JP2007120395A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device capable of inhibiting variation of fuel injection quantity of each cylinder of an engine. <P>SOLUTION: The fuel injection device 1 consists of a supply pump 4 generating high pressure fuel, a common rail 2 temporarily accumulating high pressure fuel supplied from the supply pump 4, an injector 3 injecting high pressure fuel supplied from the common rail into the cylinder of the engine, an operation condition detection means 20 detecting an operation condition of a vehicle, and a control means 5 determining command fuel injection quantity of the injector 3 and instantaneous peak speed of the cylinder of the engine based on an operation condition detected by the operation condition detection means 20, performing open and close control of the injector 3 based on command fuel injection quantity, and correcting valve close timing based on the instantaneous peak speed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection device, and more particularly to control of the opening / closing time of an injector of a common rail fuel injection device.

  In a diesel engine for automobiles, a common rail type fuel injection device is used as a fuel injection device for supplying fuel into a cylinder of the engine. This common rail type fuel injection device is configured to supply high pressure fuel from a supply pump to the common rail, and to inject the high pressure fuel accumulated in the common rail from the injector. The amount of fuel injected from the injector is controlled by sampling the common rail pressure immediately before the start of injection or immediately after the end of injection and setting the valve opening time of the injector according to the common rail pressure (Patent Document 1). reference).

  However, in this fuel injection device, even if the timing when the supply pump pumps the high-pressure fuel and the timing when the injector injects the fuel do not match, even if the injector is opened for the same time, There is a difference in the amount of fuel injected from the injector. Therefore, as described in Patent Document 1, when the valve opening time of the injector is set based on sampling data at a certain point in time, the amount of fuel injected from the injector varies, resulting in deterioration of exhaust gas emission and drivability. It becomes a factor that causes deterioration.

  To solve this problem, the common rail pressure during injector opening is constantly monitored, integration of the common rail pressure is started from the fuel injection start point of the injector, and the integrated value becomes the target integrated value corresponding to the command injection amount. A common rail type fuel injection device has been developed in which the fuel injection amount can be accurately controlled by closing the injector when it arrives (see Patent Document 2). Further, in the fuel injection device described in Patent Document 2, the fuel is injected between the time when the engine control unit (ECU) issues a valve closing command to the injector and the time when the injector actually closes. The fuel injection amount can be controlled more accurately by issuing a valve closing command to the injector at an early stage in consideration of the amount of fuel.

  However, the instantaneous peak rotation speed due to the explosion fluctuation in the cylinder has a different value for each cylinder of the engine due to variations among injectors or changes with time. Further, if the instantaneous peak rotational speed is different, the fuel injection amount for each cylinder also varies. For this reason, even if the ECU issues a valve closing command uniformly to each injector, the fuel injection amount cannot be accurately controlled.

Japanese Patent Laid-Open No. 5-125985 JP 2004-108286 A

  In view of the above problems, an object of the present invention is to provide a fuel injection device capable of accurately controlling the fuel injection amount.

  Another object of the present invention is to provide a fuel injection device capable of suppressing variations in the fuel injection amount for each cylinder of an engine.

  According to the first aspect of the present invention, the fuel injection device according to the present invention determines the commanded fuel injection amount of the injector and the instantaneous peak rotation of the cylinder of the engine based on the operating state detected by the operating state detecting means. A control means for controlling the valve opening time and the valve closing time of the injector based on the command fuel injection amount, and correcting the valve closing time based on the instantaneous peak rotational speed. Even when the instantaneous rotational speed of the engine differs from cylinder to cylinder due to individual differences or changes over time, the fuel injection amount can be accurately controlled for each cylinder.

  Further, as described in claim 2, the correction of the valve closing time is a correction indicating a correction amount corresponding to the instantaneous peak rotational speed and the command fuel injection amount in the valve closing time determined based on the command fuel injection amount. By adding the correction amount determined based on the map, the valve closing time can be corrected at high speed without the need for complicated calculations, so more up-to-date information on the instantaneous peak rotation speed, etc. should be used. It is possible to control the fuel injection amount more accurately.

  Furthermore, as described in claim 3, the common rail has a common rail pressure detecting means for detecting the fuel pressure in the common rail, and the valve opening of the injector calculated based on the common rail pressure detected by the common rail pressure detecting means When the difference between the estimated fuel injection amount and the command fuel injection amount during the period satisfies a predetermined condition, the fuel injection for each cylinder can be performed even if the injector changes with time by providing correction map correction means for correcting the correction map. Variation in the amount can be suppressed.

  The correction map correction means can be provided in the control means. Alternatively, in order to reduce the load on the control means, the correction map correction means may be provided separately from the control means.

  According to the fourth aspect of the present invention, the control means determines the commanded fuel injection amount of the injector and the instantaneous peak rotational speed of the engine cylinder based on the operating condition detected by the operating condition detecting means. Then, the injector is controlled by outputting a valve opening command or a valve closing command based on the commanded fuel injection amount, and the valve is actually closed after the valve closing command is output to the injector based on the instantaneous peak rotational speed. The post-valve command injection amount, which is the amount of fuel that is injected in the period up to, is estimated, and the sum of the fuel injection amount calculated based on the common rail pressure detected by the common rail pressure and the post-valve command injection amount is By outputting a valve closing command when the fuel injection amount exceeds the command fuel injection amount, even if the amount of fuel injected within a certain valve opening period varies with each fuel injection, Fuel injection Can be accurately controls the fuel injection amount to suppress the variation.

