel pressure, T: fuel temperature.

  The following can be said from these relational expressions (1) and (2). That is, the higher the fuel pressure P (corresponding to the supply pressure), the larger the bulk modulus K, and the higher the speed of sound a. Therefore, the pulsation cycle T10 is shortened. Further, the higher the fuel temperature T is, the smaller the bulk modulus K becomes, so the sound speed a becomes slower. Therefore, the pulsation cycle T10 becomes long.

  The plurality of types of model waveforms M3 stored in the memory 32 may be waveforms obtained by numerical analysis using the relational expressions (1), (2), etc., or may be waveforms obtained by testing. Good. Although the model waveforms M3 illustrated in FIGS. 4B to 4D have the same amplitude, a plurality of types of model waveforms M3 having different amplitudes may be stored in the memory 32.

  Returning to the description of FIG. 2, the interpolation means 33 c included in the injection command signal setting means 33 first acquires the fuel temperature detected by the fuel temperature sensor (not shown) and the supply pressure detected by the fuel pressure sensor 20. . The detection value of the non-injection cylinder fuel pressure sensor 20 may be acquired as the supply pressure, or the detection value of the injection cylinder fuel pressure sensor 20 immediately before the start of injection may be acquired as the supply pressure. Then, a model waveform M3 having a condition (fuel temperature and supply pressure) closest to the acquired fuel temperature and supply pressure is selected from the plurality of types of model waveforms M3.

  Next, the selected model waveform M3 is adjusted to the command map M2. Specifically, the calculation by the least square method is performed so that the sum of the deviation amounts between the model waveform M3 and the plurality of learning values G1 to G5 is minimized, and the phase of the model waveform M3 is associated with the command map M2 ( (See the solid line in FIG. 4A). Then, an energization period Tq corresponding to the target injection end timing R4 (target injection state) in the associated model waveform M3 is calculated. Thereby, the energization period Tq for the injection end timing R4 can be calculated by interpolating the learning values G1 to G5 using the model waveform M3 associated with the phase.

  Incidentally, the target injection state calculation means 31, the parameter acquisition means 33a, the learning means 33b, and the interpolation means 33c shown in FIG. 2 function by a microcomputer (not shown) included in the ECU 30.

  In the example of FIG. 4, the case where the injection command signal as the learning target is the energization period Tq and the parameter of the injection rate waveform as the learning target is the injection end timing R4 has been described. The pulse-on time t1 and the pulse-off time t2 may be learned. Further, regarding the parameters of the injection rate waveform, the injection start timing R1, the maximum injection rate arrival timing R2, the injection rate decrease start timing R3, the injection amount, the injection rate increase rate Rα, and the injection rate decrease rate Rβ may be learned.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) A model waveform M3 representing that the parameter of the injection rate waveform changes in pulsation with the change of the injection command signal is acquired in advance by a test or the like and stored in the memory 32. When the target injection state corresponds to the learning value, the phase of the stored model waveform M3 is associated with the command map M2 based on the learning values G1 to G5, and the associated model waveform M3 is used. An injection command signal corresponding to the target injection state is calculated by interpolating learning values G1 to G5. Therefore, the injection command signal corresponding to the target injection state can be calculated with high accuracy, and the deviation between the actual injection state and the target injection state can be reduced.

  (2) A plurality of types of model waveforms M3 set in different waveforms according to the supply pressure and the fuel temperature are stored in the memory 32, and injection is performed using the model waveforms M3 corresponding to the supply pressure and the fuel temperature at that time. Since the command signal is calculated by interpolation, the injection command signal can be calculated with higher accuracy.

  (3) By the way, the pulsation of the fuel pressure change generated in the injection hole 11b accompanying the fuel injection propagates through the high pressure passage 11a. In the case of the fuel injection valve 10 shown in FIG. 1 in which the branch passage 11e is formed, A part of the pulsation resonates in the branch passage 11e, and due to this resonance, the pulsation change of the injection rate waveform parameter with respect to the change of the injection command signal becomes remarkable. Therefore, according to the present embodiment in which the fuel injection valve 10 in which such a pulsation change appears noticeably is interpolated using the model waveform M3, “the injection command signal for the target injection state between the learning values is calculated with high accuracy. The above-mentioned effect “can be done” is remarkably exhibited.

