JP2007332816A - Fuel injection control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device capable of stabilizing operating conditions of an internal combustion engine prior to implementation for learning of an injection characteristic and implementing the learnt characteristics of respective fuel injection valves. <P>SOLUTION: The operating conditions of an engine body 11 is forcibly stabilized when learning the characteristics of a plurality of injectors 15 mounted on the engine body 11. When stabilizing the operating conditions of the engine body 11, an ECU 40 performs injection of fuel on the basis of a reduced injection pattern which reduces the number of injection than the standard injection pattern set up at a certain condition. Thus, the engine body 11 can be forcibly shifted to stable operating condition on the basis of the fuel injection in the reduced injection pattern even though the ECU 40 does not learn the characteristics of the plurality of injectors 15, and accordingly, the characteristics of the following injectors 15 can be surely learnt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection control device for an internal combustion engine.

  Conventionally, a common rail fuel injection device is known as a fuel injection device for an internal combustion engine. In a common rail type fuel injection device, high pressure fuel is stored in a pressure storage means such as a common rail, and the stored high pressure fuel is injected from a fuel injection valve into each cylinder of an internal combustion engine. In such a common rail type fuel injection device, in order to stabilize fuel combustion, reduce noise and improve exhaust performance, pilot injection that injects a small amount of fuel prior to main injection, which is the main combustion, is performed. We are carrying out.

By the way, the fuel injection valve has a difference in fuel injection characteristics for each individual due to its accurate error. In the case of pilot injection, the fuel injected from the fuel injection valve may require about 1 mm ³ / st. Therefore, when the individual difference of the fuel injection valves becomes large, pilot injection may not be performed or the fuel injection in the pilot injection may be greater than the fuel injection amount in the main injection depending on the plurality of fuel injection valves mounted on the internal combustion engine. There is a problem that the amount increases. In view of this, a fuel injection control device has been proposed that grasps the variation in the actual fuel injection amount for each fuel injection valve and learns the fuel injection characteristics of each fuel injection valve (see Patent Document 1).

  However, the learning of the injection characteristics by the fuel injection control device disclosed in Patent Document 1 is based on the stable operation of the internal combustion engine. That is, the learning of the injection characteristics is performed, for example, when the internal combustion engine is in an idle state and there is no load fluctuation. Therefore, unless the operation of the internal combustion engine becomes a stable idle state, it is not possible to shift to learning of the injection characteristics of each fuel injection valve. On the other hand, when the learning of the injection characteristics is not performed, there is a problem that the operating state of the internal combustion engine is not easily stabilized, and as a result, the learning of the injection characteristics itself becomes difficult.

JP 2004-19539 A

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel injection control device that stabilizes the operating state of an internal combustion engine and learns the characteristics of each fuel injection valve prior to the learning of the injection characteristics. .

  In the invention according to any one of claims 1 to 7, the injection control means sets the injection pattern of the fuel injection valve to the reduced injection pattern when the characteristic learning means learns the characteristic of each fuel injection valve. . In the reduced injection pattern, the number of injections is reduced from the number of fuel injections in the normal injection pattern set corresponding to the stable operation state in which the fluctuation of the load of the internal combustion engine is equal to or less than a predetermined value, and the fuel is injected. For example, when a regular injection pattern is set in which the main injection is performed once after the pilot injection is performed twice in the stable operation state, the main injection is performed after the pilot injection is performed once in the reduced injection pattern. The number of injections of the injection pattern is reduced such that the main injection is performed only once without performing the pilot injection or the pilot injection. The unstable operation of the internal combustion engine before the learning is performed is caused by an error in the injection amount of fuel injected from each fuel injection valve or an error in injection timing when a small amount of fuel is injected in pilot injection. Therefore, by reducing the number of injections, a large amount of fuel is injected per time, and the disappearance of a small amount of injection can be prevented. As a result, the operation of the internal combustion engine is stabilized, and the state shifts to a state in which the characteristics of each fuel injection valve can be learned. Therefore, prior to learning the injection characteristics of each fuel injection valve, the operating state of the internal combustion engine can be stabilized, and the characteristics of each fuel injection valve can be reliably learned.

