JP4124252B2 - Fuel injector - Google Patents

Description

  The present invention relates to a fuel injector used for a diesel engine for a vehicle, and more particularly to a fuel injector formed by providing a movable part such as a needle valve in a cylindrical member and accommodating the cylindrical member in a cylinder. .

  A fuel injector used in a diesel engine for a vehicle includes an accumulator fuel injector that injects fuel accumulated at a predetermined pressure in advance, and a booster fuel injector that pressurizes and injects fuel at the time of injection And exist.

  In both types of fuel injectors, a needle valve and a push spring are arranged in a cylindrical nozzle block having an injection opening at the tip, and the nozzle block is accommodated in a cylindrical body, and the tip injection is performed. The structure exposes the mouth.

  Among the fuel injectors described above, in particular, in the pressure-intensifying fuel injector, the final fuel injection pressure is as high as about 1350 bar, so that the urging force of the push spring against the needle valve is also large. The cylindrical nozzle block in which the needle valve and the push spring are arranged in series is usually divided into two or more blocks in the axial direction, and the block on the tip side is accommodated in the cylinder body in abutting manner. The remaining blocks are stacked and accommodated in the cylinder and assembled.

In addition, a certain amount of gap is provided between the nozzle block and the cylindrical body in order to facilitate assembly or to secure a drain passage for leaked fuel.
JP 60-222555 A

  The conventional fuel injector having the above-described structure has a structure in which blocks having radial gaps are stacked in the cylinder in the axial direction. Therefore, if one block is inclined and accommodated in the cylinder, The smooth operation is hindered, and there is a problem that the durability of movable parts such as a needle valve may be adversely affected.

  Such a problem occurs not only when a large number of blocks are stacked and accommodated in the cylinder, but also when a single block is accommodated in the cylinder.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel injector that has excellent assemblability and excellent durability.

  A fuel injector according to a first aspect of the present invention that achieves the above object includes a needle valve that injects fuel from an injection port, a cylindrical member having a push spring for the needle valve inside, and the injection port exposing the cylindrical member. In a fuel injector including a cylindrical body that is accommodated in abutting manner, a support portion that is expanded in diameter relative to the inner periphery of the cylindrical body is provided on a part of the outer periphery of the cylindrical member. According to the configuration of the first aspect of the invention, when the cylindrical member is accommodated in the cylindrical body, the diameter-enlarged support portion of the cylindrical member becomes the reference portion, the inclination of the cylindrical member with respect to the cylindrical body is corrected, and the cylindrical member cylinder The body posture is correct. The expanded diameter support portion is a part of the outer periphery of the cylindrical member and the remaining portion has a gap, so that the expanded diameter support portion does not interfere with the assembly of the cylindrical member into the cylinder. The fitting tolerance between the expanded support portion and the cylindrical body is a gap fitting tolerance that ensures a certain gap. A preferable gap is about 0.1 mm, and preferably within a range of 0.02 to 0.2 mm. If a clearance of 0.02 mm or more is secured, it becomes a drain passage for leaked fuel and can be inserted during assembly. Moreover, if it is a 0.2 mm or less clearance gap, the assembly | attachment precision of the grade which does not deteriorate the durability of a movable part is securable.

  In the fuel injector according to a second aspect of the present invention, in the first aspect, the columnar member includes a plunger that pressurizes fuel supplied to the needle valve. According to the structure of this 2nd invention, since a plunger is arrange | positioned in addition to a needle valve and a push spring in a cylindrical member, a cylindrical member becomes longer in an axial direction. Therefore, the function of maintaining the posture by the expanded support portion in the columnar member becomes more effective.

  In the fuel injector according to a third aspect of the present invention, in the first or second aspect, the support portion is formed near the center in the axial direction of the columnar member. According to the configuration of the third aspect of the invention, since there is a support portion whose diameter is increased near the center in the axial direction of the columnar member, the postures of the upper and lower columnar members are correctly held using the support portion as a fulcrum.

