JP2011106321A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve which can generate a proper quantity of cavitation bubbles from the time of low fuel pressure to the time of high fuel pressure when a fuel is atomized. <P>SOLUTION: The fuel injection valve 1A includes: a body 2 with a nozzle hole 2a formed therein; an inner needle 3 that opens and closes the nozzle hole 2a by sliding in the body 2; an outer needle 4 which is provided in the body 2 but outside the inner needle 3, forms an expansion chamber 5 at an inlet of the nozzle hole 2a with the body 2 and the inner needle 3, and is formed in a shape capable of expanding the expansion chamber 5, whose volume changes by sliding in the body 2, with the body 2 by a stepwise mode; and wax 6 which is provided between the body 2 and the outer needle 4 in a sliding direction, and changes the volume of expansion chamber 5 according to a temperature. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel injection valve, and more particularly to a fuel injection valve for atomizing fuel.

Conventionally, fuel injection valves are used in internal combustion engines and the like. In an internal combustion engine, fuel atomization and combustion can be promoted by atomizing the fuel injected from the fuel injection valve. In this regard, for example, Patent Documents 1 and 2 disclose techniques that are considered to be related to the present invention in terms of a technique for atomizing fuel.
In addition, for example, Patent Documents 3 and 4 disclose a technique for changing the cross-sectional area of the injection hole of the fuel injection valve. For example, Patent Document 5 discloses a technique for changing the fuel injection amount according to the temperature. The technologies possessed are disclosed in, for example, Patent Document 6.

JP 2004-19481 A JP 2007-309236 A JP 2003-214298 A JP 2000-27738 A JP 2006-266145 A JP 2006-316668 A

By the way, when a stagnation place is provided in a part of the fuel flow path of the fuel injection valve, a vortex is generated in the stagnation place during fuel circulation. Cavitation bubbles are generated in the vortex flow in which the central pressure is reduced below the saturated vapor pressure. Cavitation bubbles rapidly grow and collapse after fuel is injected from the nozzle holes. Thereby, atomization of the fuel can be achieved.
In this regard, for example, in the technology disclosed in Patent Document 1, the nozzle hole is constituted by a first nozzle hole part and a second nozzle hole part located downstream thereof, and a part of the fuel jet flows in the second nozzle hole part. An accommodating portion is provided for accommodating. With this configuration, cavitation bubbles are generated in the vicinity of the outer peripheral surface of the fuel jet and are used for atomization of the fuel.

However, when cavitation bubbles are generated, there are the following problems.
As shown in FIG. 11A, at the time of high fuel pressure (when the fuel flow rate is high), the fuel main flow F is separated at the stagnation site S and a vortex R is generated at the stagnation site S. In this case, since the flow rate of the fuel is high, the central pressure of the vortex R is sufficiently reduced, and more cavitation bubbles can be generated. Therefore, in this case, atomization of the fuel can be promoted by the collapse C of the cavitation bubbles.

  On the other hand, as shown in FIG. 11B, at the time of low fuel pressure (when the fuel flow rate is low), the main fuel flow F is difficult to separate, and the flow velocity of the main fuel flow F is slow even if the swirl R is generated in the stagnation site S. It has become. For this reason, in this case, the rotational speed of the vortex flow R is relatively low, and the central pressure of the vortex flow R is not sufficiently lowered. In this case, the amount of cavitation bubbles generated is reduced and the degree of promotion of fuel atomization is also reduced.

  On the other hand, in the disclosed technique of Patent Document 1, the size of the accommodating portion provided in the second nozzle hole portion is constant throughout the low fuel pressure and the high fuel pressure. For this reason, in the disclosed technology, it is conceivable that when the cavitation bubbles are generated, for example, the size of the housing portion is appropriate when the fuel pressure is high, but becomes relatively large when the fuel pressure is low. In this case, there is a problem in that it is considered that an appropriate amount of cavitation bubbles may not be generated from the low fuel pressure to the high fuel pressure.

  Accordingly, the present invention has been made in view of the above problems, and provides a fuel injection valve capable of generating an appropriate amount of cavitation bubbles from a low fuel pressure to a high fuel pressure when atomizing the fuel. Objective.

