JP2013083227A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device with a simple structure, which can be simply controlled.SOLUTION: The fuel injection device includes: an injection needle 3 blocking and opening a fuel outlet 2 communicating to an accumulated fuel source; a shell 4 covering the outside of the fuel outlet 2; a plurality of fuel injection holes 5 opened to the shell 4 along a normal line of the shell 4; a plurality of flow control needles 6 provided so as to be freely inserted and extracted with respect to the respective fuel injection holes 5 from the inside of the shell 4 to increase and decrease fuel passing areas of the fuel injection holes 5; and a piezoelectric element 7 driving the flow control needles 6 to insert and extract the needles with respect to the fuel injection holes 5.

Description

  The present invention relates to a fuel injection device that is simple in structure and easy to control.

  Diesel engines have better thermal efficiency than gasoline engines and are popular in Europe and the like from the viewpoint of preventing global warming. On the other hand, diesel engines have not been widely used in Japan except for commercial vehicles because exhaust gas contains a lot of black smoke and nitrogen oxides.

  On the other hand, in a diesel engine equipped with a common rail fuel injection device, fuel that has been boosted to a pressure sufficiently higher than the combustion chamber pressure is accumulated in the common rail. By injecting the accumulated fuel supplied from the common rail into the combustion chamber with the fuel injection device, the fuel is atomized to promote the mixing of fuel and air, and black smoke and fine particles caused by excessive combustion of the air-fuel mixture are removed. By reducing the fuel injection timing and appropriately adjusting the fuel injection timing, the combustion temperature can be lowered and the nitrogen oxides can be reduced. The fuel injection device controls the fuel injection into the combustion chamber by opening and closing the fuel outlet leading to the common rail by the reciprocating motion of the injection needle.

  As shown in FIG. 10, the conventional fuel injection device 100 has a substantially cylindrical appearance. The fuel injection device 100 includes a proximal end pressure receiving portion 101a formed at the proximal end portion, a middle abdominal pressure receiving portion 101b formed at the middle abdomen and having a smaller area than the proximal end pressure receiving portion 101a, and a conical portion 101c formed at the distal end. An injection needle 101, a housing block 102 that accommodates the injection needle 101 in a reciprocating manner, and a fuel supply path 103 that communicates from the housing block 102 to a common rail (not shown) that is a pressure accumulation fuel source, The fuel stored in the fuel supply passage 103 is filled with the pressure control chamber 104 that presses the proximal pressure receiving portion 101a of the injection needle 101 in the distal direction, and the fuel accumulated in the fuel supply passage 103 is filled. Thus, a fuel reservoir 105 that presses the middle pressure receiving portion 101b of the injection needle 101 in the proximal direction, and a bar that presses the injection needle 101 in the proximal direction. 106, a relief valve 107 for extracting fuel from the pressure control chamber 104, an electromagnetic solenoid 108 for opening and closing the relief valve 107, and a seating portion formed in a bowl shape so that the conical portion 101c of the injection needle 101 is seated. (Not shown), a fuel outlet (not shown) formed in the center of the seat, a dome-shaped outer shell 109 covering the outside of the fuel outlet, and a plurality of fuel injections opened in the dome-shaped outer shell 109 A hole (not shown).

  In the fuel injection device 100, when the electromagnetic solenoid 108 opens the relief valve 107, the pressing force of the pressure control chamber 104 is lost, and the pressing force of the fuel reservoir 105 is overcome by the pressing force of the spring 106. When the conical portion 101c of the injection needle 101 moves away from the seating portion, the fuel outlet is opened and the fuel flows out into the dome-shaped outer shell 109. ) Fuel is injected. When the electromagnetic solenoid 108 closes the relief valve 107, the pressing force of the pressure control chamber 104 and the pressing force of the spring 106 overcome the pressing force of the fuel reservoir 105, and the injection needle 101 moves in the distal direction. The conical portion 101c is seated on the seat portion so that the fuel outlet is closed.

JP 2000-329025 A

  In recent years, regulation values regarding nitrogen oxides and fine particles tend to be stricter. Therefore, a fuel injection device capable of more precise fuel injection control is desired to achieve the regulation value pass.

