JP2007170330A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve having a drive force transmitting section and inhibiting vibration caused in an actuator from being transmitted to a control valve making open and close operation unstable. <P>SOLUTION: Displacement of the piezo actuator 2 is transmitted by a piezo piston 31 and the drive force transmitting section 3 which comprises a valve piston 32 and an oil-tight chamber 33, and the control valve 41 is driven via a slide pin 34. A minute space formed between a flat lower end surface of the valve piston 32 and an opposite inner wall surface of an injector body B is set for a damper chamber 6. When the valve piston 32 is lowered by the vibration caused in the piezo actuator 2, upward force acts on the valve piston 32 due to a pressure rise for a moment in the damper chamber 6 and reduces the vibration. Operation of the control valve 4 is thus stabilized and fuel injection can be stably controlled. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection device that transmits a driving force of an actuator to a control valve via a hydraulic driving force transmission unit to raise and lower a nozzle needle.

2. Description of the Related Art In a diesel engine, a common rail type fuel injection device that stores a high pressure fuel by providing a common rail common to each cylinder is known. High pressure fuel is pumped from the fuel supply pump to the common rail and controlled to a predetermined pressure, and fuel is injected by driving the injector of each cylinder at a predetermined timing. Common rail injectors generally have a control chamber that applies a pressure in the valve closing direction to the nozzle needle and a control valve that controls the pressure in the control chamber. The actuator is driven by the actuator to increase or decrease the pressure in the control chamber. (For example, patent document 1 etc.).
JP 2004-308479 A

  A piezoelectric actuator is preferably used as the actuator. Piezo actuators are highly responsive, so advanced fuel injection control can be expected. As the control valve, for example, a three-way valve structure that selectively communicates the control chamber with the high-pressure passage or the low-pressure passage is used, and moves between the low-pressure side seat leading to the low-pressure passage and the high-pressure side seat leading to the high-pressure passage, Switch the sheet position. When the piezo actuator is extended by energization, the hydraulic driving force transmission unit drives the control valve to be separated from the low-pressure side seat, and then is seated on the high-pressure side seat. As a result, the pressure in the control chamber decreases, the nozzle needle lifts, and fuel is injected.

  The driving force transmission part forms an oil-tight chamber between two pistons and transmits the displacement of the actuator via hydraulic pressure, and absorbs the thermal expansion that varies depending on the material of the member and efficiently transmits the displacement. Can do. Further, when two pistons having different diameters are used, the displacement can be enlarged and transmitted according to the pressure receiving area ratio of the large diameter piston and the small diameter piston.

  Thus, the piezo actuator is displaced in the axial direction by energization to generate displacement and drive the control valve. However, at this time, vibration is generated by the elongation of the piezo element itself. Since this vibration is transmitted to the control valve via the driving force transmission unit, it may be difficult to stably open and close the control valve. For example, when the seat position of the control valve becomes unstable, the pressure controllability of the control chamber is lowered, and there is a problem that the injection from the fuel injection device is not stable.

  Accordingly, an object of the present invention is to provide a fuel injection device that transmits the displacement of an actuator to a control valve via a driving force transmission unit, and vibration generated by the actuator is transmitted to the control valve, so that the opening / closing operation becomes unstable. In other words, the nozzle needle is stably controlled by the control valve, and the injection amount can be controlled with high accuracy.

  According to a first aspect of the present invention, there is provided a fuel injection device comprising: an actuator that generates displacement when energized; a control valve that controls a back pressure of a nozzle needle; and a driving force transmission unit that transmits a driving force of the actuator to the control valve. . The driving force transmission unit includes first and second pistons that slide in a cylinder provided in the injector body, and an oil-tight chamber formed between the two pistons, and hydraulic pressure that accompanies displacement of the first piston on the actuator side. The second piston drives the control valve as the chamber pressure increases.

  The second piston has an end surface on the control valve side as a flat surface. On the other hand, the injector body is provided with a sliding hole continuous with the cylinder, and a pin member is slidably disposed in the sliding hole, and one end of the pin member is placed on the flat surface of the second piston. The end side is brought into contact with the control valve. Furthermore, a damper chamber defined by the end surface of the second piston, the inner peripheral surface of the cylinder, and the inner wall surface of the injector body is provided on the one end side of the pin member.

