JP6028603B2 - Fuel injection state estimation device - Google Patents

Description

  The present invention relates to a fuel injection state estimation device that acquires a first waveform representing a change in fuel pressure based on a fuel pressure detected by a fuel pressure sensor during fuel injection and estimates a fuel injection state based on the acquired first waveform.

  Conventionally, in this type of apparatus, the fuel injection state is estimated based on the waveform obtained by subtracting the waveform of the supply pulsation generated by the flow of fuel flowing from the common rail discharge port to the fuel injection valve through the fuel pipe from the first waveform. There is a thing (refer patent document 1). In the device described in Patent Document 1, the waveform of supply pulsation is modeled in advance, and the waveform of supply pulsation is calculated based on this model.

JP 2012-77653 A

  However, the actual supply pulsation waveform may deviate from the model waveform due to manufacturing variations of common rails and fuel pipes, changes in characteristics over time, and the like. In that case, since the waveform obtained by subtracting the waveform of the supply pulsation based on the model from the first waveform does not accurately reflect the fuel injection state, the accuracy of estimating the fuel injection state may be reduced.

  The present invention has been made to solve these problems, and a main object of the present invention is to suppress a decrease in estimation accuracy of the fuel injection state in the fuel injection state estimation device.

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

According to a first aspect of the present invention, there is provided a pressure accumulating container for accumulating and holding fuel, a fuel injection valve for injecting the fuel from an injection hole, a fuel passage for allowing the fuel to flow from the pressure accumulating container to the injection hole, A fuel injection state estimation device applied to a fuel injection system comprising a fuel pressure sensor for detecting a fuel pressure, based on the fuel pressure detected by the fuel pressure sensor when the fuel is injected by the fuel injection valve A first waveform acquisition unit for acquiring a first waveform representing a change in the fuel pressure, and the fuel from the pressure accumulating vessel through the fuel passage when the fuel is injected by the fuel injection valve based on a model created in advance. A calculation unit that calculates a waveform of supply pulsation generated by fuel supplied to the injection valve, and a waveform of the supply pulsation calculated by the calculation unit is removed from the first waveform. A second waveform acquisition unit that acquires the second waveform, an estimation unit that estimates an injection state of the fuel based on the second waveform acquired by the second waveform acquisition unit, and the first waveform acquisition unit An update unit that updates the model based on a predetermined portion from a point at which the fuel pressure becomes minimum to a point at which the fuel pressure rises and becomes constant among the first waveform acquired by Features.

  According to the above configuration, the fuel is accumulated and held in the accumulator, and the fuel is circulated from the accumulator to the injection hole of the fuel injection valve through the fuel passage. The fuel pressure in the fuel passage is detected by a fuel pressure sensor.

  Based on the fuel pressure detected by the fuel pressure sensor when fuel is injected by the fuel injection valve, a first waveform indicating a change in the fuel pressure is acquired. Further, based on a model created in advance, a waveform of supply pulsation generated by the fuel supplied from the pressure accumulator to the fuel injector through the fuel passage when fuel is injected by the fuel injector is calculated. Then, the waveform of the supply pulsation is removed from the first waveform, and the second waveform is acquired. The fuel injection state is estimated based on the second waveform. For this reason, it can suppress that the error by the influence of supply pulsation arises in estimation of the injection state of fuel. In addition, the said model may be the same as the model described in the said patent document 1, and may differ.

  Here, the model is updated based on the first waveform reflecting the waveform of the supply pulsation. Therefore, the model can be updated in accordance with the actual supply pulsation waveform. Further, the inventor of the present application directly reflects the waveform of the actual supply pulsation in a predetermined portion from the point where the fuel pressure becomes minimum to the point where the fuel pressure rises and becomes constant in the first waveform. I found out. In this regard, since the model is updated based on the predetermined portion of the first waveform, the accuracy of calculating the supply pulsation waveform by the model can be improved. As a result, it is possible to suppress the estimation accuracy of the fuel injection state from being lowered even if manufacturing variations of the pressure accumulator vessel and the fuel passage, changes in characteristics over time, and the like occur.

The schematic diagram which shows the outline of a fuel-injection system. The time chart which shows (a) injection command signal, (b) fuel injection rate, and (c) detection pressure. The schematic diagram explaining the generation | occurrence | production mechanism of an injection pulsation and a supply pulsation. The flowchart which shows the correction | amendment procedure of a sensor waveform, and the estimation procedure of an injection rate waveform. (A) Sensor waveform W and supply pulsation waveform Wa, (b) Model waveform Wm of supply pulsation waveform, and (c) Sensor waveform W ′ after correction. The flowchart which shows the procedure which calculates the model waveform Wm. The flowchart which shows the procedure which correct | amends the model waveform Wm.

