JP4715821B2 - Injection amount learning device - Google Patents

Description

  The present invention relates to an injection amount learning device, and more particularly to an injection amount learning device that learns an injection amount of fuel injected from an injector in a common rail fuel injection device of a diesel engine.

  Conventionally, in a diesel engine, in order to reduce combustion noise and NOx emission, it is effective to perform so-called pilot injection in which a small amount of fuel is injected prior to main injection that is main fuel injection. However, in pilot injection with a small injection amount, it is important to improve the accuracy of the injection amount in order to fully exhibit the effect. For this reason, it is necessary to appropriately correct a deviation between a target injection amount in pilot injection (hereinafter referred to as “target injection amount”) and an actual injection amount (hereinafter referred to as “actual injection amount”).

Therefore, in Patent Document 1, for example, a single micro-injection is performed when there is no injection when the target injection amount of the injector becomes 0 or less, such as during deceleration of a vehicle in which the diesel engine is in no-load operation. As a result, learning of the fuel injection amount, particularly a small amount of injection amount, is performed with high accuracy from the change in the rotation of the engine accompanying the fuel injection.
JP 2005-36788 A

  However, in the case of Patent Document 1, the capacity of the supply pump that supplies fuel pressurized to the common rail and the period required for learning the fuel injection amount are not considered. In addition, the fuel injection amount in the pilot injection varies depending on the fuel pressure inside the common rail (hereinafter, the fuel pressure inside the common rail is referred to as “rail pressure”). Therefore, it is necessary to learn the fuel injection amount for each predetermined rail pressure range. As a result, in order to learn the injection amount with a plurality of rail pressures, it takes a long time, and there is a problem that the learning frequency decreases depending on the rail pressure.

  Therefore, an object of the present invention is to provide an injection amount learning device that reliably learns a fuel injection amount in a wide range of rail pressures in a short period of time.

  In the first aspect of the invention, the highest rail pressure calculating means calculates the highest rail pressure that can be set as the rail pressure as the highest rail pressure. The maximum rail pressure is the rail pressure immediately before learning detected by the rail pressure detection means, the ability of the supply pump that supplies fuel to the common rail, and the fuel pressure for noise suppression according to the speed of the vehicle equipped with the diesel engine, etc. Is calculated from The fuel injection amount is learned at a plurality of rail pressures set in advance as rail pressure points. The rail pressure point selection means selects a rail pressure at which the fuel injection amount is learned from the plurality of rail pressure points as a learning rail pressure point. At this time, the rail pressure point selection means selects a rail pressure point equal to or lower than the maximum rail pressure as a learning rail pressure point based on the maximum rail pressure calculated by the maximum rail pressure calculation means. Thereby, since the learning rail pressure point is equal to or lower than the maximum rail pressure, the learning rail pressure point is reliably set. Therefore, it is possible to reliably learn the fuel injection amount in a short period at a plurality of rail pressure points set in a wide pressure range.

  In the invention described in claim 2, the rail pressure point selection means searches for an unlearned rail pressure point from the highest rail pressure to the rail pressure side below it, and selects the searched unlearned rail pressure point as a learned rail pressure point. To do. If the rail pressure is increased in order to learn the fuel injection amount, there is a risk of increasing noise generated from the diesel engine and deteriorating driving stability. Therefore, the learning of the fuel injection amount in the high pressure side, that is, the region where the rail pressure is high, can be performed only in a limited operating state, for example, when the vehicle is traveling at high speed. As a result, there is a problem that in the high pressure side, that is, in the region where the rail pressure is high, the opportunity for learning the fuel injection amount decreases. Therefore, in the invention described in claim 2, the rail pressure point that has not been learned at the rail pressure equal to or lower than the maximum rail pressure is preferentially selected as the learning rail pressure point. Thereby, the learning of the fuel injection amount is preferentially performed in the region where the rail pressure is high and the learning opportunity is small. Accordingly, the fuel injection amount can be learned at a plurality of rail pressure points set in a wide pressure range.

  In the invention according to claim 3, the rail pressure point selection means searches for the low frequency rail pressure point from the highest rail pressure to the rail pressure side below it, and selects the searched low frequency rail pressure point as the learning rail pressure point. To do. Thereby, the learning opportunity of the fuel injection amount is equally given to each rail pressure point. Therefore, an extreme bias in the learning state can be avoided at each rail pressure point, and the fuel injection amount can be learned reliably and in a short time in a wide pressure range.

