JP2013170476A - Fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in a conventional fuel injection nozzle, wherein if any needle axial force is generated by the fuel pressure when a nozzle valve is closed while a nozzle body is exposed to a very high temperature, a seat surface is raised on the downstream side of a seat part of the nozzle body, and the plastic deformation of the seat part recessed outward occurs, and if a needle valve is opened in the state, the very small gap on the seat downstream side is narrowed, the nozzle valve opening force is increased, and the fuel injection amount is increased more than that of an initial period.SOLUTION: A fuel injection nozzle has a deformation clearance part 95 which permits any plastic deformation in a rising manner occurring when a seat part 94 receives the needle axial force from a needle 1, on a nozzle seat 5 of a nozzle body 3. Thus, by reducing the area forming a very small gap 17 on the downstream side of the seat diameter of a valve part 2 of the needle 1, any change in the nozzle valve opening force (F4) can be controlled between the initial state of the nozzle seat 5 and the state after the aged deterioration, and thereby, the change in the fuel injection amount can be reduced.

Description

  The present invention relates to a fuel injection nozzle that directly injects fuel into a combustion chamber of an internal combustion engine (engine).

[Conventional technology]
2. Description of the Related Art Conventionally, as a fuel injection valve that injects fuel directly into a combustion chamber of an internal combustion engine (engine) such as a diesel engine, a needle that reciprocates in an axial direction and the needle are supported so as to be slidable back and forth in the axial direction. A fuel injection nozzle including a bottomed cylindrical nozzle body having a sliding hole is known (see, for example, Patent Documents 1 and 2).

Here, FIG. 4 and FIG. 5 are diagrams showing a main part of a known general fuel injection nozzle. When the fuel injection nozzle is opened, a sheet portion downstream gap 106 is formed between the valve portion 102 of the needle 101 and the nozzle seat surface 104 of the nozzle body 103. A nozzle sheet surface 104, a sac chamber 107, a plurality of nozzle holes 108, and the like are provided.
When the fuel injection nozzle is closed, an axial force in the valve closing direction is applied to the needle 101 from the piston and the spring.

When the needle 101 starts to rise when the fuel injection nozzle is opened, and high-pressure fuel flows from the fuel flow path 105 through the seat portion downstream gap 106 into the sac chamber 107, the needle 101 moves toward the valve portion 102 of the needle 101. An axial force (nozzle valve opening force: F4) that opens the valve acts. As a result, the needle 101 is detached from the nozzle sheet surface 104 of the nozzle body 103 to open the injection hole 108, and fuel is injected from the injection hole 108 into the combustion chamber.
When the fuel injection nozzle is closed, a needle axial force (nozzle closing force: F1 + F2) due to the fuel pressure and the spring load acts. As a result, the valve portion 102 of the needle 101 is seated on the nozzle seat surface 104 of the nozzle body 103 and closes the nozzle hole 108. Therefore, fuel injection from the nozzle hole 108 is stopped.
As described above, the nozzle seat surface 104 of the nozzle body 103 is repeatedly subjected to a large impact load when the valve portion 102 of the needle 101 is seated when the fuel injection nozzle is closed, so that the hardness is increased and the wear resistance is improved. desired.

[Conventional technical problems]
In recent years, in the fuel injection nozzle that injects high-pressure fuel into the combustion chamber of a diesel engine, demands for exhaust gas regulations and fuel efficiency regulations have become stricter in order to improve the environment and promote energy saving. For this reason, the improvement in the initial injection amount accuracy and the increase in the fuel injection pressure are progressing.
As the fuel injection pressure increases, the fuel injection pressure usage range further expands, and the fuel pressure at the time of nozzle closing and the needle axial force (nozzle closing force: F1 + F2) due to the spring load further increases. There is a possibility that excessive force is applied to the nozzle sheet surface 104 of the nozzle body 103 and the wear resistance of the nozzle sheet surface 104 is lowered.
Further, in order to maintain the emission performance of exhaust gas and the like, stable performance not only in the initial stage but also for a long time has been required.
However, changes in the environment of the fuel injection nozzle have become severe due to high-pressure injection and combustion temperature rise in the combustion chamber of the engine, etc., and repeated operation will cause changes in the injection performance due to aging (changes). This is a challenge to comply with fuel efficiency regulations.

By the way, in the conventional fuel injection nozzle, the peripheral portion of the nozzle hole of the nozzle body 103 is attached so as to be exposed (protruded) into the combustion chamber so that it can be directly injected into the combustion chamber of the engine. The periphery of the nozzle hole is directly exposed to heat, and the surface temperature of the nozzle body 103 tends to rise excessively under the influence of combustion heat (heated) of the engine.
At this time, when it is time to close the nozzle hole 108, as shown in FIG. 5C, due to the impact load when the valve portion 102 of the needle 101 is seated on the nozzle sheet surface 104 of the nozzle body 103, the nozzle sheet surface 104 The periphery of the sheet portion 111 is recessed outside the nozzle body 103, and plastic deformation occurs in such a manner that the sheet downstream portion 112 on the downstream side of the nozzle sheet surface 104 rises toward the inside of the nozzle body 103.

  Then, when the fuel injection nozzle is opened as shown in FIG. 5D in a state where the nozzle seat surface 104 of the nozzle body 103 is plastically deformed, the seat portion downstream gap 106 becomes narrower, so that the nozzle opening force ( F4) increases from the initial state before the aging of the nozzle sheet surface 104 occurs, and the fuel injection amount increases from the initial state.

Japanese Patent No. 4140540 JP 2008-175102 A

  In the present invention, the nozzle seat of the nozzle body is provided with a deformation relief portion that allows plastic deformation that occurs when the sheet portion receives a load from the needle, thereby reducing the area that becomes a minute gap on the downstream side of the needle diameter of the needle. Provided is a fuel injection nozzle capable of reducing a change in fuel injection amount by suppressing a change in nozzle opening force between an initial state before aging of the nozzle sheet and after aging of the nozzle sheet. For the purpose.

The invention according to claim 1 (fuel injection nozzle) has a valve portion and has a needle that can reciprocate in the axial direction and a nozzle hole that performs fuel injection, and the needle can be reciprocated in the axial direction. And a supporting nozzle body.
The nozzle body has a nozzle seat that is positioned upstream of the nozzle hole in the fuel flow direction and on which the valve portion of the needle can be seated.
The nozzle seat is a seat portion that can contact the valve portion of the needle, and a deformation relief portion that is installed between the nozzle hole and the seat portion to allow plastic deformation that occurs when the seat portion receives a load from the needle. have.