  In the invention according to any one of claims 1 to 7, when learning of the characteristics of each fuel injector is completed, the injection pattern of the fuel injector is set to a normal injection pattern. For this reason, when learning is completed, fuel is injected from the fuel injection valve in accordance with a normal injection pattern in which main injection is performed after a predetermined number of pilot injections. Therefore, after learning of the characteristics of each fuel injection valve is completed, noise generated from the internal combustion engine can be reduced and exhaust performance can be improved.

In the second aspect of the invention, the amount of fuel injected per injection in the reduced injection pattern is set to be larger than the amount of fuel injected per injection in the normal injection pattern. In the reduced injection pattern, the number of fuel injections is reduced. Therefore, in order to maintain a stable operating state of the internal combustion engine, it is necessary to increase the fuel injection amount per injection. For example, the pilot injection of 1 mm ³ / st, when 4 mm ³ / normal injection pattern and a main injection st is set, the injection of 5 mm ³ is carried out in one time is reduced injection pattern. As a result, in the reduced injection pattern, the number of injections is reduced and the fuel injection amount per time is increased. Therefore, the internal combustion engine can be operated stably.

  In the invention according to claim 3 or 4, the characteristics of the fuel injection valve are learned within a predetermined period from the start of the internal combustion engine. As a result, when a predetermined period has elapsed since the start of fuel injection after the internal combustion engine was started, learning of the characteristics of the fuel injection valves ends, and each fuel injection valve is controlled based on the learned characteristics. Therefore, the internal combustion engine can be operated stably, noise generated from the internal combustion engine can be reduced, and exhaust performance can be improved.

  According to the fourth aspect of the present invention, the characteristics of the fuel injection valve are learned particularly within a predetermined period from the initial start of the internal combustion engine. The characteristics of the fuel injector do not change significantly with continued use. For this reason, it may be sufficient to learn the characteristics of the fuel injection valve once. On the other hand, when the internal combustion engine is started for the first time, the operating state of the internal combustion engine is difficult to stabilize because the characteristics of the fuel injection valve are not learned. Therefore, it is possible to learn the characteristics of the fuel injection valve when the internal combustion engine is started for the first time, and then control the fuel injection valve based on the learned characteristics.

  According to the fifth, sixth, or seventh aspect of the invention, when the operation period of the internal combustion engine reaches a certain period, the characteristics of the fuel injection valve are learned. Thereby, even when the characteristic of the fuel injection valve changes due to continuous use, the fuel injection valve is updated to the latest characteristic at regular intervals. Therefore, the internal combustion engine can be operated stably, noise generated from the internal combustion engine can be reduced, and exhaust performance can be improved.

  In the invention according to claim 6 or 7, the learning timing of the characteristics of the fuel injection valve may be set according to the number of times the internal combustion engine is started, and the learning timing of the characteristics of the fuel injection valve is determined according to the travel distance of the vehicle on which the internal combustion engine is mounted. It may be set.

In the invention according to claim 8, when the learned characteristic of the fuel injection valve is outside the predetermined range, the characteristic learning means learns the characteristic of the fuel injection valve again. If an error occurs in the learning of the characteristics of the fuel injector due to some cause, the learned characteristics of the fuel injector are out of the predetermined range. Therefore, if an incorrect characteristic is learned, the characteristic learning means learns the characteristic of the fuel injection valve again. Therefore, the accuracy of the characteristics of the fuel injection valve to be learned can be improved.
According to the ninth aspect of the invention, when the fuel injection amount injected from the fuel injection valve is outside the predetermined range, the characteristics of the fuel injection valve are learned. The characteristics of the fuel injection valve change with time, and the fuel injection amount may change. Therefore, the characteristic learning means learns the characteristic of the fuel injection valve again when the fuel injection amount from the fuel injection valve falls outside the predetermined range. Thereby, even when the injection amount of the fuel injection valve changes with time, it can be updated to the latest characteristics.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment of a diesel engine system to which an internal combustion engine control device of the present invention is applied. A diesel engine system (hereinafter referred to as “engine system”) 10 as an example of an internal combustion engine shown in FIG. 1 includes an engine body 11. The engine body 11 has four cylinders 12. The engine system 10 includes a common rail 13, a supply pump 14, an injector 15, and an electronic control unit (hereinafter “ECU”) 40. The supply pump 14 pressurizes the fuel stored in the fuel tank 16 and discharges it to the common rail 13. The common rail 13 stores the fuel pressurized by the supply pump 14 while maintaining the pressure, that is, in a pressure accumulation state. An injector 15 installed in each cylinder 12 of the engine body 11 is connected to the common rail 13. In the case of a four-cylinder engine body 11 as in the present embodiment, four injectors 15 are connected to the common rail 13.

