JP2017048764A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve capable of suppressing change in responsiveness of a valve body.SOLUTION: A fuel injection valve includes a valve seat and a valve body configured to cooperate with each other to open/close a fuel passage, and a movable element 27 having one end part at which the valve body is provided and the other end part at which a movable iron core 27a is provided. The movable iron core 27a has, on an outer peripheral surface 27ac, a curve surface that is formed into a convex shape projecting toward a radial outside and that is curved in a center axis 27l direction of the movable element 27. The curve surface 27ac surrounds the outer peripheral surface 27ac of the movable iron core 27a and contacts with a guide surface 5e configured to guide movement of the movable element 27 in a valve opening/closing direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fuel injection valve that injects fuel.

  As a background art of this technical field, a fuel injection valve described in JP 2011-208530 A (Patent Document 1) is known. The fuel injection valve includes a valve housing formed by sequentially connecting a valve seat member, a magnetic cylinder, a non-magnetic cylinder, a fixed core, and a fuel inlet cylinder, a coil disposed on the outer periphery thereof, and a coil. A valve housing having a coil housing that welds the front end (lower end) to the outer periphery of the magnetic cylindrical body, and a movable core that is slidably fitted to the inner peripheral surface of the magnetic cylindrical body and that faces the suction surface of the fixed core In a fuel injection valve comprising a three-dimensional structure, a magnetic cylinder and a non-magnetic cylinder are arranged so that a boundary surface between them protrudes forward (downward) from the front end face (lower end face) of the coil. A journal portion that is slidably supported on the inner peripheral surface of the magnetic cylindrical body at the radially inner position of the front end portion is formed on the movable core (see summary).

  Further, in the fuel injection valve of Patent Document 1, the valve assembly is slidably supported on the valve housing at two points, a spherical valve body and a journal portion (see paragraph 0019).

JP 2011-208530 A

  In the fuel injection valve of Patent Document 1, there is a minute amount between the inner peripheral surface of the valve housing (magnetic cylindrical body) and the outer peripheral surface of the journal portion, and between the spherical valve body and the valve housing (valve seat member). There is a gap. For this reason, in the fuel injection valve of Patent Document 1, the valve assembly is tilted or biased (shifted).

  When the valve assembly falls down, the corner portion of the rear end portion (upper end portion) of the journal portion comes into contact with the inner peripheral surface of the valve housing. Further, when the valve assembly is biased, the outer peripheral surface of the journal portion contacts the inner peripheral surface of the valve housing over the entire surface in the central axis direction of the valve assembly. Such a change in the contact state between the valve assembly and the inner peripheral surface of the valve housing causes a change in the sliding resistance of the valve assembly with respect to the inner peripheral surface of the valve housing. A change in the sliding resistance of the valve assembly with respect to the inner peripheral surface of the valve housing causes a change in the responsiveness of the valve body. In particular, when the sliding resistance increases, the responsiveness of the valve body becomes worse. The change in the responsiveness of the valve body changes the fuel injection amount.

  The objective of this invention is providing the fuel injection valve which can suppress the change of the responsiveness of a valve body.

  In order to achieve the above object, the fuel injection valve of the present invention has a curved surface that is convex outward in the radial direction on the outer peripheral surface of the movable iron core and curved in the direction of the central axis of the mover. The curved surface surrounds the outer peripheral surface of the movable iron core and is configured to contact a guide surface that guides the movement of the mover in the on-off valve direction.

  ADVANTAGE OF THE INVENTION According to this invention, the change of the responsiveness of a valve body can be suppressed, and the fuel injection valve which can inject a stable quantity of fuel can be provided.

It is sectional drawing which shows the cross section which follows the center axis line 1a about one Example of the fuel injection valve which concerns on this invention. It is sectional drawing which expands and shows the vicinity of the nozzle part 8 shown in FIG. It is sectional drawing which expands and shows the vicinity of the movable iron core 27a shown in FIG. It is an external view which shows the external appearance of the movable iron core 27a shown in FIG. It is a schematic diagram explaining the state of the fall of the needle | mover 27 'and the bias | inclination about the comparative example with this invention. It is a schematic diagram explaining the state of the fall of the needle | mover 27 and the bias | inclination about one Example of this invention. It is the schematic diagram which showed typically the outer peripheral part of the movable iron core 27a shown in FIG. It is an external view which shows the external appearance of a modification about the movable iron core 27a shown in FIG.1 and FIG.4. It is an external view which shows the external appearance of another modification about the movable iron core 27a shown in FIG.1 and FIG.4. 1 is a cross-sectional view of an internal combustion engine in which a fuel injection valve 1 is mounted.

  An embodiment according to the present invention will be described with reference to FIGS.

  With reference to FIG. 1, the whole structure of the fuel injection valve 1 is demonstrated. FIG. 1 is a cross-sectional view showing a cross section taken along the central axis 1a of an embodiment of a fuel injection valve according to the present invention. The central axis 1a is aligned with the axis (valve axis) of a movable element (valve assembly) 27 in which a valve body 27c, a rod part (connecting part) 27b and a movable iron core (movable core) 27a are integrally provided. It coincides with the central axis of the cylindrical body 5.

  In FIG. 1, the upper end portion (upper end side) of the fuel injection valve 1 may be referred to as a base end portion (base end side), and the lower end portion (lower end side) may be referred to as a distal end portion (front end side). The term “proximal end portion (proximal end side)” and “distal end portion (distal end side)” are based on the fuel flow direction or the structure of the fuel injection valve 1 attached to the fuel pipe. Further, the vertical relationship described in this specification is based on FIG. 1 and is not related to the vertical direction in the form in which the fuel injection valve 1 is mounted on the internal combustion engine.