  In the invention according to claim 4, the rail pressure point selection means searches for a rail pressure point that is nearing completion of learning from the highest rail pressure to the rail pressure side below it, and the searched rail pressure point is the learned rail pressure. Select as a point. As a result, the learning of the fuel injection amount at the rail pressure point where learning is almost complete is completed preferentially. By preferentially completing learning of the fuel injection amount at a certain rail pressure point, the obtained result of learning of the fuel injection amount is applied to control of fuel injection from the injector. Therefore, the performance of the diesel engine can be improved early.

Hereinafter, an embodiment of an injection amount learning device of the present invention will be described with reference to the drawings.
(Configuration of fuel injection system)
FIG. 2 is a schematic diagram showing an embodiment of a fuel injection system to which the injection amount learning device of the present invention is applied. In the case of this embodiment, the injection amount learning device 10 is applied to a diesel engine 21 in which fuel injection is controlled by a common rail fuel injection system 20. The fuel injection system 20 includes a fuel tank 22, a suction amount control valve 23, a supply pump 24, a common rail 25, and an injector 40. The injection amount learning device 10 includes an engine control device (hereinafter referred to as “ECU: Engine Control Unit”) 11. The suction amount control valve 23 and the supply pump 24 constitute an integral pump unit 27.

  The fuel tank 22 stores normal pressure fuel. The fuel inside the fuel tank 22 is supplied to the intake amount control valve 23 via the intake pipe portion 31 by a low-pressure pump (not shown). The supply pump 24 pressurizes fuel sucked into a pressurizing chamber (not shown) by reciprocating a plunger (not shown). In the supply pump 24, the amount of fuel discharged changes according to the amount of fuel sucked into the pressurizing chamber. The plunger receives driving force from a crankshaft 28 of the diesel engine 21. The fuel pressurized by the supply pump 24 is discharged to the common rail 25. A fuel pipe portion 32 is connected to the discharge side of the supply pump 24. The fuel pipe portion 32 connects the supply pump 24 and the common rail 25.

  The common rail 25 is connected to the fuel pipe portion 32 and stores the fuel pressurized by the supply pump 24 in a pressure accumulation state. An injector 40 that injects fuel into each cylinder 29 of the diesel engine 21 is connected to the common rail 25. The injector 40 is provided for each cylinder 29. The fuel stored in the common rail 25 in an accumulated state is injected from the injector 40 into the combustion chamber formed in each cylinder 29. A reflux piping section 33 is connected to the supply pump 24, the common rail 25, and the injector 40. Surplus fuel in the supply pump 24, the common rail 25, and the injector 40 is returned to the fuel tank 22 via the return piping section 33.

  The ECU 11 is composed of, for example, a microcomputer having a CPU, a ROM, and a RAM. The CPU controls the entire fuel injection system 20 according to a computer program stored in the ROM. The ECU 11 functions as a maximum rail pressure calculation unit, a rail pressure point selection unit, and an injection amount learning unit. In the ECU 11, a pressure sensor 13, an accelerator sensor 14, a rotation sensor 15 and the like are connected to a circuit on the input side. The pressure sensor 13 is provided on the common rail 25.

The pressure sensor 13 detects the pressure of the fuel stored in the common rail 25. The pressure sensor 13 outputs the detected fuel pressure in the common rail 25, that is, the rail pressure, to the ECU 11 as an electrical signal. Thereby, the pressure sensor 13 comprises the rail pressure detection means of a claim with ECU11. The accelerator sensor 14 outputs the depression amount of an accelerator pedal (not shown) to the ECU 11 as an electric signal. The rotation sensor 15 detects the rotation of the crankshaft 28 of the diesel engine 21. The rotation sensor 15 outputs the detected rotation of the crankshaft 28 to the ECU 11 as an electrical signal.
The ECU 11 detects the operating state of the diesel engine 21 from, for example, an electrical signal related to the rotational state of the diesel engine 21 detected by the rotation sensor 15 and an accelerator pedal depression amount detected by the accelerator sensor 14. The ECU 11 sets the amount of fuel injected from the injector 40 according to the detected operating state of the diesel engine 21. The ECU 11 sets the rail pressure based on the set fuel injection amount.

