JP4140540B2 - Fuel injection valve - Google Patents

Description

The present invention relates to a fuel injection valve that injects high-pressure fuel into an internal combustion engine (engine), and in particular, supports a sliding shaft portion at the upper part of the needle or the lower part of the piston so as to be slidable, thereby increasing the pressure inside the nozzle body. And a technique for partitioning the low pressure in the lower body.
In the present invention, the fuel injection side (the injection hole side) is the lower side of the fuel injection valve.

An example of the injection nozzle which is one part of the fuel injection valve is shown in FIG.
The injection nozzle J1 includes a nozzle body J2 and a needle J3. When the fuel injection device is operated, high pressure fuel is supplied from a pressure accumulating device such as a common rail into the nozzle hole J5 through a nozzle fuel hole J4 formed in the nozzle body J2. The nozzle body J2 is always filled with high-pressure fuel.
The fuel injection valve changes the balance between the upward force received from the high-pressure fuel and the downward force received from the piston by changing the pressing force from the piston connected to the upper part of the needle J3. J3 is displaced in the vertical direction to control fuel injection.

  In the conventional injection nozzle J1, a sliding shaft portion J6 is formed on the needle J3, and the sliding shaft portion J6 can be slid on the nozzle body J2 via a sliding clearance (fine clearance). A sliding hole J7 is formed to support the sliding shaft portion J6, and the sliding length of the sliding shaft J6 and the sliding hole J7 suppresses the inclination of the needle J3. (See, for example, Patent Document 1).

In recent years, the following problem has arisen due to a dramatic increase in the pressure of high-pressure fuel supplied to the inside of the nozzle hole J5 in order to cope with stricter exhaust gas regulations.
(1) The amount of fuel leaking from the sliding clearance between the sliding shaft portion J6 and the sliding hole J7 to the low pressure side due to a dramatic increase in the pressure of the high-pressure fuel supplied into the nozzle hole J5 (static Leakage) increases. When the amount of leakage that leaks to the low-pressure side increases, in addition to the fuel that is actually injected, it is necessary to supply fuel for the leakage into the nozzle hole J5, so a high-pressure fuel pump that supplies high-pressure fuel to the pressure accumulator ( High fuel supply capacity is required for the supply pump.
(2) Since the pressure loss energy when the fuel leaks from the sliding clearance between the sliding shaft portion J6 and the sliding hole J7 to the low pressure side is converted into heat, the amount of fuel leaking from the sliding clearance to the low pressure side is reduced. If it increases, the leak temperature rises, and parts having a low heat resistance limit (for example, rubber, resin, etc.) tend to deteriorate.
(3) Each component of the fuel injection valve is processed with high precision, and there is a concern that each component of the fuel injection valve is deformed by heat due to an increase in the leak amount and an increase in the leak temperature.

In order to solve the above problem, it is necessary to reduce the amount of fuel leakage due to the sliding clearance between the sliding shaft portion J6 and the sliding hole J7. However, the conventional structure has the following problems.
(A) As the pressure of the high-pressure fuel supplied into the nozzle hole J5 increases, the inner diameter of the sliding hole J7 is deformed in the expanding direction by the pressure of the high-pressure fuel, and the sliding shaft portion J6 and the sliding hole The sliding clearance of J7 increases, and the amount of fuel leakage from the sliding clearance to the low pressure side increases.
(B) Due to the tightening axial force of the retaining nut that fastens the nozzle body J2 to the lower body of the fuel injection valve, the inner diameter of the sliding hole J7 is deformed in the expanding direction, and the sliding shaft portion J6 and the sliding hole J7 The sliding clearance increases, and the amount of fuel leakage from the sliding clearance to the low pressure side increases.