  The injectors 15 inject fuel stored in the common rail 13 in a pressure accumulation state into the cylinders of the engine body 11. The injector 15 has a needle (not shown) for intermittently injecting fuel from a nozzle hole (not shown) and an electromagnetic drive unit (not shown) for driving the needle. The electromagnetic drive unit is electrically connected to the ECU 40. Thus, each injector 15 intermittently injects fuel based on the electrical control signal output from the ECU 40.

  An intake system 20 and an exhaust system 30 are connected to the engine body 11. The intake system 20 includes an air cleaner 21, a throttle 22, and an intake pipe 23. The intake pipe 23 forms an intake passage 24. The intake passage 24 connects the air cleaner 21 and the engine body 11. Foreign matter is removed from the air sucked into the engine body 11 by the air cleaner 21. The air that has passed through the air cleaner 21 is supplied to each cylinder 12 of the engine body 11 via the throttle 22. The throttle 22 opens and closes the intake passage 24. By opening and closing the intake passage 24 with the throttle 22, the flow rate of intake air taken into the engine body 11 is adjusted.

  The exhaust system 30 has an exhaust pipe 31 and a catalyst 32. The exhaust pipe 31 forms an exhaust passage 33. The exhaust pipe 31 guides the exhaust discharged from the engine body 11 to the outside. A catalyst 32 is installed in the middle of the exhaust pipe 31. The catalyst 32 reduces or oxidizes, for example, hydrocarbons or nitrogen oxides contained in the exhaust gas, thereby detoxifying these substances. An injection valve that injects, for example, a reducing agent or an oxidant into the exhaust gas flowing through the exhaust passage 33 may be installed on the engine body 11 side of the catalyst 32.

  A supercharger 50 is installed between the intake system 20 and the exhaust system 30. The supercharger 50 includes a turbine 51 that is rotated by exhaust gas flowing through the exhaust passage 33 and a compressor 52 that pressurizes intake air that is rotated by rotation of the turbine 51 and flows through the intake passage 24. The engine system 10 may be provided with an exhaust gas recirculation device that recirculates part of the exhaust gas to the intake system, for example.

  The ECU 40 is configured by a microcomputer having a CPU, ROM and RAM (not shown). The ECU 40 integrates and controls the engine system 10 and the vehicle on which the engine system 10 is mounted according to a program recorded in the ROM. Not only the injector 15 but also the throttle 22 and the supply pump 14 are connected to the ECU 40. In addition, a pressure sensor 41, an accelerator sensor 42, a rotation speed sensor 43, a water temperature sensor 44, and a vehicle speed sensor 45 are connected to the ECU 40. The ECU 40 functions as characteristic learning means, injection pattern control means, injection control means, and injection return means in the claims.

  The pressure sensor 41 is installed on the common rail 13 and detects the pressure of fuel stored in the common rail 13. The pressure sensor 41 outputs the detected fuel pressure to the ECU 40 as an electrical signal. The accelerator sensor 42 is installed on an accelerator pedal (not shown) and detects the opening degree of the accelerator pedal. The accelerator sensor 42 outputs the detected opening of the accelerator pedal to the ECU 40 as an electrical signal. The rotation speed sensor 43 is installed in the engine body 11 and detects the rotation speed of the engine body 11. The rotation speed sensor 43 outputs the detected rotation speed of the engine body 11 to the ECU 40 as an electrical signal. The water temperature sensor 44 is installed in the engine body 11 or a radiator (not shown), and detects the temperature of cooling water that cools the engine body 11. The water temperature sensor 44 outputs the detected temperature of the cooling water to the ECU 40 as an electrical signal. The vehicle speed sensor 45 is installed in a vehicle on which the engine system 10 is mounted, and detects the speed of the vehicle. The vehicle speed sensor 45 outputs the detected vehicle speed to the ECU 40 as an electrical signal.