  The present invention for solving the above-described problems includes a body in which an injection hole is formed, an inner needle that opens and closes the injection hole by sliding in the body, an inside of the body, and an outer side of the inner needle. The expansion chamber is formed with the body and the inner needle at the entrance of the nozzle hole, and the expansion chamber whose volume is changed by sliding in the body is expanded in a stepwise manner together with the body. An outer needle formed in a shape that can be made, and a thermal expansion body that is provided between the body and the outer needle in a sliding direction and makes the volume of the expansion chamber variable according to temperature. The fuel injection valve provided.

  According to the present invention, when atomizing fuel, an appropriate amount of cavitation bubbles can be generated from low fuel pressure to high fuel pressure.

FIG. 2 is a diagram schematically showing a main part of an internal combustion engine 50 together with an ECU 30. It is a figure which shows typically the principal part of 1 A of fuel injection valves. It is an enlarged view of the A section shown in FIG. Specifically, (a) shows a state in which the distal end portion 4a of the outer needle 4 is in contact with the bottom portion 2b of the body 2, and (b) shows a state in which the distal end portion 4a is separated from the bottom portion 2b. Show. It is a figure which shows typically the map data which prescribed | regulated the position of the outer needle 4 according to the fuel pressure. It is a figure which shows operation | movement of ECU30 with a flowchart. It is a figure which shows typically the flow aspect of the fuel which distribute | circulates 1 A of fuel injection valves. Specifically, (a) shows a flow mode at a low fuel pressure, and (b) shows a flow mode at a high fuel pressure. It is a figure which shows typically the principal part of the fuel injection valve 1B. It is a figure which shows typically the principal part of 1 C of fuel injection valves. It is a figure which shows typically the flow mode of the fuel which distribute | circulates 1 C 'of fuel injection valves. It is a figure which shows typically the flow aspect of the fuel which distribute | circulates 1 C of fuel injection valves. Specifically, (a) shows the flow mode during engine cold start (low fuel pressure), and (b) shows the flow mode during temperature rise (high fuel pressure). It is a figure which shows typically the flow aspect of the fuel relevant to generation | occurrence | production of a cavitation bubble. Specifically, (a) shows the flow mode at high fuel pressure, and (b) shows the flow mode at low fuel pressure.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  The fuel injection valve 1A and related structures will be described with reference to FIGS. As shown in FIG. 1, the fuel injection valve 1 </ b> A is provided in the internal combustion engine 50. In addition to the fuel injection valve 1 </ b> A, the internal combustion engine 50 includes a cylinder block 51, a cylinder head 52, a piston 53, an intake valve 55, an exhaust valve 56, and a spark plug 57. A cylinder 51 a is formed in the cylinder block 51. A piston 53 is accommodated in the cylinder 51a. A cylinder head 52 is fixed to the upper surface of the cylinder block 51. The combustion chamber 54 is formed as a space surrounded by the cylinder block 51, the cylinder head 52 and the piston 53.

  The cylinder head 52 is formed with an intake port 52a and an exhaust port 52b. The intake port 52 a guides intake air to the combustion chamber 54, and the exhaust port 52 b exhausts the gas in the combustion chamber 54. The cylinder head 52 is provided with intake and exhaust valves 55 and 56 for opening and closing these intake and exhaust ports 52a and 52b. The cylinder head 52 is provided with a spark plug 57 with an electrode protruding substantially at the center of the upper portion of the combustion chamber 54. Further, a fuel injection valve 1A is provided in a portion of the cylinder head 52 below the intake port 52a. The fuel injection valve 1A can directly inject fuel into the cylinder. The arrangement of the fuel injection valve 1A is not limited to this.

  As shown in FIG. 2, the fuel injection valve 1 </ b> A includes a body 2, an inner needle 3, and an outer needle 4. The body 2 is a substantially bottomed cylindrical member. A nozzle hole 2 a is formed at the tip of the body 2. The rear end side of the nozzle hole 2a is a cylindrical portion 2aa, and the front end side is a tapered portion 2ab that gradually increases in diameter from the cylindrical portion 2aa toward the front end. The nozzle hole 2 a is provided so that the center thereof coincides with the central axis of the body 2. The rear end side of the nozzle hole 2 a is open to the bottom 2 b of the body 2. A recess 2ba is formed in the bottom 2b. The concave portion 2ba is provided so that the radially inner portion of the bottom portion 2b is recessed in a columnar shape from the radially outer portion, and the center thereof substantially coincides with the central axis of the body 2. Therefore, specifically, the nozzle hole 2a is opened substantially at the center of the recess 2ba.