A technique for reducing the inner diameter of the sliding hole J7 in order to suppress the increase in the pressure of the high-pressure fuel supplied into the nozzle hole J5 and the expansion of the inner diameter of the sliding hole J7 due to the tightening axial force of the retaining nut. Has been proposed. That is, it has been proposed to reduce the leak amount by increasing the thickness around the sliding hole J7 and suppressing the deformation amount of the inner diameter of the sliding hole J7.
However, when the diameter of the sliding hole J7 is reduced, it is also necessary to reduce the diameter of the needle J3 itself inserted into the nozzle body J2 from the sliding hole J7. The diameter of the needle J3 below the sliding shaft portion J6 is a dimension related to the area that receives the fuel pressure, and is a dimension that greatly affects the vertical displacement characteristic of the needle J3, that is, the injection characteristic. For this reason, the inner diameter of the sliding hole J7 is not easily reduced because it is restricted by the injection characteristics.
JP-A-2-112666

  The present invention has been made in view of the above-described problems, and its purpose is to retain the nozzle even if the pressure of the high-pressure fuel supplied into the nozzle hole increases without affecting the injection characteristics. An object of the present invention is to provide a fuel injection valve capable of suppressing or controlling the amount of fuel leakage from the nozzle body side to the lower body side even if the nozzle body is deformed by the tightening axial force of the nut.

[Means of claim 1]
In the fuel injection valve employing the means of claim 1, the pressure compartment sliding part in which the sliding hole is formed is provided as a separate part from the nozzle body and the lower body. For this reason, even if the nozzle body is deformed due to the tightening axial force of the retaining nut, etc., the pressure compartment sliding parts are not affected, and there is a problem that the inner diameter of the sliding holes of the pressure compartment sliding parts is increased. do not do.
That is, even if the nozzle body is deformed by the tightening axial force of the retaining nut or the like, there is no problem that the sliding clearance between the sliding shaft portion and the sliding hole becomes large.

As described above, as the pressure of the high-pressure fuel supplied to the inside of the nozzle hole increases, the pressure of the high-pressure fuel generates a force that deforms the inner diameter of the sliding hole in the direction of expansion.
However, since the high pressure receiving surface of the pressure compartment sliding part receives the pressure of the high pressure fuel inside the nozzle hole, the higher the pressure of the high pressure fuel supplied to the inside of the nozzle hole, the more inside the high pressure receiving surface. A force for deforming the inner diameter of the sliding hole in the direction of diameter reduction is generated.
In this way, the pressure of the high-pressure fuel simultaneously generates the force that deforms the sliding hole in the diameter-expanding direction and the force that deforms the sliding hole in the diameter-decreasing direction. There is no problem of increased sliding clearance. Thereby, the amount of fuel leakage from the nozzle body side to the lower body side can be suppressed.

  Also, by adjusting the material (hardness) of the pressure compartment sliding part, the thickness of the pressure compartment sliding part, the axial length of the high pressure pressure receiving surface, etc., the sliding hole is deformed in the reduced diameter direction by the pressure of the high pressure fuel. You can adjust the amount. As a result, the sliding clearance between the sliding shaft portion and the sliding hole can be adjusted, and the amount of fuel leakage from the nozzle body side to the lower body side can be suppressed and controlled.

Furthermore, the sliding hole is provided in the pressure compartment sliding component which is a separate part from the nozzle body, and after the needle is incorporated in the nozzle body, the pressure compartment sliding component can be incorporated. The diameter of the sliding hole does not restrict the diameter of the needle that receives the high-pressure fuel. That is, regardless of the diameter of the sliding hole, the diameter of the needle for receiving the high-pressure fuel can be freely set, and the injection characteristics are not affected.
Further, in the conventional technique, since it is necessary to insert and assemble the needle from the sliding hole provided in the nozzle body, it is necessary to make the outer diameter dimension of the sliding shaft portion of the needle the largest among the needles. However, in the fuel injection valve employing the means of claim 1, the outer diameter of the sliding shaft portion can be made smaller than that of the conventional one. By making the outer diameter dimension of the sliding shaft portion smaller than before, the passage area of the sliding clearance between the sliding shaft portion and the sliding hole can be reduced, thereby reducing the amount of leakage, Since the sliding area becomes small, sliding becomes easy and the responsiveness of the needle can be improved.

