JP2013224598A - Fuel injection device - Google Patents

Abstract

A fuel injection device capable of generating a good spray immediately after the start of needle lift is provided.
The present invention relates to a nozzle body including a nozzle hole and a seat portion located upstream from the nozzle hole, and fuel introduced to the nozzle hole located upstream from the seat portion. A turning circuit 36 for turning the needle 24, a needle 24 that is slidably disposed in the nozzle body 26, and an exit area of the turning circuit 36 over a predetermined period from the lift start time of the needle 24. A piezoelectric element 42 having an exit area smaller than an exit area corresponding to a lift amount at a predetermined period of time, and a predetermined period elapsed word having an exit area corresponding to the lift amount; Is a fuel injection device.
[Selection] Figure 3

Description

  The present invention relates to a fuel injection device.

In recent years, research on supercharged lean, large-volume EGR, and premixed self-ignition combustion has been actively conducted on internal combustion engines in order to reduce carbon dioxide (CO ₂ ) and emissions. According to these studies, in order to maximize the effects of CO ₂ reduction and emission reduction, it is necessary to obtain a stable combustion state near the combustion limit. In addition, as petroleum fuels are depleted, robustness is required so that various fuels such as biofuels can be stably burned. In order to obtain such stable combustion, it is required to reduce the variation in ignition of the air-fuel mixture and to quickly burn the fuel in the expansion stroke. In order to take measures against oil dilution and spray deterioration as well as to reduce ignition variability and achieve stable combustion, it is important to refine the bubbles contained in the fuel so that the fuel in the combustion chamber vaporizes quickly. Become.

  In-cylinder injection that directly injects fuel into the combustion chamber to improve transient response, increase volumetric efficiency due to latent heat of vaporization, and greatly retarded combustion for catalyst activation at low temperatures in fuel supply to internal combustion engines The method is adopted. However, by adopting the in-cylinder injection method, the sprayed fuel collided with the combustion chamber wall as droplets and oil dilution occurred. In order to suppress the collision of the fuel with the combustion chamber wall, it is preferable to make the bubbles fine and to make the spray low penetration. For example, Patent Document 1 discloses a technique for improving spraying by flowing fuel through a turning circuit.

JP 2000-154768 A

  However, in the prior art, the fuel flow rate is low and the swirl is not sufficient immediately after the start of lift of the needle, so it is difficult to improve the spray using the swirl flow. In view of the above problems, an object of the present invention is to provide a fuel injection device capable of generating good spray immediately after the start of needle lift.

  The present invention includes a nozzle body including a nozzle hole and a seat portion positioned upstream from the nozzle hole, and a swirl flow generating unit positioned upstream from the sheet portion and configured to swirl fuel introduced into the nozzle hole. And a needle that is slidably disposed in the nozzle body and is seated on the seat portion, and an exit area of the swirl flow generating portion over a predetermined period from a lift start time of the needle. The exit area of the swirling flow generating unit corresponding to the lift amount of the needle at the time when the period has elapsed is maintained to be smaller than the exit area of the swirling flow generating unit. A fuel injection device comprising: an adjustment unit configured to have an exit area of the swirl flow generation unit corresponding to a lift amount of

  The said structure WHEREIN: When the air fuel ratio in the internal combustion engine which the said fuel injection valve injects a fuel is leaning, the said adjustment part can be set as the structure which maintains the said exit area in the said small exit area.

  The said structure WHEREIN: The said adjustment part can be set as the structure which is a piezoelectric element which can be expanded in a downstream direction.

  The said structure WHEREIN: When the said adjustment part maintains the said exit area at the said small exit area, it can be set as the structure which comprises the pressure adjustment part which raises the pressure of the fuel which flows in into the said rotational flow production | generation part.

  In the above configuration, when the adjusting unit does not maintain the outlet area at the small outlet area, the pressure adjusting unit sets the pressure to a first pressure lower than a saturated fuel pressure, and the adjusting unit reduces the outlet area. When maintaining the small outlet area, the pressure adjusting unit may increase the pressure from the first pressure to a second pressure higher than the first pressure.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel-injection apparatus which can produce | generate favorable spray immediately after the lift start of a needle | hook can be provided.