  Hereinafter, an embodiment applied to a common rail fuel injection system of an in-vehicle diesel engine will be described with reference to the drawings. The diesel engine (internal combustion engine) includes four cylinders # 1 to # 4, and injects high-pressure fuel into the cylinders to perform compression self-ignition combustion.

  FIG. 1 is a schematic diagram showing an outline of a fuel injection system. First, an engine fuel injection system including the fuel injection valve 10 will be described.

  The fuel in the fuel tank 40 is pumped by the fuel pump 41 to the common rail 42 (pressure accumulating container) and is accumulated. The common rail 42 is connected to the fuel injection valves 10 (# 1 to # 4) of the respective cylinders via the fuel pipes 42b. The fuel in the common rail 42 is distributed and supplied from the discharge ports 42a to the fuel injection valves 10 (# 1 to # 4) through the fuel pipes 42b. The plurality of fuel injection valves 10 (# 1 to # 4) inject fuel in a predetermined order. In this embodiment, it is assumed that repeated injection is performed in the order of # 1 → # 3 → # 4 → # 2.

  A plunger pump is used as the fuel pump 41, and fuel is pumped in synchronism with the reciprocating movement of the plunger. The fuel pump 41 is driven by the crankshaft using the engine output as a drive source, and pumps the fuel by a predetermined number of times during a period of injection in the order of # 1 → # 3 → # 4 → # 2.

  The fuel injection valve 10 includes a body 11, a needle-shaped valve body 12, an electric actuator 13, and the like described below. The body 11 has a high pressure passage 11a formed therein and an injection hole 11b for injecting fuel. The valve body 12 is accommodated in the body 11 and opens and closes the injection hole 11b. The fuel pipe 42b and the high pressure passage 11a constitute a fuel passage through which fuel flows from the common rail 42 to the injection 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 electric actuator 13 operates the control valve 14 so as to switch the communication state between the high pressure passage 11a and the low pressure passage 11d and the back pressure chamber 11c. The driving of the electric actuator 13 is controlled by the ECU 30.

  When the control valve 14 is operated so that the back pressure chamber 11c communicates with the low pressure passage 11d, the fuel pressure in the back pressure chamber 11c decreases, the valve body 12 is lifted up (opening operation), and the injection hole 11b is opened. It is. As a result, the high-pressure fuel supplied from the common rail 42 to the high-pressure passage 11a is injected from the injection hole 11b into the combustion chamber. On the other hand, when the control valve 14 is operated so that the back pressure chamber 11c communicates with the high pressure passage 11a, the fuel pressure in the back pressure chamber 11c rises and the valve body 12 is lifted down (closed valve operation), and the injection hole 11b. Is closed and fuel injection is stopped.

  The fuel pressure sensor 20 includes a stem 21 (a strain generating body), a pressure sensor element 22 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 to the ECU 30 in accordance with the amount of elastic deformation generated in the diaphragm portion 21a. The fuel pressure sensor 20 is mounted on all the fuel injection valves 10.

  The ECU 30 (electronic control device) is a known microcomputer including a CPU, ROM, RAM, storage device, input / output interface, and the like. The ECU 30 calculates a target injection state (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 of the vehicle, the engine load, the engine 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, an injection command signal (see FIG. 2A) is 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, due to the deterioration of the fuel injection valve 10 such as wear of the injection hole 11b, the actual injection state with respect to the injection command signal changes. Therefore, as described later in detail, the fuel injection rate waveform is calculated based on the fuel pressure sensor waveform (first waveform) detected by the fuel pressure sensor 20 to estimate the injection state. The correlation between the estimated injection state and the injection command signal (pulse-on timing t1, pulse-off timing t2, and pulse-on period Tq) is learned, 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, a sensor waveform (see FIG. 2C) detected by the fuel pressure sensor 20 mounted on the fuel injection valve 10 during fuel injection, and an injection representing a change in the fuel injection rate applied to the fuel injection valve 10 The correlation with the rate waveform (see FIG. 2B) will be described.

  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 injection hole 11b. That is, the start of injection is instructed by the pulse on timing t1 of the injection command signal, and the end of injection is instructed by the pulse off timing t2. Therefore, the injection amount Q is controlled by controlling the valve opening time of the injection hole 11b by the pulse-on period (injection command period Tq) of the command signal.

  FIG. 2B shows a change (injection rate waveform) of the injection rate of the fuel injected from the injection hole 11b in accordance with the injection command. FIG. 2C shows a change in fuel pressure (first waveform) detected by a fuel pressure sensor 20 provided in the fuel injection valve 10 during fuel injection.

