JP2012197739A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve for applying a proper damper action to a needle part that is switchably operated for fuel injection, in the fuel injection valve of an internal combustion engine.SOLUTION: The fuel injection valve includes: an injection valve body having a fuel injection hole for injecting fuel of the internal combustion engine; a fuel chamber, which is formed inside the injection valve body, and which communicates with the fuel injection hole; a fuel passage for supplying the fuel to the fuel chamber; and the needle part, which is movably arranged in the axial direction inside the injection valve body, and which opens and closes the fuel injection hole. The fuel injection valve is provided with: a damper chamber, which communicates with the fuel passage, and the volume of which is varied according to the switching action of the fuel injection hole of the needle part to thereby apply the damper action to the needle part through the fuel from the fuel passage; and a flow path resistance variable means for changing the resistance to the movement of the fuel between the damper chamber and the fuel passage according to the switching action of the needle part.

Description

  The present invention relates to a fuel injection valve for an internal combustion engine.

  A fuel injection valve of an internal combustion engine is required to properly inject a required fuel in order to appropriately exhibit a required output and realize a suitable fuel combustion. In general, a fuel injection valve is configured such that a needle portion that opens and closes a fuel injection hole moves up and down inside the valve body. At this time, when the needle portion closes the nozzle hole, the repulsive force generated by colliding with the valve seat causes a bounce that the needle portion jumps up, causing extra fuel injection, and there is a concern that the exhaust state will deteriorate. On the other hand, if the moving speed of the needle portion is slowed down to suppress bounce, it becomes difficult to achieve proper fuel injection.

  Therefore, as a technique for suppressing the bounce, a technique for suppressing the bounce without reducing the speed at the time of opening and closing the needle portion has been developed (see, for example, Patent Document 1). In this technology, a configuration is adopted in which a damper chamber is formed by the protruding shoulder portion on the needle portion side and the enlarged hole portion on the valve body side, and the flow passage area in the damper chamber is changed along the moving direction of the needle portion. ing.

JP 2002-22050 A

  A fuel injection valve of an internal combustion engine performs fuel injection in a state where a relatively high pressure is applied to the fuel in order to achieve suitable fuel combustion. Therefore, when the fuel injection valve is opened, a pressure difference between the inside and outside of the fuel injection valve acts on the needle portion for opening the valve, so that a larger driving force is required than when the fuel injection valve is closed. In other words, the pressure environment acting on the needle portion differs greatly between when the fuel injection valve is opened and when it is closed. Therefore, even if a damper chamber having a damper function is provided between the needle portion and the injection valve body as in the above prior art, if the damper function is single, that is, the valve opening operation of the fuel injection valve In the case of a configuration that exhibits the same damper function regardless of the valve closing operation, it is not always possible to impart an appropriate damper action to the needle part, and it becomes difficult to make the movement of the needle part suitable. .

  The present invention has been made in view of the above problems, and provides a fuel injection valve that imparts a suitable damper action to a needle portion that opens and closes for fuel injection in a fuel injection valve of an internal combustion engine. Objective.

  In the present invention, in order to solve the above-mentioned problem, a damper chamber is provided in the main body of the fuel injection valve and imparts a damper action to the needle portion that opens and closes the fuel injection hole. The resistance to the fuel flow between the chamber and the fuel passage is changed according to the opening / closing operation of the needle portion. The damper chamber contains fuel inside and gives a damper action to the needle valve via the fuel. By changing the resistance in the flow path connecting the damper chamber and the outside, It is possible to impart an appropriate damper action to the needle portion according to each of the needle valve opening operation and the valve closing operation.

  More specifically, the present invention relates to a fuel injection valve for an internal combustion engine, the injection valve body having a fuel injection hole for injecting fuel of the internal combustion engine, and the fuel injection hole formed inside the injection valve body. A fuel chamber that communicates with the fuel chamber; a fuel passage that supplies fuel to the fuel chamber; a needle portion that is disposed so as to be movable in the axial direction within the injection valve body; and the fuel passage, and the fuel passage. A damper chamber that communicates with the needle portion, the volume of the needle portion changing according to the opening and closing operation of the fuel injection hole of the needle portion, and imparting a damper action to the needle portion via the fuel from the fuel passage And a flow path resistance changing means for changing a resistance against the movement of the fuel between the damper chamber and the fuel passage according to an opening / closing operation of the needle portion.

