JP2016094829A - Fuel injection state acquisition apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection state acquisition apparatus capable of highly accurately acquiring a correlation between an output of an internal combustion engine and a fuel injection quantity.SOLUTION: Provided is a fuel injection state acquisition apparatus 30 that is applied to a fuel injection system comprising a fuel injection valve 10 (#1, 3) provided in a first cylinder of an internal combustion engine, and a fuel pressure sensor 22 detecting a pressure change of a fuel generated within the fuel injection valve 10 (#1, 3) when fuel is injected from the fuel injection valve 10 (#1, 3), the fuel injection state acquisition apparatus 30 comprising: first injection-quantity calculation means for calculating a first injection quantity by which the fuel has been injected from the fuel injection valve 10 (#1, 3) on the basis of a detection value of the fuel pressure sensor 22; first output detection means for detecting a first output of the internal combustion engine to accompany the injection of the fuel by the first injection quantity; combustion determination means for determining whether the fuel injected from the fuel injection valve 10 (#1, 3) has been burned; and correlation calculation means for calculating a correlation between the output of the internal combustion engine and the injection quantity of the fuel on the basis of the first output and the first injection quantity on condition that the injected fuel has been burned.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel injection state acquisition device that acquires a correlation between an injection amount of fuel injected from a fuel injection valve and an output of an internal combustion engine.

  A fuel pressure sensor is installed in the fuel passage from the common rail discharge port to the fuel injection valve injection hole to detect the fuel pressure waveform that indicates the pressure change caused by fuel injection, and the actual injection amount is detected from the fuel pressure waveform. Techniques to do this have been proposed. According to this technique, the valve opening period command value of the fuel injection valve can be corrected based on the difference between the command injection amount and the actual injection amount. However, in order to perform correction in all the cylinders, it is necessary to mount a fuel pressure sensor on each cylinder, resulting in a great increase in cost.

  Therefore, in the fuel injection control device described in Patent Document 1, a fuel pressure sensor is mounted only on a specific cylinder, and the correlation between the output of the internal combustion engine and the actual injection amount is acquired for the specific cylinder. . In the above apparatus, the actual injection amount in the non-mounted cylinder is estimated from the output of the internal combustion engine caused by the combustion of the injected fuel and the correlation in the non-mounted cylinder not equipped with the fuel pressure sensor. ing.

JP2013-44237A

  In the minute injection amount region where the command injection amount is minute, the variation in the output of the internal combustion engine with respect to the command injection amount becomes large. For this reason, in the above apparatus, an error included in the correlation between the output of the internal combustion engine and the actual injection amount becomes large in the minute injection amount region.

  In view of the above circumstances, it is a main object of the present invention to provide a fuel injection state acquisition device that can acquire the correlation between the output of an internal combustion engine and the fuel injection amount with high accuracy.

  In order to solve the above-described problems, the present invention provides a first fuel injection valve provided in a first cylinder of an internal combustion engine, and the inside of the first fuel injection valve at the time of fuel injection from the first fuel injection valve. A fuel injection state acquisition device that is applied to a fuel injection system that includes a fuel pressure sensor that detects a pressure change of the generated fuel, and is injected from the first fuel injection valve based on a detection value of the fuel pressure sensor A first injection amount calculating means for calculating a first injection amount; a first output detecting means for detecting a first output of the internal combustion engine associated with the injection of fuel of the first injection amount by the first fuel injection valve; Detected by the first output detection means on the condition that the fuel determination means determines whether the fuel injected from the first fuel injection valve is combusted, and the injection is determined to be combusted by the combustion determination means. Said first output and Serial based on the first injection quantity calculated by the first injection amount calculating means, and a correlation calculating means for calculating the correlation between the output and the injection quantity of the fuel of the internal combustion engine.

  According to the present invention, when the fuel is injected from the first fuel injection valve provided in the first cylinder of the internal combustion engine, the fuel pressure change is detected by the fuel pressure sensor, and the first pressure is detected based on the detected pressure change. A first injection amount injected from the fuel injection valve is calculated. Further, a first output of the internal combustion engine accompanying the injection of the first injection amount of fuel by the first fuel injection valve is detected.