  According to a fourth aspect of the present invention, there is provided the fuel injector according to any one of the first to third aspects, wherein the columnar member is divided into two or more in the axial direction, and the columnar member is interposed between the columnar member and the cylindrical body. A drain passage for leaking fuel is formed. According to the configuration of the fourth aspect of the invention, the cylindrical member is divided into two or more in the axial direction, and a drain passage for leak fuel is formed between the cylindrical body and the cylindrical member, so the axial direction of the divided cylindrical member Even if the posture of the column member is easily changed, the posture of the columnar member divided by the support portion becomes correct.

  A fuel injector according to a fifth invention is the fuel injector according to the fourth invention, wherein the support portion is formed as a short cylindrical member obtained by dividing the cylindrical member. According to the configuration of the fifth aspect of the invention, a part of the divided columnar member is a short columnar member, and this portion is a support portion, so that the support portion can be easily formed and the cylindrical portion of the support portion can be formed. Can be easily inserted.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a fuel injector according to an embodiment of the present invention.

  First, the structure of the fuel injector 1 will be described. In FIG. 1, the fuel injector 1 is configured by sequentially arranging an injection mechanism 2, a pressure increasing mechanism 3, and an electromagnetic valve 4 from the bottom to the top. The fuel injector 1 is assembled to an engine such as a diesel engine in a downward posture with the injection mechanism 2 down as shown. This downward posture is not limited to the vertically downward direction, but also includes an obliquely downward direction.

  The injection mechanism 2 is configured such that an axially slidable needle 13 is accommodated in a state of being urged by a push spring 14 in a cylindrical nozzle body 12 having an injection port 11 opened at the lower end. The nozzle body 12 is formed by sequentially pressing the first cylindrical member 15, the second cylindrical member 16, and the third cylindrical member 17 from below into a cylindrical body 18 that functions as a casing.

  The first columnar member 15 has a large diameter portion 152, a shoulder portion 21, and a small diameter portion 153. The shoulder portion 21 comes into contact with the step portion 22 of the cylindrical body 18, and the small diameter portion 153 having the injection port 11 at the tip protrudes downward. Inside the first cylindrical member 15, a conical valve seat 23, a high-pressure fuel reservoir 24, and a sliding hole 25 for the needle 13 are formed from below. A needle valve is formed by the valve seat 23 of the first cylindrical member 15 and the needle 13.

  The needle 13 includes a conical valve portion 131 with respect to the valve seat 23, a small diameter portion 132, a step portion 133, a large diameter portion 134, a neck portion 135, and a spring seat 136 in order from the bottom. The second cylindrical member 16 has a holding hole 161 for the neck portion 135 of the needle 13 and an accommodation hole 162 for the push spring 14. The push spring 14 in the accommodation hole 162 is pushed into the cylindrical body 18 via the third cylindrical member 17 so as to urge the needle 13 downward.

  A supply passage 26 for high-pressure fuel passes through a position eccentric from the center of the third columnar member 17 and the second columnar member 16. The supply passage 26 communicates with the high pressure fuel reservoir 24 through the first cylindrical member 15.

  The gap 151 between the large-diameter portion 152 of the first columnar member 15 and the cylindrical body 18 has a fitting tolerance that can be inserted into the cylindrical body 18. Between the second cylindrical member 16 and the cylindrical body 18, an annular passage 27 of about 0.5 mm, for example, which becomes a drain flow path for leaked fuel is formed. Between the third columnar member 17 and the cylindrical body 18, an annular passage 47 having a minimum gap, for example, about 0.1 mm, in which a drain passage for leaked fuel can be formed. The third cylindrical member 17 includes a support portion 172 having an outer diameter larger than the outer diameters of the second cylindrical member 16 and a fourth cylindrical member 35 described later. The fitting tolerance between the third cylindrical member 17 and the cylindrical body 18 is preferably in the range of 0.02 to 0.2 mm. The third cylindrical member 17 is also a separation plate for the injection mechanism 2 and a pressure increasing mechanism 3 described later, and is formed as a short cylindrical member.