  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. First, as shown in FIG. 2 (a), after the time point t1 when the injection start command is given, the injection rate starts to increase and the injection starts 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, 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 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 estimated by estimating the injection rate waveform from the pressure waveform.

  However, the sensor waveform detected by the fuel pressure sensor 20 does not reflect the injection state as it is, and the waveform of the supply pulsation described below is superimposed on the sensor waveform. It is required to perform correction to be removed from the waveform and to estimate the injection state based on the corrected sensor waveform (second waveform).

  FIG. 3 is a schematic view of the fuel passage from the discharge port 42 a of the common rail 42 to the injection hole 11 b through the fuel pipe 42 b and the high-pressure passage 11 a of the fuel injection valve 10. Hereinafter, the generation mechanism of “injection pulsation” and “supply pulsation” will be described with reference to FIG.

  First, when fuel injection from the injection hole 11b is started, fuel pressure drop pulsation (injection pulsation Ma) occurs in the vicinity of the injection hole 11b in the high-pressure passage 11a (see FIG. 3A). Thereafter, the generated injection pulsation Ma propagates in the high-pressure passage 11a toward the common rail 42 (see FIG. 3B). Then, when the injection pulsation Ma reaches the diaphragm portion 21a of the fuel pressure sensor 20, the sensor waveform starts decreasing (that is, the change point P1 appears).

  Thereafter, when the injection pulsation Ma reaches the discharge port 42a of the common rail 42, the high-pressure fuel in the common rail 42 is supplied from the discharge port 42a to the fuel pipe 42b. When the fuel supply is started in this way, the fuel pressure rise pulsation (supply pulsation Mb) occurs in the vicinity of the discharge port 42a in the fuel pipe 42b (see FIG. 3E). Thereafter, the generated supply pulsation Mb propagates in the high-pressure passage 11a toward the injection hole 11b (see FIG. 3 (f)). Then, when the supply pulsation Mb reaches the diaphragm portion 21a of the fuel pressure sensor 20, the sensor waveform starts to rise (that is, the change point P2 appears).

  After that, in the vicinity of the fuel pressure sensor 20 in the high-pressure passage 11a, when the flow rate of the fuel supplied from the common rail 42 balances the flow rate of the fuel injected from the injection hole 11b (the change shown in FIG. 2 (c)). At the point P2a), the sensor waveform rise stops and is maintained at a constant value (equilibrium pressure).

  In short, it can be said that the waveform component due to the supply pulsation Mb (the portion of the change points P2 to P2a in FIG. 2C) is superimposed on the waveform component due to the injection pulsation Ma in the sensor waveform. In addition, since the supply pulsation Mb has not yet propagated to the fuel pressure sensor 20 in the portion of the sensor waveform up to the change point P2, the waveform represents only the injection pulsation Ma and the supply pulsation Mb is not superimposed. I can say that.

  Therefore, in this embodiment, the waveform component of the supply pulsation Mb is calculated based on a model created in advance (see FIG. 5B), and correction is performed by subtracting the calculated model waveform Wm from the sensor waveform W and removing it. . The injection state is estimated based on the corrected sensor waveform W ′ (second waveform).

  Next, an example of the above correction procedure and a procedure for estimating the injection rate waveform from the corrected sensor waveform W ′ will be described with reference to the flowchart of FIG. 4. Note that the series of processes shown in FIG. 4 is executed each time fuel is injected by the ECU 30 (fuel injection state estimation device).

  First, in step S10 shown in FIG. 4, a plurality of detection values (sensor waveform W) output at a predetermined sampling period from the fuel pressure sensor 20 of the injection cylinder during one fuel injection period are acquired. The solid line in FIG. 5A indicates the sensor waveform W, and the dotted line indicates the supply pulsation waveform Wa. In the subsequent step S20, a model waveform Wm (see FIG. 5B) of the supply pulsation waveform Wa is calculated. This calculation method will be described in detail later. In subsequent step S30, the model waveform Wm of the supply pulsation waveform Wa is corrected by the learning value. This correction method (update method) will be described in detail later.

  In subsequent step S40, the calculated model waveform Wm is subtracted from the sensor waveform W to calculate the sensor waveform W 'from which the supply pulsation waveform Wa has been removed (W' = W-Wm). The dotted line in FIG. 5C indicates the sensor waveform W (first waveform) before correction, and the solid line indicates the sensor waveform W ′ (second waveform) after correction.