  The fuel injection valve 1 is configured by a cylindrical body 5 made of a metal material so that a fuel flow path (fuel passage) 3 is substantially along the central axis 1a. The cylindrical body 5 is formed in a stepped shape in the direction along the central axis 1a by press working such as deep drawing using a metal material such as magnetic stainless steel. Thereby, as for the cylindrical body 5, the diameter of the one end side 5a is large with respect to the diameter of the other end side 5b.

  A fuel supply port 2 is provided at the proximal end of the cylindrical body 5, and a fuel filter 13 for removing foreign matters mixed in the fuel is attached to the fuel supply port 2.

  The base end portion of the cylindrical body 5 is formed with a flange portion (expanded diameter portion) 5d that is bent so as to expand toward the radially outer side, and the flange portion 5d and the base end side end portion 47a of the cover 47 are formed. An O-ring 11 is disposed in the formed annular recess (annular groove) 4.

  A valve portion 7 including a valve body 27 c and a valve seat member 15 is configured at the distal end portion of the cylindrical body 5. The valve seat member 15 is inserted on the inner side of the distal end side of the cylindrical body 5 and is fixed to the cylindrical body 5 by laser welding 19. The laser welding 19 is performed from the outer peripheral side of the cylindrical body 5 over the entire periphery. In this case, the valve seat member 15 may be fixed to the tubular body 5 by laser welding after the valve seat member 15 is press-fitted inside the distal end side of the tubular body 5.

  A drive unit 9 for driving the valve body 27c is disposed at an intermediate portion of the cylindrical body 5. The drive unit 9 is composed of an electromagnetic actuator (electromagnetic drive unit). Specifically, the drive unit 9 is disposed on the front end side with respect to the fixed iron core 25 inside the cylindrical body 5 and the fixed iron core 25 fixed inside (inner peripheral side) of the cylindrical body 5. The outer periphery of the cylindrical body 5 at a position where the mover (movable member) 27 movable in the direction along the axis 1a, and the fixed iron core 25 and the moveable iron core 27a formed on the mover 27 face each other through the minute gap δ1. The electromagnetic coil 29 is extrapolated to the side, and a yoke 33 that covers the electromagnetic coil 29 on the outer peripheral side of the electromagnetic coil 29.

  A movable element 27 is accommodated inside the cylindrical body 5, and the cylindrical body 5 faces the outer peripheral surface of the movable iron core 27a and surrounds the movable iron core 27a. The cylindrical body 5, the valve seat member 15, and the fixed iron core 25 constitute a valve housing that houses the mover 27.

  The movable iron core 27a, the fixed iron core 25, and the yoke 33 constitute a closed magnetic path through which magnetic flux generated by energizing the electromagnetic coil 29 flows. Although the magnetic flux passes through the minute gap δ1, in order to reduce the leakage magnetic flux flowing through the cylindrical body 5 at the minute gap δ1, a position corresponding to the minute gap δ1 of the cylindrical body 5 (at the outer peripheral side of the minute gap δ1). A weak magnetic part 5 c that is weaker than the nonmagnetic part or other part of the cylindrical body 5 is provided. Hereinafter, the nonmagnetic portion or the weak magnetic portion 5c will be described simply as the nonmagnetic portion 5c. The nonmagnetic portion 5 c can be formed by performing a demagnetization process on the cylindrical body 5 having magnetism with respect to the cylindrical body 5. Such demagnetization treatment can be performed by, for example, heat treatment. Alternatively, by forming an annular recess on the outer peripheral surface of the cylindrical body 5, the portion corresponding to the non-magnetic portion 5c can be made thinner.

  The electromagnetic coil 29 is wound around a bobbin 31 formed in a cylindrical shape with a resin material, and is extrapolated to the outer peripheral side of the cylindrical body 5. The electromagnetic coil 29 is electrically connected to a terminal 43 provided on the connector 41. An external drive circuit (not shown) is connected to the connector 41, and a drive current is passed through the electromagnetic coil 29 via the terminal 43.

  The fixed iron core 25 is made of a magnetic metal material. The fixed iron core 25 is formed in a cylindrical shape, and has a through hole 25a that penetrates the central portion in a direction along the central axis 1a. The fixed iron core 25 is press-fitted and fixed to the proximal end side of the small-diameter portion 5 b of the cylindrical body 5, and is positioned at the intermediate portion of the cylindrical body 5. Since the large diameter portion 5a is provided on the base end side of the small diameter portion 5b, the fixed iron core 25 can be easily assembled. The fixed iron core 25 may be fixed to the cylindrical body 5 by welding, or may be fixed to the cylindrical body 5 by using welding and press fitting together.

  The mover (valve assembly) 27 includes a movable iron core 27a, a rod portion (connecting portion) 27b, and a valve body 27c. The movable iron core 27a is an annular member. The valve body 27c is a member that contacts the valve seat 15b (see FIG. 2). The valve seat 15b and the valve body 27c cooperate to open and close the fuel passage. The rod portion 27b has an elongated cylindrical shape, and is a connection portion that connects the movable iron core 27a and the valve body 27c. The movable iron core 27a is connected to the valve body 27c, and drives the valve body 27c in the direction of the open / close valve by a magnetic attraction acting between the fixed iron core 25 and the movable iron core 27a.

