JP2009203923A - Injector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain or eliminate the elongation of a length in the axial direction caused by the existence of a valve body in the axial direction, in an injector 1. <P>SOLUTION: In this injector 1, an orifice plate 26 closes the rear end side of a back pressure chamber 20 by being joined to a body 27 by being engaged with the body 27 in a threaded manner. Thus, the orifice plate 26 is directly joined to the body 27 forming the back pressure chamber 20. Thus, even if the orifice plate 26 is not sandwiched between a separate member such as a valve body and the body 27, the orifice plate 26 can be brought into pressure-contact with the body 27. As a result, since there is no need to make the valve body exist in the axial direction, the length in the axial direction of the injector 1 can be shortened. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an injector for injecting and supplying fuel to an engine.

  Conventionally, for example, an injector 100 that injects and supplies fuel to a direct injection engine (not shown) includes a nozzle 101 that injects fuel and an electromagnetic actuator 102 that operates the nozzle 101, as shown in FIG. The nozzle 101 is attached to the front end side of the main body 103, and the electromagnetic actuator 102 is attached to the rear end side of the main body 103. The injector 100 has a nozzle hole 105 at the tip of the nozzle body 104, and starts or stops fuel injection by opening and closing the nozzle hole 105 by the tip of the valve body (needle valve 106) of the nozzle 101.

  That is, on the rear end side of the needle valve 106, a back pressure chamber 108 is formed through which fuel that applies back pressure to the needle valve 106 flows in and out via the command piston 107. The injector 100 manipulates the flow of fuel into and out of the back pressure chamber 108 by operating the electromagnetic actuator 102 to increase or decrease the back pressure, thereby moving the needle valve 106 in the axial direction to open and close the nozzle hole 105. .

  Here, the main body body 109 is provided with a through hole 110 penetrating in the axial direction, and the command piston 107 is slidably accommodated in the through hole 110 in the axial direction. The back pressure chamber 108 is formed by sealing the rearmost end of the through hole 110 with the command piston 107. Further, the rear end side of the back pressure chamber 108 is closed by an orifice plate 113 provided with an outflow side and inflow side throttles 111 and 112 for restricting the flow of fuel into and out of the back pressure chamber 108 (for example, patents). Reference 1).

  Further, the inflow side restrictor 112 is always set to communicate with the high pressure flow path 114, and the outflow side restrictor 111 is set to be opened with respect to the low pressure flow path 115 by the operation of the electromagnetic actuator 102. ing. The high pressure channel 114 is a fuel channel for guiding high pressure fuel received from a fuel supply source such as a common rail to the back pressure chamber 108 and the nozzle hole 105, and the low pressure channel 115 is for back pressure operation. 2 is a fuel flow path for guiding the fuel intentionally escaped from the back pressure chamber 108 and the fuel leaked from the back pressure chamber 108 and the nozzle chamber 116 to the outside of the injector 100.

  With the above configuration, in the injector 100, when the electromagnetic actuator 102 operates, the fuel flows out from the back pressure chamber 108 and the back pressure is reduced. Therefore, the command piston 107 and the needle valve 106 move to the rear end side and the injection hole 105 is opened. Further, when the electromagnetic actuator 102 stops operating, fuel flows into the back pressure chamber 108 and the back pressure increases, so that the command piston 107 and the needle valve 106 move to the tip side and the nozzle hole 105 is closed.

  By the way, the orifice plate 113 needs to be in strong pressure contact with an opening surface (hereinafter referred to as a back pressure chamber opening surface 117) where the through hole 110 is opened on the rear end side of the main body body 109 in order to seal high-pressure fuel. There is. Therefore, the orifice plate 113 is positioned by the knock pin 118, and at the rear end side of the orifice plate 113, the predetermined body 119 is screwed into the main body body 109 and moved to the front end side, whereby the orifice plate 113 is moved to the body 119. And the main body body 109 are firmly sandwiched.