  In the subsequent step S50, the sensor waveform W ′ after correction is a descending waveform W (P1-P2) (the waveform of the portion of P1 to P2) that is a portion where the pressure decreases as the valve element 12 starts to open. The approximate straight line La is calculated (see FIG. 2C). In the next step S60, in the corrected sensor waveform W ′, the rising waveform W (P3-P5) (the waveform of the portion of P3 to P5), which is the portion where the pressure increases as the valve body 12 starts to close. ) Of the approximate straight line Lb (modeled rising waveform) (see FIG. 2C). These approximate straight lines La and Lb may be calculated, for example, by linearly approximating a plurality of detected values constituting the descending waveform W (P1-P2) or the ascending waveform W (P3-P5) by the least square method, The tangent line at the point where the derivative value is the smallest in the falling waveform W (P1-P2) may be calculated as a linear model, or the point where the derivative value is the largest in the rising waveform W (P3-P5). You may calculate a tangent as a straight line model.

  Next, in step S70, the pressure (reference pressure Pbase) immediately before starting the pressure decrease (immediately before the change point P1) in the corrected sensor waveform W ′ is calculated, and the subsequent processing is performed based on the reference pressure Pbase. Reference straight lines Lc and Ld (see FIG. 2C) used in the above are calculated. Note that the average value of the pressure during the period from the start of the output of the injection command signal (pulse on timing t1) until the change point P1 appears may be calculated as the reference pressure Pbase. What is necessary is just to calculate the pressure average value until this time passes as the reference pressure Pbase. The same value as the reference pressure Pbase is adopted for the reference straight line Lc. A value obtained by lowering the pressure by a predetermined amount from the reference pressure Pbase is adopted for the reference straight line Ld. This predetermined amount increases as the pressure drop amount ΔP (P1-P2) from the pressure at the change point P1 to the pressure at the change point P2 increases, or as the pulse-on period (injection command period Tq) of the injection command signal increases. Set to a value.

  In subsequent step S80, the intersection of the reference straight line Lc and the approximate straight line La is calculated (see FIG. 2C). The time indicated by this intersection almost coincides with the appearance time of the change point P1. Therefore, since the timing indicated by the intersection of the reference straight line Lc and the approximate straight line La has a high correlation with the injection start timing R1, the injection start timing R1 is calculated based on this intersection. In the subsequent step S90, the intersection of the reference straight line Ld and the approximate straight line Lb is calculated. Since the timing indicated by this intersection has a high correlation with the injection end timing R4, the injection end timing R4 is calculated based on this intersection (see FIG. 2C).

  In the subsequent step S100, paying attention to the fact that the slope Rα (see FIG. 2B) of the portion where the injection rate increases and the slope of the approximate straight line La are highly correlated, the injection rate waveform is calculated based on the slope of the approximate straight line La. A rising slope Rα is calculated. In addition, paying attention to the fact that the slope Rβ (see FIG. 2B) of the portion where the injection rate decreases and the slope of the approximate line Lb are highly correlated, the slope of the drop in the injection rate waveform based on the slope of the approximate line Lb Rβ is calculated. In subsequent step S110, the pressure drop ΔP (P1-P2) from the pressure at the change point P1 to the pressure at the change point P2 is highly correlated with the maximum injection rate Rh (see FIG. 2B). Paying attention, the maximum injection rate Rh is calculated based on the pressure drop amount ΔP (P1-P2).

  According to the processing of FIG. 4 as described above, the injection start timing R1, the injection end timing R4, the injection rate increase gradient Rα, the injection rate decrease gradient Rβ, and the maximum injection rate Rh are calculated. Therefore, the injection rate waveform illustrated in FIG. 2B can be estimated. In addition, the process of step S10 corresponds to the process as a 1st waveform acquisition part, the process of step S20 corresponds to the process as a calculating part, the process of step S30 corresponds to the process as an update part, and step S40 The process corresponds to the process as the second waveform acquisition unit, and the processes in steps S50 to S110 correspond to the process as the estimation unit.

  Next, a method of calculating the model waveform Wm (see FIG. 5B) of the supply pulsation waveform Wa in step S20 will be described.

  As shown in FIG. 5A, the actual supply pulsation waveform Wa is zero pressure until the time point ta, the pressure gradually increases from the time point ta at which the superposition is started, and the pressure increase stops at the time point tb. It becomes a constant pressure. Accordingly, if the ta point at which superposition starts, the pressure increase slope Pγ from the time point ta to the time point tb, and the pressure increase amount ΔP can be estimated, the model waveform Wm (see FIG. 5B) of the supply pulsation waveform Wa can be defined. I can say that. In the present embodiment, the model waveform Wm is calculated by calculating the superposition start timing ta, the slope Pγ, and the increase amount ΔP by the following method.