FIG. 1 is a schematic view illustrating an engine system including a fuel injection device according to a first embodiment. FIG. 2 is a schematic view illustrating a fuel injection valve. FIG. 3 is an enlarged view of the vicinity of the tip of the fuel injection valve. FIG. 4A is a graph illustrating the relationship between the outlet area and the bubble diameter. FIG. 4B is a graph illustrating the relationship between the bubble diameter and the time until collapse. FIG. 5A is a functional block diagram illustrating the configuration of the ECU. FIG. 5B is a flowchart illustrating the control of the fuel injection device. FIG. 6 is an enlarged view of the vicinity of the tip of the fuel injection valve when the needle is lifted. FIG. 7A is a timing chart of the lift amount, and FIG. 7B is a timing chart of the voltage applied to the piezoelectric element. FIG. 8 is a flowchart illustrating the control of the fuel injection device. FIG. 9 is a schematic view illustrating a fuel delivery and a fuel injection valve. FIG. 10 is a flowchart illustrating the control of the fuel injection device. FIG. 11 is a graph illustrating the relationship between fuel pressure, flow velocity, bubble diameter, and collapse time.

  Embodiments of the present invention will be described with reference to the drawings.

  The fuel injection valve 20 according to the first embodiment is an example in which the area (exit area) of the outlet 36 a of the turning circuit 36 is adjusted by the piezoelectric element 42. FIG. 1 is a schematic view illustrating an engine system including a fuel injection device according to a first embodiment.

  As shown in FIG. 1, an engine system 100 includes an ECU (Engine Control Unit) 10, an engine body 12 (internal combustion engine), an intake pipe 14, an exhaust pipe 16, a fuel delivery 18, a fuel injection valve 20, and an air-fuel ratio sensor (A). / F sensor) 22. The fuel injection device includes an ECU 10, a fuel delivery 18 and a fuel injection valve 20. The intake pipe 14 supplies air to the combustion chamber 13 of the engine body 12. The exhaust gas generated in the combustion chamber 13 is exhausted through the exhaust pipe 16. The fuel delivery 18 supplies fuel to the fuel injection valve 20. The fuel injection valve 20 injects fuel into the engine body 12. The A / F sensor 22 is provided, for example, in the exhaust pipe 16 and measures the air-fuel ratio R in the engine body 12.

  FIG. 2 is a schematic view illustrating the fuel injection valve 20 according to the first embodiment. FIG. 3 is an enlarged view of the vicinity of the tip of the fuel injection valve 20. The configuration shown in FIGS. 1 to 3 is common to Examples 2 and 3 described later.

  As shown in FIGS. 2 and 3, the needle 24 of the fuel injection valve 20 is slidably disposed in the nozzle body 26 and moves up and down along the axis A. A needle guide 28 is accommodated in the nozzle body 26, and the needle 24 is guided by the inner peripheral surface of the needle guide 28. A drive unit 23 is provided on the proximal end side of the needle 24. The drive unit 23 is an actuator or an elastic member using, for example, a piezoelectric element or an electromagnet, and operates the needle 24.

  A piezoelectric element 42 (adjustment unit) is provided on the outer periphery of the needle 24. The piezoelectric element 42 has, for example, a cylindrical shape, is positioned between the needle 24 and the needle guide 28, and surrounds the needle 24. The upper end of the piezoelectric element 42 is fixed to the needle guide 28. A position indicated by a broken line B in FIG. 3 is a fixed position. The lower end of the piezoelectric element 42 is not fixed. Accordingly, the piezoelectric element 42 can extend in the downstream direction, that is, in the direction in which the exit area of the turning circuit 36 (details will be described later) becomes smaller. At least one (not shown) of the electrodes of the piezoelectric element 42 is electrically connected to the wiring 44, and the other electrode is grounded to the needle guide 28. The wiring 44 is connected to the ECU 10.

  The nozzle body 26 is provided with a pressure chamber 32, a turning circuit 36, a seat part 34, a sack part 38, and an injection hole 40 in order from the upstream side. Fuel is supplied to the pressure chamber 32 through a fuel passage 30 provided in the needle guide 28. The fuel is supplied from the pressure chamber 32 to the turning circuit 36 (swirl flow generating unit). The turning circuit 36 is, for example, a spiral groove having the axis A as the center axis, and imparts a turning component to the fuel. That is, as the fuel flows through the turning circuit 36, a swirling flow of the fuel is generated. Since the inner diameter of the nozzle body 26 decreases toward the tip side, the swirl flow is accelerated toward the tip side. The surface 25 of the needle 24 is seated on the seat portion 34. The needle 24 blocks between the turning circuit 36 and the sack portion 38. Therefore, the fuel is not supplied to the sack portion 38. When the surface 25 is separated from the seat portion 34, the turning circuit 36 and the sack portion 38 are connected, and fuel is supplied to the sack portion 38. The fuel swirls at the sack portion 38. A negative pressure is generated at the center of the swirling flow, and air is sucked into the nozzle body 26. The sucked air becomes bubbles and enters the fuel. Thus, the fuel becomes bubble fuel containing bubbles, supplied from the sack portion 38 to the nozzle hole 40, and injected from the nozzle hole 40.