[Means of claim 2]
In the fuel injection valve employing the means of claim 2, the upper side of the nozzle hole is provided with a larger diameter than the lower side.
As described above, since the sliding hole is provided in the pressure compartment sliding part which is a separate part from the nozzle body, the upper side of the nozzle hole is not limited by the inner diameter of the sliding hole, and the upper side of the nozzle hole. The inner diameter can be increased.
And by making the internal diameter of the upper side of a nozzle hole large, while processing the valve seat of the lower end surface of a nozzle hole becomes easy, the processing precision of a valve seat can be raised.

On the other hand, by providing the upper side of the nozzle hole with a large diameter, the high-pressure fuel supplied from the lower body can be supplied from the large diameter part to the periphery of the needle. As a result, it is not necessary to form nozzle fuel holes for supplying high pressure fuel to the fuel reservoir provided in the middle part of the nozzle holes, and productivity can be improved.
Further, conventionally, since the thickness near the intersection between the nozzle fuel hole and the nozzle hole becomes thin, there is a problem that the mechanical strength near the intersection is lowered. However, since the nozzle fuel hole can be eliminated, a weak portion can be removed from the injection nozzle.
Further, conventionally, a fuel reservoir for receiving high-pressure fuel supplied from the nozzle fuel hole is provided in the middle portion of the nozzle hole. However, this fuel reservoir is formed by a processing technique such as electric corrosion, and the productivity is poor. . However, since the fuel reservoir can be eliminated, the processing of the fuel reservoir becomes unnecessary, and the productivity can be improved.

[Means of claim 3 ]
The fuel injection valve adopting the means of claim 3 is a two-way type fuel injection valve that controls the pressure in the pressure control chamber by an electromagnetic valve and transmits the pressure change in the pressure control chamber to the needle through a piston. By changing the downward force of the piston by changing the pressure in the pressure control chamber, the balance between the upward force that the needle receives from the high-pressure fuel and the downward force that it receives from the piston is changed, and the needle is displaced vertically. It controls fuel injection.

The fuel injection valve of the best mode is assembled with a lower body in which a lower portion of a cylinder hole formed in a central portion is in a low pressure state, a piston slidably supported inside the cylinder hole, and a lower end surface of the lower body. A nozzle body with a nozzle hole to which high-pressure fuel is supplied is formed in the center, a needle that is slidably supported inside the nozzle hole, a lower part of the cylinder hole, and an upper part of the nozzle hole And a pressure compartment sliding component.
The pressure compartment sliding part has a sliding hole that slidably supports the sliding shaft part of the upper part of the needle or the lower part of the piston through a sliding clearance over the entire circumference, and the outer periphery of the sliding hole. The part has a high-pressure receiving surface that receives the pressure of the high-pressure fuel inside the nozzle hole, and is provided as a separate part from the lower body and the nozzle body to partition the low pressure of the cylinder hole and the high pressure of the nozzle hole.
Further, a coil spring for biasing the needle downward is mounted on the outer periphery of the needle inside the nozzle hole, and the pressure compartment sliding component receives the spring force of the coil spring and abuts on the lower end surface of the lower body. A large-diameter portion and a small-diameter portion having a small outer diameter through a step from the large-diameter portion are arranged, and the small-diameter portion is disposed inside the cylinder hole.

Hereinafter, a reference example that does not apply to the present invention will be referred to as Example 1, and Example 1 will be described with reference to FIGS. 1 to 3 , and then one example of the present invention will be described as Example 2. FIG.
(Description of fuel injection valve 1)
The overall configuration of the fuel injection valve 1 will be described with reference to FIG.
The fuel injection valve 1 is used, for example, in a pressure accumulation fuel injection device for a diesel engine, and injects high pressure fuel supplied from a pressure accumulation device (not shown) into an engine combustion chamber.
As shown in FIG. 3, the fuel injection valve 1 includes an injection nozzle 2, a lower body 3, a piston 4, an orifice plate 5, an electromagnetic valve 6, and the like.

  The injection nozzle 2 includes a nozzle body 8 having a nozzle hole 7 drilled from the upper end surface to the vicinity of the lower end and having an injection hole 8a at the tip, and a needle 9 supported slidably inside the nozzle hole 7. Is done. The needle 9 is urged downward (in the valve closing direction) by a coil spring 11 disposed around the upper portion of the needle 9. The injection nozzle 2 is fastened to the lower part of the lower body 3 by a retaining nut 12. Details of the injection nozzle 2 will be described later.

