JP6339389B2 - Fuel injection valve - Google Patents

Description

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

  As a background art in this technical field, a fuel injection valve described in Japanese Patent Application Laid-Open No. 2004-285923 (Patent Document 1) is known. The fuel injection valve described in Patent Document 1 has high wear resistance and responsiveness to both cores without subjecting the fixed core (fixed iron core) and the movable core (movable iron core) to wear processing such as troublesome plating layers. The purpose is to grant. For this purpose, the fixed core is made of a ferrite-based high-hardness magnetic material, while the movable core is made of a non-magnetic or non-magnetic material that directly contacts the fixed core and holds an air gap between the cores when the coil is excited. A stopper element that is weaker than the movable core is fixed by press-fitting (see summary). Specifically, a fitting recess is formed in the suction surface of the movable core that faces the suction surface of the fixed core, and a collar-shaped stopper element that surrounds the valve spring is press-fitted into the fitting recess (see paragraph 0033). ). This fitting recessed part is formed in the inner peripheral surface side of the movable core comprised by the recessed part in which a valve spring is inserted (refer FIG. 2).

  Further, in the fuel injection valve of Patent Document 1, the valve assembly includes a valve body including a hemispherical valve portion that opens and closes a valve hole in cooperation with a valve seat, and a valve rod portion that supports the valve portion; A movable core connected to the flange portion is provided, and a pair of journal portions that protrude radially in the outer periphery of the valve flange portion and slide on the inner peripheral surface of the guide hole are formed on the valve flange portion. Further, the movable core is inserted into these cylindrical bodies across the magnetic cylindrical body and the nonmagnetic cylindrical body (see paragraph 0023).

JP 2004-285923 A

  In the fuel injection valve of Patent Document 1, a pair of journal portions formed in a valve rod portion is configured to support a valve assembly including a valve body and a movable core at two points with respect to the inner peripheral surface of the guide hole. . For this reason, it is thought that the outer peripheral surface of a movable core is supported in the state which does not contact the magnetic cylinder body and nonmagnetic cylinder body in which a movable core is inserted.

  The valve assembly (mover) needs to be supported at two points apart in the axial direction (sliding direction), but one of them may be provided on the outer peripheral surface of the movable core. In such a configuration, when the stopper element is arranged on the inner peripheral surface side of the movable core as in the fuel injection valve of Patent Document 1, the stopper element slides on the support surface that supports the outer peripheral surface of the movable core. It does not function as a moving part. For this reason, the stopper element arrange | positioned at the inner peripheral surface side of a movable core cannot improve the abrasion resistance of a movable core outer peripheral surface.

  Further, in the configuration in which the outer peripheral surface of the movable core is slid on the support surface, a communication hole that connects the inner peripheral surface side and the outer peripheral surface side of the movable core is formed, and the fuel to be pumped is transferred to the movable core. In some cases, the lubricant is supplied from the inner peripheral surface side to the outer peripheral surface side and used as a lubricant. However, in such a configuration, the magnetic path formed in the movable core is narrowed and the amount of magnetic flux is limited, so that there is a problem that the magnetic characteristics are deteriorated.

  Further, since the valve assembly (movable element) slides with respect to the support surface, there is a gap between the support surface and the supported portion on the valve assembly (movable element) side supported by the support surface. Exists. For this reason, the axis of the valve assembly (movable element) is inclined with respect to the support surface, and the suction surface of the movable core, which faces the suction surface of the fixed core, abuts uniformly on the suction surface of the fixed core. I can't do it, and I sometimes get hit. In this case, the portion of the movable core that contacts the suction surface of the fixed core is the outer peripheral portion on the suction surface side. Also in this case, the stopper element disposed on the inner peripheral surface side of the movable core does not function as a contact portion with respect to the suction surface of the fixed core. For this reason, the stopper element arrange | positioned at the inner peripheral surface side of a movable core cannot improve the abrasion resistance of a movable core outer peripheral part.

  However, by increasing the protrusion amount of the movable core from the suction surface of the movable core, the stopper element disposed on the inner peripheral surface side of the movable core before the outer peripheral portion of the movable core contacts the suction surface of the fixed core. Can be brought into contact with the suction surface of the fixed core. However, in this case, there is a problem that the magnetic gap between the attraction surface of the movable core and the attraction surface of the fixed core is increased, and the magnetic characteristics are deteriorated.

  In the following description, the fixed core is referred to as a fixed iron core, and the movable core is referred to as a movable iron core.

  An object of the present invention is to improve the wear resistance of a movable iron core and provide a highly reliable fuel injection valve.

  In order to achieve the above object, the fuel injection valve of the present invention has a hardness higher than that of the movable core and weaker than that of the movable core at the outer peripheral portion of the suction surface of the movable core facing the suction surface of the fixed core. A magnