JP2007297962A - Fuel injection nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection nozzle 1 capable of improving the concentricity of a valve body 2 and a needle 3. <P>SOLUTION: The needle 3 is slidably supported on an inner circumference surface of a center hole 9 at a longitudinal direction center part 3a thereof, and an upper end part (needle head 3b) is slidably inserted in an inner circumference of a cylinder 4. The cylinder 4 is slidably inserted in an upper end part inner circumference of the center hole 9 with keeping minute clearance, and is pressed against a lower end surface of a plate 7 by being energized by a spring 5 to form a pressure control chamber 16 between the lower end surface of the plate 7 and an upper end surface of the needle head 3b. Consequently, the concentricity of the valve body 2 and the needle 3 can be improved since the needle head 3b can be positioned in a radial direction in relation to the valve body 2 via the cylinder 4 and also an intermediate part 3b of the needle 3 can be positioned in the radial direction in relation to the valve body 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection nozzle that injects fuel into an internal combustion engine.

Conventionally, an injector that injects high-pressure fuel accumulated in a common rail into a combustion chamber of an internal combustion engine is known. As shown in FIG. 7, the injector includes a fuel injection nozzle 100 including a valve body 110, a needle 120, a cylinder 130, and the like.
The valve body 110 has a hole 111 for housing the needle 120, a conical seat surface 112 formed at the tip (lower end in the figure) of the hole 111, and a recess provided downstream of the seat surface 112. A sac chamber 113 and a nozzle hole 114 leading to the sac chamber 113 are formed. The hole 111 is sealed by a plate 140 assembled to the upper end surface of the valve body 110 and is always filled with high-pressure fuel (about 180 to 200 MPa) introduced from a fuel supply hole 141 formed in the plate 140.

The needle 120 is inserted into the hole 111 so as to be able to reciprocate, and a sheet portion 121 that opens and closes the nozzle hole 114 is provided at the tip.
The cylinder 130 is disposed above the hole 111 and is slidably fitted to the outer periphery of the upper end portion (end portion on the side opposite to the seat portion) of the needle 120 and is urged by the spring 150 and pressed against the plate 140. A pressure control chamber 160 is formed between the plate 140 and the upper end surface of the needle 120.
The spring 150 is disposed between a spring seat 170 locked to the step of the needle 120 and a collar portion 131 provided in the cylinder 130, and urges the needle 120 in the valve closing direction (downward in the figure). .

In the pressure control chamber 160, high-pressure fuel is constantly introduced through an orifice 180 opened in the wall surface of the cylinder 130, and the pressure changes (increases / decreases) according to the open / closed state of the low-pressure passage 190 leading to the low-pressure side.
The low pressure passage 190 is provided with a valve body 200 connected to an electromagnetic actuator (not shown), and the low pressure passage 190 is opened and closed by the valve body 200.
In the fuel injection nozzle 100, when the valve body 200 opens the low pressure passage 190, the pressure in the pressure control chamber 160 is released to the low pressure side, and the fuel pressure that urges the needle 120 upward in the drawing is higher than the valve opening pressure. Then, the needle 120 is lifted and the fuel is injected from the injection hole 114. After that, when the valve body 200 closes the low pressure passage 190, the pressure in the pressure control chamber 160 increases, and when the fuel pressure that urges the needle 120 upward in the drawing becomes lower than the valve closing pressure, the needle 120 is closed. Stop fuel injection.
Special table 2003-506622 gazette

  However, the fuel injection nozzle 100 has a large clearance between the inner periphery of the hole 111 and the outer periphery of the cylinder 130. In other words, the cylinder 130 is only pressed against the plate 140 by the spring 150 and is not restricted in radial movement, and thus can freely move in the radial direction with respect to the plate 140. In this configuration, since the upper end portion of the needle 120 supported by the cylinder 130 cannot be positioned in the radial direction, the coaxiality of the needle 120 with respect to the central axis of the valve body 110 is lowered.

When the coaxiality between the valve body 110 and the needle 120 is lowered, the seat portion 121 of the needle 120 cannot be seated on the seat surface 112 of the valve body 110 from the front. That is, the entire circumference of the sheet portion 121 cannot be brought into uniform contact with the sheet surface 112. As a result, excessive stress is locally generated in the seat portion 121 and the seat surface 112, and wear of both is promoted. Therefore, the injection characteristics change with time, and the engine output characteristics are adversely affected.
The present invention has been made based on the above circumstances, and an object thereof is to provide a fuel injection nozzle capable of improving the coaxiality between a valve body and a needle.

