JP2010106820A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a remarkable increase in emission such as smoke and unburnt fuel produced by incomplete combustion caused by a decrease in fuel injection speed in association with the closing of an inner needle 22, in a fuel injection valve 16 including a variable injection hole nozzle. <P>SOLUTION: When engine speed and the total injection quantity from the fuel injection valve 16 fall within a predetermined range, it is determined whether or not fuel injection completion timing from a second nozzle port group 42 is on a delay angle side relative to the valve closing operation start timing of an outer needle 20. When it is determined that the fuel injection completion timing is on the delay angle side, the fuel injection completion timing from the second nozzle port group 42 is advanced to the valve closing operation start timing of the outer needle 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a valve body in which a plurality of injection holes are formed, and a plurality of valve members that are slidably accommodated in the valve body and are allocated to open and close each of the plurality of injection holes. The present invention relates to a fuel injection control device for an internal combustion engine that adjusts fuel injection timing from each of the plurality of nozzle holes by opening and closing the plurality of valve members of the fuel injection valve.

  In order to achieve both a reduction in diesel engine emissions and an increase in engine-generated torque, for example, as described in Patent Document 1 below, a variable nozzle nozzle that makes the nozzle hole area variable according to the operating state of the engine is provided. A fuel injection valve is known. As shown in FIG. 4, the variable nozzle hole includes a cylindrical nozzle body 100, a first nozzle hole group 112 and a second nozzle hole group 116 formed at the tip of the nozzle body 100, and the nozzle body 100. A cylindrical nozzle needle (outer needle 102) that is accommodated in the nozzle body 100 and is operable in the axial direction of the nozzle body 100, and a nozzle needle (inner needle 104) that is accommodated in the outer needle 102 and is operable in the axial direction thereof ).

  In such a configuration, the taper-shaped sheet portion (sheet portion 106) formed on the distal end side of the outer needle 102 due to the axial movement of the outer needle 102 is a circle formed on the inner wall of the nozzle body 100 facing this. The first nozzle hole group 112 is opened by separating from the annular first seat part 110, and the first nozzle hole group 112 is closed by sitting on the first seat part 110. Further, a taper-shaped seat portion (seat portion 108) formed on the distal end side of the inner needle 104 by the axial movement of the inner needle 104 is formed in an annular shape formed on the inner wall of the nozzle body 100 facing this. The second nozzle hole group 116 opens by separating from the second seat part 114, and the second nozzle hole group 116 closes by sitting on the second sheet part 114.

As a result, when the required torque of the engine is small, fuel is injected only from the first nozzle hole group 112 having a small diameter to form a spray with good atomization, thereby increasing the smoke caused by incomplete combustion. Can be suppressed. Further, when the required torque of the engine is large, fuel is injected from both the first nozzle hole group 112 and the second nozzle hole group 116, and the generated torque of the engine is increased by increasing the fuel injection rate. be able to.
JP 2007-162535 A

  By the way, in order to suppress the increase in smoke or increase the torque generated by the engine, it is necessary to improve the combustion state in the combustion chamber. That is, it is necessary to sufficiently mix fuel and air by sufficiently atomizing and diffusing the fuel injected from the fuel injection valve in the combustion chamber. This can be realized by increasing the injection speed of the fuel injected from the fuel injection valve.

  However, in a nozzle that opens and closes an injection hole with a nozzle needle, generally, fuel injection speed may decrease due to a decrease in fuel injection pressure immediately before completion of fuel injection, and emission may increase. That is, for example, in the variable nozzle hole nozzle shown in FIG. 4, the area of the passage formed by the sheet portion 106 and the first sheet portion 110 is one for each nozzle hole constituting the first nozzle hole group 112. Is smaller than the opening area of the fuel, pressure loss occurs in the fuel supplied from the fuel passage, so that the fuel injection pressure gradually decreases, and the injection speed of the fuel injected from the first nozzle hole group 112 gradually decreases. . Further, either the area of the passage formed by the sheet portion 106 and the first sheet portion 110 or the area of the passage formed by the sheet portion 108 and the second sheet portion 114 is the second injection hole group 116. When it becomes smaller than the opening area per one of the nozzle holes constituting the, the injection speed of the fuel injected from the second nozzle hole group 116 gradually decreases. When the fuel injection speed decreases in this way, the fuel (residual fuel) remaining in the vicinity of the nozzle hole without being sufficiently atomized and diffused increases, resulting in an increase in emissions such as smoke due to incomplete combustion and unburned fuel. There is a fear.

  In particular, in the variable nozzle nozzle shown in FIG. 4, the inventors have found that the increase in emissions such as smoke due to incomplete combustion and unburned fuel can be significant. This is because the injection speed of the fuel injected from the second nozzle hole group 116 is not only the area of the passage formed by the seat portion 108 and the second seat portion 114 but also the seat portion 106 and the first seat portion. 110 depends on the area of the passage formed by 110 and the like.

  In order to cope with such an increase in emissions, a countermeasure using an aftertreatment device (an oxidation catalyst, a diesel particulate filter) may be considered. However, in this case, the cost may increase due to the increase or addition of the capacity of the post-processing apparatus.

  Such a problem is not limited to the fuel injection valve provided with the variable injection nozzle shown in FIG. 4, and generally, a plurality of such problems can be obtained by operating a plurality of valve members slidably accommodated in the valve body. Any fuel injection valve capable of adjusting the timing of fuel injection from each of the nozzle holes can occur.