  According to the fifth aspect of the present invention, the post-valve command post-injection amount is estimated based on the post-valve command post-injection amount map indicating the fuel injection amount corresponding to the instantaneous peak rotational speed and the command fuel injection amount. Therefore, it is possible to estimate the injection amount after the valve closing command at high speed without requiring complicated calculation, so it is possible to use the latest information on the instantaneous peak rotational speed, etc., and more accurate fuel injection The amount can be controlled.

  Further, as described in claim 6, the difference between the fuel injection amount during a predetermined period starting from the time when the valve closing command is output and the injection amount after the valve closing command estimated based on the post-valve command injection amount map is By providing a post-validation post-instruction command injection amount map correction means that corrects the post-valve command injection amount map when a predetermined condition is met, even if the injector changes with time, variations in the fuel injection amount for each cylinder are suppressed. can do.

Hereinafter, the fuel injection device of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a common rail fuel injection device according to a first embodiment of the fuel injection device of the present invention.

  A common rail fuel injection device 1 according to a first embodiment of a fuel injection device of the present invention is a device that injects fuel into, for example, a four-cylinder diesel engine 10 (hereinafter simply referred to as an engine), and accumulates high-pressure fuel. Control of a common rail 2 that is a pressure accumulating container, an injector 3 that injects and supplies fuel into each cylinder of the engine 10, a supply pump 4 that is a fuel pump that pumps high-pressure fuel to the common rail 2, and a common rail fuel injection device 1 It is comprised by ECU5 etc. which are means.

  The common rail 2 is a pressure accumulating container for high-pressure fuel supplied to the injector 3, and is connected to a discharge port of the supply pump 4 via a fuel pipe (high-pressure fuel flow path) 6 so that a common rail pressure corresponding to the fuel injection pressure is accumulated. It is connected. The leaked fuel from the injector 3 is returned to the fuel tank 8 via a leak pipe (fuel return path) 7.

  A pressure limiter 11 is attached to a relief pipe (fuel return path) 9 from the common rail 2 to the fuel tank 8. The pressure limiter 11 is a pressure safety valve, and opens when the fuel injection pressure in the common rail 2 exceeds the limit set pressure, and suppresses the fuel injection pressure of the common rail 2 below the limit set pressure.

  Furthermore, the common rail 2 includes a common rail pressure sensor 21 that is a common rail pressure detecting unit, and can detect the fuel pressure in the common rail. The common rail pressure detected by the common rail pressure sensor 21 is output as an electric signal, further A / D converted, and transmitted to the ECU 5.

  The injector 3 is mounted in each cylinder of the engine 10 and supplies fuel into each cylinder. The injector 3 is connected to the downstream ends of a plurality of branch pipes branched from the common rail 2 and accumulated in the common rail 2. A fuel injection nozzle that injects high-pressure fuel into each cylinder and an actuator that performs lift control of a needle accommodated in the fuel injection nozzle are mounted. The actuator of the injector 3 is controlled in injection timing and injection amount by an injector driving pulse given from the ECU 5, and is opened when the injector driving pulse is given to the actuator to inject high-pressure fuel into the cylinder. When the injector drive pulse is turned off, the valve is closed and the fuel injection is stopped.

  The supply pump 4 is a fuel pump that pumps high-pressure fuel to the common rail 2, a feed pump that sucks the fuel in the fuel tank 8 to the supply pump 4, and the fuel sucked up by the feed pump to be compressed to a high pressure. 2 and a high-pressure pump that feeds pressure to 2, and the feed pump and the high-pressure pump are driven by a common camshaft 12. The camshaft 12 is rotationally driven by a crankshaft 13 of the engine 10 as shown in FIG.

  The high-pressure pump mounted on the supply pump 4 is constituted by one or a plurality of plunger pumps, and the plunger pump performs the fuel suction / compression operation by the rotation of the cam provided on the camshaft 12. Further, the supply pump 4 performs pump pumping twice by one rotation of the camshaft 12.

  The ECU 5 includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a nonvolatile memory such as a flash memory (not shown), and the like, and a program stored in the ROM Based on the valve closing time correction map for each cylinder stored in the flash memory and the signals of sensors (the instantaneous speed of the engine 10, the speed of the vehicle, the state of the driver, etc.) read into the RAM. An appropriate command fuel injection amount is calculated by the CPU according to the operating state of the engine, and the injector 3 is controlled to open and close according to the command fuel injection amount.

  The ECU 5 is connected to a vehicle driving state detecting means 20. The operating state detection means 20 is composed of various sensors, including an accelerator sensor 22 for detecting the accelerator opening, a rotation speed sensor 23 for detecting an engine speed pulse, and a coolant temperature of the engine 10. A water temperature sensor 24 that detects the temperature of the intake air taken into the engine 10, a fuel temperature sensor 26 that detects the temperature of the leaked fuel from the injector 3, and the like.