  The operation of the injection mechanism 2 having such a configuration is as follows. When high-pressure fuel is supplied to the storage portion 24 through the supply passage 26, the stepped portion 133 of the needle 13 becomes a pressure receiving portion, and a pressing force that opposes the pressing spring 14 acts on the needle 13. When the pressure of the high-pressure fuel reaches a predetermined pressure, the pressing force of the high-pressure fuel and the urging force of the pressing spring 14 antagonize, the needle 13 moves upward, and the valve portion 131 at the tip separates from the valve seat 23, High pressure fuel of a predetermined pressure is ejected from the injection port 11. While high pressure fuel continues to be supplied to the reservoir 24, injection of high pressure fuel at a predetermined pressure from the injection port 11 continues. When high-pressure fuel is no longer supplied to the reservoir 24 and the pressure in the reservoir 24 drops, the valve portion 131 at the tip is seated on the valve seat 23 by the push spring 14 acting on the needle 13, and the fuel from the jet port 11 is discharged. The eruption is stopped.

  The fuel leaking from the sliding portion between the sliding hole 25 of the first cylindrical member 15 and the large diameter portion 134 of the needle 13 passes between the holding hole 161 and the neck portion 135, reaches the inside of the accommodation chamber 162, and passes through the passage 163. It reaches the annular passage 27 between the cylindrical body 18 and the second cylindrical member 16 through. Further, the leaked fuel passes through an annular passage 47 between the cylindrical body 18 and the third cylindrical member 17 and an annular passage 48 between the cylindrical body 18 and a fourth cylindrical member 35 to be described later, and the low pressure located above. The fuel supply passage 44 communicates with the annular space 441.

  The pressure increasing mechanism 3 located above the injection mechanism 2 is configured such that a plunger 32 slidable in the axial direction is connected to a pressure increasing piston 33 in a cylindrical cylinder 31 and a return spring 34 is applied to the plunger 32. Contained in a state. The cylinder 31 includes a fourth cylindrical member 35 and a fifth cylindrical member 36, and the fourth cylindrical member 35 is pushed into the cylindrical body 18 in order, and the screw portion 361 of the fifth cylindrical member 36 is replaced with the threaded portion of the cylindrical body 18. 181 is formed by screwing.

  A pressure increasing chamber 41 having a small-diameter hole is formed in the fourth cylindrical member 35, and a plunger 32 is slidably fitted into the pressure increasing chamber 41. A pressurizing chamber 42 having a large-diameter hole is formed in the fifth cylindrical member 36, and the pressure-increasing piston 33 is slidably fitted into the pressurizing chamber 42. The plunger 32 has a head 321 at the upper end, and the pressure-increasing piston 33 is engaged with the head 321. A return spring 34 is disposed between the head 321 of the plunger 32 and the upper end of the fourth cylindrical member 35.

  A fuel supply port 43 is opened on a side surface of a portion corresponding to the fourth cylindrical member 35 of the cylindrical body 18. A fuel supply passage 44 extending from the supply port 43 to the pressure increasing chamber 41 is formed across the fourth cylindrical member 35 and the third cylindrical member 17. The fuel supply passage 44 includes an annular space 441 formed by a depression around the outer periphery of the fourth cylindrical member 35, a lateral passage 442 in the fourth cylindrical member 35, a vertical passage 443 in the fourth cylindrical member 35, It is formed by a communication passage of a radial passage 171 on the upper surface of the third cylindrical member 17. A check valve 45 is disposed in a portion where the vertical passage 443 communicates with the radial passage 171 in the vertical direction and the direction toward the pressure increasing chamber 41 is the forward direction. The radial passage 171 of the third cylindrical member 17 is also in communication with the high pressure fuel supply passage 26.

  An annular passage 48 is formed between the fourth column member 35 and the cylinder 18 so that the fuel leaked from the injection mechanism 2 flows through the annular passage 47 on the outer periphery of the third column member 17. In addition, among the holes forming the pressurizing chamber 42 of the fifth cylindrical member 36, the working fluid drain from the pressure increasing chamber 41 of the plunger 32 flows into the hole 362 in which the return spring 34 is accommodated. The hole 362 communicates with the first drain passage 46. The first drain passage 46 includes a lateral groove 461 of the fourth cylindrical member 35 and a longitudinal passage 462 of the fifth cylindrical member 36, and communicates with the discharge port 58 via the second drain passage 63 described later. Yes.

