JP2008303810A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve capable of precise injection control by reducing generation of intense heat and the occurrence of erosion, by moderating a pressure drop rate of fuel discharged from a back pressure control chamber. <P>SOLUTION: This fuel injection valve is provided for injecting high pressure fuel from an injection hole by lifting a nozzle needle by discharging the high pressure fuel in the back pressure control chamber to a low pressure part, by introducing the high pressure fuel into the back pressure control chamber on the rear end side of the nozzle needle, by sending the high pressure fuel to the tip side of the nozzle needle for opening and closing the injection hole, and is characterized by having a back pressure control valve for controlling a flow rate of the high pressure fuel in the middle of a back pressure flow passage for discharging the high pressure fuel to the low pressure side from the back pressure control chamber, and having a first orifice part in the back pressure flow passage between the back pressure control chamber and the back pressure control valve, and having a second orifice part on the lower pressure part side than a seat position of the back pressure control valve. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection valve that injects fuel into an internal combustion engine or the like, and more particularly to a fuel injection valve for injecting fuel at a higher pressure than in the past.

Conventionally, a fuel injection valve having a structure as illustrated in FIG. 8 is known as a fuel injection valve used for injecting high-pressure fuel supplied from an accumulator (common rail) or the like into an internal combustion engine (Patent Document). 1).
A fuel passage 313 is formed on the front end side of the fuel injection valve 301 from the inlet connector 308 to the injector housing 302 and the nozzle body 303. The fuel passage 313 communicates with a fuel reservoir chamber 314 formed at a position where the pressure receiving portion 304A of the nozzle needle 304 is located in the middle of reaching the injection hole 316 formed at the tip portion of the nozzle body 303.

  A back pressure control chamber 319 is formed in the valve body 306 on the rear end side of the fuel injection valve 301. High pressure fuel from the common rail 312 is introduced into the back pressure control chamber 319 through the fuel passage 313, the pressure introduction chamber 321, and the introduction side orifice 320. The back pressure control chamber 319 also communicates with the opening / closing orifice 323, and the opening / closing orifice 323 is opened and closed by lift control of the valve ball 324 by the back pressure control unit 307. When the valve ball 324 is lifted by the control of the back pressure control unit 307 and the opening / closing orifice 323 is opened, the high pressure fuel in the back pressure control chamber 319 passes through a circulating passage (not shown) to the low pressure side via the opening / closing orifice 323. Returned.

  In the fuel injection valve 301 having such a configuration, when high pressure fuel is introduced into the back pressure control chamber 319 with the opening / closing orifice 323 being closed under the control of the back pressure control unit 307, the pressure of the high pressure fuel is reduced to the valve piston. It acts on the vicinity of the rear end portion 305A of 305 and the pressure receiving portion 304A of the nozzle needle 304. In this case, the nozzle needle 304 is seated on the seat portion 317 by the back pressure of the back pressure control chamber 319 and the urging force of the nozzle spring 318 received through the lift adjustment shim 328 and the valve piston 305, and the injection hole 316 is It will be closed.

  On the other hand, when the opening / closing orifice 323 is opened under the control of the back pressure control unit 307, the high pressure fuel in the back pressure control chamber 319 is circulated to the fuel low pressure side via the opening / closing orifice 323, and the valve piston 305 The high pressure acting on the rear end 305A is released. In this case, the nozzle needle 304 is separated (lifted) from the seat portion 317 against the urging force of the nozzle spring 318 due to the high pressure still acting on the pressure receiving portion 304A, and the injection hole 316 is opened. Fuel injection will be performed.