  The ECU 11 is connected to a circuit on the output side by an intake amount control valve 23 and an electronic drive unit (hereinafter, the electronic drive unit is referred to as “EDU: Electronic Drive Unit”) 12. The intake amount control valve 23 controls the flow rate of fuel supplied to the supply pump 24 based on the control current output from the ECU 11. The EDU 12 is connected to the electromagnetic valve 41 of the injector 40. The EDU 12 outputs a pulsed drive signal to the electromagnetic valve 41 of the injector 40 based on the drive signal output from the ECU 11. In the injector 40, the solenoid valve 41 is driven based on the pulse-shaped drive signal output from the EDU 12, and fuel injection is intermittently performed. As a result, the injector 40 injects the fuel stored in the common rail 25 into the combustion chamber formed in each cylinder 29 of the diesel engine 21.

Next, the operation of the injection amount learning device 10 having the above configuration will be described.
Prior to main injection, which is the main fuel injection, when performing pilot injection that injects a small amount of fuel compared to main injection, it is necessary to precisely adjust the fuel injection amount at the time of pilot injection. That is, when the accuracy of the fuel injection amount in pilot injection is low, effects obtained by pilot injection, such as noise reduction and NOx reduction, are reduced. Accordingly, it is necessary to appropriately correct the fuel injection amount in the pilot injection from each injector 40 and always maintain a predetermined injection amount.

  In the injector 40, a difference occurs in the relationship between the width of a pulse energized to the solenoid valve 41, that is, the energization period and the fuel injection amount due to individual differences and deterioration over time. Therefore, the ECU 11 needs to periodically learn the fuel injection characteristics of the injector 40, that is, the relationship between the energization time and the fuel injection amount, and correct the fuel injection amount from the injector 40. On the other hand, the fuel injection characteristic of the injector 40 also changes depending on the rail pressure. For example, even if the energization time of the injector 40 is the same, the fuel injection amount from the injector 40 increases as the rail pressure increases. Therefore, it is necessary to learn the fuel injection amount from the injector 40 according to the rail pressure.

(Rail pressure index)
The ECU 11 of the injection amount learning device 10 sets a point for performing learning, that is, a rail pressure point, according to the rail pressure, as shown in FIG. The injection amount learning device 10 does not learn the fuel injection amount in the entire range of the rail pressure set in the common rail 25, but learns the fuel injection amount for the representative rail pressure in the predetermined range. To do. In addition, the rail pressure shown in FIG. 3 can set arbitrary rail pressure as a rail pressure point according to the pressure set to the common rail 25. FIG. Further, the rail pressure point classification can also be set arbitrarily.

  In this embodiment, six points “P1”, “P2”, “P3”, “P4”, “P5”, and “P6” are set as rail pressure points. The rail pressure point P1 corresponds to the rail pressure when the diesel engine 21 is in an idle state, for example. The rail pressure points P2, P3, and P4 correspond to the rail pressure when the diesel engine 21 is at a normal and relatively low load, for example. The rail pressure point P5 corresponds to the rail pressure when the diesel engine 21 is at a relatively medium load, for example, when the vehicle equipped with the diesel engine 21 is in an acceleration state. The rail pressure point P6 corresponds to the rail pressure when the diesel engine 21 is at the maximum output. Thus, the rail pressures P1 to P6 have a relationship of P1 <P2 <P3 <P4 <P5 <P6.

  The injection amount learning device 10 defines a rail pressure index for each of these rail pressure points. That is, the injection amount learning device 10 stores the rail pressure point “P1” as the rail pressure index “# 0”, “P2” is “# 1”, “P3” is “# 2”, “P4”. Are stored as “# 3”, “P5” as “# 4”, and “P6” as “# 5”. The ECU 11 of the injection amount learning device 10 stores the rail pressure index of the rail pressure point in a ROM (not shown) or the like.

(Detailed map)
The injection amount learning device 10 stores a detailed map corresponding to the rail pressure index. As shown in FIG. 4, the detailed map includes a rail pressure index corresponding to the rail pressure point and data related to the learning implementation state in each cylinder 29 of the diesel engine 21. In the case of the four-cylinder diesel engine 21, the cylinder index is set as "# 0" for the first cylinder, "# 1" for the second cylinder, "# 2" for the third cylinder, and "# 3" for the fourth cylinder. ing. That is, the detailed map is a map that shows the state in which the injector 40 provided in each cylinder 29 is learning the fuel injection amount at the rail pressure point. At this time, the detailed map shows “0” if the fuel injection amount has not been learned, “0” if the fuel injection amount is being learned, and “0” if the fuel injection amount has been learned. 2 "is written. The ECU 11 of the injection amount learning device 10 stores a detailed map as electronic data in a RAM or ROM (not shown).