  In the present embodiment, the rod portion 27b and the movable iron core 27a are constituted by one member, but those constituted by different members may be assembled together. In the present embodiment, the rod portion 27b and the valve body 27c are formed of separate members, and the valve body 27c is fixed to the rod portion 27b. The rod part 27b and the valve body 27c are fixed by press-fitting or welding. The rod part 27b and the valve body 27c may be integrated by a single member.

  The rod portion 27b has a cylindrical shape, and has a hole 27ba that opens at the upper end of the rod portion 27b and extends in the axial direction. The rod portion 27b is formed with a communication hole (opening) 27bo that communicates the inside and the outside. A back pressure chamber 37 is formed between the outer peripheral surface of the rod portion 27 b and the inner peripheral surface of the cylindrical body 5. The fuel passage 3 in the through hole 25a of the fixed iron core 25 communicates with the back pressure chamber 37 through the hole 27ba and the communication hole 27bo. The hole 27ba and the communication hole 27bo constitute a fuel flow path 3 that communicates the fuel passage 3 and the back pressure chamber 37 in the through hole 25a.

  A coil spring 39 is provided in the through hole 25 a of the fixed iron core 25. One end of the coil spring 39 is in contact with a spring seat 27ag (see FIG. 3) provided inside the movable iron core 27a. The other end of the coil spring 39 is in contact with an adjuster (adjuster) 35 disposed inside the through hole 25 a of the fixed iron core 25. The coil spring 39 is disposed in a compressed state between the spring seat 27ag and the lower end (tip end surface) of the adjuster (adjuster) 35.

  The coil spring 39 functions as a biasing member that biases the mover 27 in a direction (valve closing direction) in which the valve element 27c abuts on the valve seat 15b (see FIG. 2). By adjusting the position of the adjuster 35 in the direction along the central axis 1a in the through hole 25a, the urging force of the movable element 27 (that is, the valve body 27c) by the coil spring 39 is adjusted.

  The adjuster 35 has a fuel flow path 3 that penetrates the central portion in a direction along the central axis 1a. The fuel supplied from the fuel supply port 2 flows through the fuel flow path 3 of the adjuster 35, then flows into the fuel flow path 3 at the tip side portion of the through hole 25 a of the fixed iron core 25, and is configured in the mover 27. It flows to the fuel flow path 3.

  The yoke 33 is made of a metallic material having magnetism, and also serves as a housing for the fuel injection valve 1. The yoke 33 is formed in a stepped cylindrical shape having a large diameter portion 33a and a small diameter portion 33b. The large diameter portion 33a has a cylindrical shape covering the outer periphery of the electromagnetic coil 29, and a small diameter portion 33b having a smaller diameter than the large diameter portion 33a is formed on the distal end side of the large diameter portion 33a. The small diameter portion 33 b is press-fitted or inserted into the outer periphery of the small diameter portion 5 b of the cylindrical body 5. Thereby, the inner peripheral surface of the small diameter portion 33 b is in close contact with the outer peripheral surface of the cylindrical body 5. At this time, at least a part of the inner peripheral surface of the small-diameter portion 33b is opposed to the outer peripheral surface of the movable iron core 27a via the cylindrical body 5, and the magnetic resistance of the magnetic path formed in this opposed portion is reduced. doing.

  An annular recess 33c is formed along the circumferential direction on the outer peripheral surface of the end portion on the front end side of the yoke 33. In the thin part formed in the bottom face of the annular recess 33 c, the yoke 33 and the cylindrical body 5 are joined over the entire circumference by laser welding 24.

  A cylindrical protector 49 having a flange portion 49 a is extrapolated to the distal end portion of the tubular body 5, and the distal end portion of the tubular body 5 is protected by the protector 49. The protector 49 covers the top of the laser welding portion 24 of the yoke 33.

  An annular groove 34 is formed by the flange portion 49a of the protector 49, the small diameter portion 33b of the yoke 33, and the step surface of the large diameter portion 33a and the small diameter portion 33b of the yoke 33, and an O-ring 46 is extrapolated to the annular groove 34. Has been. When the fuel injection valve 1 is attached to the internal combustion engine, the O-ring 46 is liquid-tight and air-tight between the inner peripheral surface of the insertion port formed on the internal combustion engine side and the outer peripheral surface of the small-diameter portion 33b of the yoke 33. Acts as a seal to ensure.

  A resin cover 47 is molded in a range from the middle portion of the fuel injection valve 1 to the vicinity of the proximal end portion. The end portion on the front end side of the resin cover 47 covers a part of the base end side of the large diameter portion 33 a of the yoke 33. Further, the connector 41 is integrally formed of a resin that forms the resin cover 47.

  Next, the configuration of the nozzle unit 8 will be described in detail with reference to FIG. FIG. 2 is an enlarged sectional view showing the vicinity of the nozzle portion 8 shown in FIG.

  The valve seat member 15 is formed with through holes 15d, 15c, 15v, 15e penetrating in the direction along the central axis 1a. A conical surface 15v whose diameter decreases toward the downstream side is formed in the middle of the through hole. A valve seat 15b is formed on the conical surface 15v, and the fuel passage is opened and closed by the valve body 27c coming into and out of contact with the valve seat 15b. The conical surface 15v on which the valve seat 15b is formed may be referred to as a valve seat surface. Further, the valve seat 15b and the portion that contacts the valve seat 15b of the valve body 27c are referred to as a seal portion.