  Further, the armature 120 of the electromagnetic actuator 102 has a guide 121 integrally on the tip side, and the body 119 has a guide hole 122 for slidably supporting the guide 121. Further, a valve body 123 for opening and closing the outflow side restrictor 111 is held at the tip of the guide 121 (hereinafter, the body 119 is referred to as a valve body 119 by focusing on the function of holding the valve body 123 via the guide 121). ).

As a result, the injector 100 has a longer axial length due to the presence of the valve body 119 in the axial direction, which is contrary to the recent demand for reduction in engine room and improvement in the degree of freedom of layout.
JP 2003-97378 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress or eliminate an increase in the axial length due to the presence of the valve body in the axial direction in the injector. There is to be.

[Means of Claim 1]
The injector according to claim 1 has an injection hole at the tip, and starts or stops fuel injection by opening and closing the injection hole by the tip of the needle valve. In addition, a back pressure chamber is formed on the rear end side of the needle valve, where fuel that applies back pressure to the needle valve flows in and out. The injector controls the back and forth flow of fuel into and out of the back pressure chamber. As a result, the needle valve is moved in the axial direction to open and close the nozzle hole. The back pressure chamber is closed at the rear end side by an orifice plate provided with a restriction for restricting the flow of fuel into and out of the back pressure chamber. The orifice plate is coupled to the body in which the back pressure chamber is formed. Yes.

  Thereby, the orifice plate is directly coupled to the body (main body) in which the back pressure chamber is formed. For this reason, the orifice plate can be brought into pressure contact with the main body body without being sandwiched between another member such as a valve body and the main body body. As a result, the valve body need not be present in the axial direction, and the axial length of the injector can be shortened.

[Means of claim 2]
According to the injector of claim 2, the orifice plate is provided with a male screw and the body is provided with a female screw. The orifice plate is coupled to the body by the male screw being screwed into the female screw. ing.
This means represents an embodiment in which the orifice plate is coupled to the main body.

[Means of claim 3]
According to the injector of the third aspect, the body is provided with the back pressure chamber opening surface in which the back pressure chamber opens, and the front end surface of the orifice plate is brought into the front end side by screwing of the male screw and the female screw. The back pressure chamber is closed by moving and pressing against the opening surface of the back pressure chamber. An annular groove that surrounds the opening of the back pressure chamber on the outer peripheral side is provided on the back pressure chamber opening surface, and a high pressure flow path for passing fuel flowing into the back pressure chamber is connected to the annular groove. In addition, an inflow passage having an inflow side restrictor that restricts the inflow of fuel into the back pressure chamber is opened at the front end surface of the orifice plate, and the front end surface of the orifice plate is the back pressure chamber opening surface. Connected to the annular groove by pressing.

  When the orifice plate is coupled to the body by screw threading, the opening of the high-pressure channel on the opening surface of the back pressure chamber and the opening of the inflow channel on the tip surface of the orifice plate are displaced in the circumferential direction. There is a possibility that the flow path and the inflow flow path are not communicated with each other. Therefore, by providing the annular groove on the opening surface of the back pressure chamber as described above, the high-pressure channel and the inflow channel can be connected via the annular groove even if the respective openings are displaced in the circumferential direction. It is possible to communicate reliably.

[Means of claim 4]
According to the injector of the fourth aspect, the orifice plate has a plurality of inflow channels, and the inflow side throttle is divided into a plurality of inflow channels.
When the high pressure channel and the inflow channel communicate with each other via an annular groove, the back pressure chamber is changed from the high pressure channel to the back pressure chamber according to the circumferential displacement between the opening of the high pressure channel and the opening of the inflow channel. There is a possibility that the flow rate of the fuel into the air fluctuates and the pressure increase rate of the back pressure varies among the individual injectors. Therefore, as described above, by dividing the inflow channel and the inflow side restriction into a plurality of portions, fluctuations in the inflow velocity due to the circumferential displacement between the high pressure channel and the inflow channel are reduced. For this reason, it can suppress that the pressure increase rate of back pressure varies between the individual injectors.