(First embodiment of learning of fuel injection amount)
Next, a first embodiment of learning of the fuel injection amount by the injection amount learning device 10 having the above-described configuration will be described.
When the diesel engine 21 shifts to an operation state suitable for learning the fuel injection amount, the ECU 11 learns the fuel injection amount. At this time, the operation state suitable for learning the fuel injection amount in the diesel engine 21 is, for example, a case where a vehicle equipped with the diesel engine 21 is in a deceleration state or the diesel engine 21 is in a no-load state. The ECU 11 detects the operating state of the diesel engine 21 from the amount of depression of the accelerator pedal detected by the accelerator sensor 14. When the ECU 11 determines that the diesel engine 21 has shifted to an operation state suitable for learning of the fuel injection amount, the ECU 11 starts extracting rail pressure points for performing learning according to FIG.

  When the ECU 11 proceeds to extraction of the rail pressure point, the ECU 11 determines whether or not there is a non-injection request in the diesel engine 21 and fuel is being injected (S101). The non-injection request is a state in which no fuel injection request is made to the diesel engine 21, for example, when the accelerator pedal depression amount is 0 and the vehicle equipped with the diesel engine 21 is decelerating. . On the other hand, if the fuel injection from the injector 40 is stopped as soon as the accelerator pedal is released, the output of the diesel engine 21 may change abruptly and the behavior of the vehicle may become unstable. Therefore, even when the accelerator pedal depression amount becomes 0 and no fuel injection is required, fuel injection is continued in an appropriate amount in order to mitigate the rapid output change of the diesel engine 21. This state corresponds to a non-injection request and fuel injection. When the operation of the diesel engine 21 is stabilized after the diesel engine 21 has requested no injection and fuel is being injected, the diesel engine 21 shifts to a non-injection period in which fuel is not injected from the injector 40. In this way, by determining whether or not there is a non-injection request and fuel injection is in progress, the ECU 11 can predict that a non-injection period suitable for learning the fuel injection amount will come after that. Therefore, the ECU 11 prepares to learn the fuel injection amount during the non-injection period while the diesel engine 21 is requesting no injection and fuel is being injected.

  When the ECU 11 determines in step S101 that the diesel engine 21 is requesting no injection and injecting fuel, the ECU 11 calculates the maximum rail pressure (S102). The maximum rail pressure is the highest rail pressure that can be set in the common rail 25. When calculating the maximum rail pressure, the ECU 11 obtains the rail pressure in the common rail 25 from the pressure sensor 13, that is, the rail pressure immediately before the learning is performed. As shown in FIGS. 5A and 5B, the maximum rail pressure Pm is the rail pressure Pc detected by the pressure sensor 13, the pressure increase amount Ps that can be increased by the supply pump 24, and the noise of the diesel engine 21. It is calculated from the decompression amount Pr set according to the suppression amount.

  Here, the pressure increase amount Ps is set so that the noise generated from the diesel engine 21 falls within an allowable range according to the rail pressures Pc1, Pc2, Pc3, Pc4, and Pc5 in the common rail 25. That is, as shown in FIG. 5A, when the rail pressure is Pc1, the boost amount is set to Ps1, similarly, when the rail pressure is Pc2, the boost amount is Ps2, and when the rail pressure is Pc3, the boost amount is Ps3 and the rail pressure Pc4. Is set to Ps4, and when the rail pressure is P5, the boost amount is set to Ps5. At this time, the relationship Pc1 <Pc2 <Pc3 <Pc4 <Pc5 is established between the rail pressures Pc1 and Pc5, and the relationship Ps1 <Ps2 <Ps3 <Ps4 <Ps5 is established between the boost amounts Ps1 and Ps5. . Here, the rail pressures Pc1 to Pc5, which are the basis for setting the pressure increase amount Ps, may be set in association with the rail pressures P1 to P6 set according to the rail pressure index, or from the rail pressure P1. It may be set regardless of P6.