  When calculating the first injection amount based on the detection value of the fuel pressure sensor, the first injection amount is calculated even if the fuel is not burned. In the case of the injection in which the fuel is not burned, the output of the internal combustion engine accompanying combustion is not obtained, and the output of the obtained internal combustion engine corresponds to noise. By including injection in which the output of the internal combustion engine resulting from the combustion of fuel is not obtained, the inventor produces variations in the output of the internal combustion engine with respect to the command injection amount, and is included in the correlation between the output of the internal combustion engine and the injection amount. The knowledge that the error to be increased becomes large.

  Therefore, on the condition that the fuel injected from the first fuel injection valve is an injection determined to be combusted, the output of the internal combustion engine and the fuel injection amount are calculated based on the first output and the first injection amount. A correlation is calculated. Thereby, the injection which has not generated the output of the internal combustion engine can be excluded, and the correlation between the output of the internal combustion engine and the fuel injection amount can be obtained with high accuracy. In particular, the correlation can be acquired with higher accuracy than in the past in the minute injection amount region.

The schematic diagram which shows the structure of a fuel-injection system. The figure which shows the change of the injection rate and fuel pressure corresponding to an injection command signal. The figure which shows distribution of the torque with respect to injection amount. The flowchart which shows the process sequence which calculates the correlation of a torque and the injection quantity.

  Hereinafter, an embodiment embodying a fuel injection state acquisition device will be described with reference to the drawings. The injection state acquisition device according to the present embodiment is assumed to be applied to a fuel injection system of a four-cylinder diesel engine (internal combustion engine).

  FIG. 1 is a schematic diagram showing an outline of a fuel injection system to which an ECU 30 (fuel injection state acquisition device) is applied. The fuel in the fuel tank 40 is pumped and stored in the common rail 42 (pressure accumulating container) by the fuel pump 41, and distributed and supplied to the fuel injection valves 10 (# 1 to # 4) of each cylinder. The plurality of fuel injection valves 10 (# 1 to # 4) sequentially inject fuel in a preset order. In this embodiment, it is assumed that injection is performed in the order of # 1 → # 3 → # 4 → # 2.

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

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

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

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

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

  The fuel pressure sensor 22 that detects the pressure change of the internal fuel of the fuel injection valve 10 is not mounted on all the fuel injection valves 10. In this embodiment, the fuel pressure sensor 22 is mounted on the # 1 and # 3 fuel injection valves 10 (sensor-injected fuel injection valves), and the fuel pressure is supplied to the # 2 and # 4 fuel injection valves 10 (non-sensor fuel injection valves). The sensor 22 is not mounted. Cylinders # 1 and # 3 correspond to the first cylinder, and cylinders # 2 and # 4 correspond to the second cylinder. Further, the fuel injection valves 10 (# 1, # 3) with sensors in the cylinders # 1, # 3 correspond to the first fuel injection valves, and the fuel injection valves 10 (# 2, # 3) with no sensors in the cylinders # 2, # 4. 4) corresponds to the second fuel injection valve.

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

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

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

  The ECU 30 includes a microcomputer including a CPU, a ROM, a RAM, an I / O, and the like. Timing, injection end timing, injection amount, etc.). The engine speed NE is detected by the crank angle sensor 50, and a detection signal detected by the crank angle sensor 50 is transmitted to the ECU 30.

  For example, the ECU 30 includes a storage device that stores an optimal injection state corresponding to the engine load and the engine rotational speed as an injection state map, and refers to the target state with reference to the injection state map based on the current engine load and the engine rotational speed NE. The injection state is calculated. Then, as shown in FIG. 2A, the ECU 30 converts the injection command signals t1, t2, Tq corresponding to the calculated target injection state into injection rate parameters td, te, Rα, Rβ, Rh, which will be described in detail later. The operation of the fuel injection valve 10 is controlled by setting based on this and outputting to the fuel injection valve 10.

  Further, the ECU 30 executes various programs stored in the ROM so that the first injection amount calculating means, the first output detecting means, the combustion determining means, the correlation calculating means, the threshold calculating means, the determining means, and the update Each function of the means, the second output detecting means, the second injection amount calculating means, and the second combustion determining means is realized.

  Next, a method for calculating the injection amount when fuel is injected from the fuel injection valve with sensor 10 (# 1, # 3) will be described with reference to FIG.

