JP2010159677A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve that can certainly improve a valve opening response and a valve closing response. <P>SOLUTION: The sum total of passage cross-sectional areas of communicating passages 53 for communicating an inter-core space 52 formed in a movable core 36 with a fuel passage 322 is larger than a cross-sectional area of a gap part 54 formed between an inner circumferential face part 351 of a fixed core 35 and an outer circumferential face part 271 of a stopper 27 of a needle 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection valve, and is suitably applied to, for example, a fuel injection valve that injects and supplies fuel to an internal combustion engine.

  As a prior art, there is a fuel injection valve disclosed in Patent Document 1 below. The fuel injection valve includes a cylindrical member that is a cylindrical housing, a fixed core that is fixed in the cylindrical member, a fixed core that is provided closer to the injection hole than the fixed core in the cylindrical member, and is energized to the coil. And a movable core that is magnetically attracted. In the movable core, a nozzle needle that is a valve member is fixed on the injection hole side, and an annular protrusion is provided on the surface on the counter injection hole side, and between the movable core and the fixed core, An opposing space that is an inter-core space is formed on the outer peripheral side of the protrusion. The movable core is formed with a communication passage penetrating in the axial direction. The communication passage communicates a fuel passage formed between the cylindrical member and the nozzle needle and the opposed space.

  When the coil is energized and the movable core is sucked into the fixed core, the fuel in the opposed space flows out to the fuel passage through the communication path, so the pressure in the opposed space when the movable core collides with the fixed core. The rise is suppressed, and the movement of the nozzle needle that quickly contacts the fixed core to bring the nozzle hole into a fully open state is completed quickly. On the other hand, when the energization of the coil is interrupted and the movable core is separated from the fixed core, the fuel in the fuel passage flows into the facing space through the communication passage, so that the pressure drop in the facing space is suppressed, and the nozzle hole The movement of the nozzle needle from the fully open state to the closed state is started immediately.

Japanese Patent No. 4168448

  However, a stopper is provided in which the valve member penetrates the movable core and protrudes radially outwardly at the end of the valve member on the side opposite to the injection hole. When adopting a configuration in which the communication path is provided in the movable core as in the above-described prior art, the fuel injection valve in which the fuel passage is formed inside the valve member while being able to contact the surface on the hole side, There may be a problem that the moving speed of the valve member and the movable core cannot be sufficiently improved, and there is a problem that the valve opening response and the valve closing response cannot be improved reliably.

  The present inventors have intensively studied the above problems, and the stopper provided on the valve member is located inside the fixed core, so that the inner peripheral surface portion of the fixed core and the stopper regardless of the movement position of the valve member and the movable core. Paying attention to the fact that a relatively narrow gap is formed between the outer peripheral surface portion and the movement speed of the valve member and the movable core is reliably improved by providing a communication path that does not easily exert the influence of the gap. I found that it was possible.

  Specifically, when the valve member and the movable core move from the valve-closed position to the fully-open position where the nozzle hole is fully opened, at the end of the valve-opening operation in which the valve member and the movable core are close to the fully-open position, the movable core Can contact the fixed core relatively quickly to complete the valve opening operation.However, when moving from the valve closing position to the fully open position, if the size of the communication path is small, the amount of fuel flowing out to the fuel path through the gap will be reduced. It has been found that the moving speed of the valve member and the movable core is not sufficiently increased due to the flow resistance.

  Further, when the valve member and the movable core move from the fully opened position where the nozzle hole is fully opened to the valve closed position, the movable core is a fixed core at the start of the valve closing operation in which the valve member and the movable core are in the vicinity of the fully opened position. Although the valve closing operation can be started relatively quickly, the flow resistance of the fuel flowing into the fuel passage through the gap is affected if the communication passage is small when moving from the fully open position to the valve closing position. And it discovered that the moving speed of a valve member and a movable core did not fully raise.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a fuel injection valve capable of reliably improving the valve opening response and the valve closing response.

In order to achieve the above object, in the invention described in claim 1,
A tubular housing;
A cylindrical fixed core to be fixed at a predetermined position in the housing;
A valve member that is provided in the housing and opens and closes the injection hole by reciprocating in the axial direction to intermittently inject fuel from the injection hole;
A movable core that is provided in a cylindrical shape around the valve member on the nozzle hole side of the fixed core in the housing, the outer peripheral surface portion is in contact with the inner peripheral surface portion of the housing, and is magnetically attracted to the fixed core when the coil is energized When,
A stopper that protrudes in a radially outward shape at the end of the valve member on the side opposite to the injection hole, is inside the fixed core, and can come into contact with the surface on the side opposite to the injection hole of the movable core,
In the housing, a space including a space inside the fixed core, a passage space formed inside the valve member, and a space formed between the housing and the valve member on the injection hole side of the movable core is jetted. A fuel passage to the hole,
A convex portion protruding in the axial direction is provided on at least one of the surface on the injection hole side of the fixed core and the surface on the anti-injection side of the movable core, and an inter-core space is formed between the fixed core and the movable core. And
At least one of the fixed core and the movable core is formed with a communication path that communicates the space between the core and the fuel path.
The passage cross-sectional area of the communication passage is characterized by being larger than the cross-sectional area of the gap formed between the inner peripheral surface portion of the fixed core and the outer peripheral surface portion of the stopper.

  According to this, when the valve member and the movable core move from the nozzle hole closed position to the fully open position, the fuel in the inter-core space can flow out to the fuel passage via the communication passage having a passage cross-sectional area larger than the gap portion. it can. Further, when the valve member and the movable core move from the nozzle hole fully open position to the valve closed position, the fuel in the fuel passage can flow into the inter-core space via the communication passage having a passage cross-sectional area larger than the gap portion. Therefore, even if the fuel flow resistance in the gap portion is large, the movement speed of the valve member and the movable core can be increased without being affected by the fuel flow resistance in the gap portion. In this way, the valve opening response and the valve closing response can be reliably improved.