Japanese Patent Laying-Open No. 2006-274742 (FIGS. 4 and 7)

  By the way, in recent years, with the increase in exhaust gas purification standards, the pressure of high-pressure fuel injected into the cylinders of internal combustion engines has been further increased. Therefore, in the fuel injection valve 301 having the conventional configuration shown in FIG. 8, when the high pressure fuel is returned from the back pressure control chamber 319 to the low pressure side via the opening / closing orifice 323, a rapid pressure drop occurs. . When this abrupt pressure drop occurs, heat is generated and bubbles are generated in the fuel, the back pressure control unit 307 is exposed to high heat, and the flow of the fuel becomes faster. Bubbles may collapse at the sheet position, and cavitation erosion around the sheet position may occur. Therefore, the accuracy of the back pressure control of the fuel injection valve is lowered, and there is a possibility that precise injection control cannot be performed.

  Therefore, the inventor of the present invention diligently studied, and in addition to the first throttle portion between the back pressure control chamber and the back pressure control valve, a second throttle portion is further provided on the low pressure portion side than the back pressure control valve. It has been found that such a problem can be solved by providing, and the present invention has been completed. That is, the present invention provides a fuel injection valve capable of performing precise injection control by gradually reducing the pressure drop of fuel discharged from the back pressure control chamber and reducing the generation of high heat and erosion. With the goal.

  According to the present invention, high-pressure fuel is sent to the front end side of the nozzle needle for opening and closing the injection hole, and high-pressure fuel is introduced into the back pressure control chamber on the rear end side of the nozzle needle so that the high pressure fuel in the back pressure control chamber is A fuel injection valve that lifts the nozzle needle by injecting fuel into the low-pressure part and injects high-pressure fuel from the injection hole. The fuel injection valve discharges high-pressure fuel from the back-pressure control chamber to the low-pressure side. A back pressure control valve for controlling the flow rate of the fuel; a back pressure passage between the back pressure control chamber and the back pressure control valve; a first throttle portion; and a seat position of the back pressure control valve. A fuel injection valve including a second throttle portion on the low pressure portion side is provided, and the above-described problems can be solved.

  In configuring the fuel injection valve of the present invention, it is preferable that the flow passage area of the second throttle portion is larger than the flow passage area of the first throttle portion.

  Further, in configuring the fuel injection valve of the present invention, the back pressure control valve includes a valve body and a valve that is slidably held inside the valve body, and the valve body receives the high pressure fuel in the back pressure control chamber. An oil sump chamber that flows in, and an inflow opening and an outflow opening for high-pressure fuel provided so as to face the oil sump chamber, and a surface where the oil sump chamber and the outflow opening continue are seated on the valve It is preferable that the second throttle portion is formed by the shape of the portion on the outflow opening side of the seat in the valve.

  Further, in configuring the fuel injection valve of the present invention, the portion on the outflow opening side of the seat in the valve is a small diameter portion smaller than the diameter of the seating portion, a notch portion in which a part of the outer peripheral surface is notched, Or it is preferable to provide either of the passage holes which connect the oil reservoir chamber side and the low pressure part side.

  According to the fuel injection valve of the present invention, since the second throttle part is provided on the low pressure part side from the back pressure control valve, the pressure of the fuel returned from the back pressure control chamber to the low pressure part is decreased stepwise. Can be made. Therefore, the pressure drop width of the high-pressure fuel passing through the first throttle portion is reduced, heat generation is suppressed and bubbles are suppressed, the back pressure control unit is prevented from being exposed to high heat, and the back pressure is reduced. The occurrence of erosion at the seat position of the control valve can be reduced. Therefore, the back pressure control is performed with high accuracy, and precise injection control can be performed.

  In the fuel injection valve of the present invention, the flow area of the second throttle portion is larger than the flow passage area of the first throttle portion, so that the pressure of the fuel returned from the back pressure control chamber to the low pressure portion is efficiently Can be lowered step by step.

  Further, in the fuel injection valve of the present invention, the second throttle portion is formed using the shape of the valve of the back pressure control valve, so that it is relatively easy to process rather than the fuel flow path returned to the low pressure portion. A valve | bulb can be processed and a 2nd aperture | diaphragm | squeeze part can be comprised.