  In the fuel injection valve according to the present invention, the needle portion moves in the axial direction inside the injection valve main body, whereby the fuel injection hole is opened and closed, thereby realizing fuel injection. Here, the damper chamber provided in the fuel injection valve is configured to be able to exchange fuel with the passage by communicating with the fuel passage. Therefore, the pressure received from the fuel stored in the damper chamber appears as a damper action on the needle portion. Since this damper action acts on the needle part according to the moving speed of the needle part, it is particularly useful for suppressing bounce of the needle part during the opening / closing operation.

  As described above, in the fuel injection valve of the internal combustion engine, pressurized fuel is injected. Therefore, when the needle valve is opened, the injection is performed in an environment where a larger pressure is applied than when the needle valve is closed. Must move inside the disc. Therefore, when the damper action of the damper chamber is single like the fuel injection valve according to the prior art, the damper action can be suitably matched to both the opening operation and the closing operation with different pressure environments. It is difficult. However, in the fuel injection valve according to the present invention, by providing the flow resistance change means, the resistance to the transfer and transfer of fuel performed between the damper chamber and the fuel passage is changed according to the opening / closing operation of the needle portion. It becomes possible to make it. That is, according to the present invention, the flow path resistance changing means changes the resistance, so that it is suitable for each operation when the needle portion performs an opening operation and when the needle portion performs a closing operation. It is possible to set the flow path resistance and diversify the damper action of the damper chamber. As a result, it is possible to achieve both a suitable moving speed of the needle portion for fuel injection and suppression of bounce of the needle portion.

  Here, in the fuel injection valve, the volume of the damper chamber increases when the needle portion opens the fuel injection hole, and the damper chamber increases when the needle portion closes the fuel injection hole. And when the needle portion performs the closing operation of the fuel injection hole, the flow path resistance changing means is configured such that the needle portion performs the opening operation of the fuel injection hole. In comparison, the resistance between the fuel passage and the damper chamber may be reduced. That is, when the needle portion is formed so that the volume of the damper chamber decreases when the fuel injection hole is closed, an effective damper action is exerted on the needle portion by the fuel in the damper chamber. Bounce during operation can be effectively suppressed. In such a configuration, since the resistance between the fuel passage and the damper chamber is reduced during the closing operation, it is possible to prevent the movement speed of the needle portion during the closing operation from being reduced unnecessarily. This is an extremely important matter in a fuel injection valve that needs to perform fuel injection at a high frequency per unit time, and it is possible to achieve both high-performance fuel injection and bounce suppression.

Here, in the fuel injection valve, the flow path resistance changing means includes a plurality of orifice portions that communicate the fuel passage and the damper chamber with an orifice passage in parallel between the fuel passage and the damper chamber. You may prepare. In this case, when the needle portion performs the closing operation of the fuel injection hole, the flow path resistance changing means has the plurality of orifice portions compared to when the needle portion performs the opening operation of the fuel injection hole. Among them, the resistance between the fuel passage and the damper chamber is reduced by increasing the number of effective orifice portions through which the fuel can flow. The term “effective orifice portion” as used herein refers to an orifice portion that can impart a damper action to the needle portion by allowing fuel to flow between the damper chamber and the fuel passage. Thus, by making the number of effective orifice portions out of the plurality of orifice portions different between the opening operation and the closing operation of the needle portion, it is possible to form a damper action suitable for each operation.

  Further, in the fuel injection valve, the flow path resistance changing means is a blocking member that is urged so as to block the orifice passage of the orifice portion by a urging means with respect to a part of the plurality of orifice portions. You may have. In this case, when the needle portion performs the closing operation of the fuel injection hole, the orifice by the closing member resists the urging force of the urging means due to the pressure difference between the damper chamber and the fuel in the fuel passage. When the closed state of the passage is eliminated and the needle portion opens the fuel injection hole, the closed state of the orifice passage by the closing member is maintained by the biasing force of the biasing means. That is, by utilizing the balance between the urging force by the urging means using the urging means and the closing member and the force generated by the pressure difference between the fuel in the damper chamber and the fuel passage, according to the opening / closing operation of the needle portion, It is possible to mechanically switch the closed state of the orifice passage. Such a structure for performing the mechanical switching operation is considered to be a useful structure for realizing reliable switching of the damper action in the fuel injection valve that frequently opens and closes the needle valve.