  In the invention according to claim 2, the communication path is provided in the movable core.

  According to this, when the movable core moves to the counter-injection hole side and the volume of the space between the cores decreases, the volume of the fuel passage on the injection hole side of the movable core increases. It is easy to let the fuel flow out into the fuel passage. Further, when the movable core moves to the nozzle hole side and the volume of the space between the cores increases, the volume of the fuel passage on the nozzle hole side of the movable core decreases. It is easy to flow into the space.

  Further, as in the third aspect of the present invention, a plurality of communication passages are provided, and the sum of the cross-sectional areas of the plurality of communication passages can be larger than the cross-sectional area of the gap portion. By providing a plurality of communication passages, it is possible to reduce the size of the core provided with the communication passages as compared with the case of a single communication passage.

  Further, the invention according to claim 4 is characterized in that the plurality of communication paths are evenly arranged on a circumference around the axis of the core in which the communication paths are formed.

  According to this, the fuel can be quickly moved between the inter-core space and the fuel passage through the plurality of communication passages arranged evenly, and the core provided with the communication passage can be reliably downsized. be able to.

It is sectional drawing which shows the structure of the injector 10 which is a fuel injection valve in one Embodiment to which this invention is applied. 2 is a cross-sectional view showing a main structure of an injector 10. FIG. 4 is a top view of the movable core 36. FIG. It is a time chart which shows the relationship between the energization state to a coil, a needle, and a movable core position, (a) shows a coil energization state, (b) shows a needle and a movable core position.

  Embodiments to which the present invention is applied will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an injector 10 according to an embodiment to which the present invention is applied. FIG. 2 is a cross-sectional view showing the main structure of the injector 10, and FIG. 3 is a top view showing the structure of the movable core of the injector 10. FIG. 4 is a time chart showing the relationship between the energized state of the coil and the needle and movable core position, where (a) shows the coil energized state and (b) shows the needle / movable core position.

  An injector 10 shown in FIG. 1 is a fuel injection valve, and is applied to, for example, a direct injection type gasoline engine. When the injector 10 is applied to a direct injection type gasoline engine, the injector 10 is mounted on an engine head (not shown).

  The injector 10 includes a cylindrical member 11 extending in a predetermined axial direction Z (opening / closing direction), an inlet member 12 provided at one end of the axial direction Z of the cylindrical member 11, and a nozzle holder provided at the other end of the axial direction Z of the cylindrical member 11. 13, a needle 14 that is accommodated so as to be reciprocally movable in the axial direction Z inside the injector 10, and a drive unit 15 that drives the needle 14.

  Hereinafter, as the direction of the injector 10, the direction in which the tubular member 11 extends is referred to as an axial direction Z (vertical direction in FIG. 1), and one of the axial directions Z is a valve opening direction Z1 (upward in FIG. 1, opposite to the injection hole side). The other of the axial directions Z may be referred to as the valve closing direction Z2 (downward in FIG. 1, the nozzle hole side).

  The cylindrical member 11 is formed in a cylindrical shape having substantially the same inner diameter in the axial direction Z. The cylindrical member 11 has a magnetic part 16 having magnetism and a nonmagnetic part 17 having no magnetism. The magnetic part 16 is located in the valve opening direction Z1 with respect to the nonmagnetic part 17. Therefore, the end portion of the cylindrical member 11 located in the valve closing direction Z <b> 2 becomes the nonmagnetic portion 17. Such a nonmagnetic portion 17 prevents a magnetic short circuit between the magnetic portion 16 and the nozzle holder 13. The magnetic part 16 and the nonmagnetic part 17 are integrally connected by, for example, laser welding. Further, the cylindrical member 11 may be partly magnetized or non-magnetic by, for example, thermal processing after being integrally formed.

  The inlet member 12 is provided at the end of the cylindrical member 11 located in the valve opening direction Z1. The inlet member 12 is press-fitted on the inner peripheral side of the cylindrical member 11. The inlet member 12 has a fuel inlet 18 penetrating in the axial direction Z. Fuel is supplied to the fuel inlet 18 from a fuel pump (not shown). A fuel filter 19 is provided at the fuel inlet 18. The fuel filter 19 removes foreign matters contained in the fuel. Therefore, the fuel supplied to the fuel inlet 18 flows into the inner peripheral side of the cylindrical member 11 via the fuel filter 19.

  The nozzle holder 13 is provided at the end of the cylindrical member 11 located in the valve closing direction Z2. Therefore, the cylindrical member 11 and the nozzle holder 13 cooperate to constitute a cylindrical housing. The nozzle holder 13 has magnetism. Therefore, the nonmagnetic portion 17 of the cylindrical member 11 is located between the magnetic portion 16 and the magnetic nozzle holder 13 in the axial direction Z. The nozzle holder 13 is formed in a cylindrical shape.

  The nozzle holder 13 has a large-diameter portion 20, a medium-diameter portion 21, a small-diameter portion 22, and a mounting portion 23 that are substantially coaxial and have different inner diameters. Of the three diameter portions 20 to 22, the large diameter portion 20 has the largest inner diameter, the medium diameter portion 21 has the next largest inner diameter, and the small diameter portion 22 has the smallest inner diameter. Further, the positional relationship of the three diameter portions 20 to 22 is such that the large diameter portion 20 is located at the end portion in the valve opening direction Z1, the small diameter portion 22 is located at the end portion in the valve closing direction Z2, and the medium diameter portion 21 is the shaft. It is located in the center of the direction Z, that is, between the large diameter portion 20 and the small diameter portion 22. The inner diameter of the large-diameter portion 20 is approximately equal to the inner diameter of the cylindrical member 11 and is disposed so as to be substantially coaxial with the cylindrical member 11. The attachment portion 23 is provided at the end of the small diameter portion 22 located in the valve closing direction Z2. Therefore, the end portion of the nozzle holder 13 in the valve closing direction Z <b> 2 becomes the attachment portion 23. The attachment portion 23 is provided with a nozzle body 24.