  When the ECU 5 determines the command fuel injection amount Qfin based on the engine rotational speed and the accelerator opening obtained from the accelerator sensor 22 and the rotational speed sensor 23, the ECU 5 causes the injector to inject predetermined fuel based on the value. On the other hand, a command injection time TQ (0) for issuing a fuel injection command and a time TQ (m) for issuing a valve closing command are determined. At this time, the command injection time TQ (m) is determined in consideration of the amount of fuel (injection amount after the valve closing command) injected during the actual valve closing after the injector valve closing command.

  Here, even if the fuel injection command pulse and the valve closing command pulse are simultaneously transmitted from the ECU 5 to each injector 3, the amount of fuel actually injected in each cylinder is different from the individual difference at the time of manufacturing the injector 3 and the time. Variations occur due to changes. Further, due to the variation, the instantaneous peak rotational speed for each cylinder has a different value. Therefore, in this embodiment, the valve closing time correction map Mt representing the correction amount of the timing at which the valve closing command is output based on the difference ΔN between the instantaneous peak rotational speed Nkp of each cylinder and its average value and the command fuel injection amount Qfin. The ECU 5 refers to the valve closing time correction map Mt and adjusts the timing for outputting the valve closing command for each cylinder.

  FIG. 2 shows an example of the valve closing time correction map Mt. One valve closing time correction map Mt is created for each cylinder. The top row of the valve closing time correction map Mt shows the instantaneous peak rotation speed Nkp of the cylinder (where k represents the cylinder number, for example, k = 1, 2, 3, 4 for a 4-cylinder engine), It represents a difference ΔN from the average value Navp of the instantaneous peak rotational speed of the cylinder. The leftmost column of the valve closing time correction map Mt represents the command fuel injection amount Qfin. In each column, the command fuel injection amount Qfin defined in the leftmost column of the table at the same height as that column and the valve closing time correction at ΔN defined in the uppermost column of the table in the same horizontal position as that column A quantity Tc is defined.

  The ECU 5 calculates the instantaneous peak rotational speed Nkp of each cylinder when a predetermined time (for example, 1 msec) has elapsed since the injector 3 opened. The instantaneous peak rotational speed Nkp can be measured based on, for example, the pulse time interval of a 60 pulse / revolution crank angle signal obtained from the rotational speed sensor 23. Further, when the instantaneous peak rotational speed Nkp of each cylinder is obtained, the ECU 5 calculates an average value Navp of the instantaneous peak rotational speed of each cylinder.

  When the average value Navp of the instantaneous peak rotational speed is obtained, the ECU 5 refers to the valve closing time correction map Mt and calculates the valve closing time correction amount Tc for each cylinder. Then, the valve closing command time TQ (m) is calculated by adding the valve closing time correction amount Tc to the valve closing command time TQ (m).

  Further, the ECU 5 estimates the amount of fuel actually injected based on the common rail pressure detected by the common rail pressure sensor 21. When the difference between the estimated fuel injection amount and the command fuel injection amount Qfin is large, the valve closing time correction map Mt is corrected. The estimation of the injected fuel and the correction of the valve closing time correction map Mt will be described later.

Next, fuel injection control by the ECU 5 will be described with reference to a flowchart.
FIG. 3 shows a flowchart of a fuel injection control procedure in the common rail fuel injection device 1 according to the present embodiment.

  When control of fuel injection is started, first, the engine speed is calculated from the output signal of the speed sensor 23, and the accelerator opening is detected from the output signal of the accelerator sensor 22 (step S01). Also, calculation is started for the instantaneous peak rotation speed Nkp of each cylinder.

  Next, the command fuel injection amount Qfin and the command injection time TQ (0) are calculated from the engine speed and the accelerator opening obtained in step S01 (step S02). Then, it is determined whether or not the engine crank angle has reached the command injection time TQ (0) (step S03). As a result of the determination, if it is determined that the crank angle of the engine has reached the command injection time TQ (0), the ECU 5 gives a drive signal that is a valve opening command to the injector 3 to open the injector 3 (step S04). . On the other hand, as a result of the determination in step S03, when it is determined that the engine crank angle has not yet reached the command injection time TQ (0), the process returns to step S01 and the engine crank angle is set to the command injection time TQ ( Steps S01 to S03 are repeated until 0) is reached.

  During the period when the injector 3 is open, the ECU 5 measures the common rail pressure by the common rail pressure sensor 21 and performs high-speed A / D conversion on the measured value. Then, using the measured value of the common rail pressure that has been A / D converted, the integration of the common rail pressure is started from the fuel injection start time by the injector 3, and the estimated fuel injection corresponding to the amount of fuel injected from the injector 3 is started. Calculation of the quantity Qest is started (step S05).

  Then, the ECU 5 performs the valve closing command time TQ ′ (m) for each cylinder based on the valve closing time correction amount Tc for each cylinder obtained by referring to the command fuel injection amount Qfin and the valve closing time correction map Mt. Is determined (step S06).