  According to the first aspect of the invention, the nozzle seat of the nozzle body is provided with a deformation relief portion that allows plastic deformation that occurs when the seat portion receives a load from the needle, so that a minute amount is provided on the downstream side of the needle diameter of the needle. Since the area that becomes the gap can be reduced, a change in the nozzle opening force between the initial state before the aging of the nozzle sheet occurs and the aging of the nozzle sheet can be suppressed. Therefore, it is possible to reduce the change in the injection amount of the fuel injected from the injection hole.

According to the invention described in claim 2, the deformation relief portion is provided by forming an annular space between the outer surface of the needle and the inner surface of the nozzle body.
According to the invention described in claim 3, the annular space is provided by denting the inner surface of the nozzle sheet on the opposite side to the valve portion side of the needle.
According to the invention described in claim 4, the fuel injection nozzle is provided with an annular gap formed between the valve portion of the needle and the nozzle seat of the nozzle body when the needle is opened.
The annular space is provided by being recessed on the opposite side with respect to the annular gap side.

According to the fifth aspect of the present invention, the valve portion of the needle has an annular seal portion that can be seated on the nozzle seat of the nozzle body.
According to the invention described in claim 6, the nozzle body includes the nozzle sheet having a conical sheet surface whose inner diameter gradually decreases toward one end.
The seal portion provided in the valve portion of the needle is seated on and removed from the seat surface provided in the nozzle seat of the nozzle body. As a result, the nozzle hole provided on the downstream side in the fuel flow direction from the sheet surface of the nozzle sheet is closed and opened. And while an injection hole is open | released, fuel is injected in the combustion chamber of the cylinder of internal combustion engines (engine), such as a diesel engine, for example.

According to the seventh aspect of the present invention, the annular fuel flow path for guiding the fuel supplied into the nozzle body to the downstream side in the fuel flow direction from the nozzle seat of the nozzle body is provided between the needle and the nozzle body. Is formed.
According to the eighth aspect of the present invention, the peripheral portion of the nozzle hole of the nozzle body communicates the fuel flow path with the nozzle hole, and collects fuel that flows in an annular manner in the fuel flow path and distributes and supplies it to the nozzle hole. A bottomed cylindrical sac portion in which a sac chamber is formed.
According to the invention described in claim 9, the nozzle holes are a plurality of nozzle holes penetrating so as to communicate the inside and outside of the sack portion. These nozzle holes are formed at a predetermined distance in the circumferential direction of the sack portion.
According to the invention described in claim 10, the nozzle body or the peripheral portion of the nozzle hole is disposed so as to be exposed (protruded) into the combustion chamber of an internal combustion engine (engine) such as a diesel engine.

It is sectional drawing which showed the injector provided with the fuel-injection nozzle (Example 1). (A) is sectional drawing which showed the principal part of the fuel-injection nozzle, (b) is sectional drawing which showed the nozzle hole periphery part of a nozzle body, (c) is an enlarged view of (b) (Example 1) ). (A), (b) is explanatory drawing which showed the opening / closing operation | movement of the initial needle, (c), (d) is explanatory drawing which showed the opening / closing operation | movement of the needle after aged deterioration (Example 1). (A) is sectional drawing which showed the principal part of the fuel-injection nozzle, (b) is sectional drawing which showed the nozzle hole periphery part of the nozzle body (conventional technique). (A), (b) is explanatory drawing which showed the initial needle opening / closing operation | movement, (c), (d) is explanatory drawing which showed the needle opening / closing operation | movement after aged deterioration (conventional technique).

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The present invention aims to suppress the change in the nozzle opening force after the aging of the nozzle seat of the nozzle body and reduce the change in the fuel injection amount when the seat portion receives a load from the needle on the nozzle seat of the nozzle body. This was realized by providing a deformation relief part that allows plastic deformation occurring in the needle to reduce the area that becomes a minute gap on the downstream side of the needle diameter of the needle.

[Configuration of Example 1]
1 to 3 show an injector (Embodiment 1) having a fuel injection nozzle to which the present invention is applied.

A fuel injection device for an internal combustion engine according to the present embodiment is a common rail fuel injection for supplying high pressure fuel into a combustion chamber of each cylinder of an internal combustion engine (hereinafter referred to as an engine) such as a multi-cylinder diesel engine mounted on a vehicle such as an automobile. A system (accumulation fuel injection device) is provided.
This common rail fuel injection system includes a supply pump with a built-in feed pump that pumps low pressure fuel from a fuel tank, a common rail into which high pressure fuel is introduced from the fuel discharge port of the supply pump, and high pressure fuel from each fuel outlet of the common rail. The high-pressure fuel accumulated in the common rail is injected and supplied into the combustion chamber of each cylinder of the engine via each injector.

The supply pump is a fuel injection pump (high pressure fuel pump) that pressurizes the fuel sucked into the pressurizing chamber from the feed pump through the electromagnetic valve to increase the pressure, and feeds the high pressure fuel to the common rail. The solenoid valve of the supply pump is a fuel metering valve that controls the amount of fuel discharged from the fuel discharge port of the supply pump by adjusting the amount of fuel drawn from the feed pump into the pressurized chamber.
A pressure accumulating chamber for accumulating high-pressure fuel corresponding to the injection pressure of the fuel to be injected and supplied into the combustion chamber for each cylinder of the engine is formed inside the common rail.
The supply pump or the common rail constitutes a high pressure generating unit that generates high pressure fuel.

Here, the injector of the present embodiment is used as a fuel control valve (fuel injection valve). As this injector, a direct-injection type fuel injection valve for an internal combustion engine (injector for a diesel engine) that supplies high-pressure fuel accumulated in the common rail in a mist form directly into the combustion chamber is employed.
The injector is an electromagnetic fuel injection valve in which a fuel injection nozzle that injects fuel into the engine and an electromagnetic valve that is fastened and fixed to a housing of the fuel injection nozzle are integrated.
The solenoid valve is configured to be electronically controlled by an injector drive current applied from an engine control unit (electronic control unit: ECU). As a result, the fuel injection amount and the injection timing at which fuel is injected from the nozzle nozzle hole of the injector are controlled.