  The present invention has been made to solve the above-described problems, and the object thereof is to operate each of a plurality of valve members slidably accommodated in a valve body so that each of the plurality of nozzle holes can be operated. It is an object of the present invention to provide a fuel injection control device for an internal combustion engine that can suitably reduce emissions without using a post-processing device when adjusting the fuel injection timing.

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

  The invention according to claim 1 is a valve body in which a plurality of injection holes are formed, and a plurality of valves that are slidably accommodated in the valve body and are allocated to open and close each of the plurality of injection holes. In a fuel injection control device for an internal combustion engine that adjusts fuel injection timing from each of the plurality of nozzle holes by opening and closing the plurality of valve members of a fuel injection valve having a member, the plurality of valve members are Of the pair of valve members constituting the fuel injection amount, the fuel injection amount is injected from the corresponding nozzle hole at the time of the valve closing operation, and the fuel injection amount during the period in which the fuel injection speed is significantly lower than when the valve closing operation is started. It is characterized by comprising adjusting means for adjusting the valve closing operation completion timing, which is assumed to be more, to be earlier than the other valve closing operation completion timing.

  As the fuel injection speed decreases, residual fuel increases and emissions may increase. In this regard, in the above invention, the fuel injection amount that is injected from the corresponding nozzle hole during the valve closing operation among the pair of valve members that constitute the plurality of valve members, and the fuel injection speed starts the valve closing operation. The valve closing operation completion timing, which is assumed to have a large amount of fuel injection in a period significantly lower than the time, is adjusted so as to be earlier than the other valve closing operation completion timing. As a result, the other valve member utilizes the jet of fuel injected from the nozzle hole to be opened and closed, and the opening and closing of the one that is assumed to be the above-mentioned one that is likely to be particularly noticeable in the residual fuel due to the structure. The fuel injected from the target nozzle hole can be diffused. For this reason, the said residual fuel can be burned and an emission can be reduced suitably by extension.

  According to a second aspect of the present invention, in the first aspect of the invention, the adjusting means performs the adjustment on the condition that a parameter indicating an operating state of the internal combustion engine is within a predetermined region. To do.

  Depending on the operating state of the internal combustion engine, the fuel injection amount may increase and the fuel injection time may become longer. In this case, the fuel is injected under a situation where the temperature of the combustion chamber after the compression stroke of the internal combustion engine is lowered, and the combustion state of the combustion chamber is deteriorated, which may increase emissions. Under such circumstances, if the opening / closing timing is adjusted by the adjusting means, the valve opening time of the nozzle hole to be opened / closed, which is assumed to be more, is limited, and the temperature of the combustion chamber decreases. Under the circumstances, there is a possibility that the fuel injected from the nozzle hole to be opened / closed of the other valve member increases. Then, if the emission increase amount exceeds the emission reduction amount by the adjusting means, the emission may increase. In this regard, in the above invention, since the opening / closing timing is adjusted in the operating state of the internal combustion engine that can surely achieve the emission reduction effect, the effect of the invention of the above-mentioned claim 1 can be particularly suitably achieved. It has a configuration.

  The parameter indicating the operating state of the internal combustion engine preferably includes at least one of a parameter correlated with the time of one combustion cycle of the internal combustion engine and a parameter correlated with the fuel injection amount.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the setting means for setting the opening / closing timing of the pair of valve members based on the parameter indicating the operating state of the internal combustion engine, and the setting means Determination means for determining whether or not the timing to be adjusted satisfies a timing condition to be adjusted by the adjusting means, and the adjusting means determines that the condition is not satisfied by the determining means, It is characterized by adjusting.

  The opening / closing timing of the pair of valve members is adapted to satisfy various adaptation elements. Here, when it adapts so that the requirement element that the timing conditions by the said adjustment means may be satisfy | filled among a pair of valve members, since the requirement element in the case of an adjustment increases, there exists a possibility that an adjustment man-hour may increase. In this regard, in the above-described invention, it is necessary to satisfy the above-described requirement element regarding the relationship between the opening / closing timings of the pair of valve members when the opening / closing timings of the basic pair of valve members are adapted by the setting means by providing the determination means Therefore, the above adjustment can be performed while suppressing an increase in the number of man-hours as much as possible.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects of the present invention, the adjusting means is configured such that the valve closing operation completion timing of the one that is assumed to be greater is the other valve closing operation start The adjustment is performed so as not to be later than the timing.

  In the above-mentioned invention, by using the jet of fuel before the fuel injection speed from the nozzle hole to be opened / closed decreases with the other valve closing operation, the above-mentioned opening / closing object, which is assumed to be more, The diffusion of the fuel injected from the injection hole can be promoted. Thereby, combustion of the residual fuel can be promoted, and the emission can be reduced more appropriately.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the valve member that is assumed to be large is the jet that is to be opened and closed among the pair of valve members. The opening area per one hole is the larger one.

  The larger the opening area of the injection hole, the larger the area of the passage formed by the valve body and the valve member when the fuel injection speed starts to decrease. For this reason, of the time from the start to the completion of the valve closing operation, the fuel injection time in a situation where the fuel injection speed is reduced becomes longer. Therefore, the larger the opening area per nozzle hole to be opened and closed, the fuel injection amount during the valve closing operation and the fuel injection during the period when the fuel injection speed is significantly lower than that at the start of the valve closing operation. The amount is thought to increase.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the valve member that is assumed to be large is the one having a lower operating speed of the pair of valve members. It is characterized by being.

  The smaller the operation speed of the valve member, the longer the time required from the start to completion of the valve closing operation. Therefore, it can be considered that the smaller the operation speed of the valve member, the longer the period during which the fuel injection speed is significantly lower than that at the start of the valve closing operation, and the greater the fuel injection amount during this period.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein a sack chamber is formed in the valve body. Although the pair of valve members are in a closed state, the nozzle holes communicating with the sac chamber are to be opened and closed.