  2 (b) and 2 (c) correspond to the injection command signal of FIG. 2 (a), FIG. 2 (b) shows the injection rate which is the injection amount per unit time, and FIG. Indicates a fuel pressure waveform which is a time change of the detected pressure detected by the fuel pressure sensor 22. The injection rate starts to rise from the point R1 when the valve body 12 starts to rise in accordance with the pulse-on of the command signal. The detected pressure starts to decrease at time P1 when C1 time has elapsed from time R1. Thereafter, as the injection hole 11b is completely opened at time R2 and the injection rate reaches the maximum injection rate, the decrease in fuel pressure stops at time P2. Next, the injection rate starts to decrease from the time point R3 when the valve body 12 starts to descend in accordance with the pulse-off of the command signal. Then, the fuel pressure starts increasing at time P3 when C3 time has elapsed from time R3. Thereafter, as the injection hole 11b is completely closed and the injection rate becomes zero and the actual injection is completed, the increase in fuel pressure is stopped.

  Therefore, the correlation between the fuel pressure waveform and the injection rate waveform is high. Specifically, there is a correlation between the time point P1 at which the pressure drop starts from the reference pressure Pbase in the pressure waveform and the actual injection start point R1. The reference pressure Pbase may be, for example, an average pressure value until a predetermined time elapses from the injection start command timing t1 of the injection command signal. Further, a pressure that is lower than the reference pressure Pbase by a predetermined pressure is set as a detected reference pressure Pd. For example, the predetermined pressure is set to a larger value as the pulse-on period Tq of the injection command signal is longer. There is a correlation between the point P4, which is the intersection of the detected reference pressure Pd and the fuel pressure waveform, and the actual injection end point R4. Further, there is a correlation between the slope Pα of the fuel pressure drop in the fuel pressure waveform and the injection rate rise slope Rα of the portion where the injection rate increases, and the portion of the fuel pressure waveform where the fuel pressure rise slope Pβ from the time point P3 and the injection rate decreases. There is a correlation with the injection rate decreasing slope Rβ. Further, there is a correlation between the pressure drop amount ΔPd from the fuel pressure at the point P1 to the fuel pressure at the point P2 and the maximum injection rate Rh.

  Thus, since the fuel pressure waveform and the injection rate waveform are highly correlated, the injection rate parameters Rα, Rβ, and Rh can be calculated from the fuel pressure waveform. Furthermore, an injection start delay timing td with respect to the injection start command timing t1 and an injection end delay timing te with respect to the injection end command timing t2 can be calculated. Therefore, the ECU 30 can calculate the injection rate parameters td, te, Rα, Rβ, Rh from the fuel pressure waveform. Further, since the area inside the injection rate waveform corresponds to the injection amount, the ECU 30 can calculate the injection amount based on the calculated injection rate parameter.

  The ECU 30 learns the calculated injection rate parameters td, te, Rα, Rβ, Rh. The injection rate parameter varies depending on the supply pressure at that time (pressure in the common rail 42), the fuel temperature, and the like, so the supply pressure or the reference pressure Pbase and the fuel temperature detected by the fuel temperature sensor 23 It is desirable to learn in association. The ECU 30 stores the learned injection rate parameter value in the injection rate parameter map for each supply pressure.

  The ECU 30 acquires the learned value of the injection rate parameter corresponding to the current supply pressure from the injection rate parameter map, and sets the injection command signals t1, t2, Tq corresponding to the target injection amount based on the acquired injection rate parameter. To do. Therefore, the injection command signal is feedback-controlled based on the actual injection state, and the actual injection amount that is the actual injection amount matches the target injection amount even if the fuel injection valve 10 deteriorates over time. Thus, the fuel injection can be controlled with high accuracy.

  However, the fuel pressure waveform detected by the fuel pressure sensor 22 is obtained by superimposing other components on the component of the injection waveform representing the change in fuel pressure due to injection. As other components, there are a pumping component of the fuel by the fuel pump 41, a pulsation component accompanying the pre-stage injection in the case of performing multi-stage injection, and the like. Therefore, it is desirable to extract the injection waveform by subtracting other components from the fuel pressure waveform detected by the fuel pressure sensor 22 and calculate the injection rate parameter from the extracted injection waveform.