  The fuel injection nozzle has a conical surface shape in which a conical surface valve portion 2 provided at one end portion in the axial direction of a needle valve (nozzle needle: needle) 1 is formed on the inner surface of the nozzle hole peripheral portion 4 of the nozzle body 3. It is an automobile part (engine part) that closes and opens a plurality of injection holes (hereinafter referred to as injection holes 8) communicating with the sac chamber 6 by being seated on and removed from the nozzle sheet 5. The sac chamber 6 is formed in a sack portion (circular top portion) 7 provided on one end side (tip end side) of the nozzle body 3 in the axial direction. At least one (a plurality of) injection holes 8 are formed through the sack portion 7 so as to penetrate therethrough.

The housing of the fuel injection nozzle includes a nozzle body 3 having a plurality of injection holes 8 for injecting fuel on one end side, an injector body 9 connected to the other end of the nozzle body 3 in the axial direction, and a joint surface of the nozzle body 3 And a retaining nut 11 that joins and integrates the injector body 9 and the nozzle body 3 with a fastening axial force in the central axis direction in a state where an annular tip packing 10 is sandwiched between the joint surface of the injector body 9 and the injector body 9. Has been.
The nozzle body 3 includes a cylindrical nozzle hole peripheral portion 4 that is exposed in the combustion chamber of the engine and directly exposed to the combustion heat of the engine. The nozzle hole peripheral portion 4 has a conical surface nozzle seat 5 on which the valve portion 2 of the needle 1 can be seated, a conical sack portion 7 that forms a sac chamber 6 inside, and a plurality of sac chambers 6 that communicate with the sac chamber 6. A nozzle hole 8 is provided.

One end of the injector body 9 in the axial direction is coupled to the other end of the nozzle body 3 via the tip packing 10. A pressure control chamber 14 that is a back pressure control chamber for the needle 1 and the command piston 12 is formed at the other end of the injector body 9 in the axial direction.
A fuel reservoir 15 is formed in the central portion of the nozzle body 3 in the axial direction. The fuel flow path 16 communicating with the fuel reservoir chamber 15 is sucked through an annular gap (hereinafter referred to as a minute gap 17) formed between the valve portion 2 of the needle 1 and the nozzle seat 5 in the peripheral portion 4 of the nozzle hole. It communicates with the chamber 6. The minute gap 17 is a fuel flow path formed downstream of the seat diameter of the valve portion 2 of the needle 1 in the fuel flow direction when the fuel injection nozzle is opened (when the nozzle is opened).

The fuel flow path 16 is formed between the outer surface of the needle 1 and the inner surface of the nozzle body 3, and the high-pressure fuel supplied from the common rail into the fuel reservoir chamber 15 is smaller than the nozzle seat 5 in the fuel flow direction downstream. It is an annular fuel flow path (clearance) for leading to the gap 17, the sac chamber 6, and each nozzle hole 8.
The tip packing 10 is a regulating member that regulates the full lift amount of the needle 1 that receives an axial load (axial force in the valve closing direction) from the command piston 12 or the coil spring 13.

Here, the injector has a cylindrical fastening portion (hereinafter referred to as a fastening portion) 23 of the injector body 9 with a tip packing (orifice plate) 22 sandwiched between the injector body 9 of the fuel injection nozzle and the valve body 21 of the solenoid valve. By fastening and fixing the retaining nut 24 to the outer periphery of the fuel, the fuel injection nozzle and the solenoid valve are fastened and integrated.
The solenoid valve includes an orifice plate 22, a ball valve (solenoid valve body) 25 that can be seated on and removed from the orifice plate 22, and an electromagnetic actuator that drives the ball valve 25 in the valve opening direction. It is constituted by. The orifice plate 22 is formed with inlet and outlet orifices 26 and 27 for adjusting the flow rate of the fuel passing therethrough. The outlet orifice 27 constitutes a valve hole of an electromagnetic valve.

The electromagnetic actuator is used as a needle actuator that controls the opening / closing operation (fuel injection) of the needle 1 by increasing or decreasing the fuel pressure in the pressure control chamber 14 of the injector body 9.
The electromagnetic actuator includes a cylindrical valve body 21, a magnetic armature 31 that is slidably supported in a sliding hole that passes through the valve body 21 in the direction of the central axis thereof, and is energized when energized. A solenoid coil (hereinafter referred to as a coil) 32 that generates a magnetic flux, and a magnetic stator core 33 that forms a magnetic path on the inner and outer peripheral sides of the coil 32 are provided. The ball valve 25 and the armature 31 are pressed against the valve seat of the orifice plate 22 by the biasing force of the coil spring 34.

The armature 31 is disposed to face the magnetic pole surface of the stator core 33 with a predetermined gap therebetween.
The coil 32 is magnetic flux generation means (magnetic force generation means) that generates a magnetic force that draws the armature 31 toward the magnetic pole surface side of the stator core 33 when supplied with electric power (when a current is applied or energized).
The terminal portion of the coil 32 is connected to a pair of external connection terminals (terminals) 35. These terminals 35 are connector terminals for connecting the coil 32 and an external circuit (external power supply or external control circuit: ECU).

When the coil 32 is energized, a magnetic circuit in which magnetic flux concentrates through the armature 31 and the stator core 33 is formed.
The coil 32 attracts the armature 31 to cause the ball valve 25 housed in the tip housing hole of the armature 31 to be detached from the valve seat of the orifice plate 22. Thereby, the outlet channel having the outlet-side orifice 27 is opened.
When energization of the coil 32 is stopped, the armature 31 is moved by the biasing force of the coil spring 34 and the ball valve 25 is seated on the valve seat of the orifice plate 22. As a result, the outlet channel having the outlet-side orifice 27 is closed.

Here, the amount of current supplied to the coil 32 of each solenoid valve of the plurality of injectors is configured to be controlled by an ECU including an injector drive circuit (EDU). The ECU incorporates a microcomputer having a known structure that includes a CPU, ROM, RAM and the like in addition to the EDU.
Further, when the ignition switch is turned on (IG / ON), the microcomputer, based on a control program stored in a memory such as ROM or RAM, fuel injection pressure into the combustion chamber for each cylinder of the engine, The fuel injection timing of each injector, the fuel injection amount from each injector, and the like are calculated, and the amount of current supplied to each coil 32 of each solenoid valve (so-called injector drive current) is electronically controlled.