  Even if the valve closing operation of the valve member is completed, there is a concern that the fuel remaining in the space formed by the valve body and the valve member is injected from the injection hole. For this reason, when the sac chamber is formed in the valve body, the amount of fuel remaining in the space increases, and the amount of fuel injected from the nozzle hole communicating with the sac chamber in accordance with the valve closing operation is It is considered that the fuel injection amount increases during a period in which the fuel injection speed is significantly lower than that at the start of the valve closing operation.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the injection hole to be opened and closed and the fuel supply port of the fuel injection valve are the one that is assumed to be large. Regardless of the open / closed state that is assumed to be large, the other valve member is shut off by being closed.

  In the configuration having the above-mentioned configuration, the passage area from the nozzle hole to be opened and closed to the fuel supply port of the fuel injection valve is increased with the valve closing operation of the other valve member. It is narrowed not only by the passage formed by the valve member and the valve body, which is assumed to be large, but also by the passage formed by the other valve member and the valve body. As a result, the fuel injection speed from the nozzle hole to be opened and closed, which is assumed to be large, tends to decrease, and the residual fuel from this nozzle hole may be particularly noticeable. For this reason, in the said invention, the merit provided with the said adjustment means is especially big.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which a fuel injection control device for an internal combustion engine according to the present invention is applied to a compression ignition type internal combustion engine (diesel engine) provided with a pressure accumulation type (common rail type) fuel injection device will be described with reference to the drawings. .

  FIG. 1 shows an overall configuration of a fuel injection system according to the present embodiment. As shown in the figure, the fuel in the fuel tank 10 is pumped up by an engine-driven fuel pump 12 and pressurized (suppressed) to the common rail 14. The common rail 14 stores the pressurized high pressure fuel, and distributes and supplies the high pressure fuel to the fuel injection valves 16 of each cylinder (here, only the fuel injection valve of one cylinder is illustrated).

  The tip of the fuel injection valve 16 is disposed so as to protrude into the combustion chamber 18 of the engine, so that fuel can be supplied to the combustion chamber 18 by injection. Specifically, the fuel injection valve 16 includes an outer needle 20, an inner needle 22, a cylindrical nozzle body 24 in which these are accommodated, and an outer needle drive mechanism that independently drives the outer needle 20 and the inner needle 22. 26 and an inner needle drive mechanism 28 mechanism.

  The nozzle body 24 is provided with a cylindrical needle storage portion 30. A cylindrical outer needle 20 operable in the axial direction of the nozzle body 24 is accommodated in the needle accommodating portion 30. Further, an inner needle 22 that is operable in the axial direction of the nozzle body 24 is accommodated in the outer needle 20.

  A tapered seat portion 32 is formed at the distal end portion of the outer needle 20, and a tapered seat portion 34 is formed at the distal end portion of the inner needle 22. An annular first sheet portion 36 and second sheet portion 38 are formed on the inner wall of the nozzle body 24 facing each of the sheet portion 32 and the sheet portion 34. Further, in the nozzle body 24, a first nozzle hole group 40 composed of a plurality of nozzle holes is formed on the tip side of the first sheet portion 36, and a plurality of nozzles are formed on the tip side of the first nozzle hole group 40. A second nozzle hole group 42 composed of holes is formed. Here, since the opening area of each nozzle hole constituting the second nozzle hole group 42 increases the fuel injection rate when the required torque of the engine is increased, the opening area of each nozzle hole constituting the first nozzle hole group 40 is increased. Is set larger than.

  A sack chamber 44 communicating with the second nozzle hole group 42 is formed in the vicinity of the second nozzle hole group 42 of the nozzle body 24. This avoids interference between the grindstone that grinds the second sheet portion 38 in the manufacturing process of the nozzle body 24 and the front end side of the inner wall of the nozzle body 24, and the tip of the inner needle 22 and the nozzle during the valve closing operation. This is provided in order to avoid interference with the inner wall of the body 24.

  In the outer needle 20 and the inner needle 22, the opposite sides (hereinafter referred to as the back side) of the nozzle body 24 opposite to the first sheet portion 36 and the second sheet portion 38 are formed in a nozzle holder (not shown). The first back pressure chamber 46 and the second back pressure chamber 48 are opposed to each other. In the first back pressure chamber 46, a first spring (not shown) is provided on the back side of the outer needle 20, and the outer needle 20 is urged toward the distal end side by the first spring. Further, in the second back pressure chamber 48, a second spring (not shown) is provided on the back side of the inner needle 22, and the inner needle 22 is urged toward the distal end side by the second spring. The outer needle 20 and the inner needle 22 operate in the axial direction when the pressures of the first back pressure chamber 46 and the second back pressure chamber 48 are operated.