  The inner needle 3 is a substantially cylindrical member, and is provided in the body 2 so that the center axis thereof coincides with the center axis of the body 2. The inner needle 3 includes a cylindrical portion 3a and a tip portion 3b. The shape of the tip portion 3b is a shape that swells more than the cylindrical portion 3a. The tip 3b is formed so as to abut on the tapered portion 2ab, and specifically, is formed in an axisymmetric shape with a pentagonal cross section. The inner needle 3 slides in the body 2 to open and close the nozzle hole 2a. Specifically, the inner needle 3 opens the nozzle hole 2a by sliding toward the front end side, and closes the nozzle hole 2a by sliding toward the rear end side. That is, the fuel injection valve 1A is an externally opened fuel injection valve. Also, the fuel injection valve 1A forms a holographic cone spray by opening and closing the injection hole 2a by the inner needle 3 formed so that the tip 3b abuts against the tapered portion 2ab.

  The outer needle 4 is a substantially cylindrical member, and is provided inside the body 2 and outside the inner needle 3 so that the center axis thereof coincides with the center axis of the body 2. The outer needle 4 is provided slidably with respect to the body 2 and the inner needle 3, and the inner needle 3 is provided slidable with respect to the outer needle 4.

  A convex portion 4aa is formed at the distal end portion 4a of the outer needle 4. The convex portion 4aa is provided so that the radially inner portion of the tip portion 4a protrudes in a columnar shape from the radially outer portion, and its central axis substantially coincides with the central axis of the outer needle 4. ing. The convex portion 4aa of the outer needle 4 and the concave portion 2ba of the body 2 have the same diameter and axial length. As a result, the front end 4 a of the outer needle 4 can come into contact with the bottom 2 b of the body 2. The outer needle 4 is provided with a fuel flow path 4b. A plurality of fuel flow paths 4b are provided substantially equally along the circumferential direction. The outer needle 4 and the body 2 and the inner needle 3 form an enlarged chamber 5 at the entrance of the nozzle hole 2a. Each fuel flow path 4 b is open to communicate with the expansion chamber 5.

As shown in FIG. 3 (a), in the state where the distal end portion 4 a of the outer needle 4 is in contact with the bottom portion 2 b of the body 2, the expansion chamber 5 specifically includes the cylindrical portion 2 aa of the body 2 and the inner needle 3. And the tip portion 4a (more specifically, the convex portion 4aa) of the outer needle 4.
On the other hand, as shown in FIG. 3B, in the state where the distal end portion 4a of the outer needle 4 is separated from the bottom portion 2b of the body 2, the expansion chamber 5 specifically includes the cylindrical portion 2aa and the recessed portion 2ba of the body 2. And the inner needle 3 and the distal end portion 4a (more specifically, the convex portion 4aa) of the outer needle 4.

  Thus, the outer needle 4 can expand the expansion chamber 5 whose volume changes by sliding in the body 2 in a stepwise manner (in other words, in a discontinuous manner) together with the body 2. It is formed into a shape. In this embodiment, the shape is specifically realized by the concave portion 2ba of the body 2 and the convex portion 4aa of the outer needle 4.

  Returning to FIG. 1, the ECU 30 includes a microcomputer (not shown) composed of a CPU, ROM, RAM, and the like, an input / output circuit, and a drive circuit. Various sensors such as a fuel pressure sensor 71 for detecting the fuel pressure are electrically connected to the ECU 30. In addition, the fuel injection valve 1A is electrically connected to the ECU 30 as a control target. In this regard, specifically, the fuel injection valve 1A is provided with an actuator (not shown), and the actuator drives the outer needle 4 to an appropriate position in response to an input from the ECU 30.

  The ROM is configured to store a program describing various processes executed by the CPU, map data, and the like. When the CPU executes a process based on a program stored in the ROM while using a temporary storage area of the RAM as necessary, various control means, determination means, detection means, calculation means, and the like are functional in the ECU 30. To be realized.