  The slope Pγ (rising speed) of the supply pulsation waveform Wa has a correlation with the slope Pα (falling speed) of the descending waveform W (P1-P2). Both slopes Pγ and Pα are in a proportional relationship, and the faster the descending speed of the descending waveform W (P1-P2), the faster the ascending speed of the supply pulsation waveform Wa. This proportional relationship equation is obtained by testing in advance, and the slope Pα of the falling waveform W (P1-P2) is calculated from the detected sensor waveform W, and the calculated gradient Pα is substituted into the proportional relationship formula and supplied. A slope Pγ of the pulsation waveform Wa is calculated. Note that the slope Pα of the descending waveform W (P1-P2) may be the same as the slope of the above-described approximate straight line La (see FIG. 2C).

  Next, a method for calculating the superposition start time ta will be described. First, the time (supply pulsation propagation time Ta) required from the descent start time Tsta to the superposition start time ta is calculated. Specifically, the supply pulsation propagation is based on the path length L from the position of the fuel pressure sensor 20 (exactly the position of the diaphragm portion 21a) to the discharge port 42a and the propagation speed a (sound speed) of the injection pulsation Ma and the supply pulsation Mb. Time Ta is calculated. Since the propagation speed a changes according to the fuel pressure at that time, the propagation speed a may be calculated based on the reference pressure Pbase described above, for example. The path length L can be calculated based on the design value, and a can be calculated based on the reference pressure Pbase. The supply pulsation propagation time Ta is calculated by dividing twice the path length L by the propagation speed a (Ta = 2L / a). Tsta can be calculated from the sensor waveform W. If the supply pulsation propagation time Ta calculated in this way is added to the descent start time Tsta, the superposition start time ta can be calculated (ta = Tsta + Ta).

  Next, a method for calculating the pressure increase amount ΔP will be described. The pressure at the descent start timing Tsta and the pressure at the overlap start timing ta are detected from the sensor waveform W, and the pressure increase amount ΔP is calculated based on these pressures (refer to Patent Document 1 for details).

  FIG. 6 is a flowchart showing an example of a procedure for calculating the model waveform Wm of the supply pulsation waveform Wa as described above, and is a subroutine process of step S20 in FIG. Here, a correlation equation showing the correlation between the slope Pα of the descending waveform W (P1-P2) and the slope Pγ of the model waveform Wm, a map showing the relationship between the reference pressure Pbase and the supply pulsation propagation time Ta, and the pressure increase ΔP The expression to be calculated is stored in the memory in advance.

  First, in step S21 of FIG. 6, the slope Pα of the descending waveform W (P1-P2) is detected from the sensor waveform W, and the detected slope Pα is substituted into the correlation equation stored in the memory, so that the model waveform Wm Is calculated.

  In the subsequent step S22, the supply pulsation propagation time Ta is calculated based on the reference pressure Pbase with reference to a map showing the relationship with the supply pulsation propagation time Ta. In the subsequent step S23, the superposition start time ta is calculated by adding the supply pulsation propagation time Ta calculated in step S22 to the descent start time Tsta detected from the sensor waveform W.

  In subsequent step S24, the pressure increase amount ΔP is calculated based on the pressure at the descent start timing Tsta and the pressure at the superposition start timing ta detected from the sensor waveform W. In the subsequent step S25, the model waveform Wm of the supply pulsation waveform Wa illustrated in FIG. 5B is defined (calculated) based on the slope Pγ calculated in steps S21, S23, and S24, the superposition start timing ta, and the increase amount ΔP. To do.

  Here, there is a possibility that the actual supply pulsation waveform Wa and the model waveform Wm (supply pulsation waveform calculated based on the model) may be shifted due to manufacturing variations of the common rail 42 and the fuel pipe 42b, changes in characteristics over time, and the like. In this case, since the sensor waveform W ′ obtained by subtracting the model waveform Wm from the sensor waveform W does not accurately reflect the fuel injection state, the accuracy of estimating the fuel injection state may be reduced. In this respect, in the present embodiment, a deviation amount between the model waveform Wm of the supply pulsation waveform and the actual supply pulsation waveform Wa is calculated, and the model waveform Wm is updated based on the deviation amount.

  Specifically, during fuel injection by the fuel injection valve 10, the fuel flowing through the fuel pipe 42b and the high-pressure passage 11a is throttled by the injection hole 11b, and a constant flow of fuel is injected from the injection hole 11b. For this reason, if the supply pulsation waveform Wa is not superimposed on the sensor waveform W, the sensor waveform W is considered to be maintained for a certain period of time after reaching the minimum value (after the removal correction in FIG. 5C). (See sensor waveform W ′). On the other hand, after the actual sensor waveform W reaches the minimum value, the minimum value is not maintained for a certain period of time (see the sensor waveform W in FIG. 5A). This is considered to be due to the superposition on the sensor waveform W ′.