[Means of claim 5]
According to the injector of claim 5, the orifice plate is provided with an outflow passage having an outflow side restriction for restricting the outflow of fuel from the back pressure chamber, and the opening of the outflow passage is formed by the electromagnetic actuator. The back pressure is increased or decreased by opening and closing. The electromagnetic actuator is fixed to the inner peripheral side of the solenoid coil and has a cylindrical stopper that passes the magnetic flux. The armature is arranged at the front end side of the stopper and is attracted by the stopper to move to the rear end side. It has a valve body that is provided and protrudes toward the rear end side and moves together with a guide, an armature, and a guide that are slidably supported on the inner peripheral side of the stopper, and opens and closes the opening of the outflow passage.

  Thereby, the support function of the guide which the valve body was carrying can be held by the stopper. For this reason, in the injector in which the valve body does not exist in the axial direction, the support function of the guide can be ensured without adding a new member.

[Means of claim 6]
According to the injector of the sixth aspect, the valve body is accommodated in the recess provided in the armature.
As a result, in the injector in which the valve body does not exist in the axial direction, the position of the armature and the guide is reversed, so that the opening / closing mechanism for the outflow passage can be configured easily.

  The injector of the best mode has an injection hole at the tip, and starts or stops fuel injection by opening and closing the injection hole by the tip of the needle valve. In addition, a back pressure chamber is formed on the rear end side of the needle valve, where fuel that applies back pressure to the needle valve flows in and out. The injector controls the back and forth flow of fuel into and out of the back pressure chamber. As a result, the needle valve is moved in the axial direction to open and close the nozzle hole. The back pressure chamber is closed at the rear end side by an orifice plate provided with a restriction for restricting the flow of fuel into and out of the back pressure chamber. The orifice plate is coupled to the body in which the back pressure chamber is formed. Yes.

The orifice plate is provided with a male screw and the body is provided with a female screw. The orifice plate is coupled to the body by the male screw being screwed into the female screw.
Further, the body is provided with a back pressure chamber opening surface in which the back pressure chamber is opened, and the tip end surface of the orifice plate is moved to the tip end side by screwing of the male screw and the female screw to the back pressure chamber opening surface. The back pressure chamber is closed by pressure welding. An annular groove that surrounds the opening of the back pressure chamber on the outer peripheral side is provided on the back pressure chamber opening surface, and a high pressure flow path for passing fuel flowing into the back pressure chamber is connected to the annular groove. In addition, an inflow passage having an inflow side restrictor that restricts the inflow of fuel into the back pressure chamber is opened at the front end surface of the orifice plate, and the front end surface of the orifice plate is the back pressure chamber opening surface. Connected to the annular groove by pressing.

In addition, the orifice plate has a plurality of inflow channels, and the inflow side restrictor is divided into a plurality of inflow channels.
In addition, the orifice plate is provided with an outflow passage having an outflow side restriction for restricting the outflow of fuel from the back pressure chamber, and the back pressure is reduced by opening and closing the opening of the outflow passage by an electromagnetic actuator. Increased or decreased. The electromagnetic actuator is fixed to the inner peripheral side of the solenoid coil and has a cylindrical stopper that passes the magnetic flux. The armature is arranged at the front end side of the stopper and is attracted by the stopper to move to the rear end side. It has a valve body that is provided and protrudes toward the rear end side and moves together with a guide, an armature, and a guide that are slidably supported on the inner peripheral side of the stopper, and opens and closes the opening of the outflow passage.
Further, the valve body is accommodated in a recess provided in the armature.

[Configuration of Example 1]
The structure of the injector 1 of Example 1 is demonstrated based on drawing.
As shown in FIGS. 1 and 2, the injector 1 includes a nozzle 2 that injects fuel, an electromagnetic actuator 3 that operates the nozzle 2, and a main body 4 on which the nozzle 2 and the electromagnetic actuator 3 are mounted.