(Invention of Claim 1)
The present invention includes a valve body in which a hole is formed in the longitudinal direction, a valve seat is formed on the inner wall surface of the hole, and an injection hole is provided on the downstream side of the valve seat. A cylinder disposed on the inner periphery of the part and a seat part that is reciprocally inserted into the hole and that opens and closes the nozzle hole by seating on and away from the valve seat are provided at the tip part, and the side opposite the seat part Has a needle that is slidably supported on the inner peripheral surface of the cylinder, and a fuel passage that introduces high-pressure fuel to the downstream side of the cylinder inside the hole, and is introduced from the fuel passage when the needle is opened. A fuel injection nozzle for injecting the high-pressure fuel thus injected from an injection hole, wherein the cylinder is guided by the inner peripheral surface of the hole and is restricted from moving in the radial direction.

  According to the above configuration, the end of the needle on the side opposite to the seat portion (hereinafter referred to as the needle head) is slidably supported on the inner peripheral surface of the cylinder, and the cylinder is guided by the inner peripheral surface of the hole and has a diameter. Directional movement is restricted. Thereby, when the needle reciprocates within the hole, the needle head can be positioned in the radial direction with respect to the valve body, so that the coaxiality between the valve body and the needle is improved. As a result, the seat portion can be seated straight with respect to the valve seat of the valve body when the needle is closed. That is, since the entire circumference of the seat portion can be brought into uniform contact with the valve seat, wear of the valve seat and the seat portion is reduced, and a change with time in injection characteristics can be suppressed.

(Invention of Claim 2)
The fuel injection nozzle according to claim 1 is characterized in that the cylinder is slidably inserted in the inner periphery of the hole.
By inserting the cylinder into the inner periphery of the hole with a very small clearance, the radial movement of the cylinder can be restricted by the clearance, so that the needle head can be positioned in the radial direction with respect to the valve body via the cylinder.

(Invention of Claim 3)
The fuel injection nozzle described in claim 1 is characterized in that the cylinder is inserted into the inner periphery of the hole in a press-fitted state.
Since the cylinder is prevented from moving in the radial direction by inserting the cylinder into the inner periphery of the hole, the needle head can be positioned in the radial direction with respect to the valve body via the cylinder.

(Invention of Claim 4)
The fuel injection nozzle described in claim 3 is characterized in that the press-fitting allowance of the cylinder with respect to the hole is set smaller than the allowance for expanding the inner diameter of the hole caused by the introduction of the high-pressure fuel. In this case, after the cylinder is press-fitted into the inner periphery of the hole and assembled, if high-pressure fuel is introduced into the hole and the inner diameter of the hole expands, a minute clearance is generated between the cylinder and the hole. The cylinder can rotate in the circumferential direction.

(Invention of Claim 5)
5. The fuel injection nozzle according to claim 1, wherein the needle has a middle portion in the longitudinal direction slidably supported on the inner peripheral surface of the hole.
As a result, in addition to the sliding portion between the needle head and the cylinder, the needle can be positioned in the radial direction with respect to the valve body even at the sliding portion between the needle intermediate portion and the hole. The degree can be further improved.

(Invention of Claim 6)
6. The fuel injection nozzle according to claim 5, wherein the needle is chamfered on the outer periphery of the intermediate portion, and has a gap between the chamfered surface formed by the chamfer and the inner peripheral surface of the hole, and through the gap. The hole on the upstream side and the hole on the downstream side from the intermediate part communicate with each other.
In this case, since it is not necessary to form in the valve body a communication path that connects the upstream side and the downstream side of the intermediate portion of the needle, the valve body can be easily processed. Further, when the communication passage is formed in the valve body, a cross hole is formed in which the hole and the communication passage intersect with each other, so that stress concentrates on the corner portion of the cross hole and is easily broken. On the other hand, according to the configuration of the present invention, since it is not necessary to provide a cross hole in the valve body, a highly reliable fuel injection nozzle can be provided.

(Invention of Claim 7)
7. The fuel injection nozzle according to claim 1, wherein a chamfer is applied to the outer periphery of the cylinder, and a gap formed between the chamfered surface formed by the chamfer and the inner peripheral surface of the hole is defined as a fuel passage. It is characterized by.
In this case, since it is not necessary to form a fuel passage in the valve body, the processing of the valve body is easy. In addition, when the fuel passage is formed in the valve body, a cross hole is formed in which the hole and the fuel passage intersect with each other. Therefore, stress concentrates on the corner portion of the cross hole and is easily broken. On the other hand, according to the configuration of the present invention, since it is not necessary to provide a cross hole in the valve body, a highly reliable fuel injection nozzle can be provided.