  Further, in the fuel injection valve according to the present invention, by forming the second throttle portion with a predetermined valve shape, the size of the gap serving as the throttle portion can be made relatively large, and the throttle having a desired passage area can be formed. The part can be easily formed.

Hereinafter, embodiments relating to the fuel injection valve of the present invention will be specifically described. However, this embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.
In addition, in each figure, what has attached | subjected the same code | symbol has shown the same member, and description is abbreviate | omitted suitably.

[First Embodiment]
A fuel injection valve according to a first embodiment of the present invention will be described with reference to FIGS.
First, the overall configuration of the common rail system including the fuel injection valve 1 of the present embodiment will be described with reference to the configuration example shown in FIGS. 1 and 2.
The common rail system includes a high pressure pump 52 that pumps fuel from a fuel tank 51, a common rail 12 that stores the high pressure fuel pumped by the high pressure pump 52, and an internal combustion engine (not shown) that stores the high pressure fuel stored in the common rail 12. The main component is a fuel injection valve 1 that is injected into the cylinder. The configuration itself of this common rail system is basically the same as a conventionally known common rail system.

  Among these, the fuel injection valve 1 includes an injector housing 2, a nozzle body 3, a nozzle needle 4, a valve piston 5, a valve body 6, a back pressure control unit 7, and an inlet connector 8 as main components. It is configured.

  The nozzle body 3 is fastened to the tip end portion (lower end side in FIG. 1) of the injector housing 2 by a nozzle nut 9. A fuel passage 13 extending from the inlet connector 8 through the injector housing 2 to the nozzle body 3 is formed in the fuel injection valve 1, and a fuel reservoir chamber 14 is formed at a portion of the nozzle needle 4 facing the pressure receiving portion 4 </ b> A. Is formed. In the injector housing 2, a fuel return path 15 is formed in the vicinity of the inlet connector 8 and branched from the fuel passage 13 to reach the fuel low pressure portion via the back pressure control portion 7.

  An injection hole 16 is formed at the tip of the nozzle body 3, and the injection hole 16 is closed when the tip of the nozzle needle 4 is seated (seat) on a seat portion 17 connected to the injection hole 16. The nozzle hole 4 is separated (lifted) from the seat portion 17 so that the injection hole 16 is opened. As a result, fuel injection can be started and stopped.

  A spring chamber 22 is formed around the central axis of the injector housing 2 connected to the nozzle body 3, and a nozzle spring 18 for biasing the nozzle needle 4 toward the seat portion 17. Is arranged. Further, the valve piston 5 is slidably inserted into the sliding hole 2A formed in the injector housing 2 and the sliding hole 6A formed in the valve body 6 so as to be positioned above the nozzle needle 4. It is installed.

Next, the structure of the valve body 6 and the back pressure control unit 7 of the fuel injection valve 1 shown in FIG. FIG. 2 shows an enlarged cross-sectional view of the vicinity of the valve body 6 and the back pressure control unit 7 surrounded by a one-dot chain line A in FIG.
A back pressure control chamber 19 is formed in the valve body 6 at a position where the vicinity of the tip of the valve piston 5 is located, and the tip of the valve piston 5 faces from the lower side (the injection hole 16 side). Yes.

  The back pressure control chamber 19 communicates with an introduction-side orifice 20 formed in the valve body 6. The introduction-side orifice 20 is communicated with the fuel passage 13 via a pressure introduction chamber 21 formed annularly in the circumferential direction of the valve body 6 between the valve body 6 and the injector housing 2. As a result, the pressure introduced from the common rail is supplied to the back pressure control chamber 19.

  The back pressure control chamber 19 also communicates with an opening / closing orifice 23 as a first throttle portion, and the opening / closing orifice 23 is opened and closed by a valve ball (control valve body) 24 of the back pressure control unit 7 described later. It is possible. The pressure receiving area of the top 5A of the valve piston 5 in the back pressure control chamber 19 is set larger than the pressure receiving area of the pressure receiving part 4A of the nozzle needle 4.