  In addition, when the valve closing command time TQ ′ (m) is reached, the ECU 5 gives a drive signal that becomes a valve closing command to the injector 3 (step S07). Then, after the valve closing command is given to the injector 3, the injector 3 actually closes after the valve closing delay time TDE has elapsed, and the ECU 5 finishes calculating the estimated fuel injection amount Qest and ends the fuel injection control. (Step S08).

  As described above, it is possible to accurately control the fuel injection amount for each cylinder by correcting the valve opening period of the injector 3 based on the instantaneous peak rotational speed of each cylinder. Therefore, the same amount of fuel can be supplied to each cylinder even if there are variations due to individual differences in injectors and changes over time.

  On the other hand, as described above, the variation in the fuel injection amount for each cylinder changes due to the change of the injector 3 with time. Therefore, the fuel injection device 1 according to the present embodiment makes it possible to accurately control the fuel injection amount regardless of the change over time of the injector 3 by appropriately correcting the valve closing time correction map Mt.

  Therefore, the ECU 5 constantly monitors the common rail pressure Pc during the valve opening period of the injector 3 (while the injector drive pulse is ON) by the common rail pressure sensor 21 and starts integration of the common rail pressure Pc from the start of injection of the injector 3. An estimated fuel injection amount Qest corresponding to the injection amount of fuel injected from the injector 3 is obtained until the valve is closed. When the difference between the estimated fuel injection amount Qest and the command fuel injection amount Qfin is large, the valve closing time correction map Mt is corrected.

  Here, the monitoring period of the common rail pressure Pc, that is, the integration period of the common rail pressure Pc for obtaining the estimated fuel injection amount Qest is determined as follows. First, the integration start time TQ (s) of the common rail pressure Pc is actually the injector after the fuel injection command pulse is output to the injector 3 and the fuel injection command pulse is output. 3 is represented by TQ (s) = TQ (0) + TDS using the valve opening delay time TDS until fuel injection is started. The valve opening delay time TDS is a value that varies according to the common rail pressure Pc. Therefore, a lookup table LUT1 representing the relationship between the common rail pressure Pc and the valve opening delay time TDS is created in advance and stored in the ECU 5. Then, the ECU 5 determines the valve opening delay time TDS by referring to the look-up table LUT1 based on the common rail pressure Pc at the time TQ (0).

  On the other hand, the integration end time TQ (e) of the common rail pressure Pc is the valve closing command time TQ ′ (m) of the injector 3 for each cylinder, until the injector 3 is actually closed after the valve closing command is output. Is expressed as TQ (e) = TQ ′ (m) + TDE. The valve closing delay time TDE is also a value that varies according to the common rail pressure Pc, similarly to the valve opening delay time TDS. Therefore, a lookup table LUT2 representing the relationship between the common rail pressure Pc and the valve closing delay time TDE is created in advance and stored in the ECU 5. Then, the ECU 5 determines the valve closing delay time TDE by referring to the look-up table LUT2 based on the common rail pressure Pc at the valve closing command time TQ '(m).

ここで、推定噴射率Ｑesrは、ノズル開口面積ｕｆ、ノズル室圧Ｐd、筒内圧Ｐz、比重などによって定まる定数ｋにより、次式で求めることができる。

上式において、ノズル室圧Ｐdは、コモンレール圧センサ２１によって測定できるコモンレール圧Ｐcと一致しているとみなすことが可能であり、ＰdにＰcを代入することができる。また、ノズル開口面積ｕｆは、インジェクタ３の仕様によって定まる数値である。
図４にノズル開口面積特性のグラフを示す。グラフの縦軸は、ノズル開口面積ｕｆを表し、グラフの横軸は、インジェクタ３の通電期間ＴＱを表す。実線ａ、ｂ、ｃはそれぞれノズル室圧Ｐd1、Ｐd2、Ｐd3の場合のノズル開口面積特性のグラフである。図４に示すように、ノズル開口面積ｕｆは、ノズル室圧Ｐdとインジェクタ３の通電期間とで求められる。 When the integration start time TQ (s) and the integration end time TQ (e) are determined as described above, the estimated fuel injection amount Qest is obtained by the following equation.

Here, the estimated injection rate Qesr can be obtained by the following equation using a constant k determined by the nozzle opening area uf, the nozzle chamber pressure Pd, the in-cylinder pressure Pz, the specific gravity, and the like.

In the above equation, the nozzle chamber pressure Pd can be regarded as being coincident with the common rail pressure Pc that can be measured by the common rail pressure sensor 21, and Pc can be substituted for Pd. The nozzle opening area uf is a numerical value determined by the specifications of the injector 3.
FIG. 4 shows a graph of nozzle opening area characteristics. The vertical axis of the graph represents the nozzle opening area uf, and the horizontal axis of the graph represents the energization period TQ of the injector 3. Solid lines a, b, and c are graphs of nozzle opening area characteristics in the case of nozzle chamber pressures Pd1, Pd2, and Pd3, respectively. As shown in FIG. 4, the nozzle opening area uf is obtained from the nozzle chamber pressure Pd and the energization period of the injector 3.