  As described above, it is preferable to inject bubble fuel containing fine bubbles. Further, when deposits are accumulated in the nozzle hole 40, the spray is deteriorated and the fuel injection amount is reduced. Next, the relationship between the area of the outlet 36a of the turning circuit 36, the bubble diameter (bubble diameter) contained in the fuel, and the deposit will be described.

  FIG. 4A is a graph illustrating the relationship between the outlet area and the bubble diameter. The horizontal axis represents the outlet area (cross-sectional area of the outlet 36a), and the vertical axis represents the bubble diameter. The smaller the outlet area, the smaller the bubble diameter. If the exit area is reduced, the speed of the fuel flowing out from the turning circuit 36 is increased, and a more accelerated swirling flow is generated in the sack portion 38 and the nozzle hole 40. As a result, the bubbles contained in the fuel become finer. On the other hand, when the exit area is increased, the miniaturization of bubbles is suppressed.

実験値及び近似値に示すように、気泡径が小さくなるほど、圧壊時間は短くなる。図４（ａ）及び図４（ｂ）より、出口３６ａが狭いほど、気泡が微細化し、圧壊時間が短くなることが分かる。この結果、気泡が噴孔４０の近傍で圧壊する。これに対し、出口３６ａが広いほど、気泡が大きくなり、圧壊時間が長くなる。気泡が噴孔４０から離れた位置で圧壊する。気泡が圧壊する際の衝撃力により、噴孔４０に堆積したデポジットを除去することができる。デポジットを除去するためには、気泡が噴孔４０の近くにおいて圧壊することが好ましい。 FIG. 4B is a graph illustrating the relationship between the bubble diameter and the time until collapse. The horizontal axis represents the bubble diameter, and the vertical axis represents the time to collapse (collapse time). The solid line is data measured by experiment, and the broken line is a graph obtained by approximating the experimental value by the following equation. In the formula, d is the bubble diameter, and T is the collapse time.

As shown in the experimental values and approximate values, the smaller the bubble diameter, the shorter the crushing time. 4 (a) and 4 (b), it can be seen that the narrower the outlet 36a, the finer the bubbles and the shorter the collapse time. As a result, the bubbles are crushed near the nozzle hole 40. In contrast, the wider the outlet 36a, the larger the bubbles and the longer the crushing time. The bubbles are crushed at a position away from the nozzle hole 40. Deposits accumulated in the nozzle hole 40 can be removed by the impact force when the bubbles are crushed. In order to remove the deposit, it is preferable that the bubbles collapse in the vicinity of the nozzle hole 40.

  FIG. 5A is a functional block diagram illustrating the configuration of the ECU 10. The ECU 10 functions as the voltage control unit 50 and the air-fuel ratio acquisition unit 52.

  FIG. 5B is a flowchart illustrating the control of the fuel injection device. Assume that the drive unit 23 is an actuator using an electromagnet, for example.

  As shown in FIG. 5B, the voltage control unit 50 energizes the drive unit 23. Thereby, the needle 24 starts to lift (step S10). After step S10, the voltage control unit 50 applies a voltage to the piezoelectric element 42 (step S11). As a result, the piezoelectric element 42 extends in the downstream direction. After step S11, the voltage control unit 50 determines whether a predetermined period t0 has elapsed from the lift start time (step S12). If no, step S12 is repeated. In the case of Yes, the voltage control part 50 stops the application of the voltage to the piezoelectric element 42 (step S13). After step S13, the voltage control unit 50 stops energization of the drive unit 23, whereby the needle 24 starts to descend (step S14). After step S14, the control ends. Next, the operation of the fuel injection valve 20 will be described with reference to the drawings.

  FIG. 6 is an enlarged view of the vicinity of the tip of the fuel injection valve 20 when the needle 24 is lifted. FIG. 7A is a timing chart of the lift amount, and FIG. 7B is a timing chart of the voltage applied to the piezoelectric element 42. The horizontal axis is time. Time advances in the order of t1 to t6. 7A represents the lift amount of the needle 24, and the vertical axis in FIG. 7B represents the voltage.