  The operation of the pressure increasing mechanism 3 having such a configuration is as follows. As will be described later, when the working fluid is supplied to the pressurizing chamber 42, the fuel in the pressurizing chamber 41 is pressurized by a pressure increasing ratio determined by the ratio of the outer diameter of the pressure increasing piston 33 and the outer diameter of the plunger 32. The high pressure fuel pressurized in the pressure increasing chamber 41 is directed to the supply passage 26 because the check valve 45 is closed. When the working fluid is discharged from the pressurizing chamber 42, the pressure-increasing piston 33 and the plunger 32 are raised by the urging force of the return spring 34, the check valve 45 is opened, and the fuel passes through the fuel supply passage 44 and the supply port 43. It is introduced into the pressure increasing chamber 41.

  Next, the structure and operation of the electromagnetic valve 4 for supplying and discharging the working fluid to and from the pressurizing chamber 42 will be described. The fifth cylindrical member 36 has a block 51 at its head. The electromagnetic valve 4 houses a valve body 52, a yoke 53, and a solenoid 54 in a block 51, and is configured as a three-way two-position switching valve. A valve hole 55 is opened in the block 51 at a right angle in the axial direction. The valve hole 55 has a supply port 56 for working fluid, an input / output port 57 communicating with the pressurizing chamber 42, and a fuel tank or a recovery device. A discharge port 58 communicating with the opening is opened. The valve body 52 is fitted in the valve hole 55 so as to be slidable in the axial direction, and a pressing spring 59 acts on a yoke 53 connected to the valve body 52, whereby the first valve 60 between the valve body 52 and the block 51 is operated. Is closed, and the second valve 62 between the valve body 52 and the valve hole partition 61 is open. In this state, the input / output port 57 communicates with the discharge port 58 via the second drain passage 63 formed by the inner periphery of the valve hole partition 61 and the passage on the side surface of the yoke 53. When the yoke 53 connected to the valve body 52 is sucked by the solenoid 54, the second valve 62 is closed and the first valve 60 is opened. In this state, the supply port 56 and the input / output port 57 communicate with each other, and the working fluid is introduced into the pressurizing chamber 42.

  The first drain passage 46 of the pressure increasing mechanism 3 is configured to communicate with the discharge port 58 via the second drain passage 63 of the electromagnetic valve 4. When fuel is used as the working fluid for the pressurizing chamber 42 of the pressure increasing mechanism 3, the first drain passage 46 and the second drain passage 63 are communicated to return the drain to a common fuel tank or recovery device. . The fuel supply passage 44 of the pressure increasing mechanism 3 communicates with the first drain passage 46 through the throttle hole 65. The throttle hole 65 constantly leaks the low-pressure fuel from the supply port 43. If air is contained in the fuel, the air can be passed along with the fuel leak.

  As described above, the cylindrical body 18 is configured to accommodate each component of the injection mechanism 2 and each component of the pressure increasing mechanism 3 and to cover with the electromagnetic valve 4. Contact surface a of the first column member 15 and the second column member 16, contact surface b of the second column member 16 and the third column member 17, contact surface c of the third column member 17 and the fourth column member 35, fourth The contact surface d of the columnar member 35 and the fifth columnar member 36 is structured to be sealed with a surface pressure. Therefore, the first to fifth columnar members 15, 16, 17, 35, and 36 are pushed into the cylindrical body 18 with the necessary preload acting in the axial direction, and the screw portion 181 of the cylindrical body 18 and the fifth The cylindrical member 36 is tightened by screwing of the screw portion 361.

  Next, a procedure for incorporating the fuel injector 1 having the above-described configuration will be described. First, the first cylindrical member 15 and the second cylindrical member 16 provided with the plunger 13 and the pressing spring 14 are pushed into the cylindrical body 18. The shoulder portion 21 of the first columnar member 15 abuts on the step portion 22 of the cylindrical body 18, and a seal surface is formed by surface pressure. Moreover, the small diameter part 153 of the 1st cylindrical member 15 protrudes, and the injection nozzle 11 is exposed.

  Next, a short cylindrical third columnar member 17 that functions as a separation plate between the injection mechanism 2 and the pressure increasing mechanism 3 is inserted into the cylindrical body 18. The third cylindrical member 17 has a fitting tolerance (about clearance fit tolerance) that can be inserted into the cylindrical body 18, and the outer peripheral surface of the third cylindrical member 17 is the second cylindrical member 16 or the fourth cylindrical member 35. The support portion 172 has a larger diameter than the outer diameter. Therefore, in order to form the annular passage 27 with respect to the cylindrical body 18, the inclination of the posture of the second columnar member 17 having a large gap is corrected by being pushed by the third columnar member 17 having the correct posture.