  In the above configuration, when the actuator is driven to generate vibration, the vibration is sequentially transmitted to the first piston, the oil tight chamber, and the second piston of the driving force transmission unit. As a result, when the second piston descends, the internal fuel in the damper chamber is momentarily compressed and boosted to generate an upward force. This upward force acts on the second piston, and the effect of suppressing vibration is obtained. Therefore, the vibration is transmitted to the control valve via the pin member, and the on-off valve can be prevented from becoming unstable, and the controllability of fuel injection can be improved.

  More specifically, the pin member is formed around the one end side of the pin member, and is defined by a flat surface of the second piston and an inner wall surface of the injector body facing the flat surface. The damper chamber can be configured in a minute space.

  According to a third aspect of the present invention, the control valve side end portion of the second piston is a flange portion projecting in the vicinity of the inner peripheral surface of the cylinder, and the end surface of the flange portion is the flat surface. Can do.

  According to a fourth aspect of the present invention, a communication passage is provided for communicating the damper chamber with the low pressure passage. After the pressure in the damper chamber rises momentarily by driving the actuator, the fuel is discharged from the communication passage to the low pressure passage, so that it is possible to prevent the second piston from being lowered.

  In the invention of claim 5, the actuator is a piezo actuator. By applying the present invention to a piezo actuator that tends to vibrate when it is extended by energization, the driving force can be effectively used to realize highly accurate and stable injection amount control.

  More specifically, a control chamber is provided that applies pressure in the valve closing direction to the nozzle needle. The control valve moves the nozzle needle up and down by switching communication / blocking between the control chamber and the low-pressure passage to increase or decrease the pressure in the control chamber.

  According to a seventh aspect of the present invention, a low pressure chamber communicating with the low pressure passage through an orifice is provided on the outer periphery of the end of the pin member on the control valve side, and the working fluid in the control chamber is supplied with the low pressure when the actuator is driven. It flows out to the low pressure passage through the chamber and the orifice.

  According to the above configuration, the nozzle opening speed at the time of low-pressure side seat opening is slowed by the orifice, and the pressure in the control chamber is applied in the valve closing direction of the high-pressure side seat so that the high-pressure side seat valve closing driving force is increased. Since it can be made small, injection controllability and energy efficiency can be improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a first embodiment in which the fuel injection device of the present invention is applied to a piezo injector for a common rail of a diesel engine. In FIG. 1A, reference numeral 1 denotes an injector which is attached to a cylinder head of an engine (not shown). The injector 1 is connected to a common rail (not shown) provided in common to each cylinder, receives fuel from the common rail, and injects fuel into the corresponding cylinder combustion chamber. The common rail has a known configuration, and the fuel pumped by the high pressure supply pump is stored at a predetermined high pressure corresponding to the injection pressure.

  In the figure, an injector 1 accommodates each member constituting a piezo actuator 2 as an actuator, a driving force transmission unit 3, a control valve unit 4 and a nozzle unit 5 in an injector body B, and becomes an injected fuel or hydraulic oil. A fuel passage is formed. The piezo actuator 2, the driving force transmission unit 3, the control valve unit 4, and the nozzle unit 5 are arranged in this order in the vertical direction. A fuel introduction port 11 communicating with the common rail is opened on the upper side wall of the injector body B, and is connected to a high-pressure passage 12 formed in the injector body B in the axial direction. A low pressure passage 13 is formed in the axial direction at the side of the high pressure passage 12 and communicates with a fuel tank (not shown) via a fuel outlet 14 that opens at the upper end surface of the injector body B.

  The piezo actuator 2 and the driving force transmission unit 3 serving as a driving source are accommodated in a vertical hole B1 provided in the upper half of the injector body B. The piezo stack 21 constituting the piezo actuator 2 is formed by alternately laminating piezoelectric ceramic layers such as PZT and electrode layers, and is charged and discharged by a drive circuit (not shown) so as to expand and contract in the laminating direction (vertical direction). ing. The space in the vertical hole B <b> 1 communicates with the low pressure passage 13 through the passage 22.