  The ECU 40 adjusts the opening degree of the throttle 22 in accordance with the opening degree of the accelerator pedal detected by the accelerator sensor 42. Further, the ECU 40 calculates the amount of fuel to be supplied to the engine body 11 based on the output from the accelerator sensor 42 and the output from the rotation speed sensor 43. The ECU 40 adjusts the flow rate of the fuel supplied from the fuel tank 16 to the supply pump 14 so that the fuel pressure inside the common rail 13 becomes a predetermined pressure based on the calculated fuel amount. At the same time, the ECU 40 adjusts the valve opening time of the injector 15 and supplies a predetermined amount of fuel to the engine body 11. At this time, the ECU 40 corrects the flow rate of the fuel, the pressure of the common rail 13, the valve opening time of the injector 15, and the like based on the output from the water temperature sensor 44 or the exhaust temperature output from an exhaust temperature sensor (not shown). Also good. Further, the ECU 40 corrects the fuel flow rate, the pressure of the common rail 13, the valve opening time of the injector 15 and the like in consideration of the supercharging pressure by the supercharger 50 or the exhaust gas circulation amount by an exhaust gas recirculation device (not shown). May be.

Next, a characteristic learning procedure of the engine system 10 configured as described above will be described.
(First learning decision)
The ECU 40 determines whether or not characteristic learning of the engine system 10 has been performed in the past or within a predetermined period prior to characteristic learning of the engine system 10.
As described above, in the case of the engine system 10 including the four-cylinder engine main body 11, the four injectors 15 are installed in the engine system 10. The injectors 15 have different characteristics such as responsiveness and fuel injection amount per unit time. Therefore, ECU40 learns the characteristic of each injector 15, and controls each injector 15 according to the learned characteristic. Thereby, ECU40 can control the some injector 15 from which a characteristic differs individually according to a request | requirement. The characteristic learning of the engine system 10 is performed when a predetermined period has elapsed from the start of the engine body 11 in order to reliably perform characteristic learning.

The engine system 10 of the present embodiment performs two pilot injections Jp as shown in FIG. 2 (A) when injecting one cycle of fuel from the injector 15 to each cylinder under predetermined conditions. A regular injection pattern for performing one main injection Jm is set. The main injection Jm is a fuel injection corresponding to the main combustion in each cylinder 12 of the engine body 11. On the other hand, the pilot injection Jp is fuel injection prior to the main injection Jm. By performing the pilot injection Jp, the combustion proceeds gently during the main injection Jm, and the noise emitted from the engine body 11 is reduced. The pilot injection Jp has a smaller fuel injection amount than the main injection Jm. For example, when injecting fuel of 5 mm ³ in normal injection pattern one cycle, twice the fuel injection of the pilot injection Jp in each 1 mm ^3, so that the fuel in the single main injection Jm in 3 mm ³ is injected Set to

  By the way, since the injectors 15 have different characteristics, it is difficult to inject an accurate amount of fuel from the injectors 15 at an accurate time until the ECU 40 learns the characteristics of each injector 15. On the other hand, the learning of the injector 15 needs to be performed when the operation of the engine body 11 is stable. That is, the characteristics of the injector 15 cannot be learned unless the operation of the engine body 11 is stable. However, in the state where the engine system 10 is assembled, since the ECU 40 does not learn the injectors 15, it is difficult to precisely control the fuel injection from each injector 15. As a result, the operation of the engine system 10 is not stable, and it is not possible to shift to learning of the characteristics of each injector 15.

  For example, when a regular injection pattern for performing two pilot injections Jp and one main injection Jm is set for one cycle of fuel injection as described above, the following problems occur depending on the characteristics of the injector 15. Occurs. For example, when the pilot injection Jp cannot be controlled in a certain injector 15, the injection pattern of the fuel injected from the injector 15 is only main injection as shown in FIG. 2 (B1) or as shown in FIG. 2 (B2). As described above, there are cases where the pilot injection Jp is performed but the injection amount is small, or the number of pilot injections Jp is small as shown in FIG. 2 (B3). As a result, the injection pattern is not a regular injection pattern as shown in FIG. On the other hand, depending on the injector 15, as shown in FIG. 2 (B4), a large amount of fuel may be injected during the pilot injection Jp, and the fuel injection amount during the main injection Jm may be reduced.