  The nozzle body 24 is formed in a cylindrical shape, and is fixed to the mounting portion 23 of the nozzle holder 13 by, for example, press fitting or welding. The inner wall surface of the nozzle body 24 is inclined so that the inner diameter becomes smaller toward the valve closing direction Z2, and is formed in a so-called sharp shape. A nozzle hole 25 that penetrates the nozzle body 24 in the axial direction Z and communicates the inner wall surface and the outer wall surface is formed at the tip of the nozzle body 24. The inner wall surface around the nozzle hole 25 functions as a valve seat 29.

  The needle 14 is a valve member and is accommodated on the inner peripheral side of the cylinder member 11, the nozzle holder 13, and the nozzle body 24 so as to be reciprocally movable in the axial direction Z. The needle 14 reciprocates in the axial direction Z to open and close the injection hole 25 and intermittently inject fuel from the injection hole 25. The needle 14 is disposed substantially coaxially with the nozzle body 24. The needle 14 has a shaft portion 26, a stopper 27, and a seal portion 28. The needle 14 is provided with a stopper 27 provided so as to protrude radially outward (in a flange shape) at one end side of the shaft portion 26, that is, the end portion on the fuel inlet 18 side (reverse injection hole side). Have. Further, the needle 14 has a seal portion 28 at the other end side of the shaft portion 26, that is, at the end opposite to the fuel inlet 18 (injection hole side). The seal portion 28 can be seated on a valve seat 29 formed on the nozzle body 24.

  The needle 14 has an inflow hole 30 and a communication hole 31 through which fuel flows. Specifically, the needle 14 is formed with an inflow hole 30 that is an upstream-side passage and a communication hole 31 that is a downstream-side passage connected to the downstream side of the inflow hole 30. A configuration including the inflow hole 30 and the communication hole 31 is a fuel supply passage supplied to the fuel passage 322 toward the injection hole 25.

  The inflow hole 30 is formed so as to extend along the axial direction Z from the position where the stopper 27 of the needle 14 is formed. Therefore, the upper end portion of the inflow hole 30 located in the valve opening direction Z1, that is, the upstream end of the supply passage opens in the valve opening direction Z1. Further, the lower end portion of the inflow hole 30 located in the valve closing direction Z2 is closed. A communication hole 31 that extends in the radial direction of the needle 14 and communicates the inflow hole 30 and the outer space is formed in the inner wall facing the lower end portion of the inflow hole 30.

  Inside the cylindrical member 11 and the nozzle holder 13 forming the housing, a fuel passage 321 that is a space inside a fixed core 35 to be described later, an inflow hole 30 that is a passage space formed inside the needle 14 that is a valve member, and communication. A space including a hole 31 and a fuel passage 322 that is a space formed between the nozzle holder 13 and the needle 14 closer to the injection hole than the movable core 36 is a fuel passage from the fuel inlet 18 toward the injection hole 25. This is a fuel passage 32.

  As a result, the fuel flowing down to the inner peripheral side of the cylindrical member 11 via the fuel filter 19 flows into the inflow hole 30 formed in the needle 14 via the fuel passage 321 inside the fixed core 35, and further into the inflow hole. It is led out of the needle 14 from a communication hole 31 formed at the lower end of the needle 30. Thereafter, the fuel flows down the fuel passage 322 formed between the needle 14 and the nozzle holder 13 and flows into the nozzle hole 25 side. The configuration of the supply passage composed of the inflow hole 30 and the communication hole 31 will be described later.

  Next, the drive unit 15 that drives the needle 14 will be described. FIG. 2 is an enlarged cross-sectional view of a portion of the injector 10 in a closed state where the needle 14 is seated. The drive unit 15 drives the needle 14 along the axial direction Z. The drive unit 15 includes a spool 33, a coil 34, a fixed core 35, a magnetic plate 50, a movable core 36, a connector 37, a first spring 39 and a second spring 46.

  The spool 33 is installed on the outer peripheral side of the cylindrical member 11. The spool 33 is formed in a cylindrical shape with resin, and a coil 34 is wound on the outer peripheral side. The coil 34 generates a magnetic force that attracts the movable core 36 to the fixed core 35 when energized. The coil 34 is electrically connected to the terminal portion 38 of the connector 37. The terminal portion 38 is electrically connected to an external electric circuit (not shown) attached to the connector 37, and the energization state of the coil 34 is controlled by the external electric circuit.

  The fixed core 35 is fixed to a predetermined installation position on the inner peripheral side of the coil 34 with the cylindrical member 11 interposed therebetween. The fixed core 35 is formed in a cylindrical shape from a magnetic material such as iron, and is fixed to the inner peripheral side of the cylindrical member 11 by, for example, press fitting. The magnetic plate 50 is made of a magnetic material and covers the outer peripheral side of the coil 34.

  The movable core 36 is installed on the inner peripheral side of the cylindrical member 11 and the inner peripheral side of the large-diameter portion 20 of the nozzle holder 13 so as to be capable of reciprocating in the axial direction Z. The movable core 36 is formed in a cylindrical shape from a magnetic material such as iron. A first spring 39 is disposed in the fixed core 35. The first spring 39 has one end in contact with the needle 14 and the other end in contact with the adjusting pipe 40. The first spring 39 has a force that extends in the axial direction Z. Therefore, the movable core 36 and the needle 14 are pressed by the first spring 39 in the valve closing direction Z2 that is seated on the valve seat 29. The adjusting pipe 40 is press-fitted into the inner peripheral side of the fixed core 35. Thereby, the load of the first spring 39 is adjusted by adjusting the press-fitting amount of the adjusting pipe 40. When the coil 34 is not energized, the movable core 36 and the needle 14 are pressed in the valve closing direction Z2, and the seal portion 28 is seated on the valve seat 29.