  Next, a method for calculating the correlation between the engine torque (output) and the fuel injection amount will be described. Here, the first fuel injection valve is the fuel injection valve 10 (# 1). The first injection amount calculation means calculates the first injection amount that is the actual injection amount injected from the fuel injection valve 10 (# 1) based on the detection value of the fuel pressure sensor 22. That is, the first injection amount calculation means calculates the injection rate parameter from the fuel pressure waveform detected by the fuel pressure sensor 22 and calculates the first injection amount. The first output detection means detects the torque T1 (first output) of the engine accompanying the combustion of the fuel of the first injection amount by the fuel injection valve 10 (# 1). The engine torque T1 is an increase in torque caused by the combustion of the first injection amount of fuel, and the increase in engine rotation speed NE caused by the injection of the first injection amount of fuel is calculated using inertia. Calculated by converting to torque.

  FIG. 3 shows the first injection amount when fuel corresponding to the command injection amount is injected a plurality of times from the fuel injection valve 10 (# 1) for each command injection amount Q1, Q2, Q3 (Q1 <Q2 <Q3). The distribution of torque T1 is shown. The cross mark and the plus mark indicate the first injection amount and the torque T1 in one injection. The area surrounded by the dotted line indicates the first injection amount and the torque T1 corresponding to the same command injection amount. The determination threshold Th (determination threshold) is a threshold with which it is possible to determine that the engine torque T1 is not noise but output from fuel combustion. A distribution in which the torque T1 is larger than the determination threshold Th indicates a case where the torque accompanying fuel combustion is obtained (X), and a distribution in which the torque T1 is smaller than the determination threshold Th is obtained by the torque associated with fuel combustion. The case where it was not done is shown (plus sign).

  As shown in FIG. 3, when the command injection amount is very small Q1, the distribution of the torque T1 with respect to the first injection amount varies, and distributions A and B in which the torque T1 is smaller than the determination threshold Th are included. .

  The following two cases can be considered as factors for not obtaining the torque associated with fuel combustion. One is a case where misfiring occurs due to a decrease in fuel ignitability due to variations in intake pressure, injection timing, and ignition timing of the cylinder (# 1) with respect to the command injection amount. In a region where the command injection amount is very small, the influence of variations in intake pressure, injection timing, and ignition timing on ignitability is large, and misfire is likely. In this case, the distribution of the torque T1 with respect to the first injection amount corresponds to the distribution B.

  The other is when the first injection amount is smaller than the minimum amount Qi that can be detected by distinguishing the torque generated by the combustion of the fuel from the noise, and only the noise level torque can be obtained even if the fuel burns. is there. Such a situation is likely to occur when the first injection amount is smaller than the command injection amount in a region where the command injection amount is very small due to deterioration of the fuel injection valve 10 (# 1) over time. In this case, the distribution of the torque T1 with respect to the first injection amount corresponds to the distribution A.

  In the conventional correlation calculation method, the present inventor calculated the correlation including injection in a misfire state and injection that has low engine torque and is difficult to distinguish from noise. The knowledge that the error included in the correlation with the quantity was large was obtained. Therefore, in this embodiment, the correlation between the engine torque and the fuel injection amount is calculated only from the injection in which the engine output larger than the noise level is generated by the combustion of the fuel.

  The combustion determination means determines whether or not the fuel injected from the fuel injection valve 10 (# 1) has burned. Specifically, the combustion determination unit determines that combustion has occurred when the torque T1 detected by the first output detection unit is greater than the determination threshold Th. In the present embodiment, when the first injection amount is smaller than the command injection amount and the fuel is combusted but the torque T1 exceeding the determination threshold Th is not obtained, it is determined that the fuel is not combusting.

  The combustion determination means may determine that the injected fuel is not combusted when the calculated first injection amount is smaller than the minimum amount Qi (distribution A). When the first injection amount is smaller than the minimum amount Qi, it is unlikely that a torque T1 larger than the determination threshold Th will be obtained even if the injected fuel burns. Therefore, when the first injection amount is smaller than the minimum amount Qi, it may be determined that the injected fuel is not combusted. The minimum amount Qi is stored in the storage device of the ECU 30 as a value calculated in advance through experiments or the like.