  For example, in the fuel injection device of Patent Document 1, two injection needles are arranged in parallel, and a fuel passage that leads from a common pressure control chamber to an individual pressure control chamber on the base end side of any of the injection needles is provided. By providing the throttle portion as a resistance mechanism, the operation start time of the injection needle is delayed. As a result, the injection amount is small in the initial stage of one fuel injection, the injection amount is increased in the latter stage, and a gentle initial combustion is ensured, and nitrogen oxides and noise can be reduced.

  However, in the fuel injection device of Patent Document 1, only the initial and late injection amount profiles (temporal changes) are fixedly determined by the shape of the throttle portion, and the total injection amount in one fuel injection is an injection needle. It is determined only by the opening / closing time control. The fuel injection device of Patent Document 1 cannot vary the total injection amount and injection amount profile in one fuel injection by electronic control. That is, since the fuel injection device of Patent Document 1 does not increase or decrease the fuel passage area of the fuel injection hole as in the present invention described later, it cannot be expected to adjust the fuel injection amount more precisely.

  Further, as shown in FIG. 11, the fuel injection device of Patent Document 1 includes two fuel injection holes 113 a and 113 b in which two injection needles 111 and 112 are arranged in parallel, and are opened and closed by the injection needle 111. Two fuel injection holes 114 a and 114 b opened and closed by the injection needle 112 are provided. The fuel injection hole 113a and the fuel injection hole 113b face in directions that do not intersect each other, and the fuel injection hole 114a and the fuel injection hole 114b also face in directions that do not intersect each other. The fuel F injected from each fuel injection hole 113a, 113b, 114a, 114b has a spray shape (spatial distribution) as shown. At this time, since the fuel injection hole 113b and the fuel injection hole 114a face each other in a crossing direction, the fuel F injected from the fuel injection hole 113b and the fuel injection hole 114a may interfere with each other (in an ellipse). . When the fuel F injected from the two fuel injection holes 113b and 114a interferes, a fuel rich region is generated in the combustion chamber, and unburned hydrocarbons, carbon monoxide, and black smoke are likely to be included in the exhaust gas.

  Further, the fuel injection device disclosed in Patent Document 1 has a complicated and difficult to process structure in which a throttle portion is provided in the fuel passage in the casing, so that the processing cost is high and it is difficult to manage the processing accuracy.

  Further, in the fuel injection device of Patent Document 1, since the throttle portion becomes a resistance of the fuel flowing through the fuel passage, the energy required for accumulating pressure is lost in the throttle portion.

  Accordingly, an object of the present invention is to provide a fuel injection device that solves the above-described problems, has a simple structure, and is easy to control.

  In order to achieve the above object, a fuel injection device according to the present invention includes an injection needle that shuts off and opens a fuel outlet that communicates with an accumulator fuel source, an outer shell that covers the outside of the fuel outlet, and an outer shell that is connected to the outer shell. A plurality of fuel injection holes opened along a normal line, and a plurality of flow rate controls that increase / decrease the fuel passage area of the fuel injection holes provided so as to be removably inserted into the fuel injection holes from the inside of the outer shell. And a piezoelectric element that drives the flow rate control needle to be inserted into and removed from the fuel injection hole.

  You may provide the transmission member which transmits the expansion-contraction of one said piezoelectric element to the two or more said needles for flow control.

  The flow rate control needle may be configured to be able to fully close the fuel injection hole.

  The present invention exhibits the following excellent effects.

  (1) The structure is simple.

  (2) Control is easy.

It is principal part sectional drawing of the fuel-injection apparatus which shows one Embodiment of this invention. It is the image figure which looked at the outer shell of the fuel injection device of Drawing 1 from the tip side. FIG. 2 is an enlarged view of the vicinity of a flow control needle of the fuel injection device of FIG. 1. It is a figure for demonstrating the principle of the fuel passage area increase / decrease in the fuel injection hole in the fuel-injection apparatus of FIG. It is principal part sectional drawing of the fuel-injection apparatus which shows other embodiment of this invention. It is an enlarged view near the needle for flow control which shows other embodiments of the present invention. It is an enlarged view of the head part vicinity of the needle for flow control showing other embodiments of the present invention. (A), (b) is a figure for demonstrating the interference avoidance control in the fuel-injection apparatus of this invention, and is an image figure of the spray shape seen from the piston side of the combustion chamber. It is a graph which shows the injection quantity profile in one fuel injection. It is sectional drawing of the conventional fuel-injection apparatus. It is an enlarged view of the front-end | tip part of the fuel-injection apparatus of patent document 1. FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The fuel injection device according to the present invention is an improvement of the tip portion of the conventional fuel injection device described with reference to FIG. 10, and only the tip portion is shown in FIG.