  Further, the noise suppression amount Pr is set according to the speed of the vehicle on which the diesel engine 21 is mounted, as shown in FIG. The noise suppression amount Pr is a pressure reduction amount set to suppress noise generated from the diesel engine 21. The noise suppression amount Pr is set to Pr1 when the speed of the vehicle on which the diesel engine 21 is mounted is V1. Similarly, when the speed is V2, the suppression amount is Pr2, and when the speed is V3, the suppression amount is Pr3. When the speed is V4, the suppression amount is Pr4, and when the speed is V5, the suppression amount is Pr5. At this time, the vehicle speed V1 is set so that the speed is substantially zero. On the other hand, the vehicle speeds V2 to V4 are set according to a speed range used for traveling in a general urban area such as 60 km / h. Further, the vehicle speed V5 is set corresponding to the maximum speed of the vehicle on which the diesel engine 21 is mounted. Therefore, a relationship of V1 <V2 <V3 <V4 <V5 is established between the vehicle speeds V1 and V5.

  Furthermore, the noise suppression amount Pr is set to suppress noise based on the speed of the vehicle on which the diesel engine 21 is mounted, and is set to increase as the vehicle speed decreases. On the other hand, as the vehicle speed increases, the noise suppression effect due to the noise suppression amount Pr decreases, and therefore, a uniform value is set in the high speed range regardless of the vehicle speed. When the vehicle speed is 0, the absolute value of Pr is set large in order to reliably reduce noise reduction. That is, a relationship of Pr1> Pr2> Pr3 = Pr4 = Pr5 is established between the noise suppression amounts Pr1 to Pr5. Thereby, when the speed of the vehicle equipped with the diesel engine 21 is 0, the maximum rail pressure Pm is calculated as 0 as a result, and the ECU 11 does not learn the fuel injection amount.

As shown in Equation 1, the maximum rail pressure Pm is calculated by adding the rail pressure Pc, the pressure increase amount Ps, and the pressure decrease amount Pr.
Pm = Pc + Ps + Pr Formula 1
As described above, the ECU 11 sets the maximum rail pressure Pm in consideration of not only the actual rail pressure detected by the pressure sensor 13 but also the capability of the supply pump 24 and the pressure reduction for noise suppression.

  After calculating the maximum rail pressure in step S102, the ECU 11 extracts an unlearned rail pressure point (S103). Here, the unlearned rail pressure point means a rail pressure point where the fuel injection amount is not learned among a plurality of rail pressure points. The extraction of the unlearned rail pressure points is performed according to the flow shown in FIG. In step S103, the ECU 11 extracts the maximum rail pressure index as shown in FIG. 6 (S301). The ECU 11 extracts a settable maximum rail pressure index based on the maximum rail pressure Pm calculated in step S103. Specifically, in the case of the rail pressure index shown in FIG. 3, it is assumed that the maximum rail pressure Pm calculated by the ECU 11 in step S103 is P4. At this time, the highest rail pressure index extracted by the ECU 11 in step S301 is “# 3” corresponding to P4. If the calculated maximum rail pressure Pm is between P5 and P6, the extracted maximum rail pressure index is “# 4” corresponding to P5. In this way, the ECU 11 extracts the rail pressure index corresponding to the highest rail pressure point closest to the highest rail pressure Pm.

  When the ECU 11 extracts the highest rail pressure index in step S301, the ECU 11 determines whether learning of the fuel injection amount at the lowest rail pressure index is unprocessed (S302). The ECU 11 learns the fuel injection amount sequentially from the highest rail pressure index to the lowest rail pressure index side. Specifically, in the case shown in FIG. 3, the fuel injection amount is learned in the order of the rail pressure index “# 5”, “# 4”, “# 3”, “# 2”, “# 1”, and “# 0”. carry out. Therefore, if learning of the fuel injection amount is completed at the rail pressure point (P1) indicated by the lowest rail pressure index, that is, “# 0”, the processing loop, that is, the rail pressure indexes “# 5” to “# 0”. It can be determined that learning of the fuel injection amount has been completed. Therefore, the ECU 11 determines whether or not the learning of the fuel injection amount at the lowest rail pressure index is unprocessed. Here, when the ECU 11 determines that the learning of the fuel injection amount at the lowest rail pressure index has been processed, the region in which the learning of the fuel injection amount is performed is determined as “none” (S311).