  The back pressure control unit 7 includes a magnet 25, an armature 27, a valve ball 24 that is integrally fixed to the armature 27, and a back pressure control chamber 19. Then, when a drive signal is supplied from the control circuit to the magnet 25, the armature 27 is attracted to the magnet 25 against the urging force of the valve spring 26, and the valve ball 24 is lifted from the opening / closing orifice 23, and back. The pressure in the pressure control chamber 19 can be opened to the fuel return path 15.

  By operating the valve ball 24 in this way, the pressure in the back pressure control chamber 19 is controlled, and by controlling the back pressure of the nozzle needle 4 via the valve piston 5, the seat on the seat portion 17 of the nozzle needle 4 is controlled. And the lift can be controlled.

In the fuel injection valve 1 configured as described above, the high-pressure fuel from the common rail 12 acts on the pressure receiving portion 4A of the nozzle needle 4 in the fuel reservoir chamber 14 from the inlet connector 8 through the fuel passage 13 and introduces pressure. It also acts on the top 5 </ b> A of the valve piston 5 in the back pressure control chamber 19 through the chamber 21 and the introduction-side orifice 20.
Therefore, when the back pressure control chamber 19 is blocked from the low fuel pressure side by the valve ball 24, the nozzle needle 4 receives the back pressure of the back pressure control chamber 19 received through the valve piston 5 and the biasing force of the nozzle spring 18. Thus, the sheet is formed on the sheet portion 17 of the nozzle body 3 and the injection hole 16 is closed.

  On the other hand, when the armature 27 is attracted to the magnet 25 by supplying a drive signal to the magnet 25 at a predetermined timing and the valve ball 24 opens the opening / closing orifice 23, the high pressure in the back pressure control chamber 19 is increased. Therefore, the high pressure applied to the top portion 5A of the valve piston 5 in the back pressure control chamber 19 is released, and the nozzle needle 4 acts on the pressure receiving portion 4A. The high pressure is lifted from the seat portion 17 against the urging force of the nozzle spring 18 and the injection hole 16 is opened to perform fuel injection.

  When the opening / closing orifice 23 is closed by the valve ball 24 by demagnetizing the magnet 25, the pressure in the back pressure control chamber 19 causes the nozzle needle 4 to move to the seat portion 17 at the seat position via the valve piston 5. The injection hole 16 is closed and the fuel injection is finished.

Here, as shown in FIG. 2, the back pressure control unit 7 of the fuel injection valve 1 of the present embodiment recirculates fuel more than the seat position of the valve ball 24 in addition to the opening / closing orifice 23 as the first throttle unit. A second throttle unit 50 is provided on the path 15 side. The second throttle portion 50 is formed by extending the lower end of the armature guide 28 that slides and holds the armature 27 and guides the moving direction, and closes the upper end of the valve body 6.
In addition, the flow path area of the formed second throttle portion 50 is larger than the flow path area of the opening / closing orifice 23. Thereby, the orifice effect by the opening / closing orifice 23 is also obtained.

FIG. 3 shows the change in the pressure of the fuel released from the back pressure control unit 7 to the fuel low pressure unit along the position where the back pressure fuel flows.
A solid line A indicates a change in fuel pressure due to the configuration of the back pressure control unit 7 of the fuel injection valve 1 of the present embodiment. On the other hand, the broken line B shows the change in the fuel pressure due to the configuration of the back pressure control unit of the conventional fuel injection valve.
The pressure of the high-pressure fuel in the back pressure control chamber according to the conventional configuration is greatly reduced before and after passing through the opening / closing orifice. Therefore, high heat is generated when passing through the opening / closing orifice, and bubbles are generated in the fuel. The generated bubbles are crushed at the seat position of the valve ball where the flow velocity is increased, and cavitation erosion occurs at the seat position.