  Thus, if fuel is injected from the injector 15 in a pattern different from the normal injection pattern, the operation of the engine body 11 is not stable. In particular, for example, when the engine system 10 is assembled for the first time or when the ECU 40 is replaced, the ECU 40 does not learn different characteristics of the injectors 15 individually. Therefore, the operation of the engine body 11 is not stable. It is difficult to shift to learning of the characteristics of the injector 15.

  Therefore, in the present embodiment, as shown in FIG. 3, prior to the performance learning of the injector 15, the ECU 40 determines whether or not the first learning has been performed (S101). That is, the ECU 40 determines whether or not learning of the operating characteristics of the injector 15 has been performed in the past. For example, when the ECU 40 has learned the operating characteristics of the injector in the past, the ECU 40 records the fact in the RAM. Note that the ECU 40 may determine whether or not a predetermined period has elapsed since the previous learning, and may determine to shift to learning when the predetermined period has elapsed.

  When it is determined that the initial learning is not performed, the ECU 40 sets a reduced injection pattern in which the number of injections is reduced from the regular injection pattern shown in FIG. 2A (S102). Here, the regular injection pattern is a state in which the engine body 11 continues to operate independently by the combustion of fuel injected from the injector 15, that is, in an idle state, and the load state of the engine body 11 does not change. 15 is an injection pattern of fuel injected from 15.

  In the case of the present embodiment, as described above, the regular injection pattern is set from two pilot injections Jp and one main injection Jm. Therefore, the ECU 40 sets the number of injections smaller than the normal injection pattern as the reduced injection pattern. In the case of the present embodiment, the ECU 40 sets, as the reduced injection pattern, an injection pattern that performs only one main injection Jm without performing the pilot injection Jp as shown in FIG.

  When a plurality of fuel injections including the pilot injection Jp and the main injection Jm are performed, the operation of the engine main body 11 is not easily stabilized if the injector 15 having the characteristics before learning is varied. On the other hand, by reducing the number of injections in one cycle of the injection pattern, variations in the characteristics of the injectors 15 are reduced. That is, by reducing the number of injections in the injection pattern, in the present embodiment, only the main injection Jm is single-stage injection. Therefore, a small amount of pilot injection Jp is not required from the injector 15. As a result, an amount of fuel corresponding to the main injection Jm is injected from the injector 15 at a time. Therefore, although the noise emitted from the engine body 11 increases and the exhaust performance decreases, the operation of the engine body 11 is stabilized.

When fuel is injected in a reduced injection pattern, an amount of fuel corresponding to the main injection Jm is injected at a time. Therefore, the fuel injection amount in one injection in the reduced injection pattern is larger than each fuel injection amount in the pilot injection Jp and the main injection Jm in the normal injection pattern. In example normal injection pattern, 1 mm ³ / twice a pilot injection Jp of the st, if the single main injection Jm of 3 mm ³ / st is performed, the total injection quantity of fuel in a single injection pattern is about 5mm ³ / st. On the other hand, in the reduced injection pattern, the total fuel injection amount for maintaining the operation of the engine body 11 does not change. Therefore, in the reduced injection pattern consisting of one main injection Jm, 5 mm ³ of fuel is injected in one main injection Jm. ECU40 will transfer to the learning algorithm which learns the characteristic of the injector 15 of the engine main body 11, if fuel injection is implemented by a reduced injection pattern.

  On the other hand, when it is determined that the first learning has been performed, the ECU 40 returns to the normal normal injection pattern, and performs the fuel injection from the injector 15 according to the normal injection pattern (S103). When the first learning is performed, the ECU 40 learns the characteristics of each injector 15. Therefore, the ECU 40 controls the injector 15 according to the characteristics. As a result, an appropriate amount of fuel is injected from the injector 15 at an appropriate time. Therefore, even when fuel is injected with a regular injection pattern, the operation of the engine main body 11 is stable, and it is possible to shift to learning of the characteristics of the injector 15.