  As described above, the drive unit 15 includes the fixed core 35 and the movable core 36. The needle 14 is inserted into the movable core 36. That is, the movable core 36 is provided in a cylindrical shape around the needle 14 that is a valve member. The movable core 36 is formed with an insertion hole penetrating in the axial direction Z at a central portion in the radial direction. An inner peripheral surface portion (hereinafter also referred to as “hole portion”) 41 facing the insertion hole is formed so that its inner diameter is slightly larger than the outer diameter of the shaft portion 26 of the needle 14. Therefore, the needle 14 can move in the axial direction Z on the inner peripheral side of the hole 41.

  Further, the outer peripheral surface portion 42 of the shaft portion 26 of the needle 14 is in contact with the hole portion 41 of the movable core 36. Therefore, since the needle 14 is displaced in the axial direction Z while being in contact with the movable core 36, the needle 14 and the movable core 36 slide. Thereby, the needle 14 is guided to move in the axial direction Z by the movable core 36 in a state where sliding resistance (friction force) is always generated by contact with the movable core 36.

  Further, the outer peripheral surface portion 43 on the radially outer side of the movable core 36 is in contact with the inner peripheral surface portion 44 of the cylindrical member 11. In the present embodiment, the outer peripheral surface portion 43 of the movable core 36 that contacts the inner peripheral surface portion 44 of the cylindrical member 11 is a convex portion 43 that protrudes radially outward from the remaining surface portion. The convex part 43 is provided in the edge part of the movable core 36 located in the valve opening direction Z1. Further, the projecting portion 43 is in contact with the cylindrical member 11 and is a portion composed of the nonmagnetic portion 17.

  Therefore, since the convex portion 43 of the movable core 36 is displaced in the axial direction Z while being in contact with the inner peripheral surface portion 44 of the nonmagnetic portion 17, the movable core 36 and the nonmagnetic portion 17 slide. As a result, the movement of the movable core 36 in the axial direction Z is guided by the nonmagnetic portion 17 in a state where sliding resistance (friction force) is always generated.

  A stopper 27 provided on the needle 14 regulates the displacement of the movable core 36 in the valve opening direction Z1. The outer diameter of the stopper 27 is larger than the inner diameter of the hole 41. Therefore, the stopper 27 of the needle 14 is in contact with the end surface portion 45 of the movable core 36 (hereinafter sometimes referred to as “the upper end surface portion 45 of the movable core 36”) located in the valve opening direction Z1. When the stopper 27 and the upper end surface portion 45 of the movable core 36 are in contact with each other, the movement of the needle 14 toward the valve seat 29 (valve closing direction Z2) between the movable core 36 and the needle 14 and the stationary core 35 of the movable core 36 are performed. The relative movement to the side is limited. Accordingly, the stopper 27 of the needle 14 limits excessive relative movement between the movable core 36 and the needle 14.

  The stopper 27 is reciprocally displaced along the axial direction Z on the inner side of the cylindrical fixed core 35. Therefore, the outer diameter of the stopper 27 is slightly smaller than the inner diameter of the fixed core 35. Accordingly, a cylindrical gap portion 54 is formed between the inner peripheral surface portion 351 of the fixed core 35 and the outer peripheral surface portion 271 of the stopper 27.

  The upper end surface portion 45, which is the surface on the side opposite to the injection hole of the movable core 36, is provided with a convex portion 51 projecting in the valve opening direction Z <b> 1 in the axial direction Z on the inner peripheral side edge. By providing the convex portion 51 protruding to the fixed core 35 side, the displacement of the movable core 35 is provided between the lower end surface portion 49 of the fixed core 35 and the upper end surface portion 45 of the movable core 36 on the outer peripheral side of the convex portion 51. The inter-core space 52 is formed regardless of the position. By providing the convex portion 51, the contact area when the fixed core 35 and the movable core 36 contact each other is reduced, and so-called squeeze force is reduced.

  The movable core 36 is formed with a communication passage 53 having a circular passage cross section that connects the inter-core space 53 and the fuel passage 322 (the space between the nozzle holder 13 and the needle 14). A plurality of communication paths 53 (six in this example) are provided in the movable core 36, and each communication path 53 penetrates the movable core 36 in the axial direction Z. As shown in FIG. 3, a top view (viewed from above in FIG. 2), the plurality of communication passages 53 are evenly arranged around the axis of the movable core 36. It is preferable to provide 4 to 8 communication paths.

The passage cross-sectional area of the communication path 53 (the area of the cross section perpendicular to the axial direction Z, in this example, the total of the cross-sectional areas of the plurality of communication paths 53, in this example, 7.3 mm ² ) The cross-sectional area of the gap portion 54 formed between the inner peripheral surface portion 351 and the outer peripheral surface portion 271 of the stopper 27 (the area of the cross section perpendicular to the axial direction Z, 2.2 mm ^{2 in} this example) is larger.

  The movable core 36 is in contact with a second spring 46, which is an elastic member, at an end 48 (hereinafter, also referred to as “lower end surface portion 48 of the movable core 36”) located in the valve closing direction Z2. The second spring 46 has a force that extends in the axial direction Z. The second spring 46 has an end located in the valve opening direction Z1 in contact with the movable core 36 and an end located in the valve closing direction Z2 in contact with the nozzle holder 13. The second spring 46 is accommodated in the large diameter part 20 and the medium diameter part 21 of the nozzle holder 13. The connecting portion between the medium diameter portion 21 and the small diameter portion 22 has a step because the inner diameters are different from each other, and a step surface portion 47 with which the end of the second spring 46 located in the valve closing direction Z2 contacts is formed. The inner diameter of the middle diameter portion 21 is selected to be slightly larger than the outer diameter of the second spring 46. Such an intermediate diameter portion 21 reduces the inclination and bending of the second spring 46. Therefore, the pressing force of the second spring 46 can be accurately maintained.