  The injector 1 is, for example, a fuel supply pump (not shown) that discharges fuel in a fuel tank (not shown) at a high pressure, and accumulates high-pressure fuel discharged from the fuel supply pump in a high pressure state. A common rail (not shown) distributed to 1 and an electronic control unit (referred to as ECU: not shown) etc. constitute an accumulator fuel supply device, and a direct injection type engine (not shown) such as a diesel engine. To high pressure fuel.

  The nozzle 2 has a nozzle hole 7 at the tip of the nozzle body 6, and starts or stops fuel injection by opening and closing the nozzle hole 7 with the tip of the needle valve 8. That is, the nozzle body 6 forms a nozzle chamber 9 that accommodates the needle valve 8 slidably in the axial direction and communicates with the nozzle hole 7. The needle valve 8 is provided with a seat portion 10 that is attached to and detached from the tip portion of the nozzle body 6, and the seat portion 10 is attached to and detached from the nozzle body 6. Is opened and closed, and fuel injection is started or stopped. The nozzle chamber 9 is connected to a high-pressure channel 11 through which high-pressure fuel supplied from the common rail flows.

  The electromagnetic actuator 3 includes an armature 15 that is driven to the rear end side by energization of the solenoid coil 14, a restoring spring 16 that biases the armature 15 toward the front end side, and a valve body 17 that moves in the axial direction together with the armature 15. Have. The electromagnetic actuator 3 drives the needle valve 8 in the axial direction by operating the back pressure acting on the needle valve 8 by the movement of the valve body 17.

  That is, a command piston 19 is in contact with the rear end of the needle valve 8, and a back pressure chamber 20 into which fuel that applies back pressure to the needle valve 8 and the command piston 19 flows into and out of the command piston 19. Is formed. The valve body 17 operates the back pressure by opening and closing the back pressure chamber 20 with respect to the low pressure channel 21. The low-pressure channel 21 is a fuel for guiding the fuel intentionally released from the back pressure chamber 20 due to the back pressure operation and the fuel leaking from the nozzle chamber 9 or the back pressure chamber 20 to the outside of the injector 1. It is a flow path.

  The main body 4 includes a command piston 19 that moves in the axial direction together with the needle valve 8, a restoring spring 23 that urges the needle valve 8 and the command piston 19 toward the distal end, and an outflow side that regulates the inflow and outflow of fuel into the back pressure chamber 20. The body plate 27 accommodates an orifice plate 26 having inflow side restrictors 24 and 25. The nozzle 2 is fastened and fixed to the front end side of the main body 4 by a retaining nut 28, and the electromagnetic actuator 3 is fastened and fixed to the rear end side by a body upper 29.

  Here, the main body body 27 is provided with the high-pressure channel 11 and the low-pressure channel 21, and is provided with a through hole 32 penetrating in the axial direction, and the command piston 19 is slidable in the axial direction in the through hole 32. Contained. The back pressure chamber 20 is formed by sealing the rearmost end portion of the through hole 32 with the command piston 19.

  Note that the through hole 32 on the tip side of the sliding shaft portion of the command piston 19 forms a spring chamber 33 that houses the restoring spring 23. The low pressure flow path 21 is connected to the spring chamber 33, and the fuel leaked from the nozzle chamber 9 and the back pressure chamber 20 flows into the spring chamber 33 and then flows into the low pressure flow path 21 to be injected into the injector 1. Guided outside.

  The orifice plate 26 is provided with an outflow passage 35 having an outflow side restrictor 24 and an inflow passage 36 having an inflow side restrictor 25, and the upstream end of the inflow passage 36 is the tip of the orifice plate 26. The outflow channel 35 is provided so as to open to the surface 37, and the downstream end is provided so that the downstream end opens to the rear end surface 38 of the orifice plate 26.