  Next, the fourth cylindrical member 35 of the pressure increasing mechanism 3 is inserted into the cylindrical body 18. The fourth cylindrical member 35 has a large gap with respect to the cylindrical body 18 due to the formation of the annular passage 48. By having the support portion 172 having an enlarged diameter and hitting the third cylindrical member 17 in the correct posture, the inclination of the fourth cylindrical member 35 is corrected.

  Next, in the state where the first to fourth cylindrical members 15, 16, 17, and 35 are inserted into the cylindrical body 18, a preload required in the axial direction is applied, and the fifth member that accommodates the plunger 32 and the pressure increasing piston 33. The screw part 361 of the columnar member 36 is screwed into the screw part 181 of the cylindrical body 18 and tightened in the axial direction.

  Necessary surface pressures are generated on the contact surfaces a, b, c, and d of the first to fifth cylindrical members 15, 16, 17, 35, and 36 so that the surface pressure can be sealed. Further, since the third cylindrical member 17 becomes the support portion 172 whose diameter is increased with respect to the cylindrical body 18, the attitude of the second cylindrical member 16 and the fourth cylindrical member 35 in the axial direction is correct with respect to the third cylindrical member 17. Become a thing.

  Next, the operation of the fuel injector 1 incorporated as described above will be described with reference to FIGS. FIG. 1 shows the operating state of the fuel injector 1 before injection, and FIG. 2 shows the operating state of the fuel injector during injection.

  In FIG. 1, low-pressure fuel is supplied from a supply port 43 prior to injection. Fuel from the supply port 43 passes through the annular space 441, the horizontal passage 442, the vertical passage 443, and the check valve 45, and is filled into the storage portion 24 through the pressure increasing chamber 41 and the supply passage 26. In this filling process, the air that was present in the fuel passage in the injection mechanism 2 or the pressure increasing mechanism 3 is discharged to the first drain passage 46 through the throttle hole 65.

  As shown in FIG. 2, when the injection is reached, the solenoid 54 of the electromagnetic valve 4 is excited, the yoke 53 is attracted, the valve body 52 moves rightward in the drawing, the first valve 60 is opened, and the second valve 62 is opened. The supply port 56 and the input / output port 57 communicate with each other, and the working fluid is introduced into the pressurizing chamber 42. The fuel in the pressure increasing chamber 41 is pressurized at a pressure increasing ratio determined by the ratio of the outer diameter of the pressure increasing piston 42 and the outer diameter of the plunger 32. At this time, the check valve 45 is in a closed state, and the high pressure in the pressure increasing chamber 41 propagates to the fuel in the reservoir 24 through the supply passage 26. When the high-pressure fuel in the reservoir 24 reaches, for example, about 200 bar, the needle 13 overcomes the urging force of the push spring 14 due to the pressure received by the stepped portion 133 and the like, the valve portion 131 is lifted up from the valve seat 23, and the injection port 11 High pressure fuel is injected. Even after the valve is opened, the injection pressure rises due to the throttling effect of the fuel passage leading to the injection port 11, and finally reaches about 1350 bar.

  When the injection of the high-pressure fuel is finished, as shown in FIG. Is closed, the second valve 62 is opened, the input / output port 57 and the discharge port 58 communicate with each other, the working fluid introduced into the pressurizing chamber 42 is discharged from the discharge port 58, and the pressure increasing piston 33 and the plunger 32 are returned. The pressure is raised by the urging force of the spring 34 and returns to the position shown in the figure, and the fuel is supplied again to the pressure increasing chamber 41. By repeating the state of FIG. 1 and the state of FIG. 2 in synchronization with the engine speed, fuel injection is performed appropriately.

The fuel injector 1 according to the embodiment described above has the following effects.
(1) A support portion 172 having an enlarged diameter relative to the inner diameter of the cylindrical body 18 is provided on the cylindrical member 17 in the middle of each cylindrical member 15, 16, 17, 35, 36 inserted into the cylindrical body 18 in abutting manner. Therefore, the posture of each cylindrical member 15, 16, 35, 36 in the axial direction is correct following the cylindrical member 17. Therefore, the movement of movable parts such as the needle 13 and the plunger 32 becomes smooth, and seizure and damage due to bending of the movable parts can be prevented.