  The threshold calculation means calculates a determination threshold Th. Specifically, for example, when the engine is operating with fuel injection stopped during deceleration, engine torque fluctuation is detected, and a value larger than the maximum value of the detected torque fluctuation is calculated as the determination threshold Th. To do. The torque of the engine when the fuel injection is stopped corresponds to noise in the same manner as the output when the fuel is not burned. By setting a value larger than the maximum noise value as the determination threshold Th, it is possible to determine whether an output accompanying combustion is obtained.

  The correlation calculating means calculates a correlation between the engine torque and the fuel injection amount based on the torque T1 and the first injection amount on the condition that the injection is determined to have been burned by the combustion determining means. Specifically, the correlation calculation unit averages the torque T1 and the first injection amount on condition that the injections correspond to the same injection command and are determined to be burned by the combustion determination unit. Then, the correlation calculation means calculates a correlation from the averaged torque T1 and the first injection amount corresponding to the plurality of command injection amounts.

  In FIG. 3, point A3 indicates a value obtained by averaging the torque T1 and the first injection amount of the injection determined to be combusted in the plurality of injections according to the command injection amount Q3. The plurality of injections corresponding to the command injection amount Q3 are injections determined to be all combusting. The same applies to point A2.

  The A1 point indicates a value obtained by averaging the torque T1 and the first injection amount of the injection determined to be combusted in a plurality of injections corresponding to the command injection amount Q1, and the point A1 ′ indicates the command injection amount Q1. In a plurality of corresponding injections, a value obtained by averaging the torque T1 and the first injection amount of all the injections is shown. Conventionally, the A1 ′ point is used for calculating the correlation, whereas in the present embodiment, the A1 point is used for calculating the correlation. A solid straight line connecting the points A1 and A2, and the points A2 and A3 corresponds to the correlation calculated in the present embodiment. On the other hand, the two-dot chain line connecting the points A1 ′ and A2, and the points A2 and A3 corresponds to the correlation calculated by the conventional method. It can be seen that the correlation calculated by the conventional method includes an error corresponding to the error between the points A1 and A1 ′. The correlation may be calculated as a curve passing through the points A1, A2, and A3.

  The update unit updates the minimum amount Qi to an injection amount corresponding to the determination threshold Th in the correlation calculated by the correlation calculation unit. That is, the initial minimum amount Qi is calculated and stored in advance through experiments or the like, but the minimum amount Qi is updated each time the correlation is calculated. Thereby, the minimum amount Qi can be set to a value according to the individual difference of the actual machine.

  The discriminating unit discriminates a factor determined by the combustion determining unit that combustion is not performed. Specifically, when the torque T1 is smaller than the determination threshold Th and the first injection amount is larger than the minimum amount Qi (distribution B), the determination unit determines the intake pressure or the injection timing or the ignition with respect to the command injection amount. Timing variation. Further, when the torque T1 is smaller than the determination threshold Th and the first injection amount is smaller than the minimum amount Qi (distribution A), the determination unit determines the variation of the first injection amount with respect to the command injection amount. By discriminating the factors in this way, the factors can be reflected in other controls.

  Next, a processing procedure for calculating the correlation between the engine torque and the fuel injection amount will be described with reference to the flowchart of FIG. This processing procedure is started by the ECU 30 at predetermined intervals.

  First, it is determined whether or not a non-injection deceleration operation is being performed (S10). If the non-injection deceleration operation is not being performed (S10: NO), this process is terminated. When the non-injection deceleration operation is being performed (S10: YES), it is determined whether there is a request for calculating the determination threshold Th (S11). Once the determination threshold Th is calculated, the calculated value can be continuously used as long as the engine characteristics do not change. Therefore, it is determined whether or not a time (first time) during which the engine characteristics change has elapsed since the previous determination threshold Th was calculated. That is, when the first time has elapsed since the previous determination threshold Th was calculated, it is determined that there is a request for calculating the determination threshold Th, and when the first time has not elapsed since the previous determination threshold Th was calculated. Determines that there is no request for calculation of the determination threshold Th. Instead of determining whether the first time has elapsed, it may be determined whether the vehicle has traveled the first distance.

  When there is a request for calculating the determination threshold Th (S11: YES), torque is detected (S12). Here, since the fuel is not injected, the detected torque corresponds to noise. Subsequently, a value larger than the maximum value of the torque detected in S12 is calculated as the determination threshold Th (S13). The process is temporarily terminated as described above, and the process starts again from S10.