The lower body 3 leaks in the cylinder hole 13 into which the piston 4 is inserted, the high-pressure passage 14 that leads the high-pressure fuel supplied from the pressure accumulator to the injection nozzle 2, the high-pressure passage 15 that leads to the orifice plate 5, and the solenoid valve 6. A low pressure passage 16 for discharging the fuel to the low pressure side, a low pressure passage 17 for guiding the fuel leaking in the lower portion of the cylinder hole 13 to the low pressure side of the electromagnetic valve 6 and the like are formed.
The piston 4 is slidably inserted into a cylinder hole 13 formed in the center of the lower body 3, and a lower end thereof is connected to the needle 9. The upper side of the piston 4 is inserted into the cylinder hole 13 through a fine sliding clearance, and fuel accumulated in a pressure control chamber 18 described later slides between the piston 4 and the cylinder hole 13. It is provided so as to suppress leakage from the clearance to the lower pressure side below the cylinder hole 13.

  The orifice plate 5 is disposed on the end surface of the lower body 3 that opens to the upper end of the cylinder hole 13. The pressure control chamber 18 is defined by the space surrounded by the upper end surface of the piston 4, the lower surface of the orifice plate 5, and the cylinder hole 13. Is formed. The high pressure fuel is supplied to the pressure control chamber 18 via the inlet orifice 21 of the inflow passage formed in the orifice plate 5, and communicates to the low pressure side via the outlet orifice 22 of the discharge passage formed in the orifice plate 5. To do.

(Description of solenoid valve 6)
The electromagnetic valve 6 opens and closes the outlet orifice 22 (discharge passage), and a movable valve (armature) 24 with a ball valve 23 attached to the lower end, and holds the movable valve 24 slidably in the vertical direction. A valve body 25 for assembling the orifice plate 5 on the lower body 3, a spring 26 for biasing the movable valve 24 downward (in the valve closing direction), a solenoid 27 for driving the movable valve 24 upward (in the valve opening direction), and the like. The upper body 28 is assembled and fixed to the upper portion of the lower body 3 by an upper body 28.

The solenoid 27 is in contact with the movable valve 24 when the movable valve 24 is attracted, the coil 31 that generates a magnetomotive force when energized, the stator core 32 that attracts the movable valve 24 by the magnetomotive force generated by the coil 31. And a stopper 33 for setting an upper limit of lift of the movable valve 24. The stator core 32 and the stopper 33 constitute a stator, and the stator core 32 and the stopper 33 may be provided integrally.
The movable valve 24 is formed by integrating a disk portion that is magnetically attracted to the stator core 32 and a shaft that is slidably supported in the axial direction by the valve body 25.

(Description of operation of fuel injection valve 1)
The high-pressure fuel supplied from the pressure accumulator to the fuel injection valve 1 is introduced into the nozzle hole 7 of the injection nozzle 2 and the pressure control chamber 18.
When the coil 31 is OFF, the movable valve 24 is pressed downward by the urging force of the spring 26, and the ball valve 23 is seated on the upper surface of the orifice plate 5 so as to close the outlet orifice 22. Is maintained at a high pressure. The high pressure in the pressure control chamber 18 acts on the needle 9 via the piston 4 and strongly urges the needle 9 together with the coil spring 11 downward (in the valve closing direction).

  On the other hand, the high-pressure fuel supplied to the nozzle hole 7 of the injection nozzle 2 acts on the pressure-receiving surface of the needle 9 and exerts an upward force that pushes the needle 9 upward (in the valve opening direction). However, when the ball valve 23 is in the state of closing the outlet orifice 22, the downward force that pushes the needle 9 downward is greater, so the needle 9 closes the nozzle hole 8 a without lifting, and thus no fuel is injected.