  In the through holes 15d, 15c, 15v, and 15e, the hole portions 15d, 15c, and 15v on the upper side from the conical surface 15v constitute a valve body housing hole that houses the valve body 27c. A guide surface 15c for guiding the valve body 27c in the direction along the central axis 1a is formed on the inner peripheral surfaces of the valve body housing holes 15d, 15c, 15v.

  The downstream guide surface 15c and the slidable contact surface 27cb of the valve element 27c slidably in contact with the downstream guide surface 15c constitute a downstream guide portion 50A that guides the displacement of the mover 27.

  On the upstream side of the guide surface 15c, a diameter increasing portion 15d that increases in diameter toward the upstream side is formed. The enlarged diameter portion 15d facilitates the assembly of the valve body 27c and serves to enlarge the fuel passage cross section. On the other hand, the lower end portions of the valve body accommodation holes 15d, 15c, and 15v are connected to the fuel introduction hole 15e, and the lower end surface of the fuel introduction hole 15e opens to the distal end surface 15t of the valve seat member 15.

  A nozzle plate 21 n is attached to the distal end surface 15 t of the valve seat member 15. The nozzle plate 21 n is fixed to the valve seat member 15 by laser welding 23. The laser welding part 23 goes around the injection hole forming region so as to surround the injection hole forming region where the fuel injection hole 110 is formed.

  The nozzle plate 21n is formed of a plate-like member (flat plate) having a uniform plate thickness, and a protruding portion 21na is formed at the center portion so as to protrude outward. The protruding portion 21na is formed of a curved surface (for example, a spherical surface). A fuel chamber 21a is formed inside the protruding portion 21na. The fuel chamber 21a communicates with a fuel introduction hole 15e formed in the valve seat member 15, and fuel is supplied to the fuel chamber 21a through the fuel introduction hole 15e.

  A plurality of fuel injection holes 110 are formed in the protruding portion 21na. The form of the fuel injection hole is not particularly limited. A swirl chamber that imparts a swirling force to the fuel may be provided upstream of the fuel injection hole 110. The central axis 110a of the fuel injection hole may be parallel to or inclined with respect to the central axis 1a of the fuel injection valve. Moreover, the structure which does not have the protruding part 21na may be sufficient.

  In this embodiment, the valve portion 7 that opens and closes the fuel injection hole 110 is constituted by a valve seat member 15 and a valve body 27c, and the fuel injection portion 21 that determines the form of fuel spray is constituted by a nozzle plate 21n. And the valve part 7 and the fuel injection part 21 comprise the nozzle part 8 for performing fuel injection. That is, the nozzle portion 8 in the present embodiment is configured by joining the nozzle plate 21n to the tip surface 15t on the main body side (valve seat member 15) of the nozzle portion 8.

  In the present embodiment, the valve element 27c is a ball valve that is spherical. For this reason, a plurality of notch surfaces 27ca are provided at intervals in the circumferential direction at a portion facing the guide surface 15c in the valve element 27c, and a fuel passage is configured by the notch surfaces 27ca. The valve body 27c can be configured by a valve body other than the ball valve. For example, a needle valve may be used.

  With reference to FIG. 3, the structure of the vicinity of the movable iron core 27a of the mover 27 will be described in detail. FIG. 3 is an enlarged sectional view showing the vicinity of the movable iron core 27a shown in FIG. 3 shows a state in which the central axis (valve axis) 271 of the mover 27 and the central axis 1a of the fuel injection valve 1 coincide with each other. That is, the movable element 27 is in a state where neither the fall nor the bias has occurred.

  The case where the center axis 271 of the mover 27 is displaced so as to be inclined with respect to the center axis 1a of the fuel injection valve 1 will be referred to as the tilt of the mover 27 and will be described. The case where the center axis 271 of the mover 27 is displaced from the center axis 1a while maintaining a state parallel to the center axis 1a of the fuel injection valve 1 will be referred to as a bias of the mover 27.

  In this embodiment, the movable iron core 27a and the rod portion 27b are integrally formed as one member. A concave portion 27aa that is recessed toward the lower end side is formed at the center of the upper end surface 27ab of the movable iron core 27a. A spring seat 27ag is formed at the bottom of the recess 27aa, and one end of the coil spring 39 is supported by the spring seat 27ag. Furthermore, an opening 27af that communicates with the inside of the rod portion 27b is formed at the bottom of the recess 27aa. The opening 27af constitutes a fuel passage through which the fuel that has flowed into the space 27ai in the recess 27aa from the through hole 25a of the fixed iron core 25 flows into the space 27bi inside the rod portion 27b.

The upper end surface 27ab of the movable iron core 27a faces the lower end surface 25b of the fixed iron core 25. The upper end surface 27ab and the lower end surface 25b constitute a magnetic attraction surface on which a magnetic attraction force acts. The outer peripheral surface 27ac of the movable iron core 27a is configured to slide on the inner peripheral surface 5e of the cylindrical body 5.
That is, the inner peripheral surface 5e constitutes a guide surface that surrounds the movable iron core 27a and guides the movement of the mover 27 in the opening / closing valve direction. In particular, the inner peripheral surface 5e constitutes an upstream guide surface with which the outer peripheral surface 27ac of the movable iron core 27a comes into sliding contact. The upstream guide surface 5e and the outer peripheral surface 27ac of the movable iron core 27a constitute an upstream guide portion 50B that guides the displacement of the mover 27.