  Next, the correction of the valve closing time correction map Mt will be described in detail using a flowchart.

FIG. 5 shows a flowchart for correcting the valve closing time correction map Mt.
First, the ECU 5 determines whether or not the valve closing time correction map Mt can be corrected (step S21). Specifically, the commanded fuel injection amount Qfin is constant for a predetermined period (eg, 10 seconds, 1 minute, etc.) during idling or traveling on a flat road at a constant speed. In this case, it is determined that the valve closing time correction map Mt can be corrected.

  Next, the ECU 5 determines whether or not the valve closing time correction map Mt needs to be corrected. For this purpose, the ECU 5 acquires the valve closing time correction amount Tc from the valve closing time correction map Mt as described above, and measures the estimated fuel injection amount Qest (step S22). Next, a deviation amount ΔQ (= Qest−Qfin) between the estimated fuel injection amount Qest and the command fuel injection amount Qfin is calculated (step S23). Then, the absolute value | ΔQ | of the deviation amount ΔQ is compared with a predetermined threshold Thd (step S24). When | ΔQ | is smaller than the threshold value Thd, the fuel injection amount can be controlled with good accuracy, and the valve closing time correction map Mt is not corrected.

  On the other hand, when | ΔQ | is equal to or greater than the threshold Thd, the valve closing time correction map Mt is corrected. Note that a value such as 0.1 msec can be used as the threshold Thd. In this case, a correction amount ΔTc for the valve closing time correction amount Tc is determined and stored in the memory of the ECU 5 (step S25). At this time, in order to designate a column to be corrected in the valve closing time correction map Mt, the position of the column of the valve closing time correction map Mt from which the valve closing time correction amount Tc has been acquired is also stored. In order to determine the correction amount ΔTc, the ECU 5 determines the correction amount ΔTc with reference to the lookup table LUT3 that indicates the value of the correction amount ΔTc in correspondence with the magnitude and sign of ΔQ. When ΔQ> 0, the correction amount ΔTc is a negative value so that the valve closing time correction amount Tc is shortened. On the other hand, when ΔQ <0, the valve closing time correction amount Tc is longer. Thus, the correction amount ΔTc is a positive value. Further, as | ΔQ | increases, the absolute value of the correction amount ΔTc increases.

  When the correction amount ΔTc is determined, the ECU 5 determines the valve closing time correction amount from the valve closing time correction map Mt at the next fuel injection in order to obtain the estimated fuel injection amount Qest when the valve closing time correction amount Tc is corrected. After obtaining Tc, a correction amount ΔTc is added to calculate a correction valve closing time correction amount Tc ′ (= Tc + ΔT). Then, map correction valve closing command time TQ "(m) (= TQ (m) + Tc ') is set using the correction valve closing time correction amount Tc' together with the normal integration end time TQ (e) ( Step S26).

  When the fuel injection starts, the ECU 5 replaces the integral end time TQ (e) with the valve closing command time TQ ′ (m) in the equation (1) together with the estimated fuel injection amount Qest, and starts the fuel injection of the injector 3. Then, the injection amount Qm at the valve closing command, which is the injection amount up to the valve closing command time, is obtained. Similarly, the integration end time TQ (e) is replaced with the valve closing command time TQ "(m) in the equation (1), and the injection amount from the start of fuel injection of the injector 3 to the map correction valve closing command time. The injection amount Qm ′ at the time of the corrected valve closing command is obtained.

  Since the difference between the injection amount Qm ′ at the time of the correction valve closing command and the injection amount Qm at the time of the valve closing command is an injection amount corresponding to the period of the correction amount ΔTc, adding this to the estimated fuel injection amount Qest It can be regarded as the estimated fuel injection amount when the time correction amount Tc is corrected by the correction amount ΔTc. Therefore, when the valve closing command injection amount Qm and the modified valve closing command injection amount Qm ′ are calculated, the ECU 5 changes the estimated fuel injection amount Qest from the corrected valve closing command injection amount Qm ′ to the valve closing command injection. A corrected estimated fuel injection amount Qest ′ (= Qest + Qm′−Qm) is obtained by adding the difference obtained by subtracting the amount Qm (step S27).

  Then, a deviation amount ΔQ ′ (= Qest′−Qfin) between the corrected estimated fuel injection amount Qest ′ and the command fuel injection amount Qfin is calculated and compared with the threshold value Thd (step S28). When the absolute value | ΔQ ′ | of ΔQ ′ is less than the threshold value Thd, it is determined that the fuel injection amount can be accurately controlled, and the correction amount ΔTc is added to the valve closing time correction amount Tc. The value in the corresponding column of the valve closing time correction map Mt is rewritten with the corrected valve closing time correction amount Tc ′ (= Tc + ΔTc) (step S29). Then, the correction of the valve closing time correction map Mt is finished.

  On the other hand, if | ΔQ ′ | is equal to or greater than the threshold value Thd, the correction of the valve closing time correction amount is considered insufficient, so the correction amount ΔTc is determined again (step S30). In this case, the re-correction amount ΔTc ′ is obtained by referring to the lookup table LUT3. Then, the correction amount ΔTc is calculated again based on the following equation.