  The orifice plate 26 is in pressure contact with the back pressure chamber opening surface 39 where the back pressure chamber 20 opens, and closes the rear end side of the back pressure chamber 20. The orifice plate 26 is incorporated so that the inflow channel 36 is always in communication with the high-pressure channel 11 and the outflow channel 35 is opened and closed by the valve body 17 that moves together with the armature 15. . The outflow side restrictor 24 is set so that the flow rate of the passing fuel is larger than that of the inflow side restrictor 25.

  With the above configuration, when energization of the solenoid coil 14 of the electromagnetic actuator 3 is started, the armature 15 and the valve body 17 move to the rear end side, and the outflow of fuel from the back pressure chamber 20 to the low pressure passage 21 starts. , Back pressure decreases. Therefore, the resultant force in the axial direction acting on the needle valve 8 becomes stronger in the direction of opening the nozzle hole 7 (that is, the component toward the rear end side becomes stronger), and the needle valve 8 moves toward the rear end side. Then, the nozzle hole 7 is opened and fuel injection is started.

  When the energization of the solenoid coil 14 is stopped, the armature 15 and the valve body 17 move to the distal end side, the fuel flow from the back pressure chamber 20 to the low pressure passage 21 stops, and the back from the high pressure passage 11 stops. The back pressure rises due to the inflow of fuel into the pressure chamber 20. For this reason, the resultant force in the axial direction acting on the needle valve 8 becomes stronger in the direction of closing the nozzle hole 7 (that is, the component toward the tip side becomes stronger), and the needle valve 8 moves toward the tip side. The injection hole 7 is closed, and fuel injection is stopped.

  The energization start and the energization stop of the solenoid coil 14 are executed according to a command from the ECU. That is, the ECU calculates the energization start timing and the energization period for the solenoid coil 14 based on various detection values indicating the engine operating state such as the engine speed, the accelerator opening, and the common rail pressure. In response to this, a command signal is synthesized and output to the solenoid coil 14.

[Features of Example 1]
The features of the injector 1 according to the first embodiment will be described with reference to FIGS.
According to the injector 1 of the first embodiment, the orifice plate 26 is coupled to the main body body 27. That is, a male screw 42 is provided on the outer periphery of the orifice plate 26, and a female screw 43 is provided on the main body body 27. The orifice plate 26 is engaged with the female screw 43 so that the main body body 27 is engaged with the male screw 42. Is bound to.

  Here, the rear end of the main body 27 is provided in a cylindrical shape whose inner peripheral diameter gradually decreases toward the distal end side. That is, the rear end of the main body 27 is provided in a circular shape on the inner peripheral side of the cylindrical portion 47 provided with a male screw 46 that is threadedly engaged with the female screw 45 of the body upper 29 on the outer periphery. 21 has an orifice plate screwing surface 49 having a female thread 43 extending vertically from the inner peripheral edge of the step 48 to the front end side through chamfering.

The back pressure chamber opening surface 39 is provided as a circular plane whose outer periphery is edged by the tip edge of the orifice plate screwing surface 49. Thereby, the front end surface 37 of the orifice plate 26 moves to the front end side by screwing the male screw 42 and the female screw 43 and presses against the back pressure chamber opening surface 39 to close the back pressure chamber 20.
A space formed between the stage 48 and the electromagnetic actuator 3 forms a part of the low-pressure channel 21.

  In addition, an annular groove 52 that surrounds the opening of the back pressure chamber 20 on the outer peripheral side is provided in the back pressure chamber opening surface 39 in an annular shape, and the high pressure flow path 11 is connected to the annular groove 52. Further, the inflow channel 36 of the orifice plate 26 is connected to the annular groove 52 by the front end surface 37 being in pressure contact with the back pressure chamber opening surface 39.

  In addition, the inflow channels 36 are provided, for example, by being divided into three at equal angular intervals, and the inflow side restriction 25 is divided into the respective inflow channels 36. The outflow side and inflow side restrictors 24 and 25 are provided such that the flow rate of fuel passing through the outflow side restrictor 24 is larger than the total flow rate of fuel passing through the three inflow side restrictors 25. . In addition, in order to increase the surface pressure exerted on the back pressure chamber opening surface 39, the tip surface 37 of the orifice plate 26 is provided with a recess 53 between the openings of the inflow channel 36, so The contact area is reduced.