The fuel injection nozzle of this embodiment is mounted on a cylinder head corresponding to each cylinder of the engine. The fuel injection nozzle is attached to the cylinder head of the engine so that the nozzle hole peripheral portion 4 which is the tip portion in the axial direction is exposed in the combustion chamber.
The fuel injection nozzle includes a housing containing a needle 1 that extends straight in the axial direction, a command piston 12 that extends straight in the axial direction, and a coil spring 13 that is spirally wound around the command piston 12. .

  The fuel injection nozzle housing includes a bottomed cylindrical nozzle body 3 that accommodates the needle 1 so as to be capable of reciprocating in the axial direction thereof, and a cylindrical injector connected to the downstream end in the fuel flow direction of the injector pipe branched from the common rail. A retaining nut 11 is fastened and fixed to the outer periphery of a cylindrical fastening portion (hereinafter referred to as a fastening portion) of the injector body 9 with the body 9 sandwiched between the nozzle body 3 and the injector body 9. The injector body 9 and the nozzle body 3 are fastened and integrated. The injector body 9 and the nozzle body 3 are divided into two in the axial direction of the housing of the fuel injection nozzle.

The needle 1 of the present embodiment is formed in a solid round bar shape from a metal material such as chromium molybdenum steel (SCM415), carbon steel (SC), or chromium steel (SCr). The needle 1 has a hardness (rigidity) that does not deform with respect to the pressure of the high-pressure fuel.
The needle 1 is installed so as to be able to reciprocate in the axial direction, and is installed on the central axis of the nozzle body 3. Then, the needle 1 is seated and separated from the nozzle sheet 5 to close and open the plurality of nozzle holes 8.

The needle 1 has a cylindrical head 41 and a cylindrical large-diameter shaft portion (hereinafter referred to as sliding) having a larger outer diameter than the head 41 and supported slidably in the sliding hole of the nozzle body 3. Part) 42 is provided. The sliding surface of the sliding portion 42 is slidable with respect to the hole wall surface of the sliding hole of the nozzle body 3.
Further, the needle 1 is mounted with a rod pressure 43 having a spring seat that receives the spring load of the coil spring 13 (axial force in the valve closing direction of the needle 1) between the needle 1 and the command piston 12.

Further, the needle 1 is provided with a small-diameter shaft portion 45 between a sliding portion 42 extending in the axial direction and a medium-diameter shaft portion 44 having an outer diameter smaller than that of the sliding portion 42. The needle 1 is provided with a pressure receiving surface 46 having a truncated cone (annular) shape between the sliding portion 42 and the small diameter shaft portion 45. The pressure receiving surface 46 serves as a first fuel pressure receiving portion that receives fuel pressure in the fuel reservoir chamber 15 (fuel pressure in the valve opening direction: hereinafter, nozzle opening force) when the needle 1 starts to lift.
Further, the valve portion 2 having an outer diameter smaller than that of the medium diameter shaft portion 44 is provided on the distal end side of the medium diameter shaft portion 44, that is, on one end portion (tip portion) in the axial direction of the needle 1.
Details of the valve portion 2 of the needle 1 will be described later.

The command piston 12 of this embodiment is formed in a round bar shape by the same metal material as the needle 1 and the nozzle body 3. The command piston 12 has a hardness (rigidity) that does not deform with respect to the pressure of the high-pressure fuel.
The command piston 12 is installed on the central axis of the injector body 9 and is arranged on the same axis as the needle 1. The command piston 12 reciprocates in the central axis direction (the vertical direction in the figure) in conjunction with the needle 1.

The command piston 12 has a cylindrical large-diameter shaft portion (hereinafter referred to as a sliding portion) 47 slidably supported in the sliding hole of the injector body 9 and an outer diameter larger than that of the sliding portion 47. A small small diameter shaft portion 48 is provided.
The sliding surface of the sliding portion 47 is slidable with respect to the hole wall surface of the sliding hole of the injector body 9. In addition, a circular contact surface that contacts the illustrated upper end surface of the head 41 of the needle 1 via the rod pressure 43 is provided on the distal end surface (the illustrated lower end surface) of the small diameter shaft portion 48.
Further, the command piston 12 is provided with a circular pressure receiving surface 49 on the end surface of the sliding portion 47. The pressure receiving surface 49 serves as a second fuel pressure receiving portion that receives the fuel pressure in the pressure control chamber 14 when the needle 1 is fully lifted.

The nozzle body 3 of the present embodiment is formed in a hollow bottomed cylindrical shape by a metal material such as chromium molybdenum steel (SCM415), carbon steel (SC), or chromium steel (SCr), like the needle 1. The nozzle body 3 has a hardness (rigidity) that does not deform with respect to the pressure of the high-pressure fuel.
On one end side (front end side) of the nozzle body 3 in the axial direction, an inverted conical nozzle hole peripheral portion 4 that forms a conical space therein is provided. The nozzle hole peripheral portion 4 is a nozzle nozzle hole portion arranged so as to be exposed (protruded) in one end side of the nozzle body 3 in the axial direction, that is, in the combustion chamber of each cylinder of the engine.

On the inner surface of the peripheral portion 4 of the nozzle hole, a conical surface nozzle seat 5 on which the valve portion 2 of the needle 1 can be seated is provided. The nozzle sheet 5 defines the fully closed position of the needle 1 when the needle 1 is seated.
In addition, a bottomed cylindrical sack portion 7 is provided downstream of the nozzle sheet 5 in the fuel flow direction. A sack chamber 6 that is a sac volume is formed inside the sack portion 7. The sac chamber 6 is a distribution chamber that communicates the fuel flow path 16 and the plurality of nozzle holes 8, collects fuel that flows in an annular shape in the fuel flow path 16, and distributes the fuel to the plurality of nozzle holes 8.