  The pressure in the first back pressure chamber 46 is determined by the first switching unit 54 so that the connection state between the first back pressure chamber 46 and the low pressure fuel passage 52 communicating with the fuel tank 10 is based on the drive current flowing through the electromagnetic solenoid 54a. It is operated by being switched. By energizing the electromagnetic solenoid 54 a, the first back pressure chamber 46 and the low pressure fuel passage 52 are communicated with each other by the first switching unit 54. By this communication, the high-pressure fuel in the first back pressure chamber 46 is discharged to the fuel tank 10 through the low-pressure fuel passage 52, and the pressure in the first back pressure chamber 46 decreases. For this reason, the resultant force of the force for urging the outer needle 20 to the tip side generated by the pressure of the first back pressure chamber 46 and the force for urging the outer needle 20 to the tip side by a first spring (not shown) is the outer needle 20. It becomes smaller than the force which urges the back side. As a result, the seat portion 32 is separated from the first seat portion 36, and the outer needle 20 starts to move toward the back side (the valve opening operation start timing of the outer needle 20), whereby high-pressure fuel is supplied from the common rail 14. Since the fuel passage 56 and the first nozzle hole group 40 communicate with each other, fuel injection from the first nozzle hole group 40 is started. Then, the outer needle 20 operates until the back side rear end portion (not shown) of the outer needle 20 comes into contact with a stopper portion (not shown) in the first back pressure chamber 46 (timing for completing the valve opening operation of the outer needle 20).

  Here, when the energization of the electromagnetic solenoid 54 a is stopped, the first back pressure chamber 46 and the low pressure fuel passage 52 are blocked by the first switching unit 54. By this interruption, the pressure in the first back pressure chamber 46 increases. For this reason, the resultant force of the force for urging the outer needle 20 to the tip side generated by the pressure of the first back pressure chamber 46 and the force for urging the outer needle 20 to the tip side by a first spring (not shown) is the outer needle 20. It becomes larger than the force which urges to the back side. Thus, the outer needle 20 starts to move toward the distal end side (the valve closing operation start timing of the outer needle 20), and the seat portion 32 is seated on the first seat portion 36 (the valve closing operation completion timing of the outer needle 20). ) Since the fuel passage 56 and the first nozzle hole group 40 are blocked, the fuel injection from the first nozzle hole group 40 is terminated.

  The pressure of the second back pressure chamber 48 is switched between the second back pressure chamber 48 and the low pressure fuel passage 52 by the second switching based on the drive current flowing through the electromagnetic solenoid 58a, as in the first back pressure chamber 46. It is operated by being switched by the unit 58. By energizing the electromagnetic solenoid 58a, the high pressure fuel in the second back pressure chamber 48 is discharged to the fuel tank 10 through the low pressure fuel passage 52, and the pressure in the second back pressure chamber 48 is reduced. For this reason, in a state where the outer needle 20 is opened, the inner needle 22 is moved to the distal end side by a force for urging the inner needle 22 generated by the pressure of the second back pressure chamber 48 toward the distal end side and a second spring (not shown). The resultant force with the urging force is smaller than the force with which the high pressure fuel from the high pressure fuel passage 50 urges the inner needle 22 to the back side. As a result, the seat portion 34 is separated from the second seat portion 38, and the inner needle 22 starts to move toward the back side (the valve opening operation start timing of the inner needle 22), whereby the fuel passage 56 and the second injection hole. Since the group 42 is in communication, fuel injection from the second nozzle hole group 42 is started. And the stopper part 59 formed in the front end side of the inner needle 22 is displaced until it contacts the stopper part 60 formed in the front end side of the outer needle 20 (the valve opening operation completion timing of the inner needle 22).

  Here, when the energization of the electromagnetic solenoid 58a is stopped, the second back pressure chamber 48 and the low pressure fuel passage 52 are blocked by the second switching unit 58, so that the pressure in the second back pressure chamber 48 increases. Therefore, the inner needle 22 starts to move toward the distal end (timing for starting the valve closing operation of the inner needle 22), and the seat portion 34 is seated on the second seat portion 38 (timing for completing the valve closing operation of the inner needle 22). ) Since the fuel passage 56 and the second nozzle hole group 42 are blocked, the fuel injection from the second nozzle hole group 42 is terminated.

  The engine is provided with a crank angle sensor 62 for detecting the rotation angle of the crankshaft in the vicinity of the crankshaft (not shown). The common rail 14 is provided with a fuel pressure sensor 64 that detects the fuel pressure (actual fuel pressure) in the common rail 14. The crank angle sensor 62, the fuel pressure sensor 64, the accelerator sensor 66 for detecting the amount of depression of the accelerator pedal, the temperature (water temperature) of the cooling water for cooling the engine, the supercharging pressure of the intake air supplied to the combustion chamber 18, etc. An output signal from various sensors such as a sensor for detecting the noise is input to an electronic control unit (hereinafter, ECU 70).

  The ECU 70 is mainly configured by a microcomputer including a known CPU, ROM, RAM, and the like. The ECU 70 executes various control programs corresponding to the engine operating state each time by executing various control programs stored in the ROM. The ECU 70 controls the fuel pressure in the common rail 14 by operating the fuel pump 12 based on these input signals, and controls the timing of fuel injection from the fuel injection valve 16 to the electromagnetic solenoids 54a and 58a. Operate the power supply. Specifically, when the required torque of the engine is small, only the electromagnetic solenoid 54a is energized, and only the outer needle 20 is opened to inject fuel from only the first nozzle hole group 40, resulting in incomplete combustion. Suppresses the increase in smoke produced. Further, when the required torque of the engine is large, both the electromagnetic solenoids 54a and 58a are energized, and both the outer needle 20 and the inner needle 22 are operated to open the first nozzle hole group 40 and the second nozzle hole group 40. Fuel is injected from both the nozzle hole group 42 to increase the torque generated by the engine.