  As indicated by an upward arrow in FIG. 6, the surface 25 of the needle 24 is separated from the seat portion 34 (lift start, time t1 in FIG. 7A). Between time t1 and t2, the exit area is an exit area corresponding to the lift amount. The exit area corresponding to the lift amount is an exit area determined by the distance between the surface 25 and the seat portion 34 and increases as the lift amount increases. The exit area from time t1 to t2 is smaller than the exit area corresponding to the lift amount of the needle 24 when a predetermined period (period from time t1 to t4) has elapsed since the lift start time.

  As shown in FIG. 7B, at time t2, a voltage is applied to the piezoelectric element 42 (step S11 in FIG. 5). Accordingly, as indicated by the downward arrow in FIG. 6, the piezoelectric element 42 extends in the downstream direction, and the exit area of the turning circuit 36 is reduced. As shown in FIG. 7A, the lift amount of the needle 24 becomes maximum at time t3. The exit area is maintained by the piezoelectric element 42 to be smaller than the exit area corresponding to the lift amount at the time when the periods t1 to t4 have elapsed.

  As shown in FIG. 7B, the application of voltage is stopped at time t4 (step S13). The piezoelectric element 42 returns to the length before voltage application. At this time, the exit area is the exit area corresponding to the lift amount at the time when t1 to t4 have elapsed. That is, the piezoelectric element 42 maintains the outlet area smaller than the outlet area corresponding to the lift amount at the time t1 to t4 has elapsed from the lift start time to the period t1 to t4. Hereinafter, the exit area that is kept small in this way may be simply referred to as a small exit area. In addition, the piezoelectric element 42 sets the exit area to the exit area corresponding to the lift amount after the period t1 to t4 has elapsed.

  As shown in FIG. 7A, the needle 24 starts to descend at time t5 (step S14). The exit area will also be reduced. At time t6, the needle 24 is seated. The period from time t1 to t4 corresponds to the period t0 in step S12. During the period t0, since the outlet 36a of the turning circuit 36 becomes narrow, the bubbles contained in the bubble fuel are refined even after the needle 24 starts to lift, and good spraying is obtained. Therefore, it is possible to reduce the penetration of the spray.

The piezoelectric element 42 to which the voltage is applied has an exit area of, for example, about 0.2 mm ² . The bubble diameter at this time is about 1 μm. When the bubble diameter is about 1 μm, the crushing time is shortened to about 10 μs, for example. In this case, the crushing occurs near the nozzle hole 40. Deposits accumulated in the nozzle hole 40 can be removed by the impact force generated by the collapse of the bubbles. Therefore, it is possible to suppress a decrease in fuel injection amount and deterioration of spray. However, in order to suppress the erosion of the fuel injection valve 20 due to the impact force of the collapse, the bubbles may be collapsed at a position far from the nozzle hole 40. Therefore, when no voltage is applied to the piezoelectric element 42, the exit area is preferably about 0.6 mm ^2, for example. The bubble diameter at this time is about 4.4 μm. When the bubble diameter is about 4.4 μm, the collapse time is, for example, about 4.6 ms. In this case, the crushing occurs at a position away from the nozzle hole 40. Thereby, erosion is suppressed.

  As described above, since the fuel is not accelerated immediately after the start of the lift, it is difficult to make the bubbles fine. As shown in FIGS. 7A and 7B, the piezoelectric element 42 reduces the exit area at time t2 immediately after the start of the lift, so that the bubbles can be miniaturized. Since the fuel is accelerated at time t4, the bubbles can be made fine without reducing the exit area. When the application of the voltage to the piezoelectric element 42 is stopped at time t4, the exit area is increased. For this reason, bubbles can be refined and the amount of fuel supplied can be increased.

  The piezoelectric element 42 may have a small exit area in synchronization with the start of lift of the needle 24. That is, the piezoelectric element 42 may be energized immediately after the start of the lift or before the lift is started, for example, so that the piezoelectric element 42 can reduce the exit area. In order to refine the bubbles immediately after the start of lift, it is preferable that the exit area of the piezoelectric element 42 is reduced before the needle 24 reaches the highest point. The application of voltage to the piezoelectric element 42 may be stopped after the needle 24 starts to descend. That is, the time t4 in FIGS. 7A and 7B may be after the time t5. The piezoelectric element 42 should just maintain the exit area in period t1-t4 smaller than the exit area corresponding to the lift amount at the time of period t1-t4 progress.