The sack portion 7 is provided with a concave curved bottom having a predetermined radius of curvature. Further, the sack portion 7 is formed with a plurality of injection holes 8 penetrating obliquely from the inner wall surface to the outer wall surface with respect to the axial direction of the nozzle body 3.
The plurality of nozzle holes 8 include a nozzle hole inlet opened at the inner wall surface of the sack portion 7, a nozzle hole outlet opened at the outer wall surface of the sack portion 7, and a nozzle hole channel that communicates the nozzle hole inlet and the nozzle hole outlet. Have. Further, a plurality of injection holes 8 are formed at predetermined intervals in the circumferential direction of the sack portion 7 so that the fuel spray efficiently spreads into the combustion chamber of each cylinder of the engine.

  Then, on the central axis of the nozzle body 3, straight from the coupling surface (contact surface) that is in liquid-tight contact with the contact surface of the injector body 9 to the sack portion 7 and the nozzle hole 8 side via the tip packing 10. An extending nozzle hole (axial hole) is provided. Inside the nozzle hole, a needle 1 disposed so as to come into contact with the command piston 12 via a rod pressure 43 is accommodated so as to be capable of reciprocating in the axial direction thereof.

A simple round hole-shaped sliding hole 52 is formed on the upper end side of the nozzle hole in the figure, that is, inside the cylindrical part (needle guide, large diameter part) 51 of the nozzle body 3. Further, a fuel reservoir chamber 15 having a diameter larger than that of the sliding hole 52 is provided in an intermediate portion of the nozzle hole. This fuel reservoir chamber 15 has a function as a first pressure chamber (oil reservoir chamber, first fuel chamber) in which the oil pressure of the fuel introduced from the injector body 9 acts in the valve opening direction of the needle 1. doing. The nozzle body 3 has a cylindrical portion (small diameter portion) 53 that forms the fuel flow path 16 communicating with the fuel reservoir chamber 15 between the nozzle 1 and the medium diameter shaft portion 44 of the needle 1. Further, the nozzle body 3 has a truncated cone part 54 between the sack part 7 and the cylindrical part 53. The lower end side of the cylindrical portion 53 and the truncated cone portion 54 are included in the nozzle hole peripheral portion 4 of the nozzle body 3.
The details of the nozzle body 3, particularly the nozzle sheet 5, will be described later.

The injector body 9 and the tip packing 10 are formed in a cylindrical shape and an annular shape from the same metal material as the needle 1 and the nozzle body 3. The injector body 9 and the tip packing 10 have a hardness (rigidity) that does not deform with respect to the pressure of the high-pressure fuel.
The injector body 9 has a cylindrical cylinder 55 into which the command piston 12 is inserted. On the central axis of the cylinder 55, a cylinder hole (axial hole) is provided that extends straight from the coupling surface (contact surface) in liquid-tight contact with the contact surface of the orifice plate 22 to the nozzle body side. A command piston 12 is accommodated in the cylinder hole so as to be reciprocally movable in the axial direction thereof.

A simple round hole-shaped sliding hole 56 is formed on the upper side of the cylinder 55 and the cylinder hole in the figure. In addition, a simple round hole-shaped spring accommodating chamber 57 having a hole diameter larger than that of an intermediate portion of the cylinder hole is formed on the lower side of the cylinder 55 and the cylinder hole in the drawing. A coil spring 13 is accommodated in the spring accommodating chamber 57.
The coil spring 13 is a needle urging means that generates an urging force (an axial force in the valve closing direction) that urges the valve portion 2 of the needle 1 against the nozzle seat 5 of the nozzle body 3 (the valve closing direction).
A pressure control chamber 14 is provided at the upper end of the cylinder hole in the figure. The pressure control chamber 14 functions as a second pressure chamber (back pressure control chamber, second fuel chamber) in which the oil pressure of the fuel introduced into the inside acts in the valve closing direction of the needle 1. .

In the nozzle body 3, the injector body 9, and the tip packing 10, fuel flow paths 62 to 66 into which high-pressure fuel is introduced from the fuel introduction flow path 61 of the pipe joint 59 connected to the injector pipe are formed. .
These fuel flow paths 62 to 66 are provided in each part of the injector (the pressure control chamber 14, the fuel reservoir chamber 15, the fuel flow path 16, the minute gap 17, the sack chamber 6, the plurality of nozzle holes 8, the inlet provided in the injector). And high pressure fuel passages for introducing (supplying) high pressure fuel to the side and outlet orifices 26, 27, etc.

The pressure control chamber 14 communicates with the fuel flow path 63 via an inlet-side orifice 26 formed in the orifice plate 22. Further, the pressure control chamber 14 communicates with a fuel discharge passage 71 formed in the valve body 21 through an outlet-side orifice 27 formed in the central portion of the orifice plate 22. The fuel discharge passage 71 communicates with a fuel discharge passage 72 formed on the side of the cylinder hole of the cylinder 55 of the injector body 9.
The fuel reservoir chamber 15 communicates with the fuel flow channel 66. Further, the fuel reservoir 15 communicates with the fuel flow path 16 formed between the outer periphery of the medium-diameter shaft portion 44 of the needle 1 and the hole wall surface of the axial hole of the nozzle body 3.

In addition, in the injector body 9, excess fuel overflowed or discharged from the cylinder hole of the injector body 9, the nozzle hole of the nozzle body 3, and the axial hole of the tip packing 10, or discharged from the fuel discharge passages 71 and 72. A fuel recovery passage 73 for recovering the surplus fuel is formed.
Excess fuel that has flowed into the fuel recovery passage 73 is returned to the fuel tank through the fuel return pipe.

Next, details of the valve portion 2 of the needle 1 of the present embodiment will be described with reference to FIGS.
Each part of the needle 1 is provided by forging or machining (cutting or grinding). In addition, the needle 1 is subjected to heat treatment for improving the wear resistance of the needle 1 and for hardening the surface of the needle 1 (carburizing and quenching treatment, tempering treatment, etc.) with respect to the forged molded body having a needle part shape that has been machined. ) Is given.

The needle 1 has a valve portion 2 that is seated on and disengaged from the nozzle sheet 5 of the nozzle body 3 at one end side (tip side, nozzle hole side end) in the axial direction to close and open the plurality of nozzle holes 8. I have. The valve portion 2 includes a cylindrical base portion 75 having an outer diameter smaller than that of the medium-diameter shaft portion 44 of the needle 1 and an outline in which the outer diameter gradually decreases from the edge line 76 toward the tip of the base portion 75. A two-stage or three-stage conical reduced-diameter portion 77 is integrally formed.
The reduced diameter portion 77 has a truncated cone-shaped first conical surface 81 whose outer diameter gradually decreases toward one end, and the outer diameter gradually decreases toward one end and is inclined more than the first conical surface 81. The second conical surface 82 with a sharp (taper) angle and a conical shape with an outer diameter gradually decreasing toward one end and a steeper (taper) angle than the second conical surface 82. A third conical surface 83 is provided.