  On the other hand, in the configuration of this embodiment, when the high-pressure fuel in the back pressure control chamber 19 is opened by the valve ball 24, the opening / closing orifice (first throttle portion) 23 and the second throttle portion 50 are sequentially formed. After passing, it returns to the fuel tank 51 through the fuel return path 15. At this time, the fuel pressure is lowered step by step each time it passes through the opening / closing orifice 23 and the second throttle 50. Therefore, generation of high heat and bubbles in the opening / closing orifice 23 can be reduced, and generation of cavitation erosion at the seat position of the valve ball 24 can be reduced.

  By providing the second throttle portion 50 in this way, the high-pressure fuel released from the back pressure control chamber 19 passes through the second throttle portion 50 after passing through the opening / closing orifice 23, The fuel is returned to the fuel return path 15. Therefore, since the pressure of the high-pressure fuel to be opened is lowered stepwise, the pressure difference before and after the opening / closing orifice 23 can be made relatively small. Therefore, generation of heat and bubbles due to a rapid pressure drop when passing through the opening / closing orifice 23 is reduced, and expansion due to heat and destruction of the generated bubbles when passing through the seat position of the valve ball 24 cause cavitation erosion. Can be prevented from occurring.

[Second Embodiment]
The basic configuration of the fuel injection valve according to the second embodiment of the present invention is the same as that of the fuel injection valve of the first embodiment, but the configuration of the back pressure control unit is different. Hereinafter, differences from the configuration of the first embodiment will be described in detail.

FIG. 4A shows an enlarged cross-sectional view of the vicinity of the valve body 56 and the back pressure control unit 57 in the fuel injection valve of the present embodiment, and FIG. 4B shows the state in FIG. The expanded sectional view of the area | region B enclosed with the dashed-dotted line is shown.
In the valve body 56, a back pressure control chamber 69 is formed at a position where the vicinity of the tip of the valve piston 55 is located, and the tip of the valve piston 55 faces from the lower side (the injection hole side). .

  The back pressure control chamber 69 communicates with an introduction side orifice 70 formed in the valve body 56. Similar to the configuration of the first embodiment, the introduction-side orifice 70 has a fuel passage through a pressure introduction chamber 71 formed annularly in the circumferential direction of the valve body 56 between the valve body 56 and the injector housing 52. 63 is communicated. As a result, the pressure introduced from the common rail is supplied to the back pressure control chamber 69.

  The back pressure control chamber 69 also communicates with a pressure discharge path 81, and an opening / closing orifice 73 serving as a first throttle portion is provided in the middle of the pressure discharge path 81. The pressure discharge path 81 provided with the opening / closing orifice 73 is communicated with the fuel return path 65, and a fuel reservoir chamber 83 is formed between the pressure discharge path 81 and the fuel return path 65.

  An armature guide hole 78 is formed at a position facing the opening of the fuel recirculation path 65 in the fuel reservoir chamber 83, and an armature 77 is slidably disposed in the armature guide hole 78. The armature 77 includes a seat portion 77 a seated on a seat surface 85 formed at the edge of the inlet of the fuel reservoir chamber 83 to the fuel return path 65, and moves up and down by the exciting force of the magnet 75. Yes. When a drive signal is supplied from the control circuit to the magnet 75, the armature 77 is attracted to the magnet 75 against the urging force of the valve spring 76, and the seat portion 77a of the armature 77 is lifted from the seat surface 85. The pressure in the back pressure control chamber 69 can be opened to the fuel return path 65 via the pressure discharge path 81.

  In this way, the pressure of the back pressure control chamber 69 is controlled by operating the armature 77 as described above, and the back pressure of the nozzle needle (not shown) is controlled via the valve piston 55, so that the nozzle needle The seat and the lift to the seat portion (not shown) can be controlled.