  The second spring 46 has a force that extends in the axial direction Z. Therefore, the movable core 36 is urged by the second spring 46 to be pressed against the fixed core 35 side (the valve opening direction Z1). A valve closing force f1 in the valve closing direction Z2 is applied to the movable core 36 via the needle 14 from the first spring 39, and a valve opening force f2 in the valve opening direction Z1 is applied from the second spring 46. In FIG. 2, for easy understanding, a direction in which the valve closing force f <b> 1 and the valve opening force f <b> 2 are not illustrated is illustrated, but the direction in which the valve closing force f <b> 1 and valve opening force f <b> 2 are actually applied is illustrated.

  The valve closing force f1 that is the pressing force of the first spring 39 is set larger than the valve opening force f2 that is the pressing force of the second spring 46. Therefore, in the valve closing state in which the coil 34 is not energized, the needle 14 in contact with the first spring 39 and the movable core 36 in contact with the stopper 27 resists the valve opening force f2 of the second spring 46. It moves to the 25 side (valve closing direction Z2). As a result, in a valve-closed state in which energization of the coil 34 is stopped, the seal portion 28 of the needle 14 is seated on the valve seat 29.

  As described above, in the injector 10 of the present embodiment, as shown in FIG. 2, the nozzle holder 13 forming a part of the housing has a large diameter portion 20, a medium diameter portion 21, and a small diameter portion 22. A movable core 36 is disposed inside the large diameter portion 20. The second spring 46 is disposed inside the large-diameter portion 20 and the medium-diameter portion 21 of the nozzle holder 13, and the end on the counter-injection hole side (the valve opening direction Z1 side) is the lower end surface portion 48 of the movable core 36. The end on the injection hole side (valve closing direction Z2 side) is supported in contact with the stepped surface portion 47 between the medium diameter portion 21 and the small diameter portion 22 of the nozzle holder 13.

  Here, the large diameter part 20 and the medium diameter part 21 are large internal diameter parts, and the small diameter part 22 is a small internal diameter part. Therefore, the nozzle holder 13 that forms a part of the housing includes a small diameter portion 22 that is a small inner diameter portion, and a medium diameter portion 21 that is a large inner diameter portion that has a larger inner diameter than the small diameter portion 22 on the side opposite to the injection hole from the small diameter portion 22. And a fuel passage 322 toward the injection hole 25 between the small diameter portion 22 and the needle 14 that is a valve member, and a medium diameter portion 21 that is a part of the large inner diameter portion. The step surface portion 47 between the small diameter portion 22 and the small inner diameter portion serves as a seat surface that supports the end portion on the injection hole side of the second spring 46 that is an elastic member.

  In the needle 14, an inflow hole 30 and a communication hole 31 that are fuel supply passages are formed. The inflow hole 30 that is the upstream side passage extends in the axial direction Z, and the communication hole 31 that is the downstream side passage connected to the downstream side of the inflow hole 30 intersects the inflow hole 30 (in the present example, orthogonal). Direction). A plurality of communication holes 31 are provided, and in this example, two communication holes 31 are provided in the axially symmetrical position in the needle 14. The needle 14 has a communication hole 31 illustrated in FIG. 2 and a communication hole (not illustrated in FIG. 2) provided on the front side of the drawing with respect to the communication hole 31 (a communication hole having the same shape as the illustrated communication hole 31). ) And are formed.

  As is clear from FIG. 2, the diameter of the communication hole 31 having a circular cross section (for example, 1.4 mm) is smaller than the diameter of the inflow hole 30 having a circular cross section (for example, 1.6 mm), but a plurality of communication holes 31 are provided. Therefore, the total cross-sectional area of the communication hole 31 is larger than the cross-sectional area of the inflow hole 30. That is, in the supply passage, the cross-sectional area of the downstream passage is larger than the cross-sectional area of the upstream passage.

  The downstream ends of the plurality of communication holes 31 are all open at a portion between the stepped surface portion 47 of the nozzle holder 13 and the end surface (lower end surface portion 48) of the movable core 36 on the injection hole 25 side in the axial direction Z. is doing. Regardless of the displacement position of the needle 14 due to the reciprocating displacement in the axial direction Z for opening and closing the valve, the communication hole 31 of the needle 14 has a downstream end opening position at the step surface portion 47 of the nozzle holder 13 and the injection hole of the movable core 36. It is formed so as to be between the end surface on the 25th side (lower end surface portion 48).

  Next, the operation of the injector 10 with the above configuration will be described with reference to FIG.

  First, the operation when the valve is opened will be described. When energization of the coil 34 is stopped, no magnetic attractive force is generated between the fixed core 35 and the movable core 36. Therefore, the needle 14 is pressed in the valve closing direction Z2 by the valve closing force f1 which is the pressing force of the first spring 39. At this time, the stopper 27 of the needle 14 is in contact with the upper end surface portion 45 of the movable core 36 (in this example, the portion on the inner peripheral side of the convex portion 51). Therefore, the movable core 36 moves in the valve closing direction Z2 together with the needle 14 in the valve closing direction due to the difference between the valve closing force f1 of the first spring 39 and the valve opening force f2 which is the pressing force of the second spring 46. Thus, the movable core 36 is separated from the fixed core 35. In this way, the seal portion 28 of the needle 14 is seated on the valve seat 29 by moving in the valve closing direction Z2 rather than when the needle 14 is in the valve open state. Therefore, fuel is not injected from the injection hole 25. In this valve-closed state, the lower end surface portion 48 of the movable core 36 is stopped at a position separated from the step surface portion 47.

  As shown in FIG. 4A, when the coil 34 is energized from the closed state at time t1, the magnetic plate 50, the magnetic part 16, the movable core 36, the fixed core 35 and the nozzle holder 13 are caused by the magnetic field generated in the coil 34. Magnetic flux flows and a magnetic circuit is formed. As a result, a magnetic attractive force is generated between the fixed core 35 and the movable core 36. When the sum of the magnetic attraction force generated between the fixed core 35 and the movable core 36 and the valve opening force f2 of the second spring 46 becomes larger than the valve closing force f1 of the first spring 39, FIG. As shown, the movable core 36 starts moving in the valve opening direction Z1 at time t2. At this time, the needle 14 with which the stopper 27 is in contact with the upper end surface portion 45 of the movable core 36 moves together with the movable core 36 in the valve opening direction Z1. As a result, the seal portion 28 of the needle 14 is separated from the valve seat 29.