  The driving force transmission unit 3 slidably holds a large-diameter piezo piston 31 as a first piston and a small-diameter valve piston 32 as a second piston in a cylindrical cylinder member 35 installed in the vertical hole B1. It becomes. Between the piezo piston 31 and the valve piston 32, an oil tight chamber 33 filled with fuel serving as hydraulic oil is formed. The piezo piston 31 has a flange-shaped upper end protruding above the cylinder member 35 and abutting against the lower end surface of the piezo stack 21 so that the piezo piston 31 can be displaced integrally with the piezo stack 21. On the outer periphery of the cylinder member 35, a cylindrical piezo spring 36 is disposed between the upper end flange portion of the piezo piston 31 and the lower end flange portion of the cylinder member 35. The piezo spring 36 has a known slit spring structure that can be deformed in the axial direction by a large number of slits formed in the cylindrical wall. The piezo spring 31 urges the piezo piston 31 upward to bring it into close contact with the piezo stack 21 so as to make contact between the two. While maintaining, a constant initial load is applied to the piezo stack 21.

  The valve piston 32 is a flange portion 321 with a lower end portion protruding outward. The cylinder member 35 has a lower end with a stepped diameter, and a valve spring 37 is disposed between the step and the flange portion 321 of the valve piston 32. The valve spring 37 is formed of a coil spring, and urges the valve piston 32 downward so as to contact the sliding pin 34 that is a pin member.

  Therefore, when the piezo stack 21 extends and presses the piezo piston 31 downward, the pressing force is converted into hydraulic pressure in the oil tight chamber 33 and transmitted to the valve piston 32. At this time, the displacement is expanded in accordance with the pressure receiving area ratio between the large-diameter valve piston 32 and the small-diameter piezo piston 31 and is transmitted to the control valve portion 4 via the slide pin 34.

  The control valve unit 4 has a three-way valve structure, and has a valve chamber 42 that is always in communication with the control chamber 52 of the nozzle unit 5 through a communication passage 46, and a control valve 41 that is accommodated in the valve chamber 42. The valve chamber 42 has a low-pressure seat 43 communicating with the low-pressure passage 13 on the top surface and a high-pressure seat 44 communicating with the high-pressure passage 12 on the bottom surface, and the control valve 41 is selected as the low-pressure seat 43 or the high-pressure seat 44. Therefore, the pressure in the control chamber 52 is increased or decreased by sitting on the seat.

  The nozzle portion 5 holds the upper end portion of the nozzle needle 51 slidably on the cylindrical cylinder member 55 installed in the injector body B, and is divided by the upper end surface of the nozzle needle 51 and the inner wall surface of the cylindrical cylinder member 55. The space to be used is a control room 52. The space around the nozzle needle 51 constitutes an oil reservoir chamber 54 that communicates with the high-pressure passage 12. The oil reservoir chamber 54 communicates with the high pressure seat 44 of the control valve unit 4 via the communication passage 15. A needle spring 56 made of a coil spring is disposed between a flange provided on the outer periphery of the intermediate portion of the nozzle needle 51 and the cylindrical cylinder member 55.

  Fuel as control oil is introduced into the control chamber 52 to generate the back pressure of the nozzle needle 5. This back pressure acts downward on the nozzle needle 51 and urges the nozzle needle 51 together with the needle spring 56 in the valve closing direction. On the other hand, the high-pressure fuel in the oil reservoir chamber 54 acts upward on the nozzle needle 51.

  FIG. 1 (a) shows a state in which the injector 1 is not injecting. The nozzle needle 51 is seated, and the fuel supply from the oil reservoir chamber 54 to the injection hole 53 provided at the tip of the injector body B is cut off. Yes. When the piezo actuator 2 is driven and the control valve unit 4 reduces the pressure in the control chamber 52, the nozzle needle 51 is lifted and fuel is injected.

  As shown in FIG.1 (b), the control valve 41 of the control valve part 4 becomes a shape which has a substantially semispherical upper half part and a cylindrical lower half part. The substantially spherical surface of the upper half constitutes a seat surface seated on the low pressure seat 43, and the flat bottom surface of the lower half constitutes a seat surface seated on the high pressure seat 44. A valve spring 45 made of a coil spring is disposed between the flange formed on the outer periphery of the intermediate portion of the control valve 41 and the bottom surface of the valve chamber 42 to urge the control valve 41 upward. If the low-pressure seat 43 is closed in the initial state, the pressure can be quickly increased by the high-pressure supply pump when the engine is started.

  The top surface of the control valve 41 is formed in a flat surface and is in contact with the lower end surface of the sliding pin 34. The sliding pin 34 is a cylindrical pin having a constant diameter, and is slidably supported in a sliding hole B4 provided in the valve body B3 constituting the injector body B. The lower half of the sliding hole B4 is expanded in diameter to form the low pressure chamber 16 between the sliding pin 34 and the lower half. The low pressure chamber 16 opens to the top surface of the valve chamber 42 and always communicates with the low pressure passage 13 via the orifice 17. Above the valve body B3, a piezo body B2 for accommodating the cylinder member 35 is disposed.