  Here, in the fuel injection valve described above, the needle part includes a nozzle part on the fuel injection hole side, and a piston part configured separately from the nozzle part and receiving a damper action from the damper chamber, Further, the nozzle part and the piston part are connected by a connecting means in a loosely fitted state so that a gap of a predetermined distance exists between the end parts of both parts along the moving direction of the needle part. May be adopted. With such a configuration, the piston portion located at a position away from the fuel injection hole is first repelled by the repulsive force received by contact with the injection valve main body side having the fuel injection hole particularly when the needle portion performs the closing operation. It becomes possible. Since this piston part can be separated from the nozzle part by the predetermined distance at the connection part by the connecting means, at least the repulsion part of the predetermined distance results in the piston part absorbing the repulsive force, and the fuel. The repulsion amount of the nozzle portion located on the nozzle hole side can be suppressed as much as possible. Of course, as long as the nozzle part and the piston part are loosely fitted, as long as there is a connection state by the connection means, the integrity as the needle part is not lost, and there is no problem in realizing the fuel injection by the movement of the needle part.

  In the fuel injection valve, by forming the piston part heavier than the nozzle part, the inertial force of the piston part can be made larger than the nozzle part, and thus the degree of absorption of the repulsive force by the piston part. Can be increased. As a result, it is possible to effectively suppress bounce when the needle portion is closed.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the fuel injection valve which provides a suitable damper effect | action with respect to the needle part which opens and closes for fuel injection in the fuel injection valve of an internal combustion engine.

It is a figure which shows schematic structure of the fuel injection valve which concerns on the Example of this invention. It is the schematic block diagram of the connector which connects the command piston and nozzle needle which comprise the needle part of the fuel injection valve shown in FIG. 1, and the enlarged view of the connection site | part vicinity. It is a figure which shows the state of a damper chamber and the fuel passage vicinity at the time of the opening / closing operation | movement in the fuel injection valve shown in FIG. It is a figure which shows the time transition of the lift amount of the command piston at the time of the opening / closing operation | movement with the fuel injection valve shown in FIG. It is a figure which shows the time transition of the lift amount of a command piston, the lift amount of a nozzle needle, and the injection rate at the time of opening / closing operation | movement with the fuel injection valve which has a connection part shown in FIG. 2, and the fuel injection valve which concerns on a reference example.

  Hereinafter, specific embodiments of the fuel injection valve according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a fuel injection valve 1 according to an embodiment of the present invention. The fuel injection valve 1 is mounted on an internal combustion engine and injects fuel to be used for combustion in a combustion chamber. Here, the main body of the fuel injection valve 1 is formed including the first body B1, the second body B2, the third body B3, and the fourth body B4, and each body B1-B4 is fastened by fastening means (not shown). Yes. First, in the first body B1, the nozzle needle 10 constituting the needle portion of the fuel injection valve 1 is inserted into a hollow portion extending in the axial direction at the central portion of the first body B1, and the hollow portion and A fuel passage 13 is formed by a gap formed between the first body B1 and the first body B1. The fuel passage 13 is connected to the fuel injection hole 12 provided in the seat portion 11 of the first body B1 on the proximal end side (the tip end side of the fuel injection valve 1). A fuel reservoir 14 formed by partially expanding the hollow portion is provided on the distal end side of the fuel passage 13. A fuel passage 15 is connected to the fuel reservoir 14, and fuel passages 16 and 36, which will be described later, are connected to the fuel passage 15, so that pressurized fuel is supplied from the fuel inlet 17.