  In the process of S11, since the previous determination threshold Th is calculated, there is no calculation request for the determination threshold Th (S11: NO). Therefore, it is next determined whether or not there is a request for calculating the correlation between the engine torque and the fuel injection amount (S14). Similarly to the determination threshold Th, once the correlation is calculated, the calculated correlation can be used as long as the characteristics of the engine and the fuel injection valve 10 do not change. Therefore, as in the process of S11, when the second time has elapsed since the previous correlation was calculated, it is determined that there is a correlation calculation request, and the second time has elapsed since the previous correlation was calculated. If not, it is determined that there is no correlation calculation request. Instead of determining whether the second time has elapsed, it may be determined whether the vehicle has traveled the second distance. The first time and the second time may be the same. Further, the first distance and the second distance may be the same.

  If there is no correlation calculation request (S14: NO), this process ends. On the other hand, when there is a correlation calculation request (S14: YES), next, fuel corresponding to the command injection amount is injected in the cylinder (# 1) equipped with the fuel pressure sensor 22 (S15). Subsequently, based on the fuel pressure waveform detected by the fuel pressure sensor 22 at the time of fuel injection in S15, a first injection amount that is the amount of injected fuel is detected (S16). Subsequently, the engine torque T1 generated with the fuel injection in S15 is detected (S17).

  Subsequently, it is determined whether or not the first injection amount detected in S16 is larger than the minimum amount Qi (S18). When the first injection amount is smaller than the minimum amount Qi (S18: NO), the detection data, that is, the first injection amount detected in S16 and the torque T1 detected in S17 are not adopted (S20). On the other hand, when the first injection amount is larger than the minimum amount Qi (S18: YES), it is next determined whether or not the torque T1 detected in S17 is larger than the determination threshold Th (S19). When the torque T1 is smaller than the determination threshold Th (S19: NO), the detection data, that is, the first injection amount detected in S16 and the torque T1 detected in S17 are not adopted (S20).

  On the other hand, when the torque T1 is larger than the determination threshold Th (S19: NO), the first injection amount detected in S16 and the torque T1 detected in S17 are employed. Further, the processes of S15 to S20 are repeatedly executed with the same command injection amount, the command injection amount is changed, and the processes of S15 to S20 are repeatedly executed for each command injection amount. Then, for each command injection amount, the employed torque T1 and the first injection amount are averaged, and the correlation between the engine torque and the fuel injection amount is calculated (S21). Subsequently, a smoothing process is performed on the correlation calculated in S21 (S22). When calculating the fuel injection amount in the sensorless cylinders (# 2, # 4), a correlation obtained by performing the annealing process is used. This process is complete | finished above.

  Next, a method for calculating the injection amount when fuel is injected from the sensorless fuel injection valve 10 (# 2, # 4) will be described. Here, the second fuel injection valve is the fuel injection valve 10 (# 2). The second output detecting means detects engine torque T2 (second output) accompanying fuel injection by the fuel injection valve 10 (# 2). The torque T2 of the engine is an increase in the torque caused by the combustion of the fuel similarly to the torque T1, and the increase in the engine rotational speed NE caused by the total combustion of the fuel is converted into a torque using the inertia. It is calculated by. The second injection amount calculation means is injected from the fuel injection valve 10 (# 2) from the correlation between the calculated engine torque and the fuel injection amount and the torque T2 detected by the second output detection means. The second injection amount that is the actual injection amount is calculated.

  Further, the second combustion determination means determines whether or not the fuel injected from the fuel injection valve 10 (# 2) has burned. Specifically, the second combustion determination unit determines that combustion has occurred when the detected torque T2 is greater than the determination threshold Th, similarly to the combustion determination unit. The second injection amount calculation means is based on the condition that the second injection amount is determined to be burned by the second combustion determination means so as not to calculate the second injection amount based on the inappropriate torque T2. May be calculated.

  According to this embodiment described above, the following effects are obtained.