(Characteristic learning procedure)
Next, learning of the characteristics of the injector 15 will be described.
As described above, when the operation of the engine main body 11 is stable or the initial learning is completed by the reduced injection pattern, the injector characteristic learning is performed according to the flow shown in FIG. Characteristic learning is the same as the procedure disclosed in Patent Document 1 described above, and will be described briefly.

  When the determination of the initial learning shown in FIG. 3 is completed, the ECU 40 determines whether or not the characteristic learning execution condition is satisfied (S201). In order to perform characteristic learning, the engine body 11 needs to be in a stable operating state. Therefore, the ECU 40 determines whether or not the operating state of the engine body 11 is stable in an idle state from various sensors and the like. For example, the rotational speed of the engine main body 11 detected by the rotational speed sensor 43 is not more than a predetermined value, the opening degree of the accelerator pedal detected by the accelerator sensor 42 is not more than a predetermined value, and the vehicle speed detected by the vehicle speed sensor 45 is When it is detected that the fuel injection amount corresponding to the control signal output to the injector 15 is equal to or smaller than the predetermined value and is equal to or smaller than the predetermined value and the shift position of the transmission (not shown) is “P range” or “N range”, the ECU 40 Determines that the engine body 11 is in a stable idle state.

  Further, the ECU 40 detects that a device that becomes a load for the operation of the engine body 11 is not operating. For example, the ECU 40 detects whether a radiator electric fan, an electric heater, a headlamp, an air conditioner, a power steering, and the like are operating. Further, the ECU 40 detects whether the control signal output to the injector 15 has changed, that is, whether the fuel injection amount from the injector 15 has not changed. The ECU 40 determines that the engine body 11 is in a stable idle state if each device is not operating and there is no change in the fuel injection amount. If ECU 40 determines that engine body 11 is not in a stable idle state, ECU 40 does not perform characteristic learning.

  When the ECU 40 determines that the operation state of the engine body 11 is a stable idle state, the ECU 40 maintains the operation state of the engine body 11 in a stable state, the conditions of fuel injection from the injector 15, and the intake and exhaust conditions. The condition is fixed (S202). For example, in order to make the combustion state of the fuel in the engine body 11 constant, the fuel injection pattern from the injector 15 is fixed to a predetermined injection pattern. In the injection pattern set in the present embodiment, fuel is injected evenly five times. Further, the ECU 40 sets the target pressure of the fuel stored in the common rail 13 to a predetermined target pressure that is set in advance. The ECU 40 drives the supply pump 14 in accordance with the set target pressure of the common rail 13. Further, the ECU 40 fixes the fuel injection timing, stops supercharging by the supercharger 50 and exhaust gas recirculation by an exhaust gas recirculation device (not shown), and fixes the opening of the throttle 22.

  When the operating condition of the engine body 11 is fixed, the ECU 40 sets a basic injection amount that is a total injection amount of fuel in one injection pattern (S203). This basic injection amount is set based on, for example, the rotational speed of the engine body 11 that is stably operated in an idle state, the temperature of the cooling water detected by the water temperature sensor 44, or the temperature of the intake air flowing through the intake passage 24. .

  Based on the set basic injection amount, the ECU 40 performs divided n times of equal injection from the injector 15 (S204). At this time, the ECU 40 equally divides the set basic injection amount into the number of injections n of a preset injection pattern. In the present embodiment, in step S204, the fuel is injected five times equally as described above. Therefore, the ECU 40 equally divides the set basic injection amount into five, and outputs a control signal corresponding to the five divided fuel injection amounts to the injector 15. Thereby, the injector 15 injects the fuel of the basic injection amount set by five equal injections. The division number n is not limited to five, and can be set arbitrarily.

  The ECU 40 sets the FCCB correction value when the equal n divided injections are performed (S205). The FCCB correction is for correcting the fuel injection amount to each cylinder 12 based on the difference in the rotational speed fluctuation amount for each of the plurality of cylinders 12 of the engine body 11. The ECU 40 sets the FCCB correction value for each cylinder 12 so that the amount of fluctuation in rotational speed between the cylinders is small. The ECU 40 sets the ISC correction value following the FCCB correction (S206). The ISC correction is a uniform correction for all the cylinders 12 in order to set the rotation speed of the engine body 11 to a target rotation speed.