(Invention of Claim 8)
The fuel injection nozzle according to any one of claims 1 to 6, wherein a through-hole penetrating the cylinder from one end surface to the other end surface is formed, and the through-hole is used as a fuel passage.
In this case, since it is not necessary to form a fuel passage in the valve body, the processing of the valve body is easy. In addition, when the fuel passage is formed in the valve body, a cross hole is formed in which the hole and the fuel passage intersect with each other. Therefore, stress concentrates on the corner portion of the cross hole and is easily broken. On the other hand, according to the configuration of the present invention, since it is not necessary to provide a cross hole in the valve body, a highly reliable fuel injection nozzle can be provided.

  The best mode for carrying out the present invention will be described in detail with reference to the following examples.

FIG. 1 is a cross-sectional view of the fuel injection nozzle 1.
The fuel injection nozzle 1 of the present embodiment is configured as, for example, an injector used in a common rail fuel injection system of a diesel engine, and is integrally combined with an electromagnetic actuator or the like (not shown).
As shown in FIG. 1, the fuel injection nozzle 1 includes a valve body 2, a needle 3, a cylinder 4, a spring 5, and the like, and is assembled by sandwiching a plate 7 at the lower end of the injector body 6. 8 is fixed to the injector body 6.

The valve body 2 has a conical valve seat formed in a hole (hereinafter referred to as a center hole 9) for accommodating the needle 3, the cylinder 4, the spring 5, and the like, and a tip portion (lower end portion in the drawing) of the center hole 9. 10, a sac chamber 11 recessed on the downstream side of the valve seat 10, an injection hole 12 leading to the sac chamber 11, and the like.
The center hole 9 is formed in the longitudinal direction from the upper end surface to the tip end portion of the valve body 2, and the upper end opening is closed by the plate 7 and is introduced from the fuel supply hole 13 formed in the plate 7. It is always filled with high-pressure fuel (about 180 to 200 MPa).

  The needle 3 is accommodated in the center hole 9 so as to be able to reciprocate, and the longitudinal intermediate portion 3a is slidably supported on the inner peripheral surface of the center hole 9 while being slidable. The upper end of the figure (hereinafter referred to as the needle head 3b) is slidably inserted in the inner periphery of the cylinder 4 with a small clearance. Further, the needle 3 is provided with a small-diameter shaft portion 3 c having a smaller outer diameter than the intermediate portion 3 a on the downstream side of the intermediate portion 3 a, and is formed between the outer peripheral surface of the small-diameter shaft portion 3 c and the inner peripheral surface of the center hole 9. An annular gap that functions as the fuel passage 14. A sheet portion 3d that opens and closes the nozzle hole 12 is provided at the tip of the small diameter shaft portion 3c. The seat portion 3d is seated on the valve seat 10 of the valve body 2 when the needle 3 is closed, and the fuel passage 14 and the injection hole 12 are liquid-tightly blocked.

  Further, as shown in FIG. 2, four cutting surfaces 3 e whose outer periphery is cut are formed in the intermediate portion 3 a, and a gap formed between the cutting surface 3 e and the inner peripheral surface of the center hole 9. Functions as the fuel passage 15 and the arc surface left on the outer periphery functions as a sliding portion. Thereby, the center hole 9 on the upstream side of the intermediate portion 3 a and the center hole 9 on the downstream side (that is, the fuel passage 14) communicate with each other through the fuel passage 15. In addition, the cutting surface 3e of the intermediate part 3a is not limited to four places, and may be two places, three places, or five places or more.

The cylinder 4 is slidably inserted in the inner periphery of the upper end portion of the center hole 9 and is slidable, and is urged by the spring 5 to be pressed against the lower end surface of the plate 7. And a pressure control chamber 16 is formed between the upper end surface of the needle head 3b.
Further, as shown in FIG. 3, the cylinder 4 is formed with four cutting surfaces 4 a whose outer periphery is plane-cut, and there are gaps formed between the cutting surface 4 a and the inner peripheral surface of the center hole 9. The circular arc surface that functions as the fuel passage 17 and remains on the outer periphery functions as a sliding portion. The fuel passage 17 communicates the fuel supply hole 13 formed in the plate 7 with the center hole 9 on the downstream side of the cylinder 4.