  On the other hand, when the ECU 11 determines that learning of the fuel injection amount at the lowest rail pressure index has not been processed, the ECU 11 determines whether or not the fuel injection amount at the rail pressure point has not been learned (S303). The relevant rail pressure point is a rail pressure point equal to or lower than the highest rail pressure index extracted in step S301. When the ECU 11 determines that the fuel injection amount at the rail pressure point is not yet learned, the ECU 11 determines the rail pressure point as a “learning rail pressure point” for learning the fuel injection amount (S304). On the other hand, if the ECU 11 determines that the fuel injection amount at the rail pressure point has been learned, the ECU 11 updates the index shown in FIG. 4 to “processed” (S321), and returns to step S302.

The procedure from step S302 to step S304 will be described based on a specific example as follows.
When “Px (P4 <Px <P5)” is calculated as the maximum rail pressure Pm in step S103, the maximum rail pressure index extracted in step S301 is “# 3”. At this time, if learning of the fuel injection amount is not completed at the rail pressure point (P4) indicated by the rail pressure index “# 3”, the ECU 11 determines the rail pressure point (“3” indicated by the rail pressure index “# 3”). P4) determines that the fuel injection amount has not yet been learned. Therefore, the ECU 11 sets an unlearned rail pressure point (P4) indicated by the rail pressure index “# 3” as a “learning rail pressure point” at which learning of the fuel injection amount is to be performed.

  On the other hand, if the learning of the fuel injection amount is completed at the rail pressure point (P4) indicated by the rail pressure index “# 3”, the ECU 11 detects the rail pressure point (P3) indicated by the rail pressure index “# 2”. ), It is determined that the fuel injection amount has not yet been learned. In this manner, the ECU 11 searches for a rail pressure point that has not been learned below the maximum rail pressure by the process shown in FIG. Then, the rail pressure point selected by the search is determined as a “learning rail pressure point”.

  The ECU 11 determines the “learning rail pressure point” in step S304 or “no” in the region where the fuel injection amount learning is performed in step S311 by performing the process shown in FIG. When the ECU 11 determines the “learning rail pressure point” or “no” in the area in which learning is performed, the ECU 11 proceeds to the process shown in FIG. 7 and sets the rail pressure in the common rail 25.

When the ECU 11 shifts to the setting of the rail pressure in the common rail 25, the ECU 11 determines whether or not there is no injection state (S201). During the period when the diesel engine 21 is in the non-injection request and injecting in step S101, the ECU 11 calculates the maximum rail pressure, determines the learning rail pressure point, and the like, so that the diesel engine 21 shifts to the non-injection state. Waiting. ECU11 sets the normal rail pressure according to the driving | running state of the diesel engine 21 in the common rail 25 until the diesel engine 21 transfers to a non-injection state (S211).
When the diesel engine 21 shifts to the non-injection state, the ECU 11 determines whether or not there is a region for learning the fuel injection amount (S202). When it is determined that the fuel injection amount learning area is “None” in step S311, the ECU 11 proceeds to step S211 and sets the normal rail pressure corresponding to the operation state of the diesel engine 21 in the common rail 25. To do.

  On the other hand, if it is determined that the fuel injection amount learning region is “present” in step S202, the ECU 11 sets the rail pressure corresponding to the “learning rail pressure point” determined in step S304 in the common rail 25 (S203). ). Thereby, the rail pressure in the common rail 25 is set to the “learning rail pressure point” determined in step S304, and the fuel injection amount injected from the injector 40 is learned. Learning of the fuel injection amount from the injector 40 is performed by a known method such as a change in the rotation of the crankshaft 28 of the diesel engine 21 detected by the rotation sensor 15. Therefore, the details of the fuel injection amount learning method will not be described.

  As described above, in the first embodiment of learning of the fuel injection amount, the maximum rail pressure is calculated according to the operating state of the diesel engine 21, and an unlearned rail pressure point below this maximum rail pressure is searched. Yes. As a result, the fuel injection amount learning is preferentially performed in the region where the rail pressure is high with less learning opportunities. Therefore, the fuel injection amount can be learned efficiently and reliably in a short period of time at a plurality of rail pressure points set in a wide pressure range, particularly at the rail pressure point on the high pressure side.