  In this respect, specifically, the ECU 30 functionally realizes a control means for controlling the position of the outer needle 4 in accordance with, for example, the fuel pressure. Specifically, this control means is realized so as to control the position of the outer needle 4 by referring to the map data shown in FIG. 4 and reading the position of the outer needle 4 according to the fuel pressure. In this regard, when the fuel pressure is low (when it is lower than the predetermined value α), the position of the outer needle 4 is controlled so as to come into contact with the bottom 2b, and when the fuel pressure is high (when the fuel pressure is higher than the predetermined value α). The position is controlled so as to be separated from the bottom 2b. Further, when the fuel pressure is high, the position of the outer needle 4 is controlled at a position farther from the bottom 2b (in a higher position) as the fuel pressure is higher.

  Next, the operation of the ECU 30 will be described using the flowchart shown in FIG. This flowchart is repeatedly executed at very short time intervals during operation of the internal combustion engine 50. The ECU 30 detects the fuel pressure (step S1). Subsequently, the ECU 30 controls the position of the outer needle 4 according to the detected fuel pressure (step S2). Thereby, the outer needle 4 can be driven to a desired position according to the fuel pressure.

Next, the function and effect of the fuel injection valve 1A will be described with reference to FIG. Here, when the fuel pressure is low, the flow rate of the fuel flowing through the fuel injection valve 1A is low. If the volume of the stagnation field, which is the cavitation generation area, is disproportionately large despite the low fuel flow rate, it is difficult to generate sufficient cavitation bubbles.
On the other hand, in the fuel injection valve 1A, as shown in FIG. 6A, the outer needle 4 is in contact with the bottom 2b when the fuel pressure is low. And at this time, the magnitude | size of the expansion chamber 5 can be made small compared with the case where the outer needle 4 is the state spaced apart from the bottom part 2b. And thereby, the volume of a stagnation place can be made into the suitable magnitude | size corresponding to the case where the flow rate of a fuel is a low flow rate. For this reason, in the fuel injection valve 1A, the center pressure of the vortex generated in the expansion chamber 5 can be sufficiently reduced even at the low fuel pressure at which the fuel flow rate is low. Therefore, in the fuel injection valve 1A, cavitation bubbles can be suitably generated even at a low fuel pressure at which the fuel flow rate is low.

On the other hand, when the fuel pressure is high, the fuel flow rate is high. If the volume of the stagnation field is disproportionately small despite the high fuel flow rate, it is difficult to sufficiently generate cavitation bubbles due to the insufficient volume of the stagnation field.
On the other hand, in the fuel injection valve 1A, as shown in FIG. 6B, the outer needle 4 is in a separated state at high fuel pressure. At this time, the volume of the expansion chamber 5 is expanded in a stepwise manner from the contact state. For this reason, in the fuel injection valve 1A, the volume change degree of the stagnation field can be increased at high fuel pressure. In the fuel injection valve 1A, by changing the volume of the stagnation field according to the fuel pressure at the time of high fuel pressure, it is possible to quickly change the volume according to the change in flow rate at the time of high fuel pressure. And thereby, the volume of a stagnation place can be made into the suitable magnitude | size corresponding to the flow rate at the time of high fuel pressure. Therefore, the fuel injection valve 1A can generate an appropriate amount of cavitation bubbles from the low fuel pressure to the high fuel pressure.

A fuel injection valve 1B according to the present embodiment will be described with reference to FIG. The fuel injection valve 1B is substantially the same as the fuel injection valve 1A except that the actuator for driving the outer needle 4 is not particularly provided and a wax 6 is provided instead. The fuel injection valve 1B can be applied to the internal combustion engine 50, for example, instead of the fuel injection valve 1A.
The wax 6 is provided between the body 2 and the outer needle 4 in the sliding direction. Specifically, the wax 6 is provided between the bottom portion 2b of the body 2 and the tip portion 4a of the outer needle 4 and in a portion between the body 2 and the convex portion 4aa of the outer needle 4 in the radial direction. . The wax 6 is a thermal expansion body that makes the volume of the expansion chamber 5 variable according to the temperature. The characteristics such as the expansion start temperature of the wax 6, the degree of expansion (inclination) with respect to the temperature change, and the maximum expansion amount can be adjusted.