  The ECU 40 detects whether or not the load fluctuation of the engine body 11 has occurred in each of the above steps (S207). Further, the ECU 40 detects whether the engine body 11 is in a stable operating state (S208). That is, the ECU 40 does not change the load state in the engine main body 11 in the equal n times divided injection in step S204, the setting of the FCCB correction value in step S205, and the setting of the ISC correction value in S206. Detects whether or not a stable operating state is maintained. When the ECU 40 determines that the engine body 11 is not maintaining a stable idle state, the ECU 40 ends the characteristic learning.

  The ECU 40 is currently set based on the set FCCB correction value and ISC correction value when it is determined that the load state of the engine main body 11 does not change and the stable operation state of the engine main body 11 is maintained. The learning value at the target pressure of the common rail 13 is calculated (S209). The learning value is calculated for each of a plurality of target pressures set on the common rail 13.

The ECU 40 determines whether or not the calculated learning value is at a predetermined level (S210). That is, the ECU 40 determines whether or not the calculated learning value is within a predetermined normal range. When the ECU 40 determines that the calculated learning value is not within the predetermined normal range, the characteristic learning ends.
When the ECU 40 determines that the calculated learning value is at a predetermined level, the ECU 40 changes the target pressure set in the common rail 13 and calculates the learning value again (S211). That is, when the calculation of the learning value for the target pressure with the common rail 13 is completed, the ECU 40 changes the target pressure and repeats the calculation of the learning value from step S202. The ECU 40 calculates learning values for a plurality of target pressures of the common rail 13 set in advance.

When the calculation of the learning value for each target pressure is completed, the ECU 40 backs up the calculated learning value (S212). That is, the ECU 40 records the learning value calculated for each target pressure in the RAM. Then, the ECU 40 returns to the normal injection pattern, and uses the recorded learning value to inject fuel from the injector 15 (S213).
Through the above procedure, the ECU 40 learns the characteristics of each injector 15.

  In the embodiment of the present invention described above, the operating state of the engine body 11 is stabilized in order to learn the characteristics of the injector 15. When the operating state of the engine body 11 is stabilized, the ECU 40 performs fuel injection according to a reduced injection pattern in which the number of injections is reduced from a predetermined regular injection pattern. As a result, even when the ECU 40 has not learned the characteristics of the plurality of injectors 15, for example, immediately after assembly of the engine body 11 or immediately after replacement of the ECU 40, the engine body is injected by fuel injection according to the reduced injection pattern. 11 forcibly shifts to a stable operating state. Therefore, it is possible to reliably learn the characteristics of the subsequent injector 15. Further, in the embodiment of the present invention, since the characteristics of the injector 15 can be surely learned, noise generated from the engine body 11 that has been learned can be reduced, and exhaust performance can be improved.

(Other embodiments)
In the above-described embodiment of the present invention, the case where the ECU 40 does not perform the initial characteristic learning of the injector 15 such as when the engine body 11 is assembled or the ECU 40 is replaced has been described as an example. However, for example, the ECU 40 may record the operation period of the engine body 11 and the ECU 40 may learn the characteristics of the injector 15 when the recorded operation period reaches a certain period. Alternatively, the ECU 40 may record the number of start times of the engine body 11 and the ECU 40 may learn the characteristics of the injector 15 when the recorded number of start times reaches a certain number. Further, the ECU 40 may record the travel distance of the vehicle on which the engine body 11 is mounted, and the ECU 40 may learn the characteristics of the injector 15 when the recorded travel distance reaches a certain distance. Further, the ECU 40 may learn the characteristics of the injector 15 when the fuel injection amount from the injector 15 becomes larger than a predetermined value.

  As described above, by learning the characteristics of the injector 15 after a certain period of time has elapsed or after the amount of fuel injection from the injector 15 has changed, the characteristics of the injector 15 change over time due to, for example, wear or adhesion of foreign matter. Even in the case of changing to, the characteristics of the injector 15 are periodically corrected. Therefore, the characteristics of the injector 15 can be stably maintained for a long time.

  Further, when the ECU 40 learns the characteristics of the injector 15, the ECU 40 may learn the characteristics of the injector 15 again when the learned characteristics are out of a predetermined range. When the ECU 15 learns the injector 15, there is a case where so-called erroneous learning occurs in which the characteristic learned for some reason deviates from a predetermined range. As described above, when the characteristic of the injector 15 learned by the ECU 40 is out of the predetermined range, the ECU 40 determines that the learning is erroneous and performs the learning of the injector 15 again. Thereby, the characteristic of the injector 15 can be learned with high accuracy.