  As described above, the fuel flowing into the injector 10 from the fuel inlet 18 flows into the fuel filter 19, the inner peripheral side of the inlet member 12, the inner peripheral side of the adjusting pipe 40, and the inner peripheral side of the fixed core 35 (fuel passage 321. ), The inflow hole 30, the communication hole 31, the inner peripheral side (fuel passage 322) of the medium-diameter portion 21, and the inner peripheral side (fuel passage 322) of the small-diameter portion 22 to the inner peripheral side of the nozzle body 24. Inflow. The fuel that has flowed into the nozzle body 24 flows into the nozzle hole 25 via the space between the needle 14 and the nozzle body 24 that are separated from the valve seat 29. Thereby, fuel is injected from the nozzle hole 25.

  Thus, not only the magnetic attractive force but also the valve opening force f2 of the second spring 46 is applied to the movable core 36. Therefore, when the coil 34 is energized, the movable core 36 and the needle 14 are quickly moved in the valve opening direction Z1 by the generated magnetic attractive force.

  When the movable core 36 and the needle 14 are moving in the valve opening direction Z1, the volume of the inter-core space 52 gradually decreases, but the volume of the fuel passage 322 on the injection hole side of the movable core 36 gradually increases. Therefore, the fuel in the inter-core space 52 can easily flow out to the fuel passage 322 through the communication passage 53 having a passage cross-sectional area larger than that of the gap portion 54.

  Therefore, the operation responsiveness of the needle 14 with respect to energization of the coil 34 can be enhanced. In addition, the electromagnetic attractive force required to drive the movable core 36 and the needle 14 is reduced. Therefore, the drive unit 15 such as the coil 34 can be downsized.

  As described above, when a magnetic attractive force is applied from the valve-closed state, the movable core 36 and the needle 14 move together in the valve-opening direction Z1 when the upper end surface portion 45 of the movable core 36 and the stopper 27 come into contact with each other. . The movable core 36 and the needle 14 are fully opened (maximum opening degree) when the upper end surface portion 45 of the movable core 36 (in this example, the outer peripheral portion of the convex portion 51) collides with the lower end surface portion 49 of the fixed core 35. ) And moves in the valve opening direction Z1 until time t3. When the movable core 36 collides with the fixed core 35, the movable core 36 and the needle 14 can move relative to each other in the axial direction Z. The movement in the valve opening direction Z <b> 1 is continued further away from the upper end surface portion 45. Even if the stopper 27 is separated as described above, the stopper 27 is kept in contact with the first spring 39, so that the stopper 27 does not collide with any other member. Therefore, irregular fuel injection from the nozzle hole 25 is reduced without the needle 14 bouncing.

  Further, the needle 14 continues to move in the valve opening direction Z1 due to the inertial force in the valve opening direction Z1, and when the movable core 36 and the stopper 27 are separated, the needle 14 has a second spring via the movable core 36. 46 valve opening force f2 is not applied. Therefore, only the pressing valve closing force f <b> 1 of the first spring 39 is applied to the needle 14. That is, when the movable core 36 and the needle 14 are separated, the force applied to the needle 14 in the valve closing direction Z2 increases. Therefore, excessive movement of the needle 14 in the valve opening direction Z1 is limited, and so-called overshoot is reduced.

  Similarly, when the needle 14 continues to move in the valve opening direction Z1 due to the inertial force in the valve opening direction Z1 and the movable core 36 and the needle 14 are separated from each other, the movable core 36 opens the valve of the second spring 46. The force f2 and the magnetic attractive force are applied, and the valve closing force f1 of the first spring 39 is not applied. That is, when the movable core 36 and the stopper 27 are separated, the force applied to the movable core 36 in the valve opening direction Z1 increases. Therefore, when the movable core 36 collides with the fixed core 35, the movable core 36 does not bounce off in the valve closing direction Z2 due to the impact, and the state where the movable core 36 is in contact with the fixed core 35 at least during the period when the coil 34 is energized from time t3. Maintained.

  The impact force when the movable core 36 collides with the fixed core 35 is reduced because the weight contributing to the impact force is reduced (because it is only the weight of the movable core 36). Since the impact force is small in this way, the movable core 36 is extremely difficult to rebound.

  Furthermore, when the needle 14 overshoots and the force applied to the needle 14 is only the valve closing force f1 of the first spring 39, the moving speed of the needle 14 in the valve opening direction Z1 decreases, and the overshoot amount is maximized. After that, the movement in the valve closing direction Z2 is started by the valve closing force f1. On the other hand, since the movable core 36 is in contact with the fixed core 35 by the magnetic attractive force and the valve opening force f2 of the second spring 46, when the needle 14 moves in the valve closing direction Z2, it contacts the fixed core 35. Movement in the valve closing direction Z2 is restricted by the movable core 36. As a result, the magnetic attraction force and the opening force f2 of the second spring 46 are again applied to the needle 14, so that the needle 14 can maintain the valve opening state. Thus, since the movable core 36 and the needle 14 are relatively movable, irregular fuel injection from the nozzle hole 25 due to the bounding of the needle 14 is reduced. Therefore, even when the energization time to the coil 34 is short, the amount of fuel injected from the nozzle hole 25 can be precisely controlled.

  Next, the operation when the valve is closed will be described. As shown in FIG. 4A, when energization to the coil 34 is stopped at the time t4 from the valve open state (fully opened state), the magnetic attractive force between the fixed core 35 and the movable core 36 disappears. As a result, as shown in FIG. 4B, the needle 14 starts moving in the valve closing direction Z2 from the time t5 together with the movable core 36 by the valve closing force f1 of the first spring 39. Therefore, the seal portion 28 of the needle 14 is again seated on the valve seat 29, and the flow of fuel between the fuel passage 32 and the injection hole 25 is blocked. Therefore, the fuel injection ends.