When the coil 31 is turned on, the movable valve 24 moves upward against the biasing force of the spring 26, the ball valve 23 is lifted upward from the upper surface of the orifice plate 5, the outlet orifice 22 is opened, and the outlet An orifice 22 communicates with the low pressure passage 16. As a result, the fuel in the pressure control chamber 18 passes through the outlet orifice 22 and is discharged from the low pressure passage 16, and the pressure in the pressure control chamber 18 decreases.
When the pressure in the pressure control chamber 18 decreases to a predetermined valve opening pressure, the force that pushes the needle 9 upward increases, the needle 9 lifts, the nozzle hole 8a is opened, and fuel injection is started.

When the coil 31 is turned off, the movable valve 24 is pressed downward by the urging force of the spring 26, and the ball valve 23 is seated on the upper surface of the orifice plate 5 so as to close the outlet orifice 22. When the ball valve 23 closes the outlet orifice 22, the fuel pressure in the pressure control chamber 18 rises again.
When the pressure in the pressure control chamber 18 rises to a predetermined valve closing pressure, the force that pushes the needle 9 downward increases, the needle 9 is pushed down, the nozzle hole 8a is closed, and the injection ends.

(Characteristics of Example 1)
As shown in FIG. 1, the fuel injection valve 1 includes a lower body 3 in which a lower portion of a cylinder hole 13 is in a low pressure state via a low pressure passage 17, and a piston 4 that is slidably supported inside the cylinder hole 13. A nozzle body 8 which is assembled to the lower end surface of the lower body 3 by a retaining nut 12 (reference numeral, see FIG. 3), and a nozzle hole 7 to which high pressure fuel is supplied through a high pressure passage 14 is formed at the center. And a needle 9 that is slidably supported inside the nozzle hole 7.
The fuel injection valve 1 is provided as a separate component from the lower body 3 and the nozzle body 8, and divides the lower part (low pressure) of the cylinder hole 13 and the upper part (high pressure) of the nozzle hole 7, and the upper part of the needle 9. Is provided with a pressure section sliding component 35 that slidably supports the pressure section.

Next, details of the injection nozzle 2 in the first embodiment will be described.
The inner diameter of the upper side of the nozzle hole 7 of the nozzle body 8 is larger than the inner diameter of the lower side of the nozzle hole 7. The upper large-diameter hole 36 is a portion that accommodates the coil spring 11, receives high-pressure fuel from the high-pressure passage 14, and supplies high-pressure fuel around the needle 9, and the lower small-diameter hole 37 is constant. The inner diameter is drilled to near the lower end.
A conical valve seat 38 is formed at the lower end of the nozzle hole 7, and a plurality of injection holes 8 a are formed on the downstream side of the valve seat 38. The nozzle hole 8a has an inlet opening on the upper surface on the downstream side of the valve seat 38, passing through a conical wall forming the lower end of the nozzle body 8, and an outlet opening on the outer peripheral surface of the conical wall.

The needle 9 has a sliding shaft portion 41, a flange 42, a chamfered sliding portion 43, and a shaft portion 44 from the upper side to the lower side, and a substantially conical valve portion 45 is formed at the lower end thereof. . In addition, the shape of the needle 9 shown in this Example 1 shows an example, and may be provided in another shape.
The sliding shaft portion 41 is slidably supported by the sliding hole 46 through a fine sliding clearance inside the sliding hole 46 of the pressure compartment sliding component 35.
The flange 42 is a spring receiving portion that receives the load of the coil spring 11.

The chamfered sliding portion 43 is a portion whose outer diameter is slightly smaller than the inner diameter of the small diameter hole 37 of the nozzle hole 7 and is slidably supported on the inner surface of the nozzle hole 7. A plurality of chamfered portions for guiding the high-pressure fuel supplied to 36 to the lower side of the small-diameter hole 37 are formed.
The shaft portion 44 has an outer diameter smaller than the inner diameter of the small-diameter hole 37 and is provided so as to guide the high-pressure fuel supplied via the chamfered portion to the valve seat 38 side.

  The valve portion 45 is composed of an upper cone portion and a lower cone portion, and a seat wire 45a that abuts on the valve seat 38 is formed at the boundary portion. In the state where the valve portion 45 is seated on the valve seat 38, the seat wire 45a of the valve portion 45 abuts on the valve seat 38 to block communication between the nozzle hole 7 and the injection hole 8a. Is separated from the valve seat 38, the seat wire 45a of the valve portion 45 is separated from the valve seat 38, the nozzle hole 7 and the injection hole 8a are communicated, and high-pressure fuel is injected from the injection hole 8a.