The spring 5 is disposed between the spring seat 18 locked to the step of the needle 3 and the lower end surface of the cylinder 4 and urges the needle 3 in the valve closing direction (downward in the drawing).
The pressure control chamber 16 is provided so as to be able to communicate with either one of the high-pressure side and the low-pressure side via a control valve described below.
The control valve includes a valve chamber 19 formed in the injector body 6, a valve body 20 disposed in the valve chamber 19, and an electromagnetic actuator (for example, a solenoid or a piezoelectric element) that drives the valve body 20. The The valve chamber 19 always communicates with the pressure control chamber 16 via a communication passage 21 formed at the center of the plate 7 and is connected to the center hole 9 (high-pressure side) via a high-pressure passage 22 also formed in the plate 7. Further, it is provided so as to be able to communicate with a low pressure side (not shown) via a low pressure passage 23 formed in the injector body 6.

The valve body 20 is disposed so as to be movable in the vertical direction in the figure in the valve chamber 19, and is urged upward of the valve chamber 19 by a spring 24 disposed in the valve chamber 19. The valve body 20 can block either one of the low pressure passage 23 leading to the upper end of the valve chamber 19 and the high pressure passage 22 leading to the lower end of the valve chamber 19. That is, when the valve body 20 closes the low pressure passage 23, the communication passage 21 and the high pressure passage 22 communicate with each other through the valve chamber 19, and when the valve body 20 closes the high pressure passage 22, the communication passage through the valve chamber 19. 21 communicates with the low pressure passage 23.
The electromagnetic actuator is electronically controlled by an external ECU (electronic control unit), and drives the valve body 20 downward in the figure when energized.

Next, the operation of the fuel injection nozzle 1 will be described.
When the energization of the electromagnetic actuator is stopped, the valve body 20 is biased by the spring 24 and closes the low pressure passage 23, so that the high pressure passage 22 and the communication passage 21 communicate with each other through the valve chamber 19. ing. Thereby, the pressure control chamber 16 is filled with the same high-pressure fuel as the inside of the center hole 9. In this state, since the fuel pressure for urging the needle 3 in the valve opening direction (upward in FIG. 1) is lower than the valve closing pressure of the needle 3, the needle 3 is in the valve closing state shown in FIG. The state of being seated on the seat 10).

When the electromagnetic actuator is energized at a predetermined injection timing, the valve body 20 driven by the electromagnetic actuator closes the high-pressure passage 22 so that the communication passage 21 and the high-pressure passage 22 are blocked, and the valve chamber 19 The communication passage 21 and the low-pressure passage 23 are communicated with each other. As a result, when the pressure in the pressure control chamber 16 is released to the low pressure side and the fuel pressure that urges the needle 3 upward becomes higher than the valve opening pressure, the needle 3 is lifted and fuel is injected from the injection hole 12. .
When energization to the electromagnetic actuator is stopped after a predetermined injection period has elapsed, the valve body 20 is biased by the spring 24 and closes the low pressure passage 23, so that there is a gap between the communication passage 21 and the low pressure passage 23. In addition to being blocked, the communication passage 21 and the high-pressure passage 22 communicate with each other through the valve chamber 19. As a result, when high-pressure fuel is introduced into the pressure control chamber 16 and the fuel pressure for urging the needle 3 upward becomes lower than the valve closing pressure, the needle 3 is closed and fuel injection is terminated.

(Effect of Example 1)
In the fuel injection nozzle 1, the cylinder 4 that supports the needle head 3 b is guided by the inner peripheral surface of the center hole 9 to restrict radial movement, and the intermediate portion 3 a of the needle 3 is the inner periphery of the center hole 9. It is slidably supported on the surface. Accordingly, the needle head 3b can be positioned in the radial direction with respect to the valve body 2 via the cylinder 4, and the intermediate portion 3a of the needle 3 can also be positioned in the radial direction with respect to the valve body 2. Compared with the conventional product, the coaxiality of the valve body 2 and the needle 3 is improved. As a result, since the inclination of the needle 3 is suppressed, the seat portion 3d can be seated straight on the valve seat 10 when the needle 3 is closed. That is, since the entire circumference of the seat portion 3d can contact the valve seat 10 uniformly, wear of the valve seat 10 and the seat portion 3d is reduced, and a change with time in the injection characteristics can be suppressed.

  Further, since the cylinder 4 is slidably inserted into the inner periphery of the center hole 9, it can rotate in the circumferential direction on the inner periphery of the center hole 9. Therefore, at the time of assembly, it is not necessary to align the fuel passage 17 formed between the cutting surface 4a of the cylinder 4 and the inner peripheral surface of the center hole 9 with the fuel supply hole 13 of the plate 7, and the fuel supply hole 13 can be at any position. Further, since the cylinder 4 can move in the vertical direction with respect to the center hole 9, the upper end surface of the cylinder 4 is brought into close contact with the lower end surface of the plate 7 by being biased by the spring 5, and the pressure control chamber 16. Can be formed. In this case, it is not necessary to finish the flatness of the upper end surfaces of the valve body 2 and the cylinder 4 with extremely high accuracy, the manufacturing cost can be suppressed, and the assembly is easy.

  Further, in the fuel injection nozzle 1 shown in the first embodiment, the gap formed between the cutting surface 4a formed in the cylinder 4 and the inner peripheral surface of the center hole 9 functions as the fuel passage 17, and similarly, the needle A gap formed between the cutting surface 3 e formed in the intermediate portion 3 a of the cylinder 3 and the inner peripheral surface of the center hole 9 functions as the fuel passage 15. According to this configuration, since it is not necessary to form a fuel passage in the valve body 2, it is possible to eliminate a cross hole where the fuel passage intersects with the center hole 9, and to provide a highly reliable fuel injection nozzle 1.

FIG. 4 is a cross-sectional view of the fuel injection nozzle 1.
The needle 3 described in the first embodiment has a configuration in which the needle body 3b and the intermediate portion 3a are positioned in the radial direction with respect to the valve body 2, but the needle head 3b alone is positioned in the radial direction. The structure which performs is also good. That is, the needle 3 shown in the second embodiment is not provided with the intermediate portion 3a (sliding portion with respect to the center hole 9) described in the first embodiment as shown in FIG. On the other hand, it is positioned in the radial direction via the cylinder 4. According to the configuration shown in the second embodiment, since the upper end portion (needle head 3b) in the longitudinal direction of the needle 3 can be positioned in the radial direction, the prior art shown in FIG. 7, that is, the upper end portion of the needle 120 is in the radial direction. Since the inclination of the needle 3 is suppressed as compared with the configuration in which the needle 3 is not positioned, the seat portion 3d can be seated straight on the valve seat 10 when the needle 3 is closed. As a result, wear of the valve seat 10 and the seat portion 3d is reduced, and a change with time in the injection characteristics can be suppressed.

FIG. 5 is a plan view showing the upper end surface of the fuel injection nozzle 1.
In the first embodiment, an example in which four cutting surfaces 4a are formed on the outer periphery of the cylinder 4 is shown, but it is not necessary to limit the number to four, and two, three, or five or more may be used. .
FIG. 5A shows an example when three cutting surfaces 4a are formed, and FIG. 5B shows an example when six cutting surfaces 4a are formed.
In the first embodiment, the gap formed between the cutting surface 4a of the cylinder 4 and the inner peripheral surface of the center hole 9 is used as the fuel passage 17. For example, as shown in FIG. It is also possible to form a through hole 4 b penetrating from the upper end surface to the lower end surface of 4 and use the through hole 4 b as the fuel passage 17.

In the first embodiment, an example in which the cylinder 4 is slidably inserted into the inner periphery of the center hole 9 with a small clearance is described. However, the cylinder 4 can be inserted into the inner periphery of the center hole 9 in a press-fitted state.
However, the press-fitting allowance of the cylinder 4 to the center hole 9 is set smaller than the enlargement allowance of the inner diameter of the center hole 9 caused by the introduction of the high-pressure fuel. As a result, after the cylinder 4 is press-fitted into the inner periphery of the center hole 9 and assembled, high pressure fuel is introduced into the center hole 9 and the inner diameter of the center hole 9 is increased. Therefore, the cylinder 4 can rotate in the circumferential direction on the inner periphery of the center hole 9. As a result, the pressure control chamber 16 can be formed inside the cylinder 4 by bringing the upper end surface of the cylinder 4 biased by the spring 5 into close contact with the lower end surface of the plate 7.

  Further, according to this structure, the cylinder 4 is pressed into the inner periphery of the center hole 9 and assembled, so that the cylinder 4 is not pushed by the spring 5 and jumps out of the center hole 9. The cylinder 4 can be sealed inside the center hole 9. Thereby, the said components (spring 5, spring seat 18, cylinder 4) do not fall apart at the time of an assembly | attachment, but an assembly | attachment can be performed easily.