  In this embodiment, the mover 27 has two points: a guide surface (downstream guide surface) 15 c formed on the valve seat member 15, and an upstream guide surface 5 e formed on the inner peripheral surface of the cylindrical body 5. Guided movement in the direction of the on-off valve. That is, the mover 27 is guided at two points, the upstream guide portion 50B and the downstream guide portion 50A (see FIG. 1), and reciprocates in the direction of the central axis 1a. In this case, the valve element 27c of the mover 27 is guided by the downstream guide surface 15c, and the outer peripheral surface 27ac of the movable iron core 27a is guided by the upstream guide surface 5e. A small clearance (clearance) is provided between the valve element 27c and the downstream guide surface 15c for assembling and reciprocating the mover 27, and the outer peripheral surface 27ac and the upstream guide surface of the movable iron core 27a. A minute gap (clearance) is provided between 5e.

  With reference to FIG. 4 together with FIG. 3, the movable iron core 27a of the mover 27 will be described in detail.

  As shown in FIGS. 3 and 4, the outer peripheral surface 27ac of the movable iron core 27a has a shape curved in a direction along the central axis line 27l. For this reason, the external appearance of the movable iron core 27a has a barrel shape. That is, the diameter of the central part of the movable iron core 27a in the direction along the central axis 271 is larger than the diameter of the upper end part and the diameter of the lower end part.

  As shown in FIG. 3, the alternate long and short dash line 27ax intersects the outer peripheral surface 27ac at a position where the diameter of the movable iron core 27a is maximized. In a state where the central axis 271 of the mover 27 is not tilted with respect to the central axis 1a of the fuel injection valve 1, the movable iron core 27a is the portion of the outer peripheral surface 27ac where the alternate long and short dash line 27ax intersects, It slides on the inner peripheral surface 5e.

  The dash-dot line 33d passes through the center of the thickness dimension W33 of the stepped portion 33c that connects the large diameter portion 33a and the small diameter portion 33b of the yoke 33. FIG. 3 shows a state in which the one-dot chain line 33d and the one-dot chain line 27ax indicating the maximum diameter position of the movable iron core 27a coincide with each other.

  FIG. 3 shows a state in which the valve element 27c is in contact with the valve seat 15b and the fuel injection valve 1 is closed. For this reason, in the present embodiment, the maximum diameter position 27ax of the movable iron core 27a is located at the center of the thickness dimension W33 of the stepped portion 33c of the yoke 33 when the valve is closed. Thereby, when energization to the coil 29 is started, the magnetic resistance against the magnetic flux flowing between the yoke 33 and the movable iron core 27a can be reduced. And the valve opening operation | movement of the needle | mover 27 can be started quickly.

  A small diameter portion 33b of the yoke 33 extends below the step portion 33c of the yoke 33. For this reason, a magnetic resistance can be made small with respect to the magnetic flux which passes below the center (position of the dashed-dotted line 33d) of the thickness dimension W33 of the level | step-difference part 33c. Therefore, it is preferable that the maximum diameter position 27ax of the movable iron core 27a be positioned below the center of the thickness dimension W33 of the stepped portion 33c (the position of the alternate long and short dash line 33d).

  Various patterns are conceivable for the shape of the contact portion between the yoke 33 and the cylindrical body 5. Various restrictions are imposed on the configuration of the fixed iron core 25, the movable iron core 27, and the yoke 33. Therefore, it is not always necessary to configure the maximum diameter position 27ax of the movable iron core 27a as described above. However, in order to reduce the magnetic resistance and facilitate the flow of the magnetic flux, the maximum diameter portion 27ax of the movable iron core 27a is within a range where the yoke 33 and the cylindrical body 5 face each other in the direction of the central axes 1a and 27l. Is preferably located.

  FIG. 4 is an external view showing the external appearance of the movable iron core 27a shown in FIG.

  In FIG. 4, an alternate long and short dash line 27ao indicates a center position (center position) of the movable iron core 27a in a direction (height direction) along the center axis line 27l. The center position 27ao of the movable iron core 27a is a central position between the upper end surface (magnetic attraction surface) 27ab and the lower end surface 27ad of the movable iron core 27a. The upper end surface 27ab of the movable iron core 27a may be provided with a protrusion 27ap to prevent the upper end surface 27ab of the movable iron core 27a from sticking to the lower end surface 25b of the fixed iron core 25. The height at which the protrusion 27ap protrudes from the upper end surface 27ab of the movable iron core 27a is very small with respect to the height dimension H27ac of the outer peripheral surface 27ac of the movable iron core 27a. For this reason, the center position 27ao in the height direction of the movable iron core 27a is defined as the center position between the upper end surface 27ab and the lower end surface 27ad.

  The maximum diameter position 27ax of the movable iron core 27a is located closer to the upper end surface 27ab than the center position 27ao in the height direction of the movable iron core 27a. In the present embodiment, the maximum diameter position 27ax is shifted toward the upper end surface 27ab by the interval δ27 with respect to the center position 27ao. By shifting the maximum diameter position 27ax to the upper end surface 27ab side from the center position 27ao, the downstream guide portion 50A provided between the valve body 27c and the valve seat member 15, the movable iron core 27a, and the cylindrical body 5 The interval with the upstream guide portion 50B provided therebetween can be increased. By increasing the interval between the downstream guide portion 50A and the upstream guide portion 50B, the angle of the tilt generated in the mover 27 can be reduced. Since the tilt angle of the mover 27 can be reduced, a fuel injection valve with high seating properties can be realized.