  As shown in FIG. 1, a fuel injection device 1 according to the present invention includes an injection needle 3 that shuts and opens a fuel outlet 2 that leads to a pressure accumulation fuel source (not shown), and an outer shell that covers the outside of the fuel outlet 2. 4, a plurality of fuel injection holes 5 formed in the outer shell 4 along the normal line of the outer shell 4, and a fuel injection hole provided to be able to be inserted into and removed from each of the fuel injection holes 5 from the inside of the outer shell 4. 5 includes a plurality of flow control needles 6 that increase or decrease the fuel passage area, and a piezoelectric element (also referred to as a piezo element) 7 that drives the flow control needle 6 to be inserted into and removed from the fuel injection hole 5.

  The outer shell 4 is formed to be convex outward. In the illustrated example, the outer shell 4 is formed into a spherical crown surface, but the outer shell 4 may be formed into a conical surface shape, a paraboloidal surface shape, an n-pyramidal surface shape (n is a natural number of 3 or more), or the like. Good. This is because if a plurality of normal lines are set on the outer convex surface, the normal lines do not intersect outside the surface. However, in the case of an n-pyramid, one normal per plane is assumed. The fact that the outer shell 4 is convex outward is suitable for avoiding interference of fuel injected from the fuel injection hole 5.

  In the fuel injection device 1, a fuel flow path constituting block 9 is superposed on the front end of a housing block 8 that accommodates the injection needle 3 in a reciprocating manner. In the fuel flow path constituting block 9, a bowl-shaped seating portion 11 is formed so that the conical portion 10 of the injection needle 3 is seated, and a fuel outlet 2 is formed at the center of the seating portion 11. A central fuel flow path 12 extending from the tip to the tip is formed. A piezoelectric element holding base 14 for holding the piezoelectric element 7 is provided at a distance from the fuel flow path constituting block 9 to be a peripheral fuel flow path 13 for guiding fuel from the central fuel flow path 12 toward the outer shell 4. Is provided. The piezoelectric element holding base 14 is integrated with the fuel flow path constituting block 9 through a plurality of support portions 15. The piezoelectric element 7 is placed on the piezoelectric element holding base 14, and the transmission member 16 is placed on the piezoelectric element 7. In the present embodiment, there is only one piezoelectric element 7, and the transmission member 16 is in contact with all the flow rate control needles 6, and the expansion and contraction of the piezoelectric element 7 can be transmitted to all the flow rate control needles 6. it can. The transmission member 16 is formed in a spherical crown shape following the outer shell 4 so that expansion and contraction of the piezoelectric element 7 generated according to the voltage is converted into uniform insertion / extraction of each flow control needle 6 into / from the fuel injection hole 5. ing.

  On the inner side of the outer shell 4, a flow rate control needle holding member 17 having a spherical surface following the outer shell 4 covering the fuel flow path constituting block 9, the piezoelectric element holding base 14 and the transmission member 16 is provided. Between the flow rate control needle holding member 17 and the outer shell 4 is an outer shell back side fuel flow path 18, and the flow rate control needle holding member 17 has an outer shell back side fuel flow path 18 and a peripheral fuel flow path 13. Is formed in the fuel flow path 19. As a result, the fuel outlet 2 to the fuel injection hole 5 communicate with each other via the central fuel flow path 12, the peripheral fuel flow path 13, the fuel flow path 19, and the outer shell back side fuel flow path 18.

  The flow rate control needle holding member 17 has a holding hole 20 through which the flow rate control needle 6 is inserted at a position facing the fuel injection hole 5 along the normal line of the flow rate control needle holding member 17. . The flow rate control needle 6 has a head portion 21 having a diameter larger than that of the holding hole 20 and a tapered portion 22 having a diameter smaller than that of the holding hole 20 and extending toward the fuel injection hole 5. The head portion 21 is positioned on the inner side of the flow rate control needle holding member 17, and an end surface thereof is in contact with the transmission member 16. The center line of the flow rate control needle 6 coincides with the center line of the holding hole 20 and the center line of the fuel injection hole 5. A stepping portion of the head portion 21 and the tapered portion 22 is provided with an extraction spring 23 for pushing the flow rate control needle 6 in the direction of extracting from the fuel injection hole 5 between the peripheral portion of the holding hole 20. ing.