  The second embodiment is an example in which the deposit is removed when the air-fuel ratio R is lean. When deposit accumulates in the nozzle hole 40, the fuel injection amount decreases. As a result, leaning occurs. That is, when leaning has occurred, it is presumed that deposits have accumulated. Next, control of the fuel injection valve 20 will be described.

  FIG. 8 is a flowchart illustrating the control of the fuel injection device. The air-fuel ratio acquisition unit 52 acquires the air-fuel ratio R (step S15). The air-fuel ratio acquisition unit 52 determines whether the air-fuel ratio R is greater than a predetermined value R0 (step S16). In the case of Yes, the voltage control part 50 refines | miniaturizes a bubble (step S17). In step S17, for example, the control shown in FIG. 5B is performed. After step S17 and if No in step S16, the control ends.

  When the air-fuel ratio R is lean, the piezoelectric element 42 maintains the exit area at a small exit area. For this reason, bubble fuel injection is performed, and deposits can be effectively removed. Further, when the air-fuel ratio R is not lean, it is assumed that no deposit is accumulated or a small amount of deposit is accumulated, so that bubble fuel is not injected. Since unnecessary injection of bubble fuel is not performed, erosion of the fuel injection valve 20 due to bubble collapse can be suppressed. R0 can be set to an arbitrary value. For example, if it is desired to increase the number of bubble fuel injections, R0 may be decreased, and if it is desired to decrease the number, R0 may be increased. The voltage application in step S17 may be performed only during the time t2 to t4 shown in FIGS. 7A and 7B, for example, or may be performed for a time other than these times.

  Example 3 is an example in which the pressure (fuel pressure) of the fuel is increased. FIG. 9 is a schematic view illustrating the fuel delivery 18 and the fuel injection valve 20.

  As shown in FIG. 9, the fuel delivery 18 includes a delivery pipe 18a and a piston 18b (pressure adjusting unit). The pump 46 is controlled by the ECU 10 and supplies fuel from a fuel tank (not shown) to the delivery pipe 18 a through the check valve 47. As indicated by the hatched grid lines, the fuel is stored in the delivery pipe 18a and supplied to the four fuel injection valves 20 from the delivery pipe 18a. A piston 18b is provided in the delivery pipe 18a. The actuator 48 is an actuator using an electromagnet or the like, for example. When the ECU 10 applies a voltage to the actuator 48, the piston 18b slides in the direction of the arrow in the figure. As the piston 18b moves to the right in the drawing, the fuel pressure in the delivery pipe 18a increases, and the pressure of the fuel flowing into the turning circuit 36 also increases. As the piston 18b moves to the left, the fuel pressure decreases.

  FIG. 10 is a flowchart illustrating the control of the fuel injection device. Steps S10 to S14 are the same as those already described. After step S <b> 11, the voltage control unit 50 applies a voltage to the actuator 48 of the fuel delivery 18. Thereby, the piston 18b is driven rightward in FIG. 10 (step S18). For example, in step S13, the piezoelectric element 42 returns to its original length, and the piston 18b returns to its original position.

  When the piezoelectric element 42 maintains the outlet area at a small outlet area, the piston 18b increases the fuel pressure. As described above, the small exit area is, for example, the exit area realized in the periods t1 to t4 in FIG. As the fuel pressure increases, the swirl flow generated in the turning circuit 36 is further accelerated. Thereby, bubbles are further refined. For this reason, a deposit can be removed effectively. Note that the fuel pressure may increase not only simultaneously with the reduction of the exit area by the piezoelectric element 42 but also immediately before and after the reduction. Further, as the fuel pressure increases, the nozzle body 26 near the nozzle hole 40 bends in the downstream direction. The nozzle body 26 is restored from the deflection as the fuel pressure is lowered. Due to the deformation of the nozzle body 26, the deposit is easily peeled off. By applying the piezoelectric element 42 and increasing the fuel pressure, the deposit can be effectively removed.

  FIG. 11 is a graph illustrating the relationship between fuel pressure, flow velocity, bubble diameter, and collapse time. The horizontal axis represents the fuel pressure, and the vertical axis represents the flow rate, the bubble diameter, and the collapse time. A one-dot chain line, a solid line, and a broken line represent a flow velocity, a bubble diameter, and a collapse time, respectively.