  With such a configuration, when the nozzle needle 10 is seated on the seat portion 11, the fuel injection hole 12 is closed, so that pressurized fuel is sealed in the fuel passage 13, the fuel reservoir 14, and the like, which will be described later. When the nozzle needle 10 is raised by the operation of the magnetic circuit 60, the enclosed fuel is ejected from the fuel injection hole 12. In addition, the description of “up” and “down” in this specification expresses a movement operation based on the direction of the needle portion (comprising a nozzle needle 10 and a command piston 30 described later) in the state shown in FIG. The movement in the absolute direction is not described as “up” or “down”. Similarly, the expressions “distal” and “proximal” in the present specification also indicate that the injection hole side of the fuel injection valve is “proximal” and the magnetic circuit side described later is “distant” in the state shown in FIG. "Relatively".

  Here, a first spring chamber 20 is provided at a portion adjacent to the second body B2 on the distal end side of the first body B1, and provided on the nozzle needle 10 side located in the center thereof. A first spring 22 having one end fixed to the plate 23 and the other end fixed to a stopper 21 provided on the first body B1 side is disposed. With this configuration, the nozzle needle 10 receives an urging force in the direction of the seat portion 11 from the first spring 22 via the plate 23.

  Next, the second body B2 is provided with a penetrating portion 25 at the center thereof. The penetrating portion 25 is formed separately from the nozzle needle 10 and the nozzle needle 10 and constitutes the needle portion of the fuel injection valve 1. The command piston 30 is connected by a connector 33. As shown in FIG. 2B, the distal end side of the nozzle needle 10 is constricted by a flange 10a and a neck portion 10b. Similarly, the proximal end side of the command piston 30 is also formed by a flange 30a and a neck portion 30b. It has a constricted shape. 2A, the connector 33 is provided with a groove 33b into which the neck portion 10b of the nozzle needle 10 slides and fits, and a groove 33a into which the neck portion 30b of the command piston 30 slides and fits. As shown in FIGS. 2 (b) and 2 (c), each neck portion is fitted into each groove.

In this connected state, the flange 10a of the nozzle needle 10 and the flange 30a of the command piston 30 are not always in contact with each other, and a gap (gap) having a maximum predetermined distance as shown in FIG. The distance between the two flanges is formed so as to be loosely fitted so as to be changeable according to an opening / closing operation caused by raising and lowering of the needle portion. FIG. 2B shows a state where the gap between the flange 10a of the nozzle needle 10 and the flange 30a of the command piston 30 is maximized, and FIG. 2C shows the flange 10a of the nozzle needle 10 and the command piston. The state which 30 flanges 30a contacted is shown. The details of the connection between the nozzle needle 10 and the command piston 30 by the connector 33 will be described later.

  The fuel passage 16 is provided in the second body B2.

  Next, in the third body B3, a command piston 30 is fitted in the center thereof, and a second spring chamber 34 connected to the penetrating portion 25 of the second body B2 is provided on the proximal end side thereof. The second spring chamber 34 is provided with a second spring 35 having one end connected to the connector 33 side and the other end connected to the third body B3 side. With this configuration, the command piston 30 receives a biasing force from the second spring 35 toward the seat portion 11. Further, when the flange 10a and the flange 30a are in contact with each other as shown in FIG. 2 (c), the nozzle needle 10 is also biased from the second spring 35 toward the seat portion 11 as shown in FIG. Receive. The first spring chamber 20 and the second spring chamber 34 described above are connected to the fuel passage 36 and are filled with fuel when the fuel injection valve 1 is operated.

  Further, an annular portion 41 formed as a hollow space is provided on the distal end side of the third body B3, and the disk portion 40 whose diameter is expanded on the distal end side of the command piston 30 is fitted therein. Thus, the annular portion 41 and the disc portion 40 form a damper chamber 42 as a closed space. The volume of the damper chamber 42 varies as the command piston 30 moves up and down by driving the magnetic circuit 60. A first orifice block 44 having a first orifice passage 43 is provided below the damper chamber 42, and the damper chamber 42 is connected to the fuel passage 36 through the fuel passage 45. With this configuration, the first orifice block 44 measures the transfer of fuel between the damper chamber 42 and the fuel passage 36 via the fuel passage 45. Further, a second orifice block 47 having a second orifice passage 46 is provided below the damper chamber 42, and the damper chamber 42 is connected to the fuel passage 36 through the fuel passage 51. Here, a valve urged toward the second orifice block 47 by a third spring 49 is provided in a lower space (a space near the connection portion between the second orifice passage 46 and the fuel passage 51) 50 of the second orifice block 47. A plate 48 is provided. With this configuration, the second orifice block 47 measures the transfer of fuel between the damper chamber 42 and the fuel passage 36 via the fuel passage 51, and the valve plate 48 is measured to the second orifice block 47. The movement of the fuel from the damper chamber 42 to the fuel passage 36 via the fuel passage 51 is permitted, and the movement of the fuel in the opposite direction is blocked.