  The outer shell 4 is integrated with the entire outer shell 24 of the fuel injection device 1. An integral part of the fuel flow path constituting block 9 and the piezoelectric element holding base 14 is overlapped on the housing block 8, and further the piezoelectric element 7 and the transmission member 16 are overlapped, and the extraction spring 23 and the flow rate are added to the needle holder 17 for flow control. The fuel injection device 1 is assembled by stacking the ones on which the control needles 6 are placed and the outer shells 4.

  As shown in FIG. 2, when the outer shell 4 of the fuel injection device 1 is viewed from the front end side, a plurality of fuel injection holes 5 are arranged at equal intervals in the circumferential direction. The shape of the fuel injection hole 5 is circular when viewed from the normal direction passing through the fuel injection hole 5. The diameter of the fuel injection hole 5 may be determined by experiment or calculation so that the fuel F injected from the adjacent fuel injection hole 5 does not interfere. The radial position of the outer shell 4 where the fuel injection holes 5 are arranged, and the number and interval of the fuel injection holes 5 are determined by experiments and calculations so that the fuel F injected from the adjacent fuel injection holes 5 does not interfere. Good.

  As shown in FIG. 3, an extraction spring 23 is provided at the periphery of the holding hole 20 so that one end is in contact with the inner surface of the flow rate control needle holding member 17. Is in contact with the stepped portion of the head portion 21 and the tapered portion 22 of the flow control needle 6. When a piezoelectric element (not shown) is compressed, the flow rate control needle 6 is stroked inward by the force of the extraction spring 23 and is extracted from the fuel injection hole 5. When the piezoelectric element expands, the flow rate control needle 6 strokes outwardly against the force of the extraction spring 23 and is inserted into the fuel injection hole 5. When the flow control needle 6 is extracted most from the fuel injection hole 5, the extraction spring 23 is most extended, and the flow control needle 6 is inserted most into the fuel injection hole 5. At the time of insertion, the extraction spring 23 is compressed most.

  Looking at the positional relationship between the tapered portion 22 and the fuel injection hole 5 in more detail, as shown in FIG. 4, the end surface of the tapered portion 22 is located on the inner side of the inner side surface of the outer shell 4 at the time of maximum extraction. In addition, since the distance g between the ridge line of the fuel injection hole 5 and the ridge line of the tapered portion 22 is large, the fuel passage area S from the outer shell back side fuel flow path 18 to the fuel injection hole 5 is large. At an intermediate time, the end surface of the tapered portion 22 is located inside the inner surface of the outer shell 4, but the distance g between the ridge line of the fuel injection hole 5 and the ridge line of the tapered portion 22 is small, and the fuel passage area S is medium. Degree. At the maximum insertion time, the tapered portion 22 is located in the fuel injection hole 5 and the distance g between the ridge line of the fuel injection hole 5 and the outer peripheral surface of the tapered portion 22 is very small, so the fuel passage area S is small. Since the amount of fuel passing is approximately proportional to the fuel passage area S, the amount of fuel sprayed from the fuel injection hole 5 to the outside (combustion chamber) is the largest at the maximum withdrawal, medium at the middle, and at the maximum insertion The least. That is, the flow control needle 6 constitutes a throttle of the fuel injection hole 5.

  Next, the operation of the fuel injection device 1 of FIG. 1 will be described.

  When the fuel is not injected, the injection needle 3 blocks the fuel outlet 2, so that the fuel supplied from the pressure accumulation fuel source does not flow out of the fuel outlet 2. When the fuel is injected, the injection needle 3 opens the fuel outlet 2, so that the fuel flows out from the fuel outlet 2. The fuel flowing out from the fuel outlet 2 reaches the fuel injection hole 5 via the central fuel flow path 12, the peripheral fuel flow path 13, the fuel flow path 19, and the outer shell back side fuel flow path 18. At this time, the amount of fuel sprayed from the fuel injection hole 5 to the outside (combustion chamber) is changed by controlling the insertion / extraction amount of the flow rate control needle 6 according to the voltage applied to the piezoelectric element 7. That is, the fuel injection device 1 according to the present invention can adjust the fuel injection amount by the voltage applied to the piezoelectric element 7.