  Further, the electromagnetic actuator 3 is fixed to the inner peripheral side of the solenoid coil 14 so as to pass a magnetic flux and magnetically attract the armature 15. The electromagnetic actuator 3 is provided integrally with the armature 15 and protrudes to the rear end side. A guide 56 is slidably supported on the inner peripheral side of the. Further, the valve body 17 is accommodated in a recess provided in the front end surface of the armature 15 to open and close the opening of the outflow passage 35, and the restoring spring 16 abuts against the rear end surface of the guide 56 and The armature 15 is urged toward the tip side.

[Effect of Example 1]
According to the injector 1 of the first embodiment, the orifice plate 26 is coupled to the main body 27 by being screwed to the main body 27 to close the rear end side of the back pressure chamber 20.
Thereby, the orifice plate 26 is directly coupled to the main body 27 in which the back pressure chamber 20 is formed. Therefore, the orifice plate 26 can be brought into pressure contact with the main body body 27 without the orifice plate 26 being sandwiched between the main body 27 and another member such as a valve body. As a result, the valve body need not be present in the axial direction, and the axial length of the injector 1 can be shortened.

Further, the back pressure chamber opening surface 39 is provided with an annular groove 52 that surrounds the opening of the back pressure chamber 20 on the outer peripheral side, and the high pressure flow path 11 through which fuel flowing into the back pressure chamber 20 passes. Is connected. Further, the inflow channel 36 of the orifice plate 26 is connected to the annular groove 52 by the front end surface 37 of the orifice plate 26 being in pressure contact with the back pressure chamber opening surface 39.
As a result, even if a circumferential shift occurs between the opening in the annular groove 52 of the high-pressure channel 11 and the opening in the front end surface 37 of the inflow channel 36, the high-pressure channel 11 and the inflow channel 36 Can be reliably communicated with each other through the annular groove 52.

In addition, the inflow channel 36 is divided into three parts, and the inflow side restrictor 25 is divided into each inflow channel 36.
When the high-pressure channel 11 and the inflow channel 36 communicate with each other via the annular groove 52, the high-pressure flow is changed according to the circumferential displacement between the opening of the high-pressure channel 11 and the opening of the inflow channel 36. There is a possibility that the inflow speed of the fuel from the passage 11 to the back pressure chamber 20 fluctuates and the back pressure increase speed varies between the individual injectors 1. On the other hand, by dividing the inflow channel 36 and the inflow side restrictor 25 into a plurality of parts, fluctuations in the inflow velocity due to the circumferential displacement between the high pressure channel 11 and the inflow channel 36 are alleviated. For this reason, it can suppress that the pressure increase rate of a back pressure varies between the individual | injectors of the injector 1. FIG.

The electromagnetic actuator 3 is fixed to the inner peripheral side of the solenoid coil 14 so as to pass a magnetic flux and magnetically attract the armature 15. The electromagnetic actuator 3 is provided integrally with the armature 15 and protrudes to the rear end side. A guide 56 is slidably supported on the inner peripheral side of the.
Thereby, the support function of the guide 56 which the valve body was carrying can be held by the stopper 55. For this reason, in the injector 1 in which the valve body does not exist in the axial direction, the support function of the guide 56 can be ensured without adding a new member.

Further, the valve body 17 is accommodated in a recess provided in the distal end surface of the armature 15.
Thereby, in the injector 1 in which the valve body does not exist in the axial direction, the opening / closing mechanism of the outflow passage 35 can be simply configured by reversing the positions of the armature 15 and the guide 56.