  From these considerations, the inventor of the present application has found that the appearance timing of the change point P2 at which the fuel pressure is minimum in the sensor waveform W substantially coincides with the timing ta at which the supply pulsation waveform Wa starts to be superimposed on the sensor waveform W. (See FIG. 5 (a)). Further, the inventor of the present application indicates that the slope of the portion of the sensor waveform W where the fuel pressure rises from the change point P2 at which the fuel pressure is minimum (the portion from the change point P2 to the change point P2a) of the supply pulsation waveform Wa. It was found that it almost coincided with the slope of the rising part. Further, the inventor of the present application indicates that the amount of increase ΔP from the change point P2 where the fuel pressure is minimum in the sensor waveform W to the change point P2a where the fuel pressure increases and becomes constant is the increase amount ΔP of the supply pulsation waveform Wa. It was found that they were almost identical.

  In the present embodiment, the model waveform Wm is corrected by a learning value representing the amount of deviation between the model waveform Wm of the supply pulsation waveform and the actual supply pulsation waveform Wa. FIG. 7 is a flowchart showing a procedure for correcting the model waveform Wm, and is a subroutine process of step S30 in FIG.

  First, in step S31 of FIG. 7, the rising slope Pγ of the supply pulsation waveform Wa is calculated based on the slope of the portion of the sensor waveform W where the fuel pressure rises from the point where the fuel pressure is minimum. Specifically, in FIG. 5A, an approximate line from the change point P2 to the change point P2a in the sensor waveform W is calculated by the least square method, and the slope of this approximate line is calculated as the slope Pγ of the supply pulsation waveform Wa. . Note that the maximum value of the differential value in the rising waveform W (P2-P2a) may be calculated as the slope Pγ of the supply pulsation waveform Wa.

  In the subsequent step S32, the difference amount between the inclination Pγ of the model waveform Wm calculated by the processing shown in FIG. 6 and the actual inclination Pγ calculated in step S31 is calculated.

  Subsequently, in step S33, a time ta at which the supply pulsation waveform Wa starts to be superimposed on the sensor waveform W is calculated based on the appearance time of the point where the fuel pressure is minimum in the sensor waveform W. Specifically, in FIG. 5A, the appearance time of the change point P2 in the sensor waveform W is calculated as the superposition start time ta of the supply pulsation waveform Wa to the sensor waveform W.

  In the subsequent step S34, the difference amount between the superposition start time ta of the model waveform Wm calculated by the process shown in FIG. 6 and the actual superposition start time ta calculated in step S33 is calculated.

  In the subsequent step S35, the amount of increase ΔP of the supply pulsation waveform Wa is calculated based on the amount of increase in the sensor waveform W from the point where the fuel pressure becomes minimum until the fuel pressure increases and becomes constant. Specifically, in FIG. 5A, the increase amount ΔP from the change point P2 to the change point P2a in the sensor waveform W is calculated as the increase amount ΔP of the supply pulsation waveform Wa.

  In the subsequent step S36, a difference amount between the increase amount ΔP of the model waveform Wm calculated by the processing shown in FIG. 6 and the actual increase amount ΔP calculated in step S35 is calculated.

  In subsequent step S37, the difference amounts calculated in steps S32, S34, and S36 are stored in the memory as learning values of the slope Pγ, the superposition start timing ta, and the increase amount ΔP.

  In subsequent step S38, the model waveform Wm is corrected based on each learning value stored in the memory in step S37. Specifically, the corrected model waveform Wm is calculated by adding the respective learned values to the slope Pγ, the superposition start time ta, and the increase amount ΔP of the model waveform Wm (updating the model waveform Wm).

  Note that the processing in steps S31 to S38 corresponds to processing as an updating unit.

  The embodiment described in detail above has the following advantages.

  The model waveform Wm is updated based on the sensor waveform W that reflects the supply pulsation waveform Wa. For this reason, the model waveform Wm can be updated in accordance with the actual supply pulsation waveform Wa. Further, the inventor of the present application directly adds the actual supply pulsation waveform Wa to a predetermined portion of the sensor waveform W from the change point P2 where the fuel pressure becomes minimum to the change point P2a where the fuel pressure rises and becomes constant. It was found to be reflected in. In this respect, since the model waveform Wm is corrected (updated) based on the predetermined portion of the sensor waveform W in particular, the accuracy of calculating the model waveform Wm of the supply pulsation waveform Wa can be improved. As a result, even if manufacturing variations of the common rail 42, the fuel pipe 42b, and the high-pressure passage 11a, changes in characteristics over time, and the like occur, it is possible to suppress a decrease in the estimation accuracy of the fuel injection state.