Here, as shown in FIGS. 4A to 4B, the back pressure control unit 57 of the fuel injection valve of the present embodiment has a seat for the armature 77 in addition to the opening / closing orifice 73 as the first throttle unit. A second throttle portion 90 is provided closer to the fuel return path 65 than the seat position of the portion 77a. The second throttle portion 90 is a gap formed by the difference in diameter between the outer peripheral surface of the extending portion 77 b extending from the seat portion 77 a of the armature 77 toward the fuel return path 65 and the inner peripheral surface of the fuel return path 65. The aperture part consists of The configuration of the second throttle portion of the first embodiment uses the lower end portion of the armature guide, and since the diameter of the lower end portion is large, the size of the gap serving as the throttle portion needs to be relatively small. On the other hand, when the second diaphragm 90 is configured using the shape of the armature 77 as described above, the size of the gap serving as the diaphragm can be made relatively large. It is easy to form a narrowed portion with a passage area.
Further, the flow path area of the formed second throttle portion 90 is larger than the flow path area of the opening / closing orifice 73. Thereby, the orifice effect by the opening / closing orifice 73 is also obtained.

  Also in the fuel injection valve of the present embodiment, when the seat portion 77a of the armature 77 is lifted by providing the second throttle portion 90 having such a configuration, the high-pressure fuel in the back pressure control chamber 69 is After passing through the opening / closing orifice 73 of the pressure discharge path 81, it passes through the second throttle portion 90 and flows to the fuel return path 65. Therefore, since the pressure of the high-pressure fuel to be opened is lowered stepwise, the pressure difference before and after the opening / closing orifice 73 can be made relatively small. Therefore, generation of heat and bubbles due to a sudden pressure drop when passing through the opening / closing orifice 73 is reduced, and expansion due to heat and destruction of the generated bubbles when passing through the sheet position of the sheet portion 77a of the armature 77 are destroyed. Thus, cavitation erosion can be prevented from occurring.

As an example of forming the second throttle portion 90 using the shape of the armature 77, various configurations other than the configuration shown in FIG. FIGS. 5A to 5B are cross-sectional views corresponding to the views of the XX cross section in FIG.
As described above, in the example of FIG. 5A, the diameter of the extending portion 77b extending toward the fuel return path 65 from the seat portion 77a of the armature 77 is made smaller than the diameter of the fuel return path 65. The gap is configured as the second diaphragm portion 50A.
On the other hand, in FIG. 5B, a notch 87 is formed on a part of the outer peripheral surface of the extending portion 77 b extending from the seat 77 a of the armature 77 toward the fuel return path 65, and is formed by the notch 87. This is an example in which the gap formed as the second aperture portion 90B.

FIGS. 6A and 6B are views showing still another example of the second diaphragm portion, and FIG. 6A shows an enlarged view around the seat portion 77a of the armature 77, and FIG. FIG. 6B is a cross-sectional view of the YY cross section in FIG.
In the example of FIGS. 6A to 6B, the fuel flow return path from the radial flow path 89 a and the radial flow path 89 a to the extending part 77 b extending to the fuel return path 65 side from the seat portion 77 a of the armature 77. In this example, an axial flow path 89b extending to the 65 side and communicating with the fuel return path 65 is provided and configured as the second throttle portion 90C.

  Further, FIG. 7 is an example in which the shape of the armature 77 is not used, but a throttle portion is formed in the middle of the fuel recirculation path 65 to form the second throttle portion 90D. In the example shown in FIG. 7, the inner surface of the fuel return path 65 is formed in the middle of the fuel return path 65 downstream of the seat position where the valve ball 74 fixed to the tip of the armature 77 is seated. Two diaphragm portions 90D are provided.