The pressure compartment sliding component 35 has a substantially pipe shape, and is formed of a hard material that is finely deformed by pressure, such as a metal material such as a steel material or ceramic.
The inner peripheral surface of the pressure compartment sliding component 35 is a sliding hole 46 that slidably supports the sliding shaft portion 41 provided on the upper portion of the needle 9 through a fine sliding clearance over the entire circumference. .
As shown in FIG. 2, the outer diameter shape of the pressure compartment sliding component 35 receives a compressive load of the coil spring 11, and has a large diameter portion 47 that contacts the lower end surface of the lower body 3, and a step difference from the large diameter portion 47. A small-diameter portion 48 whose outer periphery is small in diameter. The outer diameter of the large-diameter portion 47 is smaller than the inner diameter of the large-diameter hole 36, the high-pressure passage 14 communicates with the gap between the large-diameter portion 47 and the large-diameter hole 36, and high-pressure fuel is introduced into the nozzle hole 7. It comes to be supplied. Further, the small diameter portion 48 is disposed inside the coil spring 11.

  The pressure compartment sliding component 35 is pressed against the lower end surface of the lower body 3 using the pressure difference between the pressure (high pressure) of the high pressure fuel supplied into the nozzle hole 7 and the low pressure at the lower part of the cylinder hole 13. The contact surface between the pressure compartment sliding part 35 and the lower body 3 is sealed, and the upper edge of the sliding hole 46 is used to increase the surface pressure of the seal portion and to increase the pressure receiving area on the low pressure side. A chamfer 49 is formed over the entire circumference (see FIG. 2).

  As shown in FIG. 1, the pressure section sliding component 35 according to the first embodiment has the entire outer periphery disposed inside the nozzle hole 7, and the pressure section sliding component 35 has the entire outer peripheral surface. It is a high pressure receiving surface that receives the pressure of high pressure fuel. For this reason, as the pressure of the high-pressure fuel supplied into the nozzle hole 7 increases, the pressure of the high-pressure fuel generates a deforming force in the reduced diameter direction in a wide range of the sliding hole 46.

(Effect of Example 1)
As described above, in the fuel injection valve 1 of the first embodiment, the pressure compartment sliding component 35 in which the sliding hole 46 is formed is provided as a separate component from the nozzle body 8 and the lower body 3. For this reason, even if the nozzle body 8 is deformed by the tightening axial force of the retaining nut 12 or the like, the pressure compartment sliding component 35 is not affected by the deformation of the nozzle body 8, so There is no problem that the inner diameter of the moving hole 46 is increased.
That is, even if the nozzle body 8 is deformed by the tightening axial force of the retaining nut 12 or the like, there is no problem that the sliding clearance between the sliding shaft portion 41 and the sliding hole 46 becomes large.

The nozzle hole 7 receives supply of high-pressure fuel from the pressure accumulator, and as the pressure of the supplied high-pressure fuel increases, the fuel pressure applied to the inside of the sliding hole 46 (sliding hole 46 and sliding shaft portion 41). The pressure of the leaked fuel passing between them increases, and a force is generated that deforms the inner diameter of the sliding hole 46 in the direction of expansion.
However, since the high pressure receiving surface of the pressure compartment sliding component 35 (the entire outer periphery of the pressure compartment sliding component 35 in this embodiment 1) receives the pressure of the high pressure fuel inside the nozzle hole 7, As the pressure of the high-pressure fuel supplied increases, a force is generated that deforms the inner diameter of the sliding hole 46 on the inner side of the high-pressure receiving surface in the direction of diameter reduction.