  Next, another embodiment of the present invention will be described.

  In the fuel injection device 51 shown in FIG. 5, a plurality of piezoelectric elements 7a, 7b, 7c and transmission members 16a, 16b, 16c correspond to a plurality of flow control needles 6a, 6b, 6c in a one-to-one correspondence. Yes. Thereby, for example, if only the piezoelectric element 7a is expanded and contracted, only the flow rate control needle 6a can be stroked, and the fuel injection hole 5 whose fuel passage area is to be adjusted can be selected and controlled.

  Further, in the fuel injection device 1 of FIG. 1, the transmission member 16 is configured to transmit expansion / contraction of one piezoelectric element 7 to all the flow rate control needles 6. When there are a large number of flow control needles 6, two or more flow control needles 6 can be provided by providing a transmission member 16 that transmits the expansion and contraction of one piezoelectric element 7 to two or more flow control needles 6. The stroke can be performed by expansion and contraction of the corresponding piezoelectric element 7.

  The fuel injection hole 65 shown in FIG. 6 has a smaller diameter than the fuel injection hole 5 of FIG. 3 and is formed in a tapered shape so that the tapered portion 22 of the flow rate control needle 6 is inserted without generating a gap. Has been. Thereby, the flow rate control needle 6 can fully close the fuel injection hole 65 at the time of maximum insertion.

  The flow rate control needle holding member 77 shown in FIG. 7 is formed with a spring accommodating portion 78 for accommodating the extraction spring 23. Thereby, the extraction spring 23 is not easily displaced.

  Next, the spray shape at the time of fuel injection by the fuel injection device 1 of FIG. 1 will be considered.

  As shown in FIG. 2, fuel F is injected from six fuel injection holes 5 formed in the outer shell 4. In FIG. 2, since the outer shell 4 is viewed from the tip side, the spray shape looks planar, but the main direction of injection is along the normal of the outer shell 4 passing through the center of the fuel injection hole 5. The fuel F is evenly distributed around the main direction. In the fuel injection device 1, the main directions of the fuel F injected from the fuel injection holes 5 do not intersect with each other, so that interference of the fuel F injected from the fuel injection holes 5 can be easily avoided. Also in the fuel injection device 51 of FIG. 5, if all the fuel injection holes 5a, 5b, 5c are controlled to the same fuel passage area, the fuel injection device 51 is almost the same as FIG. 2 (injection by the central fuel injection hole 55b is added). It becomes a spray shape.

  Like the fuel injection device 51 in FIG. 5, the fuel passage areas of the fuel injection holes 5a, 5b, and 5c can be individually controlled, and the flow control needle 6 fully closes the fuel injection hole 65 as shown in FIG. When configured to be possible, the following control is possible. For example, it is assumed that the fuel injection device (not shown) of the present invention is installed at the center of the combustion chamber 81 as shown in FIG. It is assumed that the fuel injection device is provided with twelve fuel injection holes at equal intervals in the circumferential direction. It can be seen that a part of the fuel F injected from each fuel injection hole interferes. At this time, if every other fuel injection hole is fully closed in the circumferential direction, the fuel F injected from the remaining fuel injection holes does not interfere as shown in FIG. Thus, interference can be avoided by fully closing a part of the fuel injection holes involved in the interference.

  Here, in a diesel engine, the mixing time (time from injection to ignition) may be short or long depending on the engine state. When the mixing time is short, unburned hydrocarbons, carbon monoxide, and black smoke are likely to be included in the exhaust gas when ignited with the fuel-rich region generated in the combustion chamber due to interference. Therefore, as already mentioned, it is necessary to avoid interference. However, when the mixing time is long, even if a fuel-rich region occurs once in the combustion chamber due to interference, ignition occurs after the fuel-rich region is eliminated by diffusion, so unburned hydrocarbons and carbon monoxide are exhausted. It is hard to be included in. Therefore, even if interference occurs, it does not become a malfunction.

  According to this consideration, in the engine state where the mixing time is long, the fuel F may be injected from all the fuel injection holes as shown in FIG. Thereby, the fuel F can be injected evenly into the combustion chamber 81. On the other hand, in an engine state where the mixing time is short, as shown in FIG. 8B, interference is avoided by fully closing the appropriate fuel injection holes and injecting the fuel F from the remaining fuel injection holes.