(Second embodiment of learning of fuel injection amount)
A second embodiment of learning of the fuel injection amount by the injection amount learning device 10 will be described with reference to FIG. In the second embodiment, the procedure for extracting unlearned rail pressure points is different from that in the first embodiment. Therefore, differences from the first embodiment of learning of the fuel injection amount described above will be described, and detailed description of substantially the same processing will be omitted.
When the ECU 11 extracts the highest rail pressure point in step S102 shown in FIG. 1, the ECU 11 extracts the unlearned rail pressure point according to the procedure shown in FIG. The ECU 11 extracts a settable maximum rail pressure index based on the maximum rail pressure Pm calculated in step S103 (S401). When the ECU 11 extracts the maximum rail pressure index in step S401, the ECU 11 determines whether or not learning of the fuel injection amount in the minimum frequency rail pressure index is unprocessed (S402). The ECU 11 learns the fuel injection amount in order from the highest rail pressure index to the lowest frequency rail pressure index. The minimum frequency rail pressure index is a rail pressure index with the lowest learning frequency. For example, in the case of a general common rail fuel injection system 20, the higher the pressure side, the fewer the learning opportunities and the lower the learning frequency. Therefore, if the learning of the fuel injection amount is completed at the rail pressure point with a low learning frequency, the learning of the fuel injection amount is completed for the processing loop, that is, the rail pressure indexes “# 5” to “# 0”. It can be judged. Therefore, when the ECU 11 determines that the learning of the fuel injection amount in the minimum frequency rail pressure index with a low learning frequency has been processed, the region for performing the learning of the fuel injection amount is determined as “none” (S411).

  On the other hand, when the ECU 11 determines that learning of the fuel injection amount at the minimum frequency rail pressure index is not processed, the ECU 11 determines whether the fuel injection amount at the rail pressure point is unprocessed (S403). In this case, the rail pressure point is a rail pressure point that is equal to or lower than the highest rail pressure index extracted in step S401, and is a low-frequency rail pressure point with a low learning frequency. When the ECU 11 determines that the fuel injection amount at the rail pressure point, that is, the low-frequency rail pressure point is not learned, the ECU 11 determines the low-frequency rail pressure point as a “learning rail pressure point” for learning the fuel injection amount. (S404). When the ECU 11 determines that the fuel injection amount at the low-frequency rail pressure point has been learned, the ECU 11 updates the index to “processed” (S421), and returns to step S402. After determining the rail pressure according to the procedure shown in FIG. 8, the ECU 11 sets the common rail 25 to the determined rail pressure according to the procedure shown in FIG.

  In the second embodiment of learning of the fuel injection amount, a “low frequency rail pressure point” having a low learning frequency of the fuel injection amount is searched from unlearned rail pressure points that are equal to or lower than the maximum rail pressure. Thereby, a learning opportunity is equally allocated from a plurality of rail pressure points to each rail pressure point. Therefore, an extreme bias of the learning state, that is, “learning completed”, “learning”, and “unlearned” is avoided at a plurality of rail pressure points. Therefore, the fuel injection amount can be learned evenly at each rail pressure point.

(Third embodiment of learning of fuel injection amount)
A third embodiment of learning of the fuel injection amount by the fuel injection learning device will be described with reference to FIG. In 3rd Embodiment, the extraction procedure of the unlearned rail pressure point differs from 1st Embodiment and 2nd Embodiment. Accordingly, differences from the above-described first embodiment and second embodiment will be described, and detailed description of substantially the same processing will be omitted.
When the ECU 11 extracts the maximum rail pressure point in step S102 shown in FIG. 1, the ECU 11 extracts an unlearned rail pressure point according to the procedure shown in FIG. The ECU 11 extracts a maximum rail pressure index that can be set based on the maximum rail pressure Pm calculated in step S103 (S501). When the ECU 11 extracts the maximum rail pressure index in step S501, the ECU 11 searches for the presence or absence of a near-complete rail pressure point that is about to be completed (S502). Here, the near completion rail pressure point is literally the rail pressure point at which learning of the fuel injection amount is near completion. When the fuel injection amount is learned at a plurality of rail pressure points, the learning frequency differs for each rail pressure point. In this case, in the third embodiment, if there is a rail pressure point whose learning frequency is high and learning is near completion, learning is preferentially performed at the rail pressure point where learning is near completion.

  If there is no near-complete rail pressure point in step S502, the ECU 11 determines that learning has been completed at all rail pressure points, and determines that the region for learning the fuel injection amount is “none” (S511). . On the other hand, when the ECU 11 determines that there is learning of the fuel injection amount in the near-completion rail pressure index, the rail pressure point indicated by the near-completion rail pressure index is set as a “learning rail pressure point” for learning the fuel injection amount. Confirm (S504). After determining the rail pressure according to the procedure shown in FIG. 9, the ECU 11 sets the common rail 25 to the determined rail pressure according to the procedure shown in FIG.