  The upper end portion of the sliding pin 34 protrudes above the sliding hole B4 and is located in the damper chamber 6 formed in the cylinder member 35. The damper chamber 6 is surrounded by the upper end surface of the valve body B3, the flat bottom surface of the flange portion 321 provided at the lower end of the valve piston 32, and the inner peripheral wall surface of the cylinder member 35, and is determined by the protruding amount of the sliding pin 34. It is formed in a minute space. In the damper chamber 6, hydraulic oil is always present, and the vibration is reduced by the damper effect. A through hole serving as a communication passage 61 is provided in the cylinder wall of the cylinder member 35 on the side of the flange portion 321, and the damper chamber 6 and the low pressure passage 13 are communicated with each other through the space in the vertical hole B1.

  Here, the outer peripheral edge of the flange portion 321 is brought close to the inner peripheral wall surface of the cylinder member 35 so as to have a slight gap, thereby forming a substantially sealed space, and the outflow of fuel from the communication passage 61 when the pressure rises. It is better not to disturb. Thus, when the valve piston 32 is lowered, the fuel pressure in the damper chamber 6 can be increased for a moment and then decreased, and vibration can be reduced without impeding the driving of the valve piston 32.

  If one of the sheet portions is a flat sheet as in the present embodiment, sheet failure due to axial misalignment or the like is less likely to occur. In addition, if a smooth spherical or conical sheet is used, it is possible to suppress the entry of foreign matter, etc.For example, if the low pressure side is a spherical or conical sheet, the nozzle valve closing timing is delayed due to the engagement and the injection amount increases. There is an effect to prevent.

  Next, the operation of the injector 1 having the above configuration will be described. At the time of no injection in FIG. 1A, the piezo stack 21 is contracted in a discharged state, and the control valve 41 is in an upper end position where the low pressure seat 43 is closed. At this time, the high pressure seat 44 is opened, the valve chamber 2 communicates with the high pressure passage 12, and the control chamber 52 communicated with the valve chamber 42 via the communication passage 46 becomes high pressure. The nozzle needle 51 is kept closed by the pressure in the control chamber 52 and the urging force of the needle spring 56, and fuel injection is not performed.

  On the other hand, at the time of injection shown in FIG. 2, when the piezo actuator 2 is energized, the piezo stack 21 is charged and extended. As indicated by arrows in the figure (on-stroke), the piezo piston 31 of the driving force transmission unit 3 moves downward with the displacement of the piezo stack 21 to compress the hydraulic oil (here, light oil) in the oil tight chamber 33. The valve piston 32 moves downward by the pressure of the hydraulic oil, and the displacement is enlarged and transmitted to the slide pin 34 and the control valve unit 4. When the valve piston 32 pushes down the sliding pin 34, the control valve 41 is separated from the low pressure seat 43, further displaced downward, and is seated on the high pressure seat 44.

  As a result, the valve chamber 42 communicates with the low pressure passage 13 via the low pressure seat 43, the low pressure chamber 16, and the orifice 17, and the pressure in the control chamber 52 that communicates with the valve chamber 42 decreases. When the upward biasing force applied to the nozzle needle 51 exceeds the downward biasing force due to the pressure drop in the control chamber 52, the nozzle needle 5 moves upward and fuel injection is started from the nozzle hole 53. At this time, the pressure drop in the control chamber 52 becomes gentle due to the orifice 17 downstream of the low pressure chamber 16, and the nozzle opening speed becomes small. Further, the pressure in the valve chamber 42 acts as an assisting force in the direction of closing the high pressure seat 44, and the driving force required for closing the high pressure seat can be reduced.

  Here, the operation of the damper chamber 6 will be described. Vibration generated by the extension of the piezo stack 21 is transmitted from the piezo piston 31 to the valve piston 32 through the oil-tight chamber 33. In the present invention, the damper chamber 6 is provided below the valve piston 32 so that this vibration is not transmitted from the sliding pin 34 to the control valve 41. That is, when the flange portion 321 of the valve piston 32 is lowered, the fuel in the damper chamber 6 defined by the flat bottom surface and the upper surface of the valve body B32 opposite to the flat bottom surface is momentarily compressed and pressurized. For this reason, an upward force is instantaneously applied to the valve piston 32 to reduce vibration. This upward force is generated instantaneously, and when the fuel in the damper chamber 6 is subsequently discharged from the communication hole 61, the pressure is reduced, so that there is no resistance when the valve piston 32 is lowered.