  Next, the control of the injection amount profile in one fuel injection will be considered.

  As shown by a broken line in FIG. 9, in the conventional fuel injection device 100, when the conical portion 101c of the injection needle 101 starts to separate from the seating portion, the injection amount starts to increase, and thereafter, the injection amount becomes constant, As the conical portion 101c of the injection needle 101 approaches the seating portion, a monotonous injection amount profile is obtained in which the injection amount decreases. As indicated by the solid line, in the fuel injection device of Patent Document 1, since the two injection needles operate while being shifted in time, even when the total injection amount is the same, the injection amount is initially in one fuel injection. An injection amount profile with a small amount and a large injection amount can be obtained later. However, in both fuel injection devices, the injection amount profile is fixed.

  On the other hand, the fuel injection devices 1 and 51 of FIGS. 1 and 5 combine the control of the injection needle 3 and the control of the flow rate control needle 6 so that the total injection amount and injection amount profile in one fuel injection are combined. Can be varied in various ways. For example, when the injection amount profile as shown by the solid line in FIG. 9 is desired, the injection needle 3 has a longer time than the injection amount profile shown by the broken line and the peak injection amount is increased, and the flow control needle 6 Then, the fuel passage area is reduced in the initial stage, and the fuel passage area is increased in the latter period. Not limited to this, an arbitrary injection amount profile can be realized by increasing or decreasing the fuel passage area of the fuel injection hole 5 with the flow rate control needle 6 during the period in which the injection needle 3 opens the fuel outlet 2.

  As described above, according to the fuel injection devices 1 and 51 of the present invention, the fuel injection hole 5 is obtained by inserting / removing the flow control needle 6 into / from the plurality of fuel injection holes 5 formed in the outer shell 4. Further, since the flow rate control needle 6 is driven by the piezoelectric element 7, the structure is simple and the control is easy.

  According to the fuel injection devices 1 and 51 of the present invention, since the fuel passage area of the fuel injection hole 5 can be increased or decreased, the fuel injection amount is adjusted more precisely than before by combining with the control of the injection needle 3. In addition, the injection amount profile can be varied.

  According to the fuel injection devices 1 and 51 of the present invention, since the fuel F injected from the plurality of fuel injection holes 5 does not interfere, a fuel rich region does not occur in the combustion chamber, and unburned hydrocarbons and carbon monoxide are not generated. Not included in exhaust gas.

  According to the fuel injection devices 1 and 51 of the present invention, only one injection needle 3 is required, and since there is no special structure inside the housing block 8, processing and assembly are easy, and processing costs and assembly costs are low. Cheap and easy to manage machining accuracy.

  According to the fuel injection devices 1 and 51 of the present invention, since there is no resistance portion as in Patent Document 1 in the fuel passage for driving the injection needle 3, there is no useless energy loss.

  In the fuel injection device 51 of the present invention, when the flow rate control needle 6 is configured to be able to fully close the fuel injection hole 65, the spray distribution shape can be varied by fully closing the arbitrary fuel injection hole 65. can do.

DESCRIPTION OF SYMBOLS 1,51 Fuel injection apparatus 2 Fuel outlet 3 Injection needle 4 Outer shell 5, 5a, 5b, 5c Fuel injection hole 6, 6a, 6b, 6c Flow control needle 7, 7a, 7b, 7c Piezoelectric element

Claims (3)

An injection needle that shuts off and opens a fuel outlet that leads to an accumulator fuel source;
An outer shell covering the outside of the fuel outlet;
A plurality of fuel injection holes formed in the outer shell along the normal line of the outer shell;
A plurality of flow rate control needles provided so as to be freely inserted into and removed from each of the fuel injection holes from the inside of the outer shell, and increasing or decreasing the fuel passage area of the fuel injection holes;
A fuel injection device comprising: a piezoelectric element that drives the flow rate control needle and inserts and removes the needle from the fuel injection hole.   The fuel injection device according to claim 1, further comprising a transmission member that transmits expansion and contraction of one piezoelectric element to two or more needles for flow control.   3. The fuel injection device according to claim 1, wherein the flow rate control needle is configured to be able to fully close the fuel injection hole.