  (4) The resonance generated in the above-described branch passage 11e or the like occurs after the pulsation of the fuel pressure change generated in the injection hole 11b due to fuel injection is propagated to the resonance place (the branch passage 11e). Therefore, the injection rate decreases with the end of injection, compared to parameters related to the waveform immediately after the start of injection in the injection rate waveform (for example, the injection start timing R1, the injection rate increase end timing R2, the injection rate increase slope Rα, etc.). The pulsation change of the injection rate waveform parameter with respect to the change of the injection command signal appears more noticeably in the parameters related to the waveform of the going portion (for example, the injection end timing R4, the injection rate decrease start timing R3, the injection rate decrease slope Rβ, etc.) . Therefore, when a parameter in which such a pulsation change appears remarkably is applied, the above-described effect of “the injection command signal for the target injection state between the learning values can be calculated with high accuracy” is remarkably exhibited.

(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 embodiment shown in FIG. 1, the branch passage 11e branched from the high-pressure passage 11a is formed inside the body 11, and the fuel pressure sensor 20 is attached to the tip position of the branch passage 11e. The present invention is applied to the fuel injection valve 10 configured to detect the pressure change of the fuel introduced into the stem 21 from the branch passage 11e by the pressure sensor element 22.

  In contrast, as shown in FIG. 5, the present invention may be applied to a fuel injection valve 10 </ b> A configured such that the branch passage 11 e and the stem 21 are eliminated and the pressure sensor element 22 is directly attached to the body 11. In this case, the thin part 11g is formed in the body 11, and the elastic deformation (strain amount) of the thin part 11g caused by the fuel pressure in the high pressure passage 11a may be detected by the pressure sensor element 22.

  Even in the fuel injection valve 10A in which the branch passage 11e is not formed as shown in FIG. 5, for example, pulsation resonance occurs in the large-diameter passage 11f to which the filter 17 is attached. There may be a pulsation change in the injection rate waveform parameter with respect to a change in the command signal. Therefore, the fuel injection valve 10A in which such a pulsation change occurs has technical significance to which the present invention is applied.

  In the above embodiment shown in FIG. 4, the energization period Tq is equally divided into the plurality of learning regions A1 to A5, but may be divided non-uniformly. For example, it is preferable to divide a region where the amplitude of pulsation is large or a region where the frequency of pulsation is large into a learning region that is smaller than other regions, so that the state of pulsation can be accurately reflected in the interpolation.

  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 in the fuel supply path from the discharge port 42a of the common rail 42 to the injection hole 11b. Any fuel pressure sensor may be used so long as it detects the fuel pressure. 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, 20 ... Fuel pressure sensor, 32 ... Memory (memory | storage means), 33a ... Parameter acquisition means, 33b ... Learning means, 33c ... Interpolation means.

Claims (5)

A fuel injection valve that injects fuel to be burned in an internal combustion engine from an injection hole, and a fuel pressure sensor that detects a change in fuel pressure that occurs in the fuel supply path up to the injection hole as fuel is injected from the injection hole And applied to a fuel injection system comprising
Based on the detection value of the fuel pressure sensor, parameter acquisition means for acquiring a parameter of an injection rate waveform representing a change in injection rate;
Learning means for storing an injection command signal output to the fuel injection valve and the parameter corresponding to the signal as a learning value;
Storage means for storing a model waveform representing that the parameter changes with a change in the injection command signal;
Interpolation means for calculating the injection command signal and the value of the parameter corresponding to the signal by interpolating the learning value using the model waveform;
A fuel injection control device comprising: The storage means stores a plurality of types of model waveforms set in different waveforms according to the supply pressure of fuel supplied to the fuel injection valve,
The fuel injection control device according to claim 1, wherein the interpolation means performs the interpolation using the model waveform corresponding to the supply pressure. The storage means stores a plurality of types of model waveforms set to different waveforms according to fuel temperature,
The fuel injection control device according to claim 1, wherein the interpolation unit performs the interpolation using the model waveform corresponding to the fuel temperature. The fuel injection valve is configured to have a valve body that opens and closes the nozzle hole, and a body in which the valve body is housed and the fuel pressure sensor is attached.
The said body is formed with the said injection hole, the high-pressure passage which distribute | circulates fuel to the said injection hole, and the branch passage which branches from the said high-pressure passage and distribute | circulates fuel to the said fuel pressure sensor, It is characterized by the above-mentioned. The fuel-injection control apparatus as described in any one of 1-3.   The parameter is at least one of an injection end time at which the fuel injection is finished and the injection rate becomes zero, a timing at which the injection rate starts to decrease with the end of fuel injection, and a slope at which the injection rate decreases with the end of fuel injection. The fuel injection control device according to claim 1, wherein the fuel injection control device is a fuel injection control device.

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