ΔTc = ΔTc + αΔTc ′ (3)
Here, α is a coefficient for avoiding learning from not converging, and the value of α decreases monotonously as 0 <α <1 and the number of times of calculation of the correction amount ΔTc increases. The expression (3) is the same as the expression used in the source code of the computer program. ΔTc on the right side is the one before calculation, and ΔTc on the left side is the one after calculation.

  When the correction amount ΔTc is obtained, steps S26 to S28 are repeated at the subsequent fuel injection. When the rewriting of the valve closing time correction map Mt is finished, the correction of the valve closing time correction map Mt is finished.

  As described above, by appropriately correcting the valve closing time correction map Mt, the fuel injection amount can be accurately controlled even when the variation in the fuel injection amount in each cylinder varies due to the change of the injector 3 over time. .

  Next, a common rail fuel injection device 31 according to a second embodiment of the fuel injection device of the present invention will be described.

  The common rail fuel injection device 31 according to the second embodiment of the fuel injection device of the present invention is composed of the common rail 2, the injector 3, the supply pump 4, the ECU 5, and the like, similar to the common rail fuel injection device 1 described above. . However, in the common rail fuel injection device 31, the ECU 5 evaluates the variation in the fuel injection amount due to individual differences of the injectors 3 as the difference in the amount of fuel injected after the valve closing command, and changes the timing of the valve closing command. By doing so, variation in the fuel injection amount for each cylinder is suppressed. Therefore, the timing when the injector 3 injects the fuel and the timing when the supply pump 4 pumps the high-pressure fuel do not coincide with each other, and it is preferable when the valve opening period of the injector 3 needs to be adjusted for each fuel injection. Is.

  FIG. 6 shows a timing chart of the common rail fuel injection device 31 according to the second embodiment of the fuel injection device of the present invention.

  As described above, the common rail fuel injection device 31 according to the second embodiment of the present invention employs the supply pump 4 that pumps the pump twice by one rotation of the camshaft 12, and thus has a 6-cylinder configuration. When installed in the engine, it becomes a 6-injection, 4-pressure-feeding system. For this reason, in FIG. 6, the time when the injector 3 injects fuel (time when the injector drive pulse shown by the solid line A is ON) and the time when the supply pump 4 pumps high-pressure fuel (time shown by the hatching of the solid line B). Does not match and is asynchronous. Therefore, the common rail pressure may increase or decrease during the fuel injection period of the injector 3 as indicated by the solid line C representing the variation of the common rail pressure. Then, when the fuel injection timing of the injector 3 overlaps with the fuel pumping timing of the supply pump 4 and when it does not overlap, the common rail pressure fluctuates during the injection, and as a result, as shown by the solid line D, the fuel injection The amount also varies.

  Therefore, the ECU 5 constantly monitors the common rail pressure Pc during the valve opening period of the injector 3 by the common rail pressure sensor 21 to estimate the fuel injection amount, and closes the injector 3 when it is determined that the command fuel injection amount Qfin is reached. Issue a valve command.

この（４）式において、右辺の第１項は、積分の終端が時間ｔとなっている以外は、（１）式と同様である。 When the injector 3 starts fuel injection at time TQ (s) and issues a valve closing command to the injector 3 at a certain time t, the estimated fuel injection amount Qest (t) during the valve opening period of the injector 3 is The fuel injection amount after the valve closing command that is injected between the time when the valve closing command is output to 3 and the time when the injector 3 actually closes is Qdry, and is calculated based on the following equation.

In the equation (4), the first term on the right side is the same as the equation (1) except that the end of integration is time t.

  Further, the fuel injection amount Qdry after the valve closing command, which is the second term on the right side, is determined based on the injection amount map Mqd after the valve closing command. The injection amount map Mqd after the valve closing command defines the injection amount after the valve closing command based on the difference ΔN between the instantaneous peak rotational speed Nkp and the average value Navp and the command fuel injection amount Qfin.

  FIG. 7 shows an example of the post-valve closing injection amount map Mqd. One post-valve injection amount map Mqd is created for each cylinder. The top row of the post-valve command post-injection amount map Mqd represents the difference ΔN between the instantaneous peak rotational speed Nkp of that cylinder and the average value of the instantaneous peak rotational speed of each cylinder. Further, the leftmost column of the post-valve command injection amount map Mqd represents the command fuel injection amount Qfin. In each column, the command fuel injection amount Qfin defined in the leftmost column of the table having the same height as that column and the fuel correction amount in ΔN defined in the uppermost column of the table in the same horizontal position as that column. It is prescribed.

  The ECU 5 uses the fuel correction amount held in the corresponding column as the post-valve command fuel injection amount Qdry based on the command fuel injection amount Qfin and ΔN. In addition, when there is no corresponding Qfin or / and ΔN value on the post-valve command injection amount map Mqd, the closest one is interpolated or extrapolated to calculate the post-valve command fuel injection amount Qdry. To do.