(2) In the pressure-increasing fuel injector 1 according to the combination of the injection mechanism 2 and the pressure-increasing mechanism 3, the components inserted into the cylindrical body 18 are the first to fifth columnar members 15, 16, 17. , 35, and 36, the support portion 172 of the third cylindrical member 17 ensures the accuracy of assembling the cylindrical members 15, 16, 35, and 36, and both the injection mechanism 2 and the pressure-increasing mechanism 3 are combined into one. The structure accommodated in the cylinder 18 can be employed.

(3) The parts inserted into the cylindrical body 18 are divided into the first to fifth cylindrical members 15, 16, 17, 35, and 36, and the cylindrical members 16 and 35 other than the third cylindrical member 17 having the support portion 172. The annular gaps 27 and 48 can be enlarged, the cylindrical members 16 and 35 can be easily incorporated into the cylindrical body 18, and a sufficient drain passage for the leaked fuel can be secured.

(4) The third cylindrical member 17 located at the center in the axial direction of the first to fifth cylindrical members 15, 16, 17, 35, 36 is expanded in diameter relative to the cylindrical body 18. Since the support portion 172 is formed, the postures of the front and rear second columnar members 16 and the fourth columnar member 35 are kept correct with the third columnar member 17 as a fulcrum. The third cylindrical member 17 also functions as a separation plate between the injection mechanism 2 and the pressure increasing mechanism 3 and is a short cylindrical member. Therefore, by expanding the outer diameter of the third cylindrical member 17 of the short cylindrical member to form the support portion 172, the upper end of the second cylindrical member 16 and the fourth cylindrical member 35 are increased without increasing the number of parts as described later. The support portion 172 can be easily formed as compared with the case where the support portion serving as the reference portion is integrally provided at the lower end of the base plate.

In addition, embodiment is not limited to the above, For example, you may implement as changed as follows.
(1) As shown in FIG. 3, a notch 111 is provided on the outer periphery of the third cylindrical member 110, and the notch 111 can be used as a drain passage for leaked fuel. In the third columnar member 110, a sufficient support portion for the cylinder 18 is provided on the outer periphery of the third columnar member 110 by setting the gap with the inner diameter of the cylinder 18 to a minimum fitting tolerance that can be inserted. 112 can be formed, and the posture of each columnar member inserted into the cylindrical body 18 can be made correct.

(2) In FIG. 1, the third cylindrical member 17 having the support portion 172 may be integrally formed as an enlarged diameter portion at the upper end of the second cylindrical member 16 or an enlarged diameter portion at the lower end of the fourth cylindrical member 35. it can. Even in this case, the enlarged diameter portion of the second cylindrical member 16 or the enlarged diameter portion of the fourth cylindrical member 35 functions as a support portion for the cylindrical body 18.

(3) The fuel injector to which the support part in the middle of the cylindrical member is applied is not limited to the pressure-increasing fuel injector as shown in FIG. 1, but is an accumulator fuel that injects fuel accumulated at a predetermined pressure in advance. It also applies to injectors. The accumulator type fuel injector accommodates a cylindrical member in a butt shape in a cylindrical body, and a needle valve and a push spring are disposed in the cylindrical member. If the support part expanded in diameter is provided in a part of outer periphery of this cylindrical member, the attitude | position of the cylindrical member in a cylinder will become a correct thing.

  As described above in detail, according to the first invention, the support member with the expanded diameter of the cylindrical member serves as a support for the cylindrical member of the cylindrical member, and corrects the posture of the cylindrical member in the cylindrical member. The movement of the movable part inside the member can be made smooth, and the durability of the movable part can be improved. Further, since the gap other than the support portion of the cylindrical member can be increased, the cylindrical member can be easily incorporated into the cylinder.