  As described above, the force that deforms the sliding hole 46 in the diameter-expanding direction and the force that deforms the sliding hole 46 in the diameter-decreasing direction cancel each other out due to the pressure of the high-pressure fuel. The problem that the sliding clearance of the sliding hole 46 becomes large can be suppressed, and the sliding clearance can be made small. That is, by adjusting the material (hardness) of the pressure compartment sliding component 35, the thickness and shape of the pressure compartment sliding component 35, the axial length of the high pressure receiving surface, etc., the sliding hole 46 is formed by the pressure of the high pressure fuel. The amount of deformation in the direction of diameter reduction can be adjusted. This makes it possible to adjust the sliding clearance between the sliding shaft portion 41 and the sliding hole 46 with respect to the pressure of the high-pressure fuel supplied to the inside of the nozzle hole 7, and from the nozzle body 8 side to the lower body 3 side. The amount of fuel leakage can be suppressed and controlled.

The sliding hole 46 is provided in the pressure compartment sliding component 35 which is a separate component from the nozzle body 8, and the pressure compartment sliding component 35 can be assembled after the needle 9 is assembled in the nozzle body 8. Therefore, the diameter of the sliding hole 46 does not limit the diameter of the needle 9 that receives the high-pressure fuel. That is, regardless of the diameter of the sliding hole 46, the diameter of the needle 9 for receiving the high-pressure fuel can be freely set, and the injection characteristics are not affected.
Further, since the diameter of the sliding hole 46 does not restrict the diameter of the needle 9 that receives the high-pressure fuel, the outer diameter of the sliding shaft portion 41 can be made smaller than the conventional one. By making the outer diameter dimension of the sliding shaft portion 41 smaller than that of the conventional one, the passage area of the sliding clearance between the sliding shaft portion 41 and the sliding hole 46 can be reduced, and this also reduces the amount of leakage. Can be reduced. Furthermore, since the sliding area of the sliding shaft part 41 and the sliding hole 46 becomes small, the needle 9 can be easily slid and the responsiveness of the needle 9 can be improved.

Since the sliding hole 46 is provided in the pressure compartment sliding part 35 which is a separate part from the nozzle body 8, the upper side of the nozzle hole 7 is not restricted by the inner diameter of the sliding hole 46, and the nozzle hole 7 The upper inner diameter can be increased.
Since the upper inner diameter of the nozzle hole 7 is set to a large diameter, it becomes easy to insert a tool for processing the valve seat 38 on the lower end surface of the nozzle hole 7, and the processing of the valve seat 38 is facilitated. The processing accuracy of the sheet 38 can be increased.

By providing the upper side of the nozzle hole 7 with a large diameter, the high pressure fuel supplied from the high pressure passage 14 of the lower body 3 can be supplied from the large diameter portion 47 to the periphery of the needle 9. As a result, it is not necessary to form the nozzle fuel hole J4 (reference numeral, see FIG. 6) for supplying high-pressure fuel to the conventional fuel reservoir J8 (reference numeral, see FIG. 6), and productivity can be improved. .
Further, in the conventional technique, the fuel reservoir J8 (reference numeral, see FIG. 6) is provided in the middle portion of the nozzle hole 7 by a processing technique such as electric corrosion, but this fuel reservoir J8 (reference numeral, see FIG. 6) can be eliminated. Therefore, productivity can be improved.
Further, conventionally, since the thickness near the intersection of the nozzle fuel hole J4 (reference numeral, see FIG. 6) and the nozzle hole 7 is reduced, there is a problem that the mechanical strength near the intersection is lowered. However, since the nozzle fuel hole J4 (reference numeral, see FIG. 6) can be eliminated, a weak portion can be removed from the injection nozzle 2, and the reliability of the fuel injection valve 1 can be improved.
That is, the nozzle body 8 can be manufactured in a simple shape at a low cost, and the workability and processing accuracy of the valve seat 38 can be improved, and the reliability of the fuel injection valve 1 can be improved.

A second embodiment will be described with reference to FIGS. In addition, the same code | symbol as the said Example 1 shows the same function thing.
In the first embodiment, an example in which the large-diameter portion 47 and the small-diameter portion 48 of the pressure compartment sliding component 35 are both disposed in the nozzle hole 7, that is, in a portion to which the pressure of high-pressure fuel is applied. On the other hand, in the second embodiment, the large diameter portion 47 is disposed in the portion where the pressure of the high pressure fuel is applied inside the nozzle hole 7, and the small diameter portion 48 is disposed in the cylinder hole 13.
That is, in this second embodiment, the pressure compartment sliding component 35 is divided into a large diameter portion 47 that receives the pressure of the high pressure fuel from the outer peripheral side and a small diameter portion 48 that does not receive the pressure of the high pressure fuel. The outer peripheral surface of the diameter portion 47 is a high pressure receiving surface.