  When the fuel injection amount Qdry after the valve closing command is determined and Qest (t) is calculated, the ECU 5 compares Qest (t) with Qfin, and when Qest (t) ≧ Qfin, the injector 3 To close the fuel injection.

  Next, a fuel injection control procedure of the common rail fuel injection device 31 according to the second embodiment of the present invention will be described with reference to a flowchart.

  FIG. 8 shows a flowchart of a fuel injection control procedure in the fuel injection device according to the present embodiment.

  When the fuel injection control is started, first, the engine speed is calculated and the accelerator opening is detected (step S41). Further, the acquisition of the instantaneous peak rotation speed of each cylinder is always started.

  Next, the command fuel injection amount Qfin, the command injection time TQ (0), and the command common rail pressure Pfin are calculated from the engine speed and the accelerator opening determined in step S41 (step S42). Then, it is determined whether or not the crank angle of the engine has reached the command injection time TQ (0) (step S43). As a result of the determination, if it is determined that the crank angle of the engine has reached the command injection time TQ (0), the ECU 5 gives a drive signal that is a valve opening command to the injector 3 to open the injector 3 (step S44). . On the other hand, as a result of the determination in step S43, if it is determined that the engine crank angle has not yet reached the command injection time TQ (0), the process returns to step S41 and the engine crank angle is set to the command injection time TQ ( Steps S41 to S43 are repeated until 0) is reached.

  During the period when the injector 3 is open, the ECU 5 measures the common rail pressure by the common rail pressure sensor 21, and performs high-speed A / D conversion on the measured value (step S45). Then, using the measured value of the common rail pressure that has been A / D converted, the integration of the common rail pressure is started from the fuel injection start time by the injector 3, and the estimated fuel injection corresponding to the amount of fuel injected from the injector 3 is started. The amount Qest is calculated for each cylinder based on the equation (4) with reference to the post-valve command injection amount map Mqd (step S46).

  Then, the ECU 5 compares the estimated fuel injection amount Qest for each cylinder with the commanded fuel injection amount Qfin (step S47).

  When Qest ≧ Qfin is satisfied with respect to the estimated fuel injection amount Qest for each cylinder, the ECU 5 gives a drive signal as a valve closing command to the injector 3 of the corresponding cylinder (step S48). On the other hand, if Qest <Qfin, the process returns to step S45 and steps S45 to S47 are repeated. Finally, when a valve closing command is issued to the injectors 3 of all the cylinders, the fuel injection control is terminated.

  With the above-described configuration, the common rail fuel injection device 31 according to the second embodiment of the present invention is a case where the fuel injection timing of the injector 3 is asynchronous with the fuel pumping timing of the supply pump 4. However, variation in the fuel injection amount for each cylinder can be suppressed, and the fuel injection amount can be accurately controlled.

  Also in the common rail type fuel injection device 31, it is necessary to correct the post-valve closing injection amount map Mqd due to the change of the injector 3 with time.

  Therefore, hereinafter, a correction procedure of the post-valve command injection amount map Mqd in the common rail fuel injection device 31 according to the second embodiment of the present invention will be described with reference to a flowchart.

FIG. 9 shows a flowchart of the correction procedure for the post-valve closing injection amount map Mqd.
As in the case of the common rail fuel injection device 1, first, the ECU 5 determines whether or not the post-valve command injection amount map Mqd can be corrected (step S61). Specifically, the commanded fuel injection amount Qfin is constant for a predetermined period (eg, 10 seconds, 1 minute, etc.) during idling or traveling on a flat road at a constant speed. In this case, it is determined that the post-valve closing injection amount map Mqd can be corrected.

ここでＴＱ（ｍ）は、ＥＣＵ５が閉弁指令を出した時間であり、ＴＤＥは、閉弁指令が出されてから実際に閉弁されるまでの閉弁遅延時間を表し、第１の実施形態における閉弁遅延時間と同一である。なお、閉弁遅延時間ＴＤＥは、ＴＱ（ｍ）の時点でのコモンレール圧にしたがって決定される。 When it is determined that the injection amount map Mqd after the valve closing command can be corrected, the ECU 5 issues the valve closing command to the injector 3 separately from the estimated fuel injection amount Qest (t), and then is actually closed. The amount Qmd of the fuel injected until this time is calculated according to the following equation (step S62).

Here, TQ (m) is a time when the ECU 5 issues a valve closing command, and TDE indicates a valve closing delay time from when the valve closing command is issued until the valve is actually closed. It is the same as the valve closing delay time in the embodiment. The valve closing delay time TDE is determined according to the common rail pressure at the time point TQ (m).

  Next, a difference ΔQd (= Qdry−Qmd) between Qmd and the post-valve closing fuel injection amount Qdry is calculated (step S63). Then, the absolute value | ΔQd | of ΔQd is compared with a predetermined threshold Thd2 (step S64). If | ΔQd | <Thd2, the correction of the post-valve command injection amount map Mqd is not necessary and the correction of the post-valve command injection amount map Mqd is terminated.