  Further, the outer peripheral surface 27ac of the movable iron core 27a of the present embodiment is formed with a constant curvature from the upper end surface 27ab to the lower end surface 27ad. By forming the outer peripheral surface 27ac with a constant curvature, the contact state between the outer peripheral surface 27ac and the inner peripheral surface 5e of the cylindrical body 5 can be maintained in a constant relationship even when the mover 27 falls down. it can. Here, the contact state between the outer peripheral surface 27ac and the inner peripheral surface 5e is the range of the outer peripheral surface 27ac in contact with the inner peripheral surface 5e and the shape of the outer peripheral surface 27ac in contact with the inner peripheral surface 5e.

  Next, with reference to FIG. 5 and FIG. 6, the contact state between the outer peripheral surface 27ac of the movable iron core 27a and the inner peripheral surface 5e of the cylindrical body 5 when the mover 27 is tilted or biased will be described. To do. FIG. 5 is a schematic diagram for explaining a state in which the movable element 27 ′ is tilted and biased in a comparative example with the present invention. FIG. 6 is a schematic diagram for explaining a state in which the mover 27 is tilted and biased according to an embodiment of the present invention.

  In the mover 27 ′ shown in FIG. 5, a sliding surface 27 as 1 ′ formed linearly in the direction along the central axis 271 is formed on the outer peripheral surface of the movable iron core 27 a ′. That is, the sliding surface 27as1 'is formed in a cylindrical surface and protrudes from the outer peripheral surface of the movable iron core 27a'. Therefore, a corner portion 27as2 is formed at the upper end portion in the direction along the central axis line 27l of the sliding surface 27as1 '.

  FIG. 5A shows a state in which the movable element 27 ′ is not tilted or biased. FIG. 5B shows a state in which the movable element 27 'has fallen. When the mover 27 ′ falls, a corner 27 as 2 formed at the upper end of the sliding surface 27 as 1 ′ comes into contact with the inner peripheral surface 5 e of the cylindrical body 5. For this reason, a large sliding resistance is generated during the opening / closing valve operation of the mover 27 ′, and the valve opening operation time varies. The variation in the valve opening operation time is directly related to the variation in the fuel injection amount. In particular, during the valve opening operation, a large sliding resistance may occur due to the contact state between the corner portion 27as2 and the inner peripheral surface 5e.

  Even if the corner portion 27as2 is rounded for chamfering, its curvature is very large. Therefore, the sliding resistance generated between the corner portion 27as2 where the roundness is formed and the inner peripheral surface 5e has a large value.

  FIG. 5C shows a state in which the mover 27 'is biased. In this case, the entire part from the upper end to the lower end of the sliding surface 27as1 'of the movable iron core 27a' contacts the inner peripheral surface 5e of the cylindrical body 5 on the side where the movable element 27 'is biased. For this reason, the phenomenon that the sliding surface 27as1 'sticks to the inner peripheral surface 5e occurs, and the sliding resistance of the sliding surface 27as1' with respect to the inner peripheral surface 5e increases. This increase in sliding resistance causes a delay in the valve opening operation and may deteriorate the linearity between the injection pulse time (the valve opening command time) and the fuel injection amount in the region where a small amount of fuel is injected. There is. Further, if the sliding resistance varies depending on the biased state of the mover 27 ', the valve opening operation time varies.

  FIG. 6A shows a state in which the mover 27 is not tilted or biased. FIG. 6B shows a state in which the movable element 27 has fallen. FIG. 6C shows a state in which the mover 27 is biased. As shown in FIG. 6, in this embodiment, the outer peripheral surface 27ac of the movable iron core 27a is formed of a curved surface (sliding surface 27as1). In FIG. 6, a curved sliding surface 27as1 is provided in a strip shape on a part of the outer peripheral surface 27ac of the movable iron core 27a.

  The sliding surface 27as1 according to the present embodiment is the same as the sliding surface 27as1 when the movable element 27 is tilted or biased with respect to the sliding surface 27as1 ′ formed linearly in the direction along the central axis line 27l. The contact state with the inner peripheral surface 5e of the cylindrical body 5 is difficult to change. For example, as shown in FIG. 6B, even when the mover 27 falls down or as shown in FIG. 6C, the sliding surface 27as1 And the inner peripheral surface 5e are unlikely to change.

  That is, the present embodiment can reduce the shape change of the sliding surface 27as1 that contacts the inner peripheral surface 5e of the cylindrical body 5. For this reason, the change of the sliding resistance between the sliding surface 27as1 and the inner peripheral surface 5e can be suppressed. Then, variation in valve opening operation time can be reduced, and variation in fuel injection amount can be reduced.

  Further, in this embodiment, as shown in FIG. 6C, even when the mover 27 is biased, the entire portion from the upper end to the lower end of the sliding surface 27as1 of the movable iron core 27a is the cylindrical body 5. There is no contact with the inner peripheral surface 5e. That is, only a part of the curved surface curved from the upper end to the lower end of the sliding surface 27as1 is in contact with the inner peripheral surface 5e. For this reason, the phenomenon that the sliding surface 27as1 sticks to the inner peripheral surface 5e does not occur, and the sliding resistance of the sliding surface 27as1 with respect to the inner peripheral surface 5e does not increase. Therefore, the delay of the valve opening operation hardly occurs, and deterioration of linearity between the injection pulse time and the fuel injection amount can be suppressed in a region where a minute amount of fuel is injected.

  As described above, by forming the sliding surface 27as1 from the upper end to the lower end so as to have a constant curvature, the contact state between the sliding surface 27as1 and the inner peripheral surface 5e of the cylindrical body 5 is constant. Can be maintained in a relationship.