In the fourth embodiment, an example in which the press-fitting allowance of the cylinder 4 with respect to the center hole 9 is set smaller than the enlargement allowance of the center hole 9 caused by the introduction of the high-pressure fuel is described. The press-fitting allowance of the cylinder 4 is set to be larger than the enlargement allowance of the center hole 9 so that the press-fitted state can be maintained even after being introduced.
In this case, since there is no clearance between the center hole 9 and the cylinder 4, the radial position of the needle 3 with respect to the valve body 2 is determined only by the clearance between the cylinder 4 and the needle head 3b. For this reason, the coaxial accuracy of the needle 3 and the valve body 2 is further improved. Further, as in the case of the fourth embodiment, the cylinder 4 is press-fitted into the inner periphery of the center hole 9 and assembled, so that the spring 5, the spring seat 18 and the cylinder 4 do not fall apart during assembly, and the assembly is easy. Can be.

(Example 1) which is sectional drawing of a fuel-injection nozzle. It is sectional drawing (AA sectional drawing of FIG. 1) of a needle intermediate part. (Example 1) which was the top view which looked at the fuel-injection nozzle from the upper part. (Example 2) which is sectional drawing of a fuel-injection nozzle. (Example 3) which was the top view which looked at the fuel-injection nozzle from the upper part. (Example 3) which was the top view which looked at the fuel-injection nozzle from the upper part. It is sectional drawing of a fuel injection nozzle (explanation of a prior art).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection nozzle 2 Valve body 3 Needle 3a The intermediate part (intermediate part) of a needle
3d Sheet part 3e Cutting surface (chamfered surface) formed in the middle part of the needle
4 Cylinder 4a Cutting surface (chamfered surface) formed on the cylinder
4b Through hole (fuel passage) formed in the cylinder
9 Center hole (hole)
10 Valve seat 12 Injection hole 17 Fuel passage

Claims (8)

A valve body having a hole in the longitudinal direction, a valve seat formed on the inner wall surface of the hole, and an injection hole on the downstream side of the valve seat;
A cylinder disposed on the inner periphery of the end of the hole opposite to the injection hole;
A seat portion that is reciprocally inserted into the hole and that opens and closes the nozzle hole by being seated and separated from the valve seat is provided at the tip portion, and an end portion on the side opposite to the seat portion is the cylinder A needle slidably supported on the inner peripheral surface of
A fuel passage for introducing high-pressure fuel to the downstream side of the cylinder inside the hole;
A fuel injection nozzle that injects the high-pressure fuel introduced from the fuel passage when the needle is opened from the injection hole;
The fuel injection nozzle according to claim 1, wherein the cylinder is guided by an inner peripheral surface of the hole to restrict movement in a radial direction. The fuel injection nozzle according to claim 1,
The fuel injection nozzle, wherein the cylinder is slidably inserted into an inner periphery of the hole. The fuel injection nozzle according to claim 1,
The fuel injection nozzle, wherein the cylinder is inserted into the inner periphery of the hole in a press-fitted state. The fuel injection nozzle according to claim 3,
The fuel injection nozzle according to claim 1, wherein an allowance for press-fitting the cylinder into the hole is set smaller than an enlargement allowance for the inner diameter of the hole caused by introduction of high-pressure fuel. In any one of fuel injection nozzles described in Claims 1-4,
The needle is supported by the inner peripheral surface of the hole so as to be slidable in the middle in the longitudinal direction. The fuel injection nozzle according to claim 5,
The needle is chamfered on the outer periphery of the intermediate portion, and has a gap between the chamfered surface formed by the chamfer and the inner peripheral surface of the hole, and through the gap, the needle is located upstream of the intermediate portion. The fuel injection nozzle, wherein the hole and the hole on the downstream side communicate with each other. The fuel injection nozzle according to any one of claims 1 to 6,
A fuel injection nozzle, wherein a chamfer is formed on the outer periphery of the cylinder, and a gap formed between the chamfered surface formed by the chamfer and the inner peripheral surface of the hole is used as the fuel passage. The fuel injection nozzle according to any one of claims 1 to 6,
A fuel injection nozzle, wherein a through-hole penetrating the cylinder from one end surface to the other end surface is formed, and the through-hole serves as the fuel passage.

Images