Next, the function and effect of the fuel injection valve 1B will be described. Here, the fuel is pumped by a fuel pump (not shown) that is driven by the power of the internal combustion engine 50. In this case, the fuel pressure generally becomes low because the increase in fuel pressure at a low temperature during engine cold start is slow. For this reason, at the low temperature at the time of engine cold start, the flow rate of the fuel flowing through the fuel injection valve 1B also becomes low.
On the other hand, in the fuel injection valve 1B, the volume of the expansion chamber 5 can be relatively reduced because the wax 6 contracts when the engine is cold. And thereby, the volume of a stagnation place can be made into the suitable magnitude | size corresponding to the case where the flow rate of a fuel is a low flow rate. Therefore, the fuel injection valve 1B can sufficiently reduce the center pressure of the vortex generated in the expansion chamber 5 even at a low temperature when the engine is cold, and can suitably generate cavitation bubbles.

On the other hand, when the temperature rises, the fuel pressure increases and the fuel flow rate increases.
On the other hand, in the fuel injection valve 1B, the outer needle 4 further expands the volume of the expansion chamber 5 expanded in a stepwise manner by expanding the wax 6 in response to the temperature rise. For this reason, in the fuel injection valve 1B, when changing the volume of the stagnation field, it is possible to change the volume quickly according to the change in the flow velocity even at the high fuel pressure that requires a greater degree of change. And thereby, the volume of a stagnation place can be made into the suitable magnitude | size corresponding to the flow rate even at the time of high fuel pressure. Therefore, the fuel injection valve 1B can generate an appropriate amount of cavitation bubbles from the low fuel pressure to the high fuel pressure. Furthermore, the fuel injection valve 1B can be configured to be advantageous in terms of cost as compared with the fuel injection valve 1A because an actuator, a drive circuit, and a control program for driving the outer needle 4 are not required.

  A fuel injection valve 1C according to the present embodiment will be described with reference to FIG. The fuel injection valve 1 </ b> C includes a nozzle body 11 and a nozzle needle 12. The nozzle body 11 is a substantially bottomed cylindrical member, and includes a nozzle hole 11b in the bottom portion 11a. In this regard, the fuel injection valve 1C is a multi-hole type fuel injection valve, and a plurality of injection holes 11b are provided at substantially equal intervals along the circumferential direction. The nozzle hole 11b has a tapered diameter increasing toward the tip end, and the center axis of the nozzle hole 11b is inclined so that the distance from the center axis of the nozzle body 11 gradually increases toward the tip end. ing. As a result, in the nozzle hole 11b, the wall surface 11ba located on the radially outer side is more inclined with respect to the central axis of the nozzle body 11 than the wall surface 11bb located on the radially inner side.

A storage portion 11bc is provided at an intermediate portion of the nozzle hole 11b (more specifically, the wall surface 11ba). The storage portion 11bc extends from the nozzle hole 11b along the radial direction. The storage portion 11bc has a substantially constant height and width. The width of the storage portion 11bc is set in accordance with the width of the intermediate portion of the corresponding nozzle hole 11b.
The storage portion 11bc is provided with a movable partition wall 13 and a spring 14. The partition wall 13 has the same height (thickness) and width as the storage portion 11bc, and is slidably provided in the storage portion 11bc. Further, the tip of the partition wall 13 is formed in a shape along the wall surface 11ba so as to form a flush surface with the wall surface 11ba in a state of being completely stored in the storage portion 11bc. The spring 14 is provided in a portion of the storage portion 11 bc that is radially outward from the partition wall 13.

Of the nozzle body 11, a cylinder portion 11c is provided at a radially outer portion of the storage portion 11bc. The cylinder part 11c is provided on the same axis as the storage part 11bc in the radial direction, and extends in a cylindrical shape along the extending direction of the storage part 11bc.
The cylinder part 11c is provided with a piston member 15 and wax 6. The piston member 15 is a columnar member and is slidably provided on the cylinder portion 11c. The wax 6 is provided in a portion radially inward of the piston member 15 in the cylinder portion 11c.
The partition wall 13 and the piston member 15 are connected by a rod 16. The storage portion 11bc and the cylinder portion 11c communicate with each other in a manner that allows the rod 16 to slide.

  The nozzle needle 12 is a substantially cylindrical member, and is provided in the nozzle body 11 so that the center axis thereof coincides with the center axis of the nozzle body 11. The nozzle needle 12 slides in the nozzle body 11 to open and close the nozzle hole 11b. Specifically, the nozzle needle 12 opens toward the rear end side to open the nozzle hole 11b, and slides toward the front end side to close the nozzle hole 11b. That is, the fuel injection valve 1C is an internal opening type fuel injection valve.