  Next, with reference to FIG. 7, the magnetic resistance when the outer peripheral surface 27ac or the sliding surface 27as1 of the movable iron core 27a is formed of a curved surface will be described. FIG. 7 is a schematic view schematically showing the outer periphery of the movable iron core 27a shown in FIG.

  In FIG. 7, the movable iron core 27a shown in FIG. 4 is indicated by a solid line. Further, the movable iron core 27a 'corresponding to the comparative example shown in FIG.

  In a portion where the sliding surface 27as1 ′ of the comparative example indicated by the broken line and the inner peripheral surface 5e of the cylindrical body 5 face each other, a gap G27a ′ formed between the sliding surface 27as1 ′ and the inner peripheral surface 5e is The gap G27a formed between the outer peripheral surface 27ac and the inner peripheral surface 5e of the movable iron core 27a of the present embodiment is narrower.

  However, in the portion of the outer peripheral surface 27ac ′ other than the sliding surface 27as1 ′, the gap G27a formed between the outer peripheral surface 27ac and the inner peripheral surface 5e of the present embodiment is different from the outer peripheral surface 27ac ′ of the comparative example. It is narrower than the gap formed between the inner peripheral surface 5e. In the entire range where the yokes 33b and 33c are provided, the present embodiment has a reduction effect of the gap formed between the outer peripheral surfaces 27ac and 27ac ′ and the inner peripheral surface 5e, compared to the comparative example. You can see that it ’s big.

  Therefore, in this embodiment, the outer peripheral surface 27ac of the movable iron core 27a is formed of a curved surface that is convex outward in the radial direction, thereby reducing the magnetic resistance of the magnetic path formed between the yoke 33 and the movable iron core 27a. can do.

  Next, a modified example in which the shape of the movable iron core 27a is changed will be described.

  FIG. 8 is an external view showing the external appearance of a modification of the movable iron core 27a shown in FIGS.

  In this modification, the curvature of the outer peripheral surface 27ac is made smaller than the shape of the movable iron core 27a shown in FIG. In FIG. 8, the outer peripheral surface 27ac of the movable iron core 27a in the case of FIG. 4 is indicated by a broken line.

  The curvature of the outer peripheral surface 27ac affects the magnitude of the magnetic resistance of the magnetic path formed between the yoke 33 and the outer surface 27ac. The curvature of the outer peripheral surface 27ac of this modification is smaller than the curvature (broken line) of the outer peripheral surface 27ac shown in FIG. Thereby, in this modification, the magnitude | size of the clearance gap formed between the inner peripheral surfaces 5e can be made small overall. And the magnetic resistance of the magnetic path comprised between the movable iron core 27a of this modification and the yoke 33 can be made smaller than the movable iron core 27a shown in FIG.

  Although the magnetic resistance of the magnetic path can be reduced by reducing the curvature of the outer peripheral surface 27ac, the movement resistance when the mover 27 moves in the direction of the on-off valve increases. Therefore, the curvature of the outer peripheral surface 27ac may be determined in consideration of the magnetic resistance and movement resistance of the magnetic path.

  In the movable iron core 27a shown in FIGS. 4 and 8, the outer peripheral surface 27ac from the upper end surface 27ab to the lower end surface 27ad is formed with a constant curvature. That is, it is formed in the entire region from the upper end portion to the lower end portion of the outer peripheral surface 27ac of the movable iron core 27a. For this reason, the outer peripheral surface 27ac gradually expands the gap G27a (see FIG. 7) with the inner peripheral surface 5e of the cylindrical body 5 from the maximum diameter position 27ax toward the upper end surface 27ab and the lower end surface 27ad. Therefore, in the movable iron core 27a shown in FIGS. 4 and 8, expansion of the gap G27a formed between the outer circumferential surface 27ac and the yoke 33 is suppressed in a wide range in the height direction of the outer circumferential surface 27ac of the movable iron core 27a. be able to. Thereby, the magnetic resistance of the magnetic path formed between the movable iron core 27a and the yoke 33 can be reduced.

  The configuration related to the maximum diameter position 27ax and the like can be configured similarly to the configuration described in FIG. Moreover, the same effect as demonstrated in FIG. 4 can be acquired with the structure.

  FIG. 9 is an external view showing the external appearance of another modified example of the movable iron core 27a shown in FIGS.

  The movable iron core 27a of the present modification includes an outer peripheral surface 27ac composed of a cylindrical surface having a central axis arranged in a direction along the central axis line 27l, and a belt-like sliding surface between the upper end portion and the lower end portion of the outer peripheral surface 27ac. 27as1.

  The belt-like sliding surface 27as1 is provided closer to the upper end surface 27ab than the center position 27ao in the height direction of the movable iron core 27a. The belt-like sliding surface 27as1 is configured by a curved surface that is curved in a direction along the central axis line 27l. In the present embodiment, the curved surface of the sliding surface 27as1 is formed with a constant curvature from the upper end to the lower end of the sliding surface 27as1.

  The sliding surface 27as1 is curved so as to protrude outward in the radial direction, and has a maximum diameter position 27ax having a maximum diameter between the upper end portion and the lower end portion. In the present embodiment, the maximum diameter position 27ax is located at the center between the upper end portion and the lower end portion of the sliding surface 27as1. Further, the maximum diameter position 27ax is at a position separated by δ27 from the center position 27ao in the height direction of the movable iron core 27a toward the upper end surface 27ab.

  In the present embodiment, since the maximum diameter position 27ax is located on the upper end surface 27ab side with respect to the center position 27ao of the movable iron core 27a, the tilt angle of the movable element 27 can be reduced. And since the angle of inclination of the needle | mover 27 can be made small, a fuel injection valve with high sheet | seat property is realizable.