  When energization to the piezo actuator 2 is completed, the piezo stack 21 contracts again, and the reverse operation indicated by the arrow in the figure (off stroke) moves the piezo piston 31 upward, and the pressure in the oil tight chamber 33 drops. The pressing force of the valve piston 32 and the sliding pin 34 is released. Then, the control valve 41 is separated from the high-pressure seat 44 and further seated on the low-pressure seat 43, so that the control chamber 52 and the low-pressure passage 13 are disconnected. As a result, the pressure in the control chamber 52 rises again, and the nozzle needle 51 is closed. At this time, if the low-pressure side seat diameter is smaller than the high-pressure side seat diameter, the pressure in the control chamber 52 rises quickly and the nozzle closing speed increases.

  In the configuration of the present embodiment, vibration generated by driving the piezo actuator 2 can be reduced by the damper chamber 6 and can be prevented from being transmitted from the slide pin 34 to the control valve 41. Therefore, the problem that the control valve 41 vibrates and the seat position becomes unstable does not occur, and a stable opening / closing valve of the control valve 41 becomes possible, so that the fuel injection from the injector 1 can be stably performed. it can.

  Further, as described above, the orifice 17 slows down the nozzle opening speed when the low pressure seat 43 is opened, and the pressure in the control chamber 52 is applied in the valve closing direction of the high pressure seat 44 to drive the high pressure seat. Since the force can be reduced, energy efficiency is improved. At this time, by increasing the diameter of the high-pressure sheet 44 and increasing the nozzle closing speed, the injection end timing variation (injection amount variation) is reduced, and the injection amount controllability is improved.

  Further, by using the piezo actuator 2, fuel injection can be performed with high responsiveness. In this case, since the displacement of the piezo stack 21 is very small, the driving force transmission unit 3 is configured by combining the large-diameter piezo piston 31 and the small-diameter valve piston 32, and the displacement is enlarged and transmitted more efficiently. A driving force can be transmitted.

  FIG. 3 shows another example of the configuration of the damper chamber 6 according to the second embodiment of the present invention. The basic configuration of the injector 1 is the same as that of the first embodiment, and the following description will focus on the differences. In the present embodiment, the valve piston 32 of the driving force transmission unit 3 is not provided with the flange portion 321, and has a cylindrical shape with a constant diameter. The space formed between the flat lower end surface of the valve piston 32 and the upper surface of the valve body B3 facing this is defined as a damper chamber 6. A communication passage 61 is formed at the lower end portion of the cylinder member 35 serving as a side wall of the damper chamber 6 so that the damper chamber 6 communicates with the low pressure passage 13.

  Also with the above configuration, the same damper effect as in the first embodiment can be obtained, the operation of the control valve 41 can be stabilized, and the fuel injection control can be performed satisfactorily.

  FIG. 4 shows another configuration example of the damper chamber 6 according to the third embodiment of the present invention. The basic configuration of the injector 1 is the same as that of the first embodiment, and the following description will focus on the differences. In the present embodiment, an intermediate portion of the valve piston 32 of the driving force transmission portion 3 has a small diameter, and a flange portion 321 is provided at the lower end portion. A gap through which fuel can flow is formed between the flange portion 321 and the inner peripheral wall surface of the cylinder member 35. In addition to the space formed between the flat lower end surface of the flange portion 321 and the upper surface of the valve body B3, A space around the small-diameter intermediate portion of the valve piston 32 is a damper chamber 6. A communication passage 61 that communicates with the low-pressure passage is formed in the cylinder member 35 serving as a side wall of the damper chamber 6 on the side of the small diameter intermediate portion of the valve piston 32.

  In the above configuration, when the piezo actuator 2 is driven and the valve piston 32 is lowered, the pressure in the damper chamber 6 below the flange portion 321 increases momentarily. Thereafter, the fuel flows out from the communication passage 61 through the gap on the outer periphery of the flange portion 321 and the damper chamber 6 above the flange portion 321. A similar effect can be obtained in which vibration is reduced by the upward acting force generated at this time.