  When energization of the coil 34 is stopped at time t4, the movable core 36 and the needle 14 are quickly moved in the valve closing direction Z2 against the valve opening force f2 of the second spring 46 by the valve closing force f1 of the first spring 39. Move to.

  When the movable core 36 and the needle 14 are moving in the valve closing direction Z <b> 2, the volume of the inter-core space 52 gradually increases, but the volume of the fuel passage 322 closer to the injection hole than the movable core 36 is gradually increased. Therefore, the fuel in the fuel passage 332 can easily flow into the inter-core space 52 via the communication passage 53 having a passage cross-sectional area larger than that of the gap portion 54.

  When the seal portion 28 of the needle 14 is seated on the valve seat 29, the needle 14 tries to rebound in the valve opening direction Z1 due to the impact of the collision. Here, since the movable core 36 and the needle 14 are relatively movable, even if the seal portion 28 of the needle 14 is seated on the valve seat 29, the movable core 36 is closed as it is due to the inertial force in the valve closing direction Z2. The movement in the valve direction Z2 is continued, and the movable core 36 and the needle 14 are separated.

  Therefore, only the valve closing force f 1 of the first spring 39 is applied to the needle 14, and only the valve opening force f 2 of the second spring 46 is applied to the movable core 36. Accordingly, when the movable core 36 and the needle 14 are separated from each other, the resultant force acting on the needle 14 is only the valve closing force f1, and the needle 14 is prevented from rebounding in the valve opening direction Z1. Thereby, when the energization to the coil 34 is stopped, the fuel injection from the nozzle hole 25 is quickly stopped. Therefore, irregular fuel injection is reduced, and the amount of fuel injected from the nozzle hole 25 can be precisely controlled.

  The impact force when the needle 14 collides with the valve seat 29 is reduced because the weight contributing to the impact force is reduced (because it is only the weight of the needle 14 minutes). Thus, since the impact force is small, the needle 14 is extremely difficult to rebound.

  As shown in FIG. 4B, when the needle 14 is seated at time t6, the movable core 36 that can be displaced relative to the needle 14 opens the movable core 36 by the inertial force in the valve closing direction Z2. The valve opening force f2 of the second spring 46 biased in the valve direction Z1 is overcome, and the valve is excessively displaced in the valve closing direction Z2, so-called undershoot.

  When the movable core 36 undershoots and the force applied to the movable core 36 is only the valve opening force f2 of the second spring 46, the moving speed of the movable core 36 in the valve closing direction Z2 decreases, and the amount of undershoot is maximum. After that, the movement in the valve opening direction Z1 is started by the valve opening force f2. On the other hand, the needle 14 is in a state where the seal portion 28 is seated on the valve seat 29 by the valve closing force f <b> 1 of the first spring 39. The movable core 36, which moves in the valve opening direction Z1 by the valve opening force f2, is stopped by the movement of the needle 14 being restricted by the stopper 27 of the needle 14, and enters a valve closing state in which the next valve opening operation can be started.

  According to the configuration and operation described above, the sum of the passage cross-sectional areas of the communication passage 53 is such that the gap portion 54 formed between the inner peripheral surface portion 351 of the fixed core 35 and the outer peripheral surface portion 271 of the stopper 27 of the needle 14 is broken. It is larger than the area. Therefore, when the needle 14 and the movable core 36 move from the nozzle hole 25 closed position to the fully open position, the fuel in the inter-core space 52 is supplied to the fuel passage 322 via the communication passage 53 having a passage cross-sectional area larger than the gap portion 54. Can be drained into. Further, when the needle 14 and the movable core 36 move from the nozzle hole 25 fully open position to the valve closing position, the fuel in the fuel passage 322 is supplied to the inter-core space 52 via the communication passage 53 having a passage cross-sectional area larger than the gap portion 54. Can be allowed to flow into. Thus, even if the passage cross-sectional area of the gap 54 is relatively small and the fuel flow resistance is large, the needle 14 and the movable core 36 can be moved quickly without being affected by the fuel flow resistance of the gap 54. The valve opening responsiveness and the valve closing responsiveness can be greatly improved.

  When the communicating path is not provided in the movable core 36, the inter-core space 52 is only communicated with the fuel passage 321 mainly through the gap 54. Therefore, when the needle 14 and the movable core 36 move, Under the influence of the fuel flow resistance of the gap portion 54, for example, the moving speed decreases as in the comparative example shown by the broken line in FIG. In addition, when the movable core 36 collides with the fixed core 35 from the vicinity of the nozzle hole fully open position, the passage sectional area of the contact portion between the movable core 36 and the fixed core 35 is larger than the passage sectional area of the gap portion 54. Therefore, due to the damper effect of the inter-core space 52, it takes a relatively long time for the needle 14 and the movable core 36 to reach the fully open position as shown by the broken line in FIG. When the movable core 36 moves away from the fixed core 35, the state in which the passage cross-sectional area of the contact portion between the movable core 36 and the fixed core 35 continues to be smaller than the passage cross-sectional area of the gap portion 54. Due to the effect, it takes a relatively long time for the needle 14 and the movable core 36 to increase in moving speed from the fully open position, as indicated by a broken line in FIG.

  On the other hand, according to this embodiment, the effect of the communication passage 53 can not only improve the moving speed when the needle 14 and the movable core 36 move between the nozzle hole 25 closed position and the fully opened position. In addition, the damper effect of the inter-core space 52 when the movable core 36 contacts the fixed core 35 or when the movable core 36 leaves the fixed core 35 is suppressed, and the valve opening response and the valve closing response are greatly improved. be able to.