  By the way, in the fuel injection valve 16, the fuel injection speed decreases due to a decrease in fuel injection pressure just before the completion of fuel injection. That is, when the outer needle 20 is closed, the area of the passage formed by the seat portion 32 and the first seat portion 36 is larger than the opening area of each nozzle hole constituting the first nozzle hole group 40. If it becomes smaller, pressure loss is generated in the fuel supplied from the fuel passage 56, so that the fuel injection pressure gradually decreases, and the injection speed of the fuel injected from the first nozzle hole group 40 gradually decreases. When both the outer needle 20 and the inner needle 22 are closed, the area of the passage formed by the seat portion 32 and the first seat portion 36 or the seat portion 34 and the second seat portion 38 If any one of the areas of the formed passages is smaller than the opening area of each nozzle hole constituting the second nozzle hole group 42, pressure loss occurs in the fuel supplied from the fuel passage 56. As a result, the fuel injection pressure gradually decreases, and the injection speed of the fuel injected from the second nozzle hole group 42 gradually decreases.

  As described above, when the fuel injection speed is reduced, the residual fuel increases, which may increase the emission of smoke due to incomplete combustion and unburned fuel.

  In particular, in the fuel injection valve 16 of the present embodiment, the fuel injection amount in a situation where the injection speed of the fuel injected from the second injection hole group 42 is reduced due to the following factors (a) to (c). As the amount increases, the residual fuel increases, and the amount of increase in emissions tends to become significant.

  (A) Since the opening area per each nozzle hole constituting the second nozzle hole group 42 is set larger than the opening area per nozzle hole constituting the first nozzle hole group 40. The fuel injection time under a situation where the fuel injection speed during the valve closing operation is greatly reduced compared to the time when the valve closing operation is started is longer than the fuel injection time from the first nozzle hole group 40 under the situation where the fuel injection speed is greatly reduced. The factor that becomes.

  (A) After the valve closing operation of the inner needle 22 is completed, the second nozzle hole group 42 and the sac chamber 44 are in communication with each other, and therefore remain in the space formed by the inner wall of the nozzle body 24 and the seat portion 34. A factor that fuel is injected from the second injection hole group 42 at a low fuel injection speed.

  (C) Since the inner needle 22 accommodated in the outer needle 20 is smaller than the outer needle 20, the strength of the inner needle 22 is lower than the strength of the outer needle 20. For this reason, in this embodiment, the operating speed of the inner needle 22 is set smaller than the operating speed of the outer needle 20. As a result, the fuel injection time from the second nozzle hole group 42 in a situation where the fuel injection speed has decreased is a factor.

  Further, in the fuel injection valve 16 of the present embodiment, the passage area from the second nozzle hole group 42 to the fuel passage 56 is reduced between the seat portion 34 and the second seat portion 38 in accordance with the valve closing operation of the outer needle 20. It is narrowed not only by the formed passage but also by a passage formed by the seat portion 32 and the first seat portion 36. For this reason, the fuel injection speed from the second nozzle hole group 42 tends to decrease, and the residual fuel tends to be particularly noticeable.

  Therefore, in the present embodiment, in order to avoid such a situation, the valve closing operation completion timing of the inner needle 22 is adjusted (advanced) to the valve closing operation start timing of the outer needle 20, and the first nozzle hole group 40 The residual fuel injected from the second nozzle hole group 42 is diffused by using the jet of injected fuel.

  FIG. 2 shows a procedure for adjusting the fuel injection timing according to the present embodiment. This process is repeatedly executed by the ECU 70, for example, at a predetermined cycle.

  In this series of processing, first, in step S10, an injection amount command for the fuel injection valve 16 is based on the engine speed based on the detection value of the crank angle sensor 62 and the accelerator operation amount based on the detection value of the accelerator sensor 66. A value (total injection amount) is calculated.

  In subsequent step S12, the target fuel pressure in the common rail 14 is calculated based on the total injection amount and the engine speed. Then, the fuel pump 12 is operated so that the actual fuel pressure in the common rail 14 matches the target fuel pressure.

  In step S14, the fuel injection timing from the first nozzle hole group 40 is calculated. Specifically, the fuel injection amount from the first nozzle hole group 40 is calculated based on the engine rotation speed and the total injection amount, and this fuel injection amount, the actual fuel pressure in the common rail 14, the engine rotation speed, and the accelerator operation amount are calculated. Further, based on the water temperature, the supercharging pressure, etc., the timing for starting fuel injection from the first nozzle hole group 40 (starting the valve opening operation of the outer needle 20) and the timing for completing the fuel injection (closing the valve closing operation of the outer needle 20) And calculate.

  In step S <b> 16, the fuel injection amount from the second injection hole group 42 is calculated as a difference value between the total injection amount and the fuel injection amount from the first injection hole group 40.

  In step S18, it is determined whether or not there is fuel injection from the second nozzle hole group. Specifically, when the fuel injection amount from the second nozzle hole group 42 calculated in step S16 is larger than a predetermined value (for example, 0), it is determined that there is fuel injection. If it is determined in step S18 that there is fuel injection, the process proceeds to step S20, and the fuel injection timing from the second injection hole group 42 is calculated. Specifically, based on the fuel injection amount from the second nozzle hole group 42, the actual fuel pressure in the common rail 14, the engine rotation speed, the accelerator operation amount, the water temperature, the supercharging pressure, etc. The fuel injection start (inner needle 22 valve opening operation start) timing and fuel injection completion (inner needle 22 valve closing operation completion) timing are calculated.