  According to the second invention, since the plunger other than the needle valve is arranged in the cylindrical member, the cylindrical member becomes longer in the axial direction, and the posture of the cylindrical member in the cylindrical member is increased by the support portion whose diameter is increased in the cylindrical member. This makes it possible to incorporate a plunger other than a needle valve in a single cylinder. According to the third invention, since there is a support portion whose diameter is enlarged near the axial center of the cylindrical member, the posture of the upper and lower cylindrical members is corrected with the support portion as a fulcrum, and the posture is effectively corrected with a short support portion. be able to. According to the fourth invention, since the cylindrical member is divided into two or more in the axial direction, it is easy to assemble and the annular passage for the leaked fuel can be easily formed. According to the fifth aspect, since the outer periphery of the divided short columnar member is used as the support portion, a necessary support portion can be formed without increasing special parts.

It is an assembly section of a fuel injector of an embodiment of the present invention, and is a sectional view showing the state before the start of injection. It is an assembly section of a fuel injector of an embodiment of the present invention, and is a sectional view showing a state at the time of injection start. It is a top view which shows the other support part in a cylindrical member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injector 2 Injection mechanism 3 Pressure increase mechanism 13 Needle (needle valve)
14 Pressing spring 15 First cylindrical member 16 Second cylindrical member 17 Third cylindrical member 172 Support portion 27 Annular passage (drain passage)
47 Annular passage (drain passage)
48 Annular passage (drain passage)
32 Plunger 35 Fourth cylindrical member 36 Fifth cylindrical member

Claims (7)

A fuel comprising: a needle valve that injects fuel from an ejection port; a cylindrical member that has a push spring for the needle valve therein; and a cylindrical body that accommodates the cylindrical member so that the ejection port is exposed. In the injector,
The columnar member is formed in a columnar shape and includes separate first columnar member, second columnar member, and third columnar member, and the first columnar member, the second columnar member, and the third columnar member. The cylindrical member is configured by being coaxially arranged in this order from the side where the jet port is provided in the axial direction,
The first cylindrical member includes the jet port,
Between the outer peripheral surface of the second cylindrical member and the third cylindrical member and the inner peripheral surface of the cylindrical body, a gap serving as a drain passage for leaked fuel is formed,
The outer diameter of the third cylindrical member is larger than the outer diameter of the second cylindrical member,
The gap between the outer peripheral surface of the third cylindrical member and the inner peripheral surface of the cylindrical body is smaller than the gap between the outer peripheral surface of the second cylindrical member and the inner peripheral surface of the cylindrical body. A fuel injector characterized by.   The fuel injector according to claim 1, wherein the third columnar member is formed as a short columnar member.   The fuel injector according to claim 1 or 2, wherein the gap serving as the drain passage is formed in an annular shape over the entire circumference of the second columnar member and the third columnar member.   The clearance gap between the outer peripheral surface of the said 3rd cylindrical member and the internal peripheral surface of the said cylinder is a notch provided in the outer periphery of the said 3rd cylindrical member, The Claim 1 or 2 characterized by the above-mentioned. The fuel injector as described. In the cylindrical body, the first cylindrical member, the second cylindrical member, and the third cylindrical member are inserted in this order,
Between the first columnar member and the second columnar part, and between the second columnar member and the third columnar member are respectively sealed with surface pressure while abutting on the contact surface,
When the attitude of the second cylindrical member in the axial direction is inclined, the inclination of the attitude of the second cylindrical member is caused by the second cylindrical member being pushed by the third cylindrical member in the correct attitude. The fuel injector according to any one of claims 1 to 4, wherein the fuel injector is corrected in an axial direction. The columnar member is formed in a columnar shape and includes a first columnar member, a second columnar member, a third columnar member, and a fourth columnar member that are separate from each other, and the first columnar member and the second columnar member. The member, the third columnar member, and the fourth columnar member are configured by being coaxially arranged in this order from the side where the jet port is provided in the axial direction,
Between the outer peripheral surface of the fourth cylindrical member and the inner peripheral surface of the cylindrical body, a gap serving as a drain passage for leaked fuel is formed,
The outer diameter of the third cylindrical member is larger than the outer diameter of the fourth cylindrical member,
The fuel injector according to any one of claims 1 to 5, wherein the gap of the third columnar member is smaller than the gap of the fourth columnar member.   The fuel injector according to any one of claims 1 to 6, wherein the cylindrical member includes a plunger that pressurizes fuel supplied to the needle valve.

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