  -Engine torque and fuel injection based on the torque T1 and the first injection amount on the condition that the fuel injected from the fuel injection valves 10 (# 1, # 3) is determined to be burned. A correlation with the quantity is calculated. Thereby, the injection which does not generate the engine torque can be excluded, and the correlation between the engine torque and the fuel injection amount can be obtained with high accuracy. In particular, in the minute injection amount region, the correlation between the engine torque and the fuel injection amount can be obtained with higher accuracy than before.

  When the torque T1 is larger than the determination threshold Th, it is considered that the engine torque is generated by the combustion of the fuel, so that it can be determined that the combustion has occurred.

  The torque of the engine when the fuel injection is stopped corresponds to noise in the same manner as the torque when the injected fuel is not burned. Therefore, by setting a value larger than the maximum value in the fluctuation of the engine torque when the fuel injection is stopped as the determination threshold, when the engine torque is surely larger than the noise, that is, the torque accompanying the combustion of the fuel is obtained. It can be determined that the fuel is burned only when the fuel is burned.

  When the first injection amount is smaller than the fuel combustible injection amount or the first injection amount is smaller than the injection amount that generates a detectable engine torque, the injection is excluded from the correlation acquisition. be able to. Therefore, the correlation can be acquired with higher accuracy.

  The torque T1 and the first injection amount are averaged only when the injection corresponds to the same command injection amount and the fuel is burned, and the averaged torque T1 corresponding to a plurality of command injection amounts and A correlation between the engine torque and the fuel injection amount is calculated from the first injection amount. Thereby, the correlation between the engine torque and the fuel injection amount can be calculated with high accuracy.

  ・ Variations in intake pressure, injection timing, and ignition timing affect ignitability. In particular, in the minute injection amount region, the influence of these variations on the ignitability is large, and these variations cause unburned fuel. Therefore, when it is determined that the fuel is not combusting and the first injection amount is larger than the minimum amount, the factor that is determined that the fuel is not combusting is determined as the intake pressure of the first cylinder, or It can be determined from the variation in the injection timing of the first fuel injection valve or the ignition timing of the fuel.

  If the first injection amount varies with respect to the command injection amount and the first injection amount becomes smaller than the minimum amount Qi, engine torque due to fuel combustion cannot be obtained. Therefore, when it is determined that the fuel is not combusted and the first injection amount is smaller than the minimum amount, the factor determined that the fuel is not combusting is determined as the variation in the first injection amount. it can.

  The injection amount corresponding to the determination threshold Th can be calculated from the correlation between the engine torque and the fuel injection amount and the determination threshold Th. Since the injection amount corresponding to the determination threshold Th corresponds to the minimum amount at which the engine torque can be detected, the minimum amount can be updated to the injection amount corresponding to the determination threshold Th.

  The engine torque T2 accompanying the fuel injection is detected by the fuel injection valves 10 (# 2, # 4) provided in the cylinders (# 2, # 4) of the engine. Since the correlation between the engine output and the fuel injection amount in the cylinders (# 1, # 3) and the correlation in the cylinders (# 2, # 4) can be considered equal, the cylinders (# 1, # 3) From the correlation calculated in 3) and the torque T2, the second injection amount injected from the fuel injection valve 10 (# 2, # 4) is calculated. Therefore, the injection amount can be calculated with high accuracy even in the cylinders (# 2, # 4) not equipped with the fuel pressure sensor 22.

  The second injection amount is calculated from the correlation and the torque T2 on condition that the fuel injected from the fuel injection valves 10 (# 2, # 4) is determined to be burned. Therefore, when the fuel injected from the fuel injection valves 10 (# 2, # 4) is not combusting, and the torque greater than the noise level is not generated with the combustion of the fuel, the torque T2 becomes inappropriate. Based on this, it is possible to suppress the calculation of the second injection amount.

(Other embodiments)
The fuel corresponding to the command injection amount may be injected once for each command injection amount, and the correlation may be calculated from the torque T1 and the first injection amount detected for each command injection amount.

  The engine output may be an increase amount of the engine rotational speed NE accompanying fuel combustion. Moreover, when the cylinder pressure sensor is mounted on the cylinders (# 1 to 4), the increase in the cylinder pressure accompanying the combustion of fuel may be used as the engine output.

  In the flowchart of FIG. 4, the process of S18 may be omitted. That is, whether or not the fuel is combusting may be determined based only on whether or not the torque T1 is larger than the determination threshold Th.