  After completion of the processing in step S20, in step S22, it is determined whether or not the engine rotation speed and the total injection amount are within a predetermined region. This process is a situation in which it is possible to reliably achieve an emission reduction effect by adjusting the fuel injection timing from each of the first nozzle hole group 40 and the second nozzle hole group 42 in the above-described manner. It is provided to determine whether or not. Here, the predetermined region is a region other than a region where the engine speed is equal to or higher than a predetermined value and the required torque is equal to or higher than a predetermined value. In other words, when the engine speed increases and the time required for rotation at a predetermined crank angle interval is shortened, the crank angle interval required for fuel injection becomes longer if the total injection amount increases due to an increase in the required torque of the engine. For this reason, there is a possibility that smoke and unburned fuel generated by incomplete combustion increase due to the fuel being injected under a situation where the temperature of the combustion chamber 18 after the compression stroke of the engine is lowered. Nevertheless, if the fuel injection timing is adjusted according to the above-described mode in a region other than the predetermined region, the valve opening time of the second injection hole group 42 is limited and the temperature of the combustion chamber 18 is lowered. There is a concern that the fuel injected from the first nozzle hole group 40 may increase. Then, the amount of increase in the emission exceeds the amount of reduction in the emission due to the adjustment of the fuel injection timing, so that the emission may increase.

  Therefore, in the present embodiment, the timing for completing the fuel injection from the second nozzle hole group 42 is advanced in a region (the predetermined region) excluding the situation where the engine speed is high and the total injection amount is also large. On the other hand, in areas other than the predetermined area, the fuel injection timing is not adjusted, so that fuel injection is completed as early as possible using both the first nozzle hole group 40 and the second nozzle hole group 42. Let's make it.

  If it is determined in step S22 that it is in the predetermined region, the process proceeds to step S24, and the timing of completion of fuel injection from the second injection hole group 42 (completion of valve closing operation of the inner needle 22) is set as the outer threshold value. It is determined whether or not the timing (retard side) is later than the valve closing operation start timing of the needle 20. In this process, whether the fuel injection from the second nozzle hole group 42 is completed before the area of the passage formed by the seat portion 32 and the first seat portion 36 is narrowed by the valve closing operation of the outer needle 20. It is provided to determine whether or not. That is, the fuel is injected from the second nozzle hole group 42 according to the fuel injection timing from the first nozzle hole group 40 calculated in step S14 and the fuel injection timing from the second nozzle hole group 42 calculated in step S20. This is to determine whether the residual fuel amount becomes significant.

  If it is determined in step S24 that the angle is retarded, the process proceeds to step S26, and the timing of completion of fuel injection from the second nozzle hole group 42 (completion of valve closing operation of the inner needle 22) is advanced to a predetermined timing. Horn. Here, in this embodiment, the predetermined timing is set to the valve closing operation start timing of the outer needle 20.

  In the present embodiment, the timing for completing the fuel injection from the second nozzle hole group 42 is advanced, and the timing for starting the fuel injection from the second nozzle hole group 42 (starting the valve opening operation of the inner needle 22) is set to the first timing. The advance is made by the advance amount of the fuel injection completion timing from the two nozzle hole group 42. In this process, since the total injection amount from the fuel injection valve 16 is in accordance with the operating state of the engine, the second injection can be achieved only by advancing the fuel injection completion timing from the second injection hole group 42. This is done in view of the possibility that the fuel injection amount from the hole group 42 decreases and the generated torque of the engine decreases.

  When a negative determination is made in steps S18, S22, and S24, or when the process of step S26 is completed, this series of processes is temporarily terminated.

  FIG. 3 shows an example of adjustment of the fuel injection timing by the above processing.

  FIG. 3A shows a case where the engine speed and the total injection amount are within the predetermined region. As shown in the figure, the time t1, which is the fuel injection start timing from the first nozzle hole group 40, is calculated by the process of step S14 shown in FIG. 2 as shown by the solid line in FIG. 2, the time t2 and the time t4 which are the fuel injection start timing and the completion timing from the second nozzle hole group 42 are obtained as shown by the one-dot chain line in FIG. Calculated. Then, since the time t4 that is the timing for completing the fuel injection from the second nozzle hole group 42 is on the retarded side with respect to the time t3 that is the timing for starting the valve closing operation of the outer needle 20, step S24 shown in FIG. Is affirmed. As a result, as shown by the thick line in FIG. 3A, the fuel injection completion timing from the second nozzle hole group 42 is advanced to time t3, and the fuel injection start timing from the second nozzle hole group 42 is increased. It is advanced by the advance amount of the fuel injection completion timing (until time t2 ′).

  Based on the fuel injection timing set in this way, the fuel injected from the first nozzle hole group 40 can be used to diffuse the fuel injected from the second nozzle hole group 42. Here, in the present embodiment, since the jet of fuel before the fuel injection speed from the first nozzle hole group 40 is reduced is used, the diffusion of fuel can be promoted, and the emission is more preferably reduced. can do.

  On the other hand, FIG. 3B shows a case where the engine speed and the total injection amount are not within the predetermined region. In this case, as shown by the thick line, the fuel injection timing from the second nozzle hole group 42 is not adjusted, and the fuel injection is performed as early as possible using both the first nozzle hole group 40 and the second nozzle hole group 42. To finish.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The fuel injection completion timing from the second nozzle hole group 42 is advanced to the valve closing operation start timing of the outer needle 20. Thereby, the fuel injected from the 2nd nozzle hole group 42 can be diffused, and by extension, emission can be reduced more suitably. Furthermore, since the emission can be reduced without using the post-processing device, it is possible to avoid an increase in the capacity of the post-processing device and an increase in cost due to the addition.

  (2) When the fuel injection completion timing from the second nozzle hole group 42 is advanced, the fuel injection start timing from the second nozzle hole group 42 is advanced. Thereby, the fuel injection time from the 2nd nozzle hole group 42 is ensured, and the fall of the generated torque of an engine can be avoided as much as possible.