  On the other hand, when | ΔQd | ≧ Thd2, the ECU 5 replaces the value of the fuel correction amount defined in the corresponding column of the post-valve command injection amount map Mqd with Qmd, and replaces the post-valve command post-injection map Mqd. Correction is made (step S65). For example, a value such as 0.1% of the command fuel injection amount Qfin can be used as the threshold Thd2.

  As described above, the common rail fuel injection device 31 according to the second embodiment of the present invention appropriately modifies the post-valve command post-injection amount map Mqd, so that the fuel injection in each cylinder is caused by the change over time of the injector 3. Even if the amount of variation varies, the fuel injection amount can be accurately controlled.

  The fuel injection device according to the present invention is not limited to the embodiment described above. For example, in the above-described embodiment, the fuel injection device is applied to a common rail type fuel injection device in which leak fuel is generated when the injector 3 is operated. However, the fuel injection device is also used in a device that does not generate leak fuel. be able to.

  As described above, the fuel injection device according to the present invention can be appropriately optimized within the scope of the present invention as necessary.

1 is a schematic configuration diagram of a fuel injection device according to a first embodiment of the present invention. It is an example of the valve closing time correction map used with the fuel injection device concerning a 1st embodiment of the present invention. It is a flowchart which shows the operation | movement procedure of the fuel-injection apparatus which concerns on the 1st Embodiment of this invention. It is a graph which shows the opening area characteristic of noise. It is a flowchart which shows the correction procedure of a valve closing time correction map. It is a timing chart for operation | movement description of the fuel-injection apparatus which concerns on the 2nd Embodiment of this invention. It is an example of the injection amount map after valve closing instruction | command used with the fuel-injection apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the operation | movement procedure of the fuel-injection apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the correction procedure of the injection amount map after valve closing instruction | command.

Explanation of symbols

1 Fuel injection device 2 Common rail 3 Injector 4 Supply pump 5 ECU
6 Fuel Piping 7 Leak Piping 8 Fuel Tank 9 Relief Piping 10 Engine 11 Pressure Limiter 12 Camshaft 20 Operating State Detection Means 21 Common Rail Pressure Sensor 22 Acceleration Sensor 23 Rotation Speed Sensor 24 Water Temperature Sensor 25 Intake Air Temperature Sensor 26 Fuel Temperature Sensor Mt Closed Valve Time correction map Mqd Injection amount map after valve closing command

Claims (6)

A supply pump that produces high-pressure fuel;
A common rail for temporarily storing high-pressure fuel supplied from the supply pump;
An injector for injecting high-pressure fuel supplied from the common rail into a cylinder of an engine;
Driving state detection means for detecting the driving state of the vehicle;
Based on the operating state detected by the operating state detecting means, a command fuel injection amount of the injector and an instantaneous peak rotation speed of the cylinder of the engine are determined, and the valve opening time of the injector is determined based on the command fuel injection amount. Control means for controlling the valve closing time and correcting the valve closing time based on the instantaneous peak rotational speed;
A fuel injection device comprising:   The correction of the valve closing time is performed by adding a correction amount determined based on a correction map representing a correction amount corresponding to the instantaneous peak rotational speed and the command fuel injection amount to the valve closing time. The fuel injection device described. The common rail has a common rail pressure detecting means for detecting fuel pressure in the common rail, and the control means is an estimated fuel during the valve opening period of the injector based on the common rail pressure detected by the common rail pressure detecting means. Calculate the injection amount,
3. The fuel injection device according to claim 2, further comprising a correction map correction unit that corrects the correction map when a difference between the estimated fuel injection amount and the command fuel injection amount satisfies a predetermined condition. A supply pump that produces high-pressure fuel;
A common rail that temporarily stores high-pressure fuel supplied from the supply pump, the common rail having a common rail pressure detecting means for detecting fuel pressure in the common rail;
An injector for injecting high-pressure fuel supplied from the common rail into a cylinder of an engine;
Driving state detection means for detecting the driving state of the vehicle;
A control unit that determines a command fuel injection amount of the injector and an instantaneous peak rotational speed of a cylinder of the engine based on the operation state detected by the operation state detection unit, and opens based on the command fuel injection amount; The injector is controlled by outputting a valve command or a valve closing command, and is injected between the output of the valve closing command to the injector and the actual valve closing based on the instantaneous peak rotational speed The fuel injection amount calculated based on the common rail pressure detected by the common rail pressure and the fuel injection amount after the valve closing command are estimated as the fuel injection amount after estimating the fuel injection amount after the valve closing command. Control means for outputting the valve closing command when the above is reached;
A fuel injection device comprising:   5. The fuel injection according to claim 4, wherein the estimation of the injection amount after the valve closing command is performed based on an injection amount map after the valve closing command that represents the fuel injection amount corresponding to the instantaneous peak rotational speed and the command fuel injection amount. apparatus.   When the difference between the fuel injection amount during a predetermined period starting from the output time of the valve closing command and the injection amount after valve closing command estimated based on the injection amount map after valve closing command satisfies a predetermined condition, The fuel injection device according to claim 5, further comprising a post-close command post injection instruction map correction unit that corrects the post-close command post injection map.

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