In the third embodiment of learning of the fuel injection amount, a “nearly completed rail pressure point” that is close to completion of learning of the fuel injection amount is searched from unlearned rail pressure points that are equal to or lower than the maximum rail pressure. Thereby, the learning of the fuel injection amount at any rail pressure point is completed at an early stage. Therefore, the ECU 11 uses the learned fuel injection amount for controlling the diesel engine 21 even if it is a part of the plurality of rail pressure points. Therefore, the learning result can be quickly reflected in the control of the diesel engine 21, and the performance of the diesel engine 21 can be improved early. In particular, in the third embodiment, the learning of the fuel injection amount is preferentially performed at the rail pressure point having a higher learning frequency. The rail pressure point with a high learning frequency is also frequently used in the control of the diesel engine 21. Therefore, the fuel injection characteristics can be preferentially improved as the rail pressure point is used more frequently.
The present invention described above is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

Schematic which shows the flow of learning of the fuel injection amount by the injection amount learning apparatus by one Embodiment of this invention. Schematic which shows the fuel-injection system to which the injection quantity learning apparatus by one Embodiment of this invention is applied. The figure which shows the correspondence table of the rail pressure index applied to the injection quantity learning apparatus by one Embodiment of this invention. The figure which shows the conversion table of the detailed map applied to the injection quantity learning apparatus by one Embodiment of this invention. (A) is a figure which shows the correspondence table of rail pressure and the pressure | voltage rise amount of a supply pump, (B) is a figure which shows the correspondence table of the speed of a vehicle, and a noise suppression amount. Schematic showing the flow of the first embodiment of rail pressure point extraction by the injection amount learning device Schematic showing the flow of rail pressure setting by the injection amount learning device Schematic which shows the flow of 2nd Embodiment of rail pressure point extraction by the injection quantity learning apparatus. Schematic which shows the flow of 3rd Embodiment of rail pressure point extraction by the injection quantity learning apparatus.

Explanation of symbols

  In the drawings, 10 is an injection amount learning device, 11 is an ECU (rail pressure detection means, maximum rail pressure calculation means, rail pressure point selection means, injection amount learning means), 13 is a pressure sensor (rail pressure detection means), and 20 is A fuel injection system (fuel injection device), 21 is a diesel engine, 25 is a common rail, 29 is a cylinder, and 40 is an injector.

Claims (4)

In a common rail type fuel injection device that injects fuel pressurized by a supply pump and stored in a common rail into each cylinder of the diesel engine, fuel injection amount from the injector in pilot injection performed prior to main injection An injection amount learning device for learning
Rail pressure detecting means for detecting the fuel pressure in the common rail as a rail pressure;
The rail pressure detected by the rail pressure detecting means immediately before the learning, by adding the boosting can boost the amount by the supply pump, and pressure reduction amount that is set in accordance with the noise suppression quantity of said diesel engine, The highest rail pressure calculating means for calculating the highest rail pressure that can be set as the rail pressure as the highest rail pressure;
From the plurality of rail pressure points set as the rail pressure for learning the fuel injection amount from the injector, the fuel injection amount is learned from the rail pressure point that is equal to or lower than the maximum rail pressure calculated by the maximum rail pressure calculating means. Rail pressure point selection means to select as a learning rail pressure point to be implemented;
An injection amount learning means for learning a fuel injection amount from the injector at the learning rail pressure point selected by the rail pressure point selection means;
An injection amount learning device comprising:
  The rail pressure point selection means searches for an unlearned rail pressure point from the highest rail pressure to a lower rail pressure side, and selects the searched unlearned rail pressure point as the learned rail pressure point. Injection quantity learning device.   The rail pressure point selection means searches for a low-frequency rail pressure point with less learning frequency from the highest rail pressure to a lower rail pressure side, and selects the searched low-frequency rail pressure point as the learned rail pressure point. The injection amount learning apparatus according to claim 1.   The rail pressure point selection means searches for a rail pressure point that is nearing completion of learning from the highest rail pressure to a lower rail pressure side, and selects the rail pressure point that is nearing completion of learning as the learning rail pressure point. The injection amount learning apparatus according to claim 1.

Images