  The inventor of the present application has found that the appearance time of the change point P2 at which the fuel pressure is minimum in the sensor waveform W substantially coincides with the time ta at which the supply pulsation waveform Wa starts to be superimposed on the sensor waveform W. At this point, since the timing ta at which the model waveform Wm starts to be superimposed on the sensor waveform W is corrected (updated) based on the appearance time of the change point P2 at which the fuel pressure is minimum in the sensor waveform W, the model waveform Wm is The accuracy of calculation can be improved.

  The inventor of the present application has found that the slope of the portion of the sensor waveform W where the fuel pressure rises from the change point P2 at which the fuel pressure is minimum substantially matches the slope of the raised portion of the supply pulsation waveform Wa. . In this respect, the slope Pγ of the rising portion of the model waveform Wm is corrected (updated) based on the slope of the portion of the sensor waveform W where the fuel pressure rises from the change point P2 where the fuel pressure is minimum. The accuracy of calculating the model waveform Wm can be improved.

  The inventor of the present application indicates that the amount of increase from the change point P2 where the fuel pressure is minimum in the sensor waveform W to the change point P2a where the fuel pressure rises and becomes constant is substantially equal to the increase amount ΔP of the supply pulsation waveform Wa. I found out. In this respect, in the sensor waveform W, the increase amount ΔP of the model waveform Wm is corrected (updated) based on the increase amount from the change point P2 at which the fuel pressure becomes minimum to the change point P2a at which the fuel pressure increases and becomes constant. Therefore, the accuracy of calculating the model waveform Wm can be improved.

  The amount of updating the model waveform Wm is stored as a learning value, and the model waveform Wm is corrected based on this learning value. Therefore, not only the model waveform Wm is corrected in accordance with the actual supply pulsation waveform Wa, but also the deviation from the model waveform Wm before correction (the model waveform Wm serving as a reference) can be grasped as a learning value.

  In addition, it is not limited to the said embodiment, You may implement as changed as follows.

  In the above embodiment, the superposition start time ta, the slope Pγ, and the increase amount ΔP of the supply pulsation waveform Wa are calculated to define the model waveform Wm. However, a plurality of patterns of models are stored in advance, and the decrease waveform The optimum model may be selected from a plurality of patterns based on W (P1-P2) (for example, the descent start timing Tsta, the inclination Pα, etc.).

  In the above embodiment, the fuel pressure sensor 20 is mounted on the fuel injection valve 10, but the fuel pressure sensor is arranged to detect the fuel pressure in the fuel path from the discharge port 42a of the common rail 42 to the injection hole 11b. Any fuel pressure sensor may be used. Therefore, for example, a fuel pressure sensor may be mounted on the fuel pipe 42b.

  In the above embodiment, the difference amounts calculated in steps S32, S34, and S36 in FIG. 7 are stored in the memory as learning values of the slope Pγ, the superposition start time ta, and the increase amount ΔP, and the slope Pγ of the model waveform Wm is stored. The corrected model waveform Wm was calculated by adding the respective learning values to the superimposition start time ta and the increase amount ΔP. However, instead of this, in steps S32, S34, and S36 of FIG. 7, the respective ratios of the slope Pγ, the superposition start time ta, and the increase amount ΔP with respect to the model waveform Wm are stored in the memory as respective learning values, and the model waveform Wm The corrected model waveform Wm may be calculated by multiplying the slope Pγ, the superposition start time ta, and the increase amount ΔP by the respective learning values.

  In the above embodiment, the amount of updating the model waveform Wm is stored as a learning value, and the model waveform Wm is corrected based on this learning value. However, after updating the model waveform Wm so that each learning value is reflected, the supply pulsation waveform Wa may be calculated based on the updated model waveform Wm.

  In the above embodiment, the model waveform Wm is calculated according to the procedure shown in FIG. However, according to the procedure shown in FIG. 7, the inclination Pγ, the superposition start timing ta, and the increase amount ΔP are calculated for the reference fuel injection system (master fuel injection valve, etc.), and the reference model waveform Wm is calculated based on these. It can also be created.

  -The injection state estimation apparatus of this embodiment can also be applied not only to a diesel engine but to a direct injection gasoline engine provided with a delivery pipe.

  DESCRIPTION OF SYMBOLS 10 ... Fuel injection valve, 11a ... High pressure passage, 11b ... Injection hole, 20 ... Fuel pressure sensor, 30 ... ECU, 42 ... Common rail, 42b ... Fuel piping.