  (3) In the fuel injection valve 16, the opening area of each nozzle hole constituting the second nozzle hole group 42 is larger than the opening area of each nozzle hole constituting the first nozzle hole group 40. The configuration is also large. As described above, since the residual fuel injected from the second nozzle hole group 42 is likely to increase due to the size of the opening area of the nozzle hole, the timing for completing the fuel injection from the second nozzle hole group 42 is advanced. The utility value of the cornering process is particularly great.

  (4) The fuel injection valve 16 is configured such that the operating speed of the inner needle 22 is lower than the operating speed of the outer needle 20. As described above, since the residual fuel injected from the second nozzle hole group 42 is likely to increase due to the operation speed, the utility value of the processing for advancing the timing of fuel injection completion from the second nozzle hole group 42 is increased. Is particularly large.

  (5) The fuel injection valve 16 is configured such that the sac chamber 44 formed on the inner wall of the nozzle body 24 and the second injection hole group 42 communicate with each other even when the inner needle 22 is closed. As described above, since the residual fuel injected from the second injection hole group 42 is likely to increase due to the increase in the space formed by the inner wall of the nozzle body 24 and the seat portion 34, the second injection hole group 42 is provided. The utility value of the process for advancing the fuel injection completion timing from is particularly great.

  (6) In the fuel injection valve 16, the second injection hole group 42 and the fuel passage 56 are blocked by the completion of the valve closing operation of the outer needle 20 regardless of the open / closed state of the inner needle 22. In such a configuration, since the increase in emission can be significant, the utility value of the control for advancing the timing of completion of fuel injection from the second nozzle hole group 42 is particularly great.

  (7) When it is determined that the engine rotation speed and the total injection amount are within the predetermined range, the timing for completing the fuel injection from the second nozzle hole group 42 is advanced. Thereby, the emission reduction effect can be reliably achieved.

  (8) The engine rotation speed and the total injection amount are within a predetermined region, and the fuel injection completion timing from the second nozzle hole group 42 is on the retard side with respect to the valve closing operation start timing of the outer needle 20. When it is determined, the fuel injection completion timing from the second nozzle hole group 42 is advanced. As a result, it is possible to suppress an increase in required elements when adapting the fuel injection timing.

(Other embodiments)
The above embodiment may be modified as follows.

  In the above embodiment, the engine rotation speed and the total injection amount are used as parameters indicating the operating state of the engine for determining the predetermined region, but the present invention is not limited to this. For example, the engine speed and the accelerator operation amount may be used.

  In the above embodiment, when it is determined that the parameters (engine rotation speed, total injection amount) indicating the operating state of the engine are within the predetermined region, the timing of completion of fuel injection from the second nozzle hole group 42 is advanced. However, it is not limited to this. For example, the fuel injection completion timing from the second nozzle hole group 42 may be advanced regardless of whether or not the predetermined region is present. Even in this case, the effects (1) to (6) and (8) of the above embodiment can be obtained.

  In the above embodiment, the fuel injection timing from the second injection hole group 42 is calculated by the process of step S20 shown in FIG. 2, but the present invention is not limited to this. For example, the fuel injection timing may be calculated together with the fuel injection amount in the process of step S16.

  In the above-described embodiment, the opening area per one nozzle hole constituting the second nozzle hole group 42 is larger than the opening area per nozzle hole constituting the first nozzle hole group 40. However, it is not limited to this. For example, the opening area per one nozzle hole constituting the second nozzle hole group 42 is the same as the opening area per nozzle hole constituting the first nozzle hole group 40 or the second nozzle hole group 42 may be configured such that the opening area per one of the nozzle holes constituting 42 is smaller than the opening area per one of the nozzle holes constituting the first nozzle hole group 40. Even in this case, the effects (1), (2) and (4) to (8) of the embodiment can be obtained.

  -In the above-mentioned embodiment, although the 1st nozzle hole group 40 and the 2nd nozzle hole group 42 were constituted by a plurality of nozzle holes, it is not restricted to this. For example, either one or both of the first nozzle hole group 40 and the second nozzle hole group 42 may be configured by one nozzle hole.

  In the above embodiment, the operation speed of the inner needle 22 is lower than the operation speed of the outer needle 20, but the present invention is not limited to this. For example, the operation speed of the inner needle 22 may be the same as the operation speed of the outer needle 20 or the operation speed of the inner needle 22 may be higher than the operation speed of the outer needle 20. Even in this case, the effects (1) to (3) and (5) to (8) of the above embodiment of the above embodiment can be obtained.

  In the above embodiment, the sac chamber 44 is formed on the inner wall of the nozzle body 24. However, the present invention is not limited to this. A configuration in which the suck chamber 44 is not formed on the inner wall of the nozzle body 24 may be employed. Even in this case, the effects (1) to (4) and (6) to (8) of the embodiment can be obtained.

  In the above embodiment, the outer needle 20 or the inner needle 22 is independently operated by operating the pressures of the first back pressure chamber 46 or the second back pressure chamber 48. However, the present invention is not limited thereto. Absent. For example, only one back pressure chamber is formed in the nozzle holder, the outer needle 20 is operated by manipulating the pressure in the back pressure chamber, the inner needle 22 is operated based on the operation of the outer needle 20, and the outer The structure provided with the mechanism which can adjust the valve closing operation completion timing of the inner needle 22 with respect to the valve closing operation start timing of the needle 20 may be sufficient.

  In the above-described embodiment, the configuration is such that the pressure in the back pressure chamber is operated by operating the first switching unit 54 and the second switching unit 58 with an electromagnetic solenoid. For example, the structure which operates the 1st switching part 54 and the 2nd switching part 58 with a piezoelectric element may be sufficient.