  Next, before describing the function and effect of the fuel injection valve 1C, the case of the fuel injection valve 1C ′ that is substantially the same as the fuel injection valve 1C except that the partition wall 13 is not provided will be described with reference to FIG. explain. As shown in FIG. 9, the fuel flows between the nozzle body 11 ′ and the nozzle needle 12, and then reaches the nozzle hole 11b. At this time, the fuel flows at an acute angle with respect to the nozzle hole 11b. For this reason, the fuel is strongly pressed against the wall surface 11bb and tries to flow along the wall surface 11bb in the injection hole 11b. This promotes fuel thinning. Further, when the fuel flows into the nozzle hole 11b, the fuel is separated at the inlet of the nozzle hole 11b and the portion on the wall surface 11ba side. For this reason, the part in the nozzle hole 11b and the wall surface 11ba side becomes a stagnation place.

  In such a fuel flow mode, when the fuel pressure is low (when the fuel flow rate is low), the rotational speed of the vortex generated in the stagnation field is relatively lower than when the flow rate is high. Therefore, in this case, the degree of decrease in the central pressure of the vortex is relatively reduced, and as a result, the amount of cavitation bubbles generated is reduced. In this case, it is difficult to reduce the thickness of the fuel. As a result, the effect of promoting fuel atomization is reduced.

  On the other hand, in the fuel injection valve 1C, as shown in FIG. 10A, the wax 6 contracts at a low temperature when the engine is cold. As a result, in the fuel injection valve 1 </ b> C, the tip of the partition wall 13 protrudes from the storage portion 11 bc by the urging force of the spring 14. As a result, the volume of the stagnation field can be reduced, so that the rotational speed of the generated vortex can be increased, so that more cavitation bubbles can be generated as compared with the fuel injection valve 1C ′. Further, in this case, a backflow of air from the inside of the cylinder is generated in the nozzle hole 11b and in the downstream side (tip side) of the partition wall 13. For this reason, in this case, the liquid film thickness of the thinned fuel can be maintained, and hence deterioration of fuel atomization due to the inhibition of thinning can be suppressed.

  On the other hand, when the temperature rises, the wax 6 expands and the partition wall 13 moves backward, and finally the partition wall 13 is stored in the storage portion 11bc as shown in FIG. On the other hand, when the temperature rises, the fuel pressure and the flow rate of the fuel are higher than when the engine is cold, so that a sufficient amount of cavitation bubbles can be generated by securing a larger stagnation place. Further, since the amount of cavitation bubbles generated is sufficient, it is possible to reduce the thickness of the fuel, and as a result, it is possible to favorably promote fuel atomization.

The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.
For example, in the first and second embodiments described above, a case has been described in which the fuel injection valves are the externally opened fuel injection valves 1 </ b> A and 1 </ b> B that form a hollow cone-shaped fuel spray. This is structurally easy for the fuel injection valve to which the present invention is applied, and such a fuel injection valve has a structure advantageous for direct in-cylinder fuel injection, and is therefore used for direct in-cylinder fuel injection. In many cases, this is due to the desire for further atomization of the fuel. However, the present invention is not necessarily limited to this, and the fuel injection valve may be another appropriate fuel injection valve.

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Body 2a Injection hole 2b Bottom part 2ba Concave 3 Inner needle 4 Outer needle 4a Tip part 4aa Convex part 5 Expansion chamber 6 Wax 11 Nozzle body 12 Nozzle needle 13 Partition 14 Spring 15 Piston member 30 ECU
50 Internal combustion engine

Claims (1)

A body in which a nozzle hole is formed;
An inner needle that opens and closes the nozzle hole by sliding in the body;
The expansion chamber that is provided inside the body and outside the inner needle, forms an expansion chamber together with the body and the inner needle at the inlet of the nozzle hole, and changes the volume by sliding in the body. An outer needle formed into a shape that can be expanded in a stepwise manner with the body;
A fuel injection valve, comprising: a thermal expansion body provided between the body and the outer needle in a sliding direction and configured to make the volume of the expansion chamber variable according to temperature.

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