  A stopper plate 52 is provided at the edge of the annular portion 41 of the third body B3 so as to protrude from the annular portion 41. The disc plate portion 40 of the command piston 30 interferes with the stopper plate 52, the amount of ascent of the command piston 30 is restricted, the maximum volume of the damper chamber 42 is defined, and the nozzle needle connected to the command piston 30 The amount of increase will also be regulated.

Next, the magnetic circuit 60 is accommodated in the fourth body B4. The magnetic circuit 60 includes an armature 61 fastened to the command piston 30, an internal stator 62 fixed to the fourth body B 4 side by a fixing ring 66, an outer peripheral stator 63, a bobbin 64, and a coil 65. When the coil 65 is energized by supplying power from the armature 61, the armature 61 is attracted to the internal stator 62, and the ascending force is transmitted to the nozzle needle 10 via the command piston 30 and the connector 33 fastened to the armature 61. . The fourth body B4 is preferably formed of a non-magnetic material in order to reduce leakage of magnetic flux from the magnetic circuit 60 and improve the performance of the magnetic circuit. A space 67 is provided in the lower part of the magnetic circuit 60 inside the fourth body B4, and communicates with the fuel inlet 17 via a fuel passage (not shown).

  Here, the raising and lowering operations of the command piston 30 constituting the needle portion of the fuel injection valve 1 will be described with reference to FIG. FIG. 3A is a view showing a state in the vicinity of the damper chamber 42 when the command piston 30 is raised. The command piston 30 is lifted by the drive of the magnetic circuit 60, and as a result, the volume of the damper chamber 42 is increased by the disk portion 40 being lifted. When the volume of the damper chamber 42 increases in this manner, the pressure inside the damper chamber 42 decreases, so that the valve plate 48 is biased by the third spring 49 due to the pressure difference between the damper chamber 42 and the fuel passage 51 or the lower space 50. In combination, the state where the second orifice passage 46 is blocked is maintained. As a result, when the command piston 30 is raised, the fuel flow between the damper chamber 42 and the outside of the fuel passage 36 and the like is measured only by the first orifice block 44.

  On the other hand, FIG. 3B is a view showing a state in the vicinity of the damper chamber 42 when the command piston 30 is lowered. When the exciting magnetic field by the magnetic circuit 60 is eliminated, the command piston 30 is lowered by the urging force of the first spring 22 and the second spring 35. As a result, the volume of the damper chamber 42 is reduced by lowering the disk portion 40. It is in the process of going. When the volume of the damper chamber 42 decreases in this way, the internal pressure increases and becomes higher than the pressure in the fuel passage 51 and the lower space 50, so that the valve plate 48 resists the urging force of the third spring 49. Opened. As a result, when the command piston 30 is lowered, the fuel flow between the damper chamber 42 and the outside of the fuel passage 36 and the like is measured by both the first orifice block 44 and the second orifice block 47.

  In the fuel injection valve 1 having the damper chamber 42 configured as described above, when the command piston 30 is raised, the damper chamber is formed from the fuel passage 36 suitable for the pressure environment around the damper chamber 42 generated at that time. The first orifice block 44 may be adjusted to create a resistance to fuel flow to 42. In other words, the fluctuation of the pressure difference between the damper chamber 42 and the fuel passage 36 due to the increase in the volume of the damper chamber 42 is adjusted, and the orifice area of the first orifice passage 43 is adjusted from the viewpoint of suppressing bounce of the needle portion at the time of rising and the moving speed. do it. On the other hand, when the command piston 30 is lowered, it is mainly used to form a resistance against the fuel flow from the damper chamber 42 to the fuel passage 36, which is suitable for the pressure environment around the damper chamber 42 described above. The second orifice block 47 may be adjusted. That is, the fluctuation of the pressure difference between the damper chamber 42 and the fuel passage 36 due to the decrease in the volume of the damper chamber 42 is determined by reducing the orifice area of the first orifice passage 43, etc. Based on this, the orifice area and the like of the second orifice passage 46 may be adjusted.