[Modification]
According to the injector 1 of the first embodiment, the orifice plate 26 is coupled to the main body 27 by screwing to the main body 27. However, the orifice plate 26 is press-fitted into the main body 27 to be inserted into the main body 27. It may be combined.
Further, according to the injector 1 of the first embodiment, the annular groove 52 is provided in the back pressure chamber opening surface 39 of the main body 27, but the annular groove 52 may be provided in the distal end surface 37 of the orifice plate 26. When the annular groove 52 is provided on the distal end surface 37, it is necessary to make the orifice plate 26 thick according to the depth or the like.

  Further, the injector 1 of the first embodiment constitutes an accumulator fuel supply device and injects high-pressure fuel into a direct injection type engine such as a diesel engine. However, fuel is injected into the intake pipe of the engine. The first embodiment may be applied to an injector for injection.

It is a block diagram of an injector (Example 1). It is a principal part block diagram of an injector (Example 1). (Example 1) which was the top view which looked at the main body from the rear end side. (Example 1) which is the bottom view which looked at the orifice plate from the front end side. It is a block diagram of an injector (conventional example).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injector 3 Electromagnetic actuator 7 Injection hole 8 Needle valve 11 High pressure flow path 14 Solenoid coil 15 Armature 17 Valve body 20 Back pressure chamber 24 Outflow side throttle (throttle)
25 Inlet side throttle (throttle)
26 Orifice plate 27 Body (Body)
35 Outflow channel 36 Inflow channel 37 Tip surface (tip surface of orifice plate)
39 Back pressure chamber opening surface 42 Male screw 43 Female screw 52 Annular groove 55 Stopper 56 Guide

Claims (6)

In an injector having a nozzle hole at the tip and starting or stopping fuel injection by opening and closing the nozzle hole by the tip of the needle valve,
On the rear end side of the needle valve, a back pressure chamber into which fuel that exerts a back pressure on the needle valve flows in and out is formed,
By operating the fuel flow into and out of the back pressure chamber to increase or decrease the back pressure, the needle valve is moved in the axial direction to open and close the nozzle hole,
The back pressure chamber is closed at the rear end side by an orifice plate provided with a throttle that restricts the flow of fuel into and out of the back pressure chamber.
The orifice plate is coupled to a body in which the back pressure chamber is formed. The injector according to claim 1, wherein
The orifice plate is provided with a male screw, and the body is provided with a female screw,
The injector, wherein the orifice plate is coupled to the body by screwing the male screw into the female screw. Injector according to claim 2,
The body is provided with a back pressure chamber opening surface in which the back pressure chamber opens,
The front end surface of the orifice plate is moved to the front end side by screwing the male screw and the female screw and is pressed against the back pressure chamber opening surface, thereby closing the back pressure chamber.
The back pressure chamber opening surface is provided with an annular groove surrounding the opening of the back pressure chamber on the outer peripheral side,
This annular groove is connected to a high-pressure channel through which fuel flows into the back pressure chamber,
An inflow passage provided with an inflow side restrictor for restricting the inflow of fuel into the back pressure chamber is opened at the front end surface of the orifice plate,
The inflow channel is connected to the annular groove by the tip surface of the orifice plate being in pressure contact with the back pressure chamber opening surface. Injector according to claim 3,
The orifice plate has a plurality of the inflow channels,
The inflow side restrictor is provided with being divided into a plurality of the inflow channels. In the injector according to any one of claims 1 to 4,
The orifice plate is provided with an outflow passage having an outflow side restrictor for restricting the outflow of fuel from the back pressure chamber,
By opening and closing the opening of this outflow channel by an electromagnetic actuator, the back pressure is increased or decreased,
The electromagnetic actuator is
A cylindrical stopper that is fixed to the inner peripheral side of the solenoid coil and passes magnetic flux,
An armature that is arranged on the front end side of the stopper and is magnetically attracted to the stopper and moves to the rear end side;
A guide that is provided integrally with the armature, protrudes toward the rear end, and is slidably supported on the inner peripheral side of the stopper;
An injector having a valve body that moves together with the armature and the guide to open and close the opening of the outflow passage. Injector according to claim 5,
The injector is characterized in that the valve body is accommodated in a recess provided in the armature.

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