  In the case of the movable iron core 27a of the present modified example, the sliding surface 27as1 formed of a curved surface is provided in a band shape on a part of the outer peripheral surface 27ac, and thus stepped portions are formed at the upper end portion and the lower end portion of the sliding surface 27as1. Will be. In this step portion, the gap between the outer peripheral surface 27ac of the movable iron core 27a and the inner peripheral surface 5e of the cylindrical body 5 is rapidly expanded. That is, the gap between the outer peripheral surface 27ac of the movable iron core 27a and the yoke 33 is rapidly expanded. For this reason, as described with reference to FIG. 7, there is a possibility that the magnetic resistance of the magnetic path formed between the movable iron core 27 a and the yoke 33 may increase. Therefore, it is preferable to arrange the sliding surface 27as1 at a position where the magnetic flux density is high (the position indicated by the one-dot chain line 33d in FIG. 3). Moreover, it is preferable to make the width dimension of the sliding surface 27as1 (the dimension in the height direction of the movable iron core 27a) as large as possible.

  The curved surface constituting the belt-like sliding surface 27as1 has the same effects as those of the above-described embodiments and modified examples. The configuration related to the maximum diameter position 27ax and the like can be configured similarly to the configuration described in FIG. Moreover, the same effect as demonstrated in FIG. 4 can be acquired with the structure.

  In the movable iron core 27a shown in FIGS. 4, 8, and 9, the outer peripheral surface 27ac composed of a curved surface (in the case of FIGS. 4 and 8) even when the movable element 27 falls down at the maximum possible angle. ) And the sliding surface 27as1 (in the case of FIG. 9) abut against the inner peripheral surface 5e of the cylindrical body 5.

  With reference to FIG. 10, an internal combustion engine equipped with the fuel injection valve 1 according to the present invention will be described. FIG. 10 is a cross-sectional view of the internal combustion engine on which the fuel injection valve 1 is mounted.

  A cylinder 102 is formed in the engine block 101 of the internal combustion engine 100, and an intake port 103 and an exhaust port 104 are provided at the top of the cylinder 102. The intake port 103 is provided with an intake valve 105 that opens and closes the intake port 103, and the exhaust port 104 is provided with an exhaust valve 106 that opens and closes the exhaust port 104. An intake pipe 108 is connected to an inlet side end 107 a of an intake passage 107 formed in the engine block 101 and communicating with the intake port 103.

  A fuel pipe 110 is connected to the fuel supply port 2 (see FIG. 1) of the fuel injection valve 1.

  An attachment portion 109 for the fuel injection valve 1 is formed in the intake pipe 108, and an insertion port 109 a for inserting the fuel injection valve 1 is formed in the attachment portion 109. The insertion port 109a penetrates to the inner wall surface (intake passage) of the intake pipe 108, and the fuel injected from the fuel injection valve 1 inserted into the insertion port 109a is injected into the intake passage. In the case of two-way spraying, each fuel spray is injected toward each intake port 103 (intake valve 105) for an internal combustion engine in which two intake ports 103 are provided in the engine block 101.

  Note that the present invention is not limited to the above-described embodiments, and some configurations can be deleted, and other configurations not described can be added. Further, the above-described embodiment and its modification examples can be applied to each other as long as the configurations described in the respective descriptions are not contradictory.

  DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve, 1a ... Center axis line, 5 ... Cylindrical body, 5e ... Inner peripheral surface (upstream guide surface) of cylindrical body 5, 25 ... Fixed iron core, 25b ... Lower end surface of fixed iron core 25, 27 ... Movable element 27a ... movable iron core, 27ab ... upper end surface of movable iron core 27a, 27ac ... outer peripheral surface of movable iron core 27a, 27ad ... lower end surface of movable iron core 27a, 27ao ... central position in the height direction of movable iron core 27a, 27as1 ... Sliding surface of movable iron core 27a, 27c ... valve body, 27l ... central axis of mover 27, 27ax ... maximum diameter position of movable iron core 27a, 33 ... yoke, 33a ... large diameter portion of yoke 33, 33b ... yoke 33 Small diameter portion, 33c: step portion of yoke 33, 50A: downstream guide portion, 50B: upstream guide portion.

Claims (5)

A valve seat and a valve body that cooperate to open and close the fuel passage;
A movable element in which the valve body is provided at one end and a movable iron core is provided at the other end;
The movable iron core has a curved surface that is convex toward the outer side in the radial direction and curved in the direction of the central axis of the mover;
The fuel injection valve configured to contact the guide surface that surrounds the outer peripheral surface of the movable iron core and guides the movement of the mover in the on-off valve direction. The fuel injection valve according to claim 1, wherein
The fuel injection valve according to claim 1, wherein the curved surface is formed with a constant curvature from an upper end portion to a lower end portion in a height direction of the movable iron core. The fuel injection valve according to claim 2,
The fuel injection valve according to claim 1, wherein a position having the maximum diameter of the curved surface is located closer to an upper end surface side of the movable iron core than a center in a height direction of the movable iron core. The fuel injection valve according to claim 3,
The fuel injection valve according to claim 1, wherein the curved surface is formed in an entire region from an upper end portion to a lower end portion of the outer peripheral surface of the movable iron core. The fuel injection valve according to claim 3,
The fuel injection valve according to claim 1, wherein the curved surface is formed in a band shape in a range of a part of an outer peripheral surface of the movable core in the height direction of the movable core.

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