  In the above embodiment, the predetermined timing is set as the valve closing operation start timing of the outer needle 20 in the process of step S26 shown in FIG. 2, but the present invention is not limited to this. For example, the timing may be any timing on the advance side of the valve closing operation start timing of the outer needle 20. Even in this case, since the jet of fuel before the fuel injection speed from the first nozzle hole group 40 can be used, the emission can be suitably reduced. In this case, the threshold value is on the advance side with respect to the closing operation completion timing of the inner needle 22 before advanced by the processing of step S26 shown in FIG. It may be an arbitrary timing on the retard side from the completion timing. Further, for example, the predetermined timing is retarded from the valve closing operation start timing of the outer needle 20 and the timing of completion of fuel injection from the first nozzle hole group 40 (completion of valve closing operation of the outer needle 20) is reached. Any timing on the advance side may be used. Even in this case, if the fuel injected from the second nozzle hole group 42 can be diffused by using the jet of fuel injected from the first nozzle hole group 40, the emission can be reduced. Can do.

  In the above embodiment, when the determination in step S22 and step S24 shown in FIG. 2 is affirmative, the fuel injection completion timing from the second injection hole group 42 is advanced, but the present invention is not limited to this. For example, the fuel injection timing calculated in the processing of steps S16 and S20 of FIG. 2 is used as the engine operating state so that the closing operation completion timing of the inner needle 22 is before the closing operation start timing of the outer needle 20. You may pre-fit every time.

  In the above embodiment, both the engine rotation speed and the total injection amount are used as parameters indicating the operating state of the engine for determining the predetermined region, but the present invention is not limited to this. It may be at least one of the engine speed and the total injection amount.

  In the above embodiment, the second nozzle hole group 42 and the fuel passage 56 are blocked by the closing of the outer needle 20 regardless of whether the inner needle 22 is open or closed. For example, a configuration in which the second nozzle hole group 42 and the fuel passage 56 or the first nozzle hole group 40 and the fuel passage 56 are respectively communicated or blocked by the open / close state of the inner needle 22 or the outer needle 20 may be employed. . Even in this case, the effects (1) to (5), (7) and (8) of the above embodiment can be obtained.

  In the above embodiment, the compression ignition type internal combustion engine is targeted as the internal combustion engine, but is not limited thereto. For example, an in-cylinder spark ignition internal combustion engine may be used.

The figure which shows the whole structure of the fuel-injection system concerning one Embodiment. The flowchart which shows the procedure of the adjustment process of the fuel injection timing concerning the embodiment. The time chart which shows the adjustment process aspect of the fuel injection timing concerning the embodiment. Sectional drawing which shows the cross-sectional structure of the variable injection hole nozzle of a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 16 ... Fuel injection valve, 20 ... Outer needle, 22 ... Inner needle, 24 ... Nozzle body, 40 ... 1st nozzle hole group, 42 ... 2nd nozzle hole group, 44 ... Suck chamber, 56 ... Fuel passage, 62 ... Crank Angle sensor, 70... ECU (an embodiment of a fuel injection control device for an internal combustion engine)

Claims (8)

A fuel injection valve comprising: a valve body in which a plurality of injection holes are formed; and a plurality of valve members slidably accommodated in the valve body and allocated to open and close each of the plurality of injection holes. In a fuel injection control device for an internal combustion engine that adjusts fuel injection timing from each of the plurality of nozzle holes by opening and closing the plurality of valve members,
Of the pair of valve members constituting the plurality of valve members, the fuel injection amount is injected from the corresponding injection hole at the time of the valve closing operation, and the fuel injection speed is greatly reduced compared to the time when the valve closing operation is started. Fuel injection control for an internal combustion engine, characterized by comprising adjustment means for adjusting the valve closing operation completion timing, which is assumed to have a large amount of fuel injection during the period, to be earlier than the other valve closing operation completion timing apparatus.   2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the adjustment means performs the adjustment on condition that a parameter indicating an operation state of the internal combustion engine is within a predetermined region. Setting means for setting an opening / closing timing of the pair of valve members based on a parameter indicating an operating state of the internal combustion engine;
Determination means for determining whether or not the timing set by the setting means satisfies a timing condition to be adjusted by the adjustment means;
3. The fuel injection control device for an internal combustion engine according to claim 1, wherein the adjustment unit performs the adjustment when the determination unit determines that the condition is not satisfied.   4. The adjustment unit according to claim 1, wherein the adjustment unit performs the adjustment so that the valve closing operation completion timing, which is assumed to be greater, does not become later than the other valve closing operation start timing. The fuel injection control device for an internal combustion engine according to claim 1.   The valve member that is assumed to be large is the larger one of the pair of valve members that has a larger opening area per nozzle hole to be opened and closed. A fuel injection control device for an internal combustion engine according to any one of the preceding claims.   The fuel of the internal combustion engine according to any one of claims 1 to 5, wherein the valve member that is assumed to be more is a valve member having a lower operating speed of the pair of valve members. Injection control device. A sack chamber is formed in the valve body,
The valve member that is assumed to be large is that the nozzle hole communicating with the sac chamber is to be opened / closed even though the pair of valve members are in a closed state. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 6.   Regardless of the opening / closing state of the one that is assumed to be large, the nozzle hole that is to be opened / closed and the fuel supply port of the fuel injection valve, which are assumed to be more, are closed by the closing of the other valve member. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 7, wherein the fuel injection control device is cut off.

Images