Claims (6)

A pressure accumulating container (42) for accumulating and holding fuel, a fuel injection valve (10) for injecting the fuel from the injection hole (11b), and a fuel passage (42b, 11a) for circulating the fuel from the pressure accumulating container to the injection hole And a fuel pressure sensor (20) for detecting the fuel pressure in the fuel passage, a fuel injection state estimating device (30) applied to a fuel injection system,
A first waveform acquisition unit that acquires a first waveform representing a change in the fuel pressure based on the fuel pressure detected by the fuel pressure sensor when the fuel is injected by the fuel injection valve;
Based on a model created in advance, a calculation unit that calculates a waveform of supply pulsation generated by fuel supplied from the pressure accumulator to the fuel injection valve through the fuel passage when the fuel is injected by the fuel injection valve;
A second waveform acquisition unit that acquires a second waveform obtained by removing the supply pulsation waveform calculated by the calculation unit from the first waveform;
An estimation unit that estimates an injection state of the fuel based on the second waveform acquired by the second waveform acquisition unit;
Of the first waveforms acquired by the first waveform acquisition unit, a timing at which the waveform of the supply pulsation in the model starts to be superimposed on the first waveform is based on the appearance time of the point at which the fuel pressure is minimum. An update section to update;
The fuel-injection state estimation apparatus characterized by the above-mentioned. The update unit has a waveform of the supply pulsation in the model based on a slope of a portion of the first waveform acquired by the first waveform acquisition unit where the fuel pressure increases from a point at which the fuel pressure is minimum. The fuel injection state estimation apparatus according to claim 1, wherein the inclination of the rising portion is updated. A pressure accumulating container (42) for accumulating and holding fuel, a fuel injection valve (10) for injecting the fuel from the injection hole (11b), and a fuel passage (42b, 11a) for circulating the fuel from the pressure accumulating container to the injection hole And a fuel pressure sensor (20) for detecting the fuel pressure in the fuel passage, a fuel injection state estimating device (30) applied to a fuel injection system,
A first waveform acquisition unit that acquires a first waveform representing a change in the fuel pressure based on the fuel pressure detected by the fuel pressure sensor when the fuel is injected by the fuel injection valve;
Based on a model created in advance, a calculation unit that calculates a waveform of supply pulsation generated by fuel supplied from the pressure accumulator to the fuel injection valve through the fuel passage when the fuel is injected by the fuel injection valve;
A second waveform acquisition unit that acquires a second waveform obtained by removing the supply pulsation waveform calculated by the calculation unit from the first waveform;
An estimation unit that estimates an injection state of the fuel based on the second waveform acquired by the second waveform acquisition unit;
Of the first waveform acquired by the first waveform acquisition unit, the rising portion of the waveform of the supply pulsation in the model is based on the slope of the portion where the fuel pressure increases from the point where the fuel pressure is minimum. An update unit for updating the inclination;
The fuel-injection state estimation apparatus characterized by the above-mentioned.   In the model, the update unit is based on the amount of increase in the first waveform acquired by the first waveform acquisition unit from the point where the fuel pressure becomes minimum until the fuel pressure increases and becomes constant. The fuel injection state estimation device according to any one of claims 1 to 3, wherein an increase amount of the waveform of the supply pulsation is updated. A pressure accumulating container (42) for accumulating and holding fuel, a fuel injection valve (10) for injecting the fuel from the injection hole (11b), and a fuel passage (42b, 11a) for circulating the fuel from the pressure accumulating container to the injection hole And a fuel pressure sensor (20) for detecting the fuel pressure in the fuel passage, a fuel injection state estimating device (30) applied to a fuel injection system,
A first waveform acquisition unit that acquires a first waveform representing a change in the fuel pressure based on the fuel pressure detected by the fuel pressure sensor when the fuel is injected by the fuel injection valve;
Based on a model created in advance, a calculation unit that calculates a waveform of supply pulsation generated by fuel supplied from the pressure accumulator to the fuel injection valve through the fuel passage when the fuel is injected by the fuel injection valve;
A second waveform acquisition unit that acquires a second waveform obtained by removing the supply pulsation waveform calculated by the calculation unit from the first waveform;
An estimation unit that estimates an injection state of the fuel based on the second waveform acquired by the second waveform acquisition unit;
Of the first waveform acquired by the first waveform acquisition unit, the waveform of the supply pulsation in the model based on the amount of increase from the point where the fuel pressure becomes minimum until the fuel pressure increases and becomes constant. An update unit that updates the amount of increase
The fuel-injection state estimation apparatus characterized by the above-mentioned. The update unit stores the amount of updating the model as a learning value, the fuel injection state estimating apparatus according to any one of claims 1 to 5 for correcting the model based on the learning value.

Images