  As shown in FIG. 11, the higher the fuel pressure, the smaller the bubble diameter and the shorter the collapse time. Since the fuel flows through the nozzle hole 40 as a gas-liquid two-phase flow, the flow velocity of the fuel is regulated by the speed of sound due to the void ratio. Therefore, the fuel pressure has a saturated fuel pressure. The saturated fuel pressure is a fuel pressure at which the fuel flow rate becomes substantially constant even when the fuel pressure becomes equal to or higher than the saturated fuel pressure. For example, in FIG. 11, the saturated fuel pressure is 14 MPa. As shown in FIG. 11, when the fuel pressure becomes equal to or higher than the saturated fuel pressure, the fuel flow rate becomes substantially constant. As a result, the bubble diameter and the collapse time are substantially constant above the saturation fuel pressure. Therefore, even if the fuel pressure is increased from 14 MPa to 16 MPa, for example, in step S18, it is difficult to increase the deposit removal effect.

  In normal times when the piezoelectric element 42 does not maintain a small exit area, the fuel pressure is set to a fuel pressure (first pressure) lower than 14 MPa, such as 3 MPa. When the piezoelectric element 42 maintains the outlet area at a small outlet area, the piston 18b preferably increases the fuel pressure to a fuel pressure (second pressure) higher than 3 MPa, for example, 14 MPa (corresponding to step S18). Thereby, the bubble diameter is reduced and the crushing time is shortened, so that the deposit is effectively removed. In step S18, the piston 18b may increase the fuel pressure to a value between the first pressure and the saturated fuel pressure, for example, 10 MPa, or may increase the fuel pressure to a value higher than the saturated fuel pressure, for example, 16 MPa.

  For example, the fuel pressure can be increased by increasing the pressure of the pump 46. However, energy loss due to driving of the pump 46 increases. By using the piston 18b, energy loss in the pump 46 can be suppressed. In addition, the fuel pressure can be increased with a simple configuration, and the cost can be reduced. In addition to the actuator using an electromagnet, the actuator 48 may drive the piston 18b, such as an actuator using a piezoelectric element, an elastic body, or the like. For example, the number of fuel injection valves 20 may be two or eight.

  In addition to the piezoelectric element 42, the outlet 36a may be narrowed by an actuator using an electromagnet, for example. The turning circuit 36 may be provided in, for example, the needle guide 28 other than the nozzle body 26 and may have any structure as long as the fuel is turned.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

10 ECU
DESCRIPTION OF SYMBOLS 12 Engine main body 18 Fuel delivery 18a Delivery pipe 18b Piston 20 Fuel injection valve 22 A / F sensor 24 Needle 26 Nozzle body 28 Needle guide 30 Fuel passage 32 Pressure chamber 34 Seat part 36 Turning circuit 38 Suck part 40 Injection hole 42 Piezoelectric element 50 Voltage control unit 52 Air-fuel ratio acquisition unit

Claims (5)

A nozzle body comprising a nozzle hole and a seat portion located upstream from the nozzle hole;
A swirl flow generating unit that is located upstream from the seat unit and that swirls fuel introduced into the nozzle hole;
A needle slidably disposed in the nozzle body and seated on the seat portion;
The exit area of the swirl flow generation unit over a predetermined period from the start of lift of the needle is larger than the exit area of the swirl flow generation unit corresponding to the lift amount of the needle at the elapse of the predetermined period. An adjusting unit that maintains a small exit area and sets the exit area of the swirling flow generating unit to the exit area of the swirling flow generating unit corresponding to the lift amount of the needle after the predetermined period has elapsed. The fuel-injection apparatus characterized by the above-mentioned.   2. The fuel injection device according to claim 1, wherein when the air-fuel ratio in the internal combustion engine in which the fuel injection valve injects fuel is lean, the adjustment unit maintains the outlet area at the small outlet area.   3. The fuel injection device according to claim 1, wherein the adjustment unit is a piezoelectric element that can be expanded in a direction to reduce an exit area of the swirl flow generation unit.   4. The pressure adjusting unit according to claim 1, further comprising a pressure adjusting unit configured to increase a pressure of fuel flowing into the swirl flow generating unit when the adjusting unit maintains the outlet area at the small outlet area. The fuel injection device according to item. When the adjusting unit does not maintain the outlet area at the small outlet area, the pressure adjusting unit sets the pressure to a first pressure lower than a saturated fuel pressure,
The pressure adjusting unit increases the pressure from the first pressure to a second pressure higher than the first pressure when the adjusting unit maintains the outlet area at the small outlet area. 4. The fuel injection valve according to 4.

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