An annular intersection ridge line (sheet line) is formed between the first conical surface 81 and the second conical surface 82. This sheet line has a function as a seal portion 84 having a predetermined sheet diameter that is in liquid-tight contact with the nozzle sheet 5 of the nozzle body 3.
In addition, an annular intersection ridge line (edge line) 85 is formed between the second conical surface 82 and the third conical surface 83.
The third conical surface 83 includes a third fuel pressure receiving portion that receives fuel pressure (fuel pressure in the valve opening direction; hereinafter referred to as nozzle opening force) in the sac chamber 6 and in the minute gap 17 when the needle 1 starts to lift. Become.

Next, details of the nozzle sheet 5 of the nozzle body 3 of this embodiment will be described with reference to FIGS.
As with the needle 1, the nozzle body 3 is provided with the above-described portions by forging, machining (cutting, grinding), or the like. In addition, the nozzle body 3 improves the wear resistance of the nozzle body 3 and heat treatment for carburizing the surface of the nozzle body 3 (carburizing and tempering treatment, etc.) on the machined nozzle body-shaped forged molded body. ) Is given.

The nozzle body 3 receives the heat (nozzle heat) from the engine, that is, the nozzle body 3 is exposed to a very high temperature (for example, about 250 ° C. to 300 ° C .: nozzle heat) to increase the surface temperature around the nozzle hole 4. I have. The nozzle hole peripheral portion 4 includes a nozzle seat 5 on which the valve portion 2 of the needle 1 can be seated when the fuel injection nozzle is closed (when the nozzle is closed). The nozzle sheet 5 has a frustoconical nozzle sheet surface whose inner diameter gradually decreases toward one end.
The nozzle sheet 5 includes an annular seat portion 94 with which the seal portion 84 can abut when the nozzle is closed, and when the seat portion 94 receives an axial load (needle axial force) from the valve portion 2 of the needle 1 (nozzle An annular deformation relief recess 95 that allows plastic deformation (plastic deformation in a rising form) that occurs when the valve is closed) is provided.

The inner surface (including the bottom surface) of the deformation relief recess 95 is a concave curved surface having a predetermined radius of curvature centered on a predetermined center point. Further, the inner shape of the deformation relief recess 95 may be a combination of a flat surface and a curved surface, or only a flat surface.
An annular cross ridge line (sheet line) 96 is formed between the inner surface (concave curved surface) of the deformation relief recess 95 and the inner surface (nozzle sheet surface) of the nozzle sheet 5. In addition, an annular intersecting ridge line (sheet line) 97 is formed between the inner surface (concave curved surface) of the deformation relief recess 95 and the inner surface (conical frustum surface) of the nozzle body 3. An annular cross ridge line (sheet line) 98 is formed between the inner surface (conical frustum surface) of the nozzle body 3 and the inner surface (concave surface) of the sack portion 7.

The deformation relief recess 95 is opened, for example, on the inner surface (nozzle sheet surface) of the nozzle sheet 5, and has an annular circumference extending from the opening to the bottom (outer side) with a predetermined inclination angle with respect to the nozzle sheet surface. An annular space 99 is formed between the second conical surface 82 of the valve portion 2 of the needle 1 and the inner surface of the nozzle body 3 (the bottom surface of the deformation relief recess 95).
The annular space 99 is provided by denting the nozzle seat surface to the opposite side with respect to the valve portion 2 side of the needle 1. Further, the annular space 99 is provided by being recessed on the opposite side to the minute gap 17 side on the downstream side of the seat diameter of the seal portion 84 of the needle 1.
The internal volume of the deformation relief recess 95, that is, the volume of the annular space 99 is set in consideration of the volume of the recess A and the bulge B formed by plastic deformation on the inner surface of the nozzle sheet 5 after the aging of the nozzle sheet 5. (See FIG. 3). It is preferable to determine the internal volume (groove depth and groove width) of the deformation relief recess 95 in consideration of at least the volume of the raised portion B.

[Operation of Example 1]
Next, the operation of the injector of this embodiment will be briefly described with reference to FIGS.
The high-pressure fuel supplied from the common rail to the injector reaches the fuel introduction passage 61 of the injector. The fuel that has reached the fuel introduction flow path 61 passes through the fuel flow paths 62 to 66, and reaches each part of the injector (inlet side orifice 26, pressure control chamber 14, outlet side orifice 27, fuel reservoir chamber 15, fuel flow path 16. Etc.).
As a result, the needle 1 receives a force (axial force) in a direction to be pushed down by the fuel pressure in the pressure control chamber 14 (the valve closing direction of the needle 1) via the command piston 12 and the fuel in the fuel reservoir chamber 15. A force (axial force) in the direction of pushing up by the pressure (the valve opening direction of the needle 1) is received.

  Here, when the ECU 32 does not energize the coil 32 of the solenoid valve and the ball valve 25 of the solenoid valve is seated on the valve seat of the orifice plate 22 and closes the outlet-side orifice 27, the pressure control chamber 14 and the fuel reservoir 15 are filled with high-pressure fuel. Therefore, the pressure receiving area for receiving the fuel pressure in the pressure control chamber 14 on the pressure receiving surface 49 of the command piston 12 is larger than the pressure receiving area for receiving the fuel pressure in the fuel reservoir chamber 15 on the pressure receiving surface 46 of the needle 1. In addition, a biasing force (axial force) is applied to the needle 1 by the coil spring 13 to bias the valve portion 2 of the needle 1 in the valve closing direction (the side that closes the nozzle hole 8 and the side that presses the nozzle seat 5).