  Thus, the shape of the valve piston 32 and other members constituting the damper chamber 6 can be changed as appropriate. In the above embodiment, the sliding pin 34 is a cylindrical pin having the same diameter as the entire length. However, the present invention is not limited to this. For example, the sliding pin 34 may have other shapes such as a pin having a diameter smaller than that of the sliding portion. You can also In order to prevent wear of the sliding pin 34 and to ensure slidability, it is preferable to use a structure using an ultra-hard material or ceramic at least on the sliding surface.

  In the above embodiment, the large-diameter piezo piston 31 and the small-diameter valve piston 32 are combined as the two pistons of the driving force transmission unit. However, the present invention is not limited to this, and is driven by two pistons having the same diameter and an oil-tight chamber between them. The force transmission part 3 can also be comprised.

  Any actuator may be used as long as it is an element that generates a displacement by energization. In addition to the piezoelectric element used in each of the above embodiments, a magnetostrictive element or the like can also be used.

(A) is sectional drawing which shows the whole structure of the injector which shows the 1st Embodiment of this invention, (b) is the principal part expanded sectional view. It is a figure which shows the state at the time of injection of the injector in 1st Embodiment. It is a principal part expanded sectional view of the injector which shows 2nd Embodiment. It is a principal part expanded sectional view of the injector which shows 3rd Embodiment.

Explanation of symbols

B Injector body B1 Vertical hole B2 Piezobody B3 Valve body B4 Sliding hole 1 Injector 11 Fuel inlet 12 High pressure passage 13 Low pressure passage 14 Fuel outlet 15 Communication passage 16 Low pressure chamber 17 Orifice 2 Piezo actuator (actuator)
21 Piezo stack 22 Communication path 3 Drive force transmission part 31 Piezo piston (first piston)
32 Valve piston (second piston)
321 Flange part 33 Oil tight chamber 34 Sliding pin (pin member)
35 Cylinder member 36 Piezo spring 37 Valve spring 4 Control valve portion 41 Control valve 42 Valve chamber 43 Low pressure side seat 44 High pressure side seat 45 Valve spring 46 Communication path 5 Nozzle portion 51 Nozzle needle 52 Control chamber 53 Injection hole 54 Oil reservoir chamber 6 Damper room 61 passage

Claims (7)

An actuator that generates displacement by energization, a control valve that controls the back pressure of the nozzle needle, and a driving force transmission unit that transmits the driving force of the actuator to the control valve,
The driving force transmission unit includes first and second pistons that slide in a cylinder provided in the injector body, and an oil-tight chamber formed between the two pistons, and hydraulic pressure that accompanies the displacement of the first piston on the actuator side. A fuel injection device in which the second piston drives the control valve by an increase in pressure in the chamber;
The control valve side end surface of the second piston is a flat surface,
The injector body is provided with a sliding hole continuous with the cylinder, and one end of a pin member slidably disposed in the sliding hole is used as the flat surface of the second piston, and the other end as the control valve. And abut
A fuel injection device characterized in that a damper chamber defined by an end surface of the second piston, an inner peripheral surface of the cylinder, and an inner wall surface of the injector body is provided on the one end side of the pin member.   The damper chamber is formed in a minute space formed around the one end side of the pin member and defined by a flat surface of the second piston and an inner wall surface of the injector body facing the flat surface. 1. The fuel injection device according to 1.   3. The fuel injection device according to claim 1, wherein the second piston has a flange portion projecting near the inner peripheral surface of the cylinder, and the end surface of the flange portion is the flat surface.   The fuel injection device according to any one of claims 1 to 3, further comprising a communication passage that allows the damper chamber to communicate with a low-pressure passage.   The fuel injection device according to any one of claims 1 to 4, wherein the actuator is a piezoelectric actuator.   6. A control chamber for applying a pressure in the valve closing direction to the nozzle needle, wherein the control valve increases or decreases the pressure in the control chamber by switching between communication and blocking between the control chamber and the low pressure passage. The fuel injection device according to any one of the above.   A low-pressure chamber that communicates with the low-pressure passage through an orifice is provided on the outer periphery of the control valve side end of the pin member, and when the actuator is driven, the working fluid in the control chamber passes through the low-pressure chamber and the orifice to the low-pressure chamber. The fuel injection device according to any one of claims 1 to 6, wherein the fuel injection device is configured to flow out into the passage.