  On the other hand, when the movable core 36 is provided with a communication passage having a smaller passage cross-sectional area than the gap portion 54 (for example, a plurality of communication passages having a total passage cross-sectional area smaller than that of the gap portion 54), the inter-core space 52 is The fuel passages 321 and 322 communicate with the fuel passages 321 and 322 through the gap portion 54 and the communication passage. When the needle 14 and the movable core 36 move, the fuel flow in the communication passage having a smaller passage cross-sectional area than the gap portion 54 and the gap portion. Under the influence of resistance, for example, the moving speed decreases as in the comparative example indicated by the two-dot chain line in FIG. On the other hand, according to the present embodiment, the needle 14 and the movable core 36 move between the nozzle hole 25 closed position and the fully opened position due to the effect of the communication passage 53 having a larger passage cross-sectional area than the gap portion 54. Thus, the moving speed can be improved, and the valve opening response and the valve closing response can be improved.

  Further, when the movable core 36 moves to the counter-injection hole side and decreases the volume of the inter-core space 52, the volume equivalent to the decreasing volume is increased in the fuel passage 322 on the injection hole side with respect to the movable core 36, and the movable core 36 is movable. When the core 36 moves to the injection hole side and increases the volume of the inter-core space 52, the volume equivalent to the increasing volume is reduced in the fuel passage 322 on the injection hole side of the movable core 36. Therefore, by providing the communication path 53 in the movable core 36, the fuel can be easily distributed through the communication path 53.

  Further, by forming the communication path 53 in the movable core 36, the projected area of the movable core 36 viewed from the axial direction Z can be reduced. Therefore, the resistance when the movable core 36 moves in the axial direction Z in the fuel oil can be reduced.

  Further, a plurality of communication paths 53 are provided, and the plurality of communication paths 53 are evenly arranged around the axis of the movable core 36. Accordingly, it is possible to reduce the outer diameter of the movable core 36 by reducing the diameter per one of the communication passages, and the inter-core space 52 and the fuel passage 322 via the plurality of communication passages 53 that are evenly arranged. It is possible to quickly move the fuel between the two and the magnetic properties of the movable core 36.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the above embodiment, the communication path 53 is provided in the movable core 36, but it may be provided in the fixed core 35 or may be provided in both cores. The communication path only needs to communicate with the inter-core space 52 and the fuel path 32. For example, when the communication path is provided in the fixed core 35, the communication path may communicate the inter-core space 52 and the fuel path 321, or may be upstream of the inter-core space 52 and the fuel path 321. The fuel passage 32 may be communicated.

  In the above embodiment, the plurality of communication passages 53 are provided in the movable core 36 and are evenly arranged at the center of the shaft. However, the present invention is not limited to this. As long as the properties, the magnetic characteristics, and the like are satisfied, the number may be singular or the number may be unevenly arranged.

  In the above-described embodiment, the communication hole is provided in the movable core 36 so as to form a through hole extending in parallel with the axis. However, the present invention is not limited to this. For example, it may be provided inclined on the shaft. Further, instead of the through-hole structure, for example, a groove structure may be formed on the outer peripheral surface of the core.

  In the above-described embodiment, the convex portion 51 is provided on the surface of the movable core 36 on the side opposite to the injection hole, and the inter-core space 52 is formed between the fixed core 35 and the movable core 36. What is necessary is just to provide in the at least any one of the surface by the side of the injection hole of the fixed core 35, and the surface by the side of the anti-injection of the movable core 36.

  In the above embodiment, the tubular member 11 and the nozzle holder 13 constitute the housing. However, the present invention is not limited to this. For example, the housing may be constituted by three or more members. .

  In the above embodiment, the injector 10 is applied to a direct-injection gasoline engine, but is not limited to a direct-injection gasoline engine, and is applied to a port-injection gasoline engine, a diesel engine, or the like. May be.

10 Injector (fuel injection valve)
11 Tube member (part of housing)
13 Nozzle holder (part of housing)
14 Needle (Valve member)
25 Injection hole 27 Stopper 32 Fuel passage 34 Coil 35 Fixed core 36 Movable core 51 Convex part 52 Inter-core space 53 Communication path 54 Gap part 271 Outer peripheral part (outer peripheral part of stopper 27)
322 Fuel passage (part of fuel passage 32)
351 inner peripheral surface portion (inner peripheral surface portion of fixed core 35)

Claims (4)

A tubular housing;
A cylindrical fixed core fixed to a predetermined position in the housing;
A valve member provided in the housing, which opens and closes the injection hole by reciprocating in the axial direction, and intermittently injects fuel from the injection hole;
Provided in a cylindrical shape around the valve member on the nozzle hole side of the fixed core in the housing, the outer peripheral surface portion is in contact with the inner peripheral surface portion of the housing, and the coil is energized so that the fixed core is magnetized. A movable core to be sucked;
A stopper projecting in a radially outward direction at the end of the valve member on the side opposite to the injection hole, inside the fixed core, and capable of contacting the surface on the side opposite to the injection hole of the movable core; Prepared,
In the housing, a space inside the fixed core, a passage space formed inside the valve member, and a space formed between the housing and the valve member on the injection hole side of the movable core, A space including a fuel passage toward the nozzle hole,
A convex portion protruding in the axial direction is provided on at least one of the surface on the injection hole side of the fixed core and the surface on the anti-injection side of the movable core, and the gap between the cores is provided between the fixed core and the movable core. A space is formed,
At least one of the fixed core and the movable core is formed with a communication path that connects the inter-core space and the fuel path,
The fuel injection valve characterized in that a passage sectional area of the communication passage is larger than a sectional area of a gap portion formed between an inner peripheral surface portion of the fixed core and an outer peripheral surface portion of the stopper.   The fuel injection valve according to claim 1, wherein the communication path is provided in the movable core.   3. The fuel injection valve according to claim 1, wherein a plurality of the communication passages are provided, and a sum total of passage cross-sectional areas of the plurality of communication passages is larger than a cross-sectional area of the gap portion.   4. The fuel injection valve according to claim 3, wherein the plurality of communication passages are arranged uniformly on a circumference centering on an axis of a core in which the communication passages are formed. 5.

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