That is, the needle 1 has a valve closing direction axial force (nozzle valve closing force: F1) due to the fuel pressure in the pressure control chamber 14 transmitted via the command piston 12 and a valve closing due to the spring load of the coil spring 13. The axial force in the direction (nozzle valve closing force: F2) and the axial force in the valve opening direction due to the fuel pressure in the fuel reservoir chamber 15 (nozzle valve opening force: F3) work, and F1 + F2> F3 is established. Yes. For this reason, if the ECU does not energize the coil 32 of the solenoid valve and the ball valve 25 of the solenoid valve is closed, the downward force shown in FIG.
As a result, when the solenoid valve is closed, the valve portion 2 of the needle 1 is seated on the nozzle seat 5 in the nozzle hole peripheral portion 4 of the nozzle body 3 to block each nozzle hole 8.
Therefore, the injector is in a closed (full closed) state in which the needle 1 is closed, and fuel is not injected into the combustion chamber of the engine.

On the other hand, when the ECU energizes the coil 32 of the solenoid valve, a magnetic attractive force is generated in the coil 32 and the stator core 33, and the armature 31 is attracted to the magnetic pole surface side of the stator core 33.
Thereby, the ball valve 25 is detached from the orifice plate 22 and the outlet side orifice 27 of the orifice plate 22 is opened. Therefore, the fuel filled in the pressure control chamber 14 is returned from the pressure control chamber 14 to the fuel tank through the outlet-side orifice 27 → the fuel discharge passage 71 → the fuel discharge passage 72 → the fuel recovery passage 73.

The fuel pressure (nozzle valve closing force: F1) in the pressure control chamber 14 rapidly decreases with the opening operation of the solenoid valve itself, and when F1 + F2 <F3 is established, the fuel pressure in the fuel reservoir 15 The needle 1 and the command piston 12 are raised (the lift is started) by (nozzle valve opening force: F3). As a result, the high-pressure fuel stored in the fuel reservoir 15 and the fuel flow path 16 flows into the minute gap 17 formed between the valve portion 2 of the needle 1 and the nozzle seat 5 of the nozzle body 3, and the minute gap A force (nozzle opening force: F4) in the direction in which the needle 1 is pushed up by the fuel pressure in the nozzle 17 is further applied (nozzle opening force: F4), and the valve portion 2 of the needle 1 is rapidly separated from the nozzle seat 5 of the nozzle body 3 (separation, Separated). As a result, the needle 1 is opened (full open), and the high-pressure fuel in the fuel reservoir 15 and the fuel flow path 16 is injected from each injection hole 8 through the minute gap 17 and the sac chamber 6. .
Therefore, the injector starts to inject fuel into the combustion chamber of the engine.

  When the command injection period elapses from the injection timing, the energization to the coil 32 of the solenoid valve is stopped. Then, the armature 31 moves in the valve closing direction by the urging force (spring load) of the coil spring 34, and the ball valve 25 is pressed against the valve seat of the orifice plate 22. When the solenoid valve is closed, the fuel pressure in the pressure control chamber 14 (nozzle closing force: F1) rises rapidly, and F1 + F2> F3 is established, so that the needle 1 and the command piston 12 are in the valve closing direction. Moving. As a result, in the injector, the valve portion 2 of the needle 1 is seated on the nozzle seat 5 of the nozzle body 3, so that the plurality of injection holes 8 are closed. That is, the needle 1 returns to the closed (full closed) state. Thus, the fuel injection into the combustion chamber of the engine is completed.

[Features of Example 1]
The features of the fuel injection nozzle of the present embodiment will be described with reference to FIGS.
When an injector equipped with a fuel injection nozzle having the above structure is attached to a cylinder head of an engine, the fuel injection nozzle is closed in the initial state before the aging of the nozzle seat 5 occurs (when the nozzle is closed). 3), as shown in FIG. 3A, the valve portion 2 provided at one end in the axial direction of the needle 1 by the needle axial force (F1 + F2) caused by the fuel pressure and the spring load is the peripheral portion of the nozzle body 3 nozzle hole. By being seated on the inner surface (conical surface of the nozzle sheet) of the nozzle sheet 5 formed at 4, fuel injection from the plurality of injection holes 8 is not performed.
On the other hand, when the fuel injection nozzle is opened (when the nozzle is opened) in the initial state, the valve portion 2 of the needle 1 is generated by the nozzle opening force (F3 + F4) due to the fuel pressure, as shown in FIG. Is released from the inner surface of the nozzle seat 5 of the nozzle body 3, whereby fuel is injected from the plurality of nozzle holes 8 into the combustion chamber of each cylinder of the engine.

  After the aging of the nozzle sheet 5, when the nozzle hole 3 peripheral portion 4 and the nozzle sheet 5 are exposed to a very high temperature in the combustion chamber of the engine, that is, heated by the engine (nozzle heat). When the needle axial force (F1 + F2) due to the fuel pressure is generated and the valve portion 2 of the needle 1 is seated on the nozzle seat 5 and receives a large impact load, the seat portion 94 of the nozzle seat 5 is more affected. While the bottom surface of the deformation relief recess 95 provided on the downstream side rises and plastic deformation occurs in a manner in which the vicinity of the sheet portion 94 of the nozzle sheet 5 is recessed, the sheet portion downstream gap (the valve portion 2 of the needle 1) The minute gap 17) formed on the downstream side of the seat diameter is wider than that of the conventional fuel injection nozzle.

Here, in the conventional fuel injection nozzle, when the nozzle is opened, the size (gap size) of the seat portion downstream gap 106 is the initial state before the aging of the nozzle seat surface 104 occurs (see FIG. 5B). The nozzle sheet surface 104 greatly changes after the aging (see FIG. 5D). That is, the sheet portion downstream gap 106 becomes very narrow.
In contrast to such a conventional fuel injection nozzle, in the fuel injection nozzle of this embodiment, a deformation relief recess 95 is provided on the downstream side of the nozzle portion 5 of the nozzle seat 5 (upstream of the sack chamber 6). Thus, the above performance was obtained by reducing the amount of plastic deformation in the form in which the downstream side of the sheet portion 94 swells. The volume of the deformation relief recess 95 is taken into consideration so that the top portion (minimum inner diameter portion) of the raised portion B formed by plastic deformation does not protrude toward the valve portion 2 side of the needle 1 from the extended line of the nozzle sheet surface. Yes.