In general, in a fuel injection valve that injects pressurized fuel as in an internal combustion engine, the needle portion rises (opens) from a state in which high-pressure fuel is sealed inside, so that the fuel from the fuel injection hole Injection is performed. Therefore, when the needle part is raised, the force against the urging force of a spring or the like, the force calculated by multiplying the area of the seat part by the pressure difference between the fuel pressure and the external pressure of the fuel injection valve, and the needle part itself are accelerated. It is necessary for the magnetic circuit to exhibit the total force for The sum of forces for this opening operation is called “valve opening force”. On the other hand, when the needle portion is lowered, the lowering (closing operation) is basically performed by an urging force such as a spring. The total force for this closing operation is called “valve closing force”. Thus, since there is a large difference between the valve opening force and the valve closing force, if the resistance of the fuel flow between the damper chamber and the outside is determined based on one of the forces, the other force acts. Then, when the needle portion is operated, the damper action is too weak to suppress the bounce appropriately, or the damper action becomes unnecessarily strong, leading to a decrease in the moving speed of the needle portion.

  However, as described above, in the fuel injection valve 1 according to the present invention, the orifice area of the first orifice passage 43 and the orifice area of the second orifice passage 46 according to each of the closing operation and the opening operation of the needle portion. Therefore, it is possible to realize a preferable operation as the whole fuel injection valve. Here, FIG. 4A shows the transition of the lift amount of the command piston in the fuel injection valve 1 according to the present invention, and FIG. 4B shows the lift of the command piston in the fuel injection valve according to the prior art. Shows the change in quantity. The valve closing force in these cases is a condition of 1/4 of the valve opening force. In the fuel injection valve 1 according to the present invention, the orifice area (total) at the time of closing is 2 of the orifice area at the time of opening. 1 (ie, the orifice area of the first orifice passage 43 = the orifice area of the second orifice passage 46). In the fuel injection valve according to the prior art, in the fuel injection valve shown in FIG. In this configuration, only the first orifice passage 43 is disposed between them (that is, the orifice area when the valve is closed and the orifice area when the valve is opened are not changed).

  As shown in FIG. 4B, in the fuel injection valve according to the prior art, the speed of the command piston (inclination of the lift amount) decreases to about half of that when the valve closing force is lowered, and the valve closes quickly. Operation is hindered. On the other hand, as shown in FIG. 4 (a), in the fuel injection valve 1 according to the present invention, the speed of the command piston can be made the same as that at the time of rising even when the valve closing force is weakened. The closing action is guaranteed. As described above, in the fuel injection valve 1 according to the present invention, the fuel resistance between the damper chamber 42 and the fuel passage 36, which is suitable for each of the closing operation and the opening operation, can be adjusted. Application of action is realized.

  Here, as shown in FIG. 2, the needle portion of the fuel injection valve 1 is composed of the nozzle needle 10 and the command piston 30, and both are connected by a connector 33 with a gap of a predetermined distance at the maximum. Has been. The nozzle needle 10 is lighter than the command piston 30. In the fuel injection valve 1 having the needle portion configured as described above, when the needle portion is closed, the flange 10a of the nozzle needle 10 and the flange 30a of the command piston 30 are in contact with each other in the connector 33. The tip of the nozzle needle 10 collides with the sheet portion 11. At this time, due to the difference in inertia force, the heavier command piston 30 bounces first due to the repulsive force. Since the command piston 30 and the nozzle needle 10 are separate structures, while the command piston 30 is initially bounced, the nozzle needle 10 is seated by the fuel pressure, the urging force of the first spring 22, and the like. 11 is brought into contact. This state is maintained until the command piston 30 is separated from the nozzle needle 10 by the gap of the predetermined distance set in the connector 33. Therefore, preferably, the predetermined distance related to the gap is set to be equal to or larger than the assumed bounce size of the command piston 30. The value varies depending on the specific configuration of the fuel injection valve 1 and the specific aspect of the required fuel injection, and includes a gap of 20 to 50 μm, for example.