  In any of the configurations of FIGS. 5 to 7, the flow passage areas of the second throttle portions 90 </ b> A to 90 </ b> D are configured to be larger than the flow passage area of the opening / closing orifice 73 as the first throttle portion. Yes. Therefore, since the pressure of the high-pressure fuel to be released is lowered stepwise, the pressure difference before and after the opening / closing orifice 73 can be made relatively small. Therefore, generation of heat and bubbles due to a rapid pressure drop when passing through the opening / closing orifice 73 is reduced, and expansion due to heat and the generated bubbles pass through a sheet position where the sheet portion 77a of the armature 77 is set as a sea. It is possible to prevent the occurrence of cavitation erosion due to destruction.

It is a block diagram which shows the structure of the common rail system provided with the fuel injection valve concerning the 1st Embodiment of this invention. It is an expanded sectional view of the back pressure control part periphery of a fuel injection valve of a 1st embodiment. It is a figure which shows the pressure change of the high pressure fuel discharged | emitted. It is an expanded sectional view around a back pressure control part of a fuel injection valve concerning a 2nd embodiment of the present invention. It is a structural example of the 2nd aperture_diaphragm | restriction part comprised using the shape of the armature. It is a figure which shows the example which provided the orifice in the armature. It is a figure which shows the example which provided the orifice in the fuel return path. It is a figure for demonstrating the structure of the conventional fuel injection valve.

Explanation of symbols

1: Fuel injection valve, 2: Injector housing, 2A: Sliding hole, 3: Nozzle body, 4: Nozzle needle, 4A: Pressure receiving part, 5: Valve piston, 6.56: Valve body, 7.57: Back pressure Control unit, 12: common rail, 13/63: fuel passage, 15/65: fuel return passage, 16: injection hole, 19/69: back pressure control chamber, 20/70: inlet-side orifice, 21/71: pressure introduction Chamber, 23/73: opening / closing orifice, 24/74: valve ball, 25/75: magnet, 26/76: valve spring, 27: armature, 28: armature guide, 50: second restrictor, 77: armature 77a: sheet part, 77b: extension part, 78: armature guide hole, 81: pressure discharge path, 83: pressure reservoir, 85: sheet surface, 87: notch part, 9 · 90A · 90B · 90C · 90D: the second diaphragm portion

Claims (4)

High pressure fuel is sent to the front end side of the nozzle needle for opening and closing the injection hole, high pressure fuel is introduced into the back pressure control chamber on the rear end side of the nozzle needle, and the high pressure fuel in the back pressure control chamber is reduced in pressure. In the fuel injection valve that lifts the nozzle needle by discharging it to the part and injects the high-pressure fuel from the injection hole,
The back pressure control valve for controlling the flow rate of the high pressure fuel in the middle of a back pressure flow path for discharging the high pressure fuel from the back pressure control chamber to the low pressure side;
The back pressure flow path between the back pressure control chamber and the back pressure control valve is provided with a first throttle portion, and a second throttle portion is provided closer to the low pressure portion than the seat position of the back pressure control valve. A fuel injection valve comprising:   2. The fuel injection valve according to claim 1, wherein a flow passage area of the second throttle portion is larger than a flow passage area of the first throttle portion. The back pressure control valve includes a valve body and a valve slidably held inside the valve body,
The valve body includes an oil reservoir chamber into which the high-pressure fuel flows in the back pressure control chamber, and an inflow opening and an outflow opening of the high-pressure fuel provided to face the oil reservoir chamber, The surface where the oil reservoir chamber and the outflow opening are continuous is the seat position where the seating portion of the valve is seated,
3. The fuel injection valve according to claim 1, wherein the second throttle portion is formed by a shape of a portion of the valve that is closer to the outflow opening than the seating portion.   The portion of the valve that is closer to the outflow opening than the seating portion is a small-diameter portion that is smaller than the diameter of the seating portion, a notch portion in which a part of the outer peripheral surface is notched, or the oil reservoir chamber side and the low pressure The fuel injection valve according to claim 3, further comprising any one of passage holes that connect the portion side.

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