  -The fuel pressure sensor 22 should just be mounted in the at least 1 cylinder.

  10 (# 1, # 3) ... 1st fuel injection valve, 10 (# 2, # 4) ... 1st fuel injection valve, 22 ... Fuel pressure sensor, 30 ... ECU.

Claims (10)

Fuel generated inside the first fuel injection valve when the fuel is injected from the first fuel injection valve (10 # 1, # 3) provided in the first cylinder of the internal combustion engine and the first fuel injection valve A fuel pressure sensor (22) for detecting a pressure change of the fuel injection state acquisition device (30) applied to a fuel injection system comprising:
First injection amount calculating means for calculating a first injection amount injected from the first fuel injection valve based on a detection value of the fuel pressure sensor;
First output detecting means for detecting a first output of the internal combustion engine accompanying the injection of fuel of the first injection amount by the first fuel injection valve;
Combustion determination means for determining whether the fuel injected from the first fuel injection valve has burned;
The first output detected by the first output detection means and the first injection amount calculated by the first injection amount calculation means on condition that the injection is determined to have been burned by the combustion determination means. And a correlation calculating means for calculating a correlation between the output of the internal combustion engine and the fuel injection amount.   2. The fuel injection state acquisition device according to claim 1, wherein the combustion determination unit determines that combustion has occurred when the first output detected by the first output detection unit is greater than a determination threshold value.   A threshold value for detecting a change in the output of the internal combustion engine when stopping the fuel injection and operating the internal combustion engine, and calculating a value larger than the maximum value in the detected change in the output as the determination threshold value The fuel injection state acquisition device according to claim 2, further comprising a calculation unit.   The combustion determination means is injected from the first fuel injection valve when the first injection amount calculated by the first injection amount calculation means is smaller than a minimum amount that can detect the output of the internal combustion engine. The fuel injection state acquisition device according to any one of claims 1 to 3, wherein the fuel is determined not to be burned. The first fuel injection valve injects fuel corresponding to the command injection amount a plurality of times for each command injection amount,
The correlation calculating means sets the first output and the first injection amount on the condition that the injection corresponds to the same command injection amount and is determined to be burned by the combustion determination means. The fuel injection state acquisition device according to any one of claims 1 to 4, wherein the correlation is calculated from the averaged first output and the first injection amount corresponding to a plurality of the command injection amounts while averaging.   The factor determined by the combustion determination means that combustion is not performed when the first injection amount calculated by the first injection amount calculation means is greater than the minimum amount by which the output of the internal combustion engine can be detected. The fuel injection state according to any one of claims 1 to 5, further comprising: a determination unit that determines a variation in the intake pressure of the first cylinder, the injection timing of the first fuel injection valve, or the ignition timing of the fuel with respect to the command injection amount. Acquisition device.   Factor determined by the combustion determining means that the first injection amount calculated by the first injection amount calculating means is not combusting when the first injection quantity is smaller than the minimum amount capable of detecting the output of the internal combustion engine. The fuel injection state acquisition device according to any one of claims 1 to 6, further comprising: a determination unit that determines a variation in the first injection amount with respect to the command injection amount. The combustion determination means determines that combustion has occurred when the first output detected by the first output detection means is greater than a determination threshold;
The fuel injection state acquisition device according to claim 6 or 7, comprising update means for updating an injection amount corresponding to the determination threshold in the correlation calculated by the correlation calculation means as the minimum amount. The fuel injection system includes a second fuel injection valve provided in the second cylinder of the internal combustion engine,
Second output detecting means for detecting a second output of the internal combustion engine accompanying fuel injection by the second fuel injection valve;
Second injection for calculating a second injection amount injected from the second fuel injection valve from the correlation calculated by the correlation calculating means and the second output detected by the second output detecting means. A fuel injection state acquisition device according to any one of claims 1 to 8, further comprising: an amount calculation unit. Comprising a second combustion determining means for determining whether the fuel injected from the second fuel injection valve has burned;
The second injection amount calculating means includes the correlation calculated by the correlation calculating means and the second output detecting means on the condition that the injection is determined to be burned by the second combustion determining means. The fuel injection state acquisition device according to claim 9, wherein a second injection amount injected from the second fuel injection valve is calculated from the detected second output.

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