  Here, FIG. 5A shows the transition of the lift amount of the command piston, the lift amount of the nozzle needle, and the injection rate in the fuel injection valve 1 according to the present invention (the configuration having the gap), and FIG. Includes a lift amount of a command piston in a fuel injection valve according to the prior art (a configuration in which the needle portion is not separated as in the present invention, but is configured integrally, that is, a configuration in which there is no gap), Changes in the lift amount and injection rate of the nozzle needle are shown. As is clear from FIG. 5, by providing a gap in the needle portion as in the present invention, it is possible to suppress the bounce of the nozzle needle when the valve is closed, and thus it is possible to reliably avoid the occurrence of secondary injection. .

DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve 10 ... Nozzle needle 11 ... Seat part 12 ... Fuel injection hole 13, 15, 16, 36, 45, 51 ... Fuel passage 20 ... ··· First spring chamber 22 ··· First spring 30 ··· command piston 33 ··· connector 40 · · · disk portion 41 · · · annular portion 42 · · · damper chamber 43・ ・ ・ ・ First orifice passage 44 ・ ・ ・ ・ First orifice block 46 ・ ・ ・ ・ Second orifice passage 47 ・ ・ ・ ・ Second orifice block 48 ・ ・ ・ ・ Valve plate 49 ・ ・ ・ ・ Third spring 60 ... Magnetic circuit B1 ... First body B2 ... Second body B3 ... Third body B4 ... Fourth body

Claims (6)

An injection valve body having a fuel injection hole for injecting fuel of an internal combustion engine;
A fuel chamber formed inside the injection valve body and communicating with the fuel injection hole;
A fuel passage for supplying fuel to the fuel chamber;
A needle portion that is arranged so as to be movable in the axial direction inside the injection valve body, and that opens and closes the fuel injection hole;
A damper chamber communicating with the fuel passage, the volume of which changes according to the opening and closing operation of the fuel injection hole of the needle portion, and imparts a damper action to the needle portion through the fuel from the fuel passage A damper chamber,
A flow path resistance changing means for changing a resistance to the movement of the fuel between the damper chamber and the fuel passage according to an opening / closing operation of the needle portion;
A fuel injection valve comprising: The volume of the damper chamber increases when the needle portion performs the opening operation of the fuel injection hole, and the volume of the damper chamber decreases when the needle portion performs the operation of closing the fuel injection hole,
When the needle portion performs the closing operation of the fuel injection hole, the flow path resistance changing means is less than that when the needle portion performs the opening operation of the fuel injection hole. Reduce the resistance between,
The fuel injection valve according to claim 1. The flow path resistance changing means includes a plurality of orifice portions in parallel between the fuel passage and the damper chamber, the orifice portion communicating the fuel passage and the damper chamber with an orifice passage,
When the needle portion performs the closing operation of the fuel injection hole, the flow path resistance changing means is configured so that the fuel of the plurality of orifice portions is more fuel than when the needle portion performs the opening operation of the fuel injection hole. Reducing the resistance between the fuel passage and the damper chamber by increasing the number of effective orifices that can be circulated;
The fuel injection valve according to claim 2. The flow path resistance changing means has a closing member urged so as to close an orifice passage of the orifice part by a urging means with respect to a part of the plurality of orifice parts.
When the needle portion closes the fuel injection hole, the orifice passage is closed by the closing member against the urging force of the urging means due to a pressure difference between the damper chamber and the fuel in the fuel passage. The condition is resolved,
When the needle portion performs the opening operation of the fuel injection hole, the closed state of the orifice passage by the closing member is maintained by the biasing force of the biasing means.
The fuel injection valve according to claim 3. The needle part has a nozzle part on the fuel injection hole side, and a piston part configured separately from the nozzle part and receiving a damper action from the damper chamber,
The nozzle part and the piston part are connected by a connecting means in a loosely fitted state so that a gap of a predetermined distance exists between the end parts of both parts along the moving direction of the needle part,
The fuel injection valve according to any one of claims 1 to 4. The piston part is formed heavier than the nozzle part.
The fuel injection valve according to claim 5.

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