  In the above-described embodiment, a pattern composed of two pilot injections Jp and one main injection Jm is set as a normal injection pattern, and only one main injection Jm is formed as a reduced injection pattern. An example of setting a pattern has been described. However, in the reduced injection pattern, the number of injections may be reduced as compared with the normal injection pattern. For example, in the case of the regular injection pattern described above, an injection pattern that performs one pilot injection Jp and one main injection Jm may be set as the reduced injection pattern. Further, for example, when an injection pattern composed of one pilot injection Jp and one main injection Jm is set as a normal injection pattern, an injection pattern for performing one main injection Jm is set as a reduced injection pattern. can do. Thus, the number of injections of the normal injection pattern can be set arbitrarily, and the number of injections of the reduced injection pattern can be set according to the number of injections of the set normal injection pattern.

  As described above, the present invention 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 engine system to which the fuel-injection control apparatus by one Embodiment of this invention is applied. Schematic which shows the injection pattern of the fuel by the fuel-injection control apparatus by one Embodiment of this invention. Schematic which shows the flow of an operation | movement of the engine system to which the fuel-injection control apparatus by one Embodiment of this invention is applied. Schematic which shows the flow of an operation | movement of the engine system to which the fuel-injection control apparatus by one Embodiment of this invention is applied.

Explanation of symbols

  10: engine system (fuel injection control device), 11: engine body (internal combustion engine), 12: cylinder, 15: injector (fuel injection valve), 40: ECU (characteristic learning means, injection pattern control means, injection control means, Injection return means)

Claims (9)

A plurality of fuel injection valves for injecting fuel into a plurality of cylinders of the internal combustion engine;
Characteristic learning means for learning the characteristics of the plurality of fuel injection valves;
A regular injection pattern including two or more fuel injections set corresponding to a stable operation state in which the fluctuation of the load of the internal combustion engine is a predetermined value or less, as an injection pattern of fuel injected from the fuel injection valve Or an injection pattern control means for setting one of the reduced injection patterns less than the number of injections of the regular injection pattern;
Injection control means for setting the injection pattern of the fuel injection valve to the reduced injection pattern by the injection pattern control means when learning the characteristics of the fuel injection valve by the characteristic learning means;
Injection learning means for setting the injection pattern of the fuel injection valve to the normal injection pattern by the injection pattern control means when learning of the characteristics of the fuel injection valve is completed by the characteristic learning means;
A fuel injection control device comprising:   The fuel injection control device according to claim 1, wherein the amount of fuel injected per injection in the reduced injection pattern is larger than the amount of fuel injected per injection in the regular injection pattern.   The fuel injection control device according to claim 1 or 2, wherein the characteristic learning means learns characteristics of the plurality of fuel injection valves within a predetermined period from the start of the internal combustion engine.   The fuel injection control device according to claim 3, wherein the characteristic learning means learns characteristics of the plurality of fuel injection valves within a predetermined period from an initial start of the internal combustion engine.   The fuel injection control device according to claim 1 or 2, wherein the characteristic learning means learns characteristics of the plurality of fuel injection valves when an operation period of the internal combustion engine reaches a certain period.   The fuel injection control device according to claim 5, wherein the characteristic learning unit learns characteristics of the plurality of fuel injection valves when the number of times the internal combustion engine is started reaches a predetermined number.   6. The fuel injection control device according to claim 5, wherein the characteristic learning means learns characteristics of the plurality of fuel injection valves when a travel distance of a vehicle on which the internal combustion engine is mounted reaches a predetermined distance.   The fuel injection according to any one of claims 1 to 7, wherein when the learned characteristics of the plurality of fuel injection valves are out of a predetermined range, the characteristic learning unit learns the characteristics of the plurality of fuel injection valves again. Control device. 3. The fuel injection control device according to claim 1, wherein the characteristic learning unit learns characteristics of the plurality of fuel injection valves when an injection amount of fuel injected from the fuel injection valves is out of a predetermined range.

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