[Effect of Example 1]
As described above, in the fuel injection nozzle of the present embodiment, the deformation that allows the plastic deformation of the swelled state that occurs when the seat portion 94 receives the needle axial force from the needle 1 on the inner surface of the nozzle sheet 5 of the nozzle body 3. By providing the relief portion 95, the area of the minute gap 17 on the downstream side of the seat diameter of the valve portion 2 of the needle 1 can be reduced. Thereby, the change of the nozzle valve opening force (F4) between the initial state before the aging of the nozzle sheet 5 occurs and after the aging of the nozzle sheet 5 can be suppressed.
Therefore, it is possible to reduce the change in the fuel injection amount injected from the plurality of injection holes 8 into the combustion chamber of each cylinder of the engine.

[Modification]
In this embodiment, as a fuel injection valve provided with the present invention, an injector (fuel injection valve integrating a fuel injection nozzle and a solenoid valve) that injects high-pressure fuel accumulated in the common rail into the cylinder of the engine. Although the applied example has been described, as a fuel injection valve provided with the present invention, fuel is directly pumped into a fuel reservoir chamber from a fuel injection pump such as a row type fuel injection pump or a distribution type fuel injection pump. When the fuel pressure (nozzle valve opening force) exceeds the spring energizing force (axial force in the valve closing direction: nozzle closing force), the needle opens and fuel is injected into the engine cylinder. You may apply to the fuel-injection nozzle used for the fuel-injection apparatus.

In this embodiment, the actuator for opening and closing the needle 1 for opening and closing the nozzle hole for injecting fuel is opened and closed in the axial direction by an electromagnetic actuator composed of a coil, a stator, an armature, and the like. As an actuator that opens and closes in the axial direction, the displacement accompanying the expansion and contraction of the piezo stack is transmitted to the pressurizing piston, and the fuel pressure in the pressure control chamber is increased or decreased along with the reciprocating displacement of the pressurizing piston. A piezo actuator that controls (fuel injection) may be used.
Further, the actuator that opens and closes the needle 1 in the axial direction thereof may be constituted by an electric actuator provided with a motor, a speed reduction mechanism, and a conversion mechanism.

In this embodiment, the nozzle hole 8 formed on one end side (tip side) in the axial direction of the nozzle body 3 of the present invention is opened at the inner surface of the sack portion 7 that partitions the sac chamber 6 and the outside (combustion chamber). However, the nozzle hole 8 formed on the tip side of the nozzle body 3 of the present invention may be provided so as to open on the inner surface (nozzle sheet surface) of the nozzle sheet 5.
Further, the sack chamber 6 and the sack portion 7 may be eliminated from the tip end side of the nozzle body 3 in the axial direction. Further, an nozzle hole penetrating the tip wall portion (circular top portion) of the nozzle body 3 in the axial direction may be provided on one end side (tip side) of the nozzle body 3 in the axial direction.
The fuel injection valve provided with the fuel injection nozzle of the present invention may be applied to a fuel injector that directly injects fuel into a cylinder of an internal combustion engine such as a gasoline engine.

DESCRIPTION OF SYMBOLS 1 Needle 2 Needle valve part 3 Nozzle body 4 Nozzle body peripheral part 5 Nozzle sheet (nozzle sheet surface)
8 Nozzle body nozzle hole 17 Small clearance (annular clearance) on the downstream side of the needle seat diameter
94 Sheet portion of nozzle sheet 95 Deformation relief recess of nozzle sheet 99 Annular space

Claims (10)

A needle (1) having a valve part (2, 77) and capable of reciprocating in the axial direction;
A fuel injection nozzle having a nozzle body (3) having a nozzle hole (8) for performing fuel injection and supporting the needle (1) so as to be reciprocally movable in the axial direction thereof.
The nozzle body (3) is located upstream of the nozzle hole (8) in the fuel flow direction, and has a nozzle seat (5) on which the valve portion (2, 77) of the needle (1) can be seated. ,
The nozzle seat (5) is installed between the seat portion (94) with which the valve portions (2, 77) can contact, and between the nozzle hole (8) and the seat portion (94), A fuel injection nozzle comprising a deformation relief (95) that allows plastic deformation that occurs when the seat (94) receives a load from a needle (1). The fuel injection nozzle according to claim 1,
The fuel injection nozzle according to claim 1, wherein the deformation relief portion (95) is provided by forming an annular space (99) between an outer surface of the needle (1) and an inner surface of the nozzle body (3). The fuel injection nozzle according to claim 2,
The annular space (99) is provided by denting the inner surface of the nozzle sheet (5) to the opposite side with respect to the valve part (2, 77) side of the needle (1). nozzle. The fuel injection nozzle according to claim 2 or claim 3,
An annular gap (17) formed between the valve portion (2, 77) and the nozzle sheet (5) when the needle (1) is opened;
The fuel injection nozzle according to claim 1, wherein the annular space (99) is provided by being recessed on the opposite side with respect to the annular gap (17) side. The fuel injection nozzle according to any one of claims 1 to 4,
The fuel injection nozzle, wherein the valve portion (2, 77) has an annular seal portion (84) that can be seated on the nozzle seat (5). The fuel injection nozzle according to any one of claims 1 to 5,
The nozzle sheet (5) has a conical seat surface whose inner diameter gradually decreases toward one end. The fuel injection nozzle according to any one of claims 1 to 6,
An annular fuel for guiding the fuel supplied in the nozzle body (3) to the downstream side in the fuel flow direction from the nozzle seat (5) between the nozzle body (3) and the needle (1). A fuel injection nozzle having a flow path (16). The fuel injection nozzle according to claim 7,
The peripheral portion (4) of the nozzle hole (8) communicates the fuel flow path (16) and the nozzle hole (8), and collects fuel that flows in an annular shape in the fuel flow path (16). A fuel injection nozzle having a bottomed cylindrical sac portion (7) in which a sac chamber (6) to be distributed and supplied to the injection hole (8) is formed. The fuel injection nozzle according to claim 8,
The nozzle hole (8) is a plurality of nozzle holes (8) penetrating so as to communicate with the inside and outside of the sack portion (7),
The fuel injection nozzle, wherein the plurality of injection holes (8) are formed at a predetermined distance in a circumferential direction of the sack portion (7). The fuel injection nozzle according to any one of claims 1 to 9,
The fuel injection nozzle, wherein the nozzle body (3) or the peripheral portion (4) of the nozzle hole (8) is disposed so as to be exposed in a combustion chamber of an internal combustion engine.

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