With this arrangement, a force in the diameter reducing direction is generated only in the sliding hole 46 inside the large diameter portion 47 that receives the pressure of the high-pressure fuel, and leak fuel (sliding) is generated in the sliding hole 46 inside the small diameter portion 48. The force in the diameter expansion direction is slightly generated by the pressure of the fuel passing between the moving hole 46 and the sliding shaft portion 41.
The amount of leakage with respect to the pressure of the high-pressure fuel supplied into the nozzle hole 7 is adjusted by adjusting the axial lengths of the large-diameter portion 47 where the sliding hole 46 is reduced in diameter and the small-diameter portion 48 where the diameter is increased. can do.

[Modification ]
In the embodiment example above, the sliding clearance is provided between the pressure section picture sliding part 35 and the needle 9, an example of partitioning the high pressure side and low pressure side, the pressure section picture sliding part 35 and the piston 4 A sliding clearance may be provided between the high pressure side and the low pressure side.
In the above embodiment, the coil spring 11 is arranged around the needle 9, but the coil spring 11 may be arranged around the piston 4.

(Example 1) which is sectional drawing of an injection nozzle. (Example 1) which is sectional drawing of a pressure division sliding component. (Example 1) which is sectional drawing of a fuel injection valve. (Example 2) which is sectional drawing of an injection nozzle. (Example 2) which is sectional drawing of a pressure division sliding component. It is sectional drawing of an injection nozzle (conventional example).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 3 Lower body 4 Piston 6 Electromagnetic valve 7 Nozzle hole 8 Nozzle body 9 Needle 11 Coil spring 13 Cylinder hole 18 Pressure control chamber 21 Inlet orifice (inflow passage)
22 Outlet orifice (discharge passage)
35 Pressure compartment sliding part 36 Large diameter hole (above nozzle hole)
37 Small hole (under nozzle hole)
41 Sliding shaft portion 46 Sliding hole 47 Large diameter portion 48 Small diameter portion

Claims (3)

(A) a lower body in which a lower portion of a cylinder hole drilled in a central portion is in a low pressure state;
(B) a piston slidably supported within the cylinder hole;
(C) a nozzle body that is assembled to the lower end surface of the lower body and has a nozzle hole that is supplied with high-pressure fuel at the center;
(D) a needle that is slidably supported within the nozzle hole;
(E) having a sliding hole for slidably supporting the sliding shaft at the upper part of the needle or the lower part of the piston through a sliding clearance over the entire circumference, and at the outer peripheral part of the sliding hole, A pressure partition slide having a high pressure receiving surface that receives the pressure of the high pressure fuel inside the nozzle hole, and is provided as a separate part from the lower body and the nozzle body, and divides the lower part of the cylinder hole and the upper part of the nozzle hole A moving part ,
A coil spring that urges the needle downward is attached to the outer periphery of the needle inside the nozzle hole,
The pressure section sliding component receives a spring force of the coil spring, and includes a large diameter portion that comes into contact with a lower end surface of the lower body, and a small diameter portion having a small outer diameter through a step from the large diameter portion,
The fuel injection valve according to claim 1, wherein the small-diameter portion is disposed inside the cylinder hole . The fuel injection valve according to claim 1, wherein
The fuel injection valve according to claim 1, wherein the upper side of the nozzle hole is provided with a larger diameter than the lower side. The fuel injection valve according to claim 1 or 2,
A pressure control chamber to which high-pressure fuel is supplied through an inflow passage is formed at the upper part of the cylinder hole.
The piston is configured to transmit the pressure in the pressure control chamber to the needle,
The pressure control chamber includes a discharge passage communicating with the low pressure side;
A fuel injection valve characterized in that the discharge passage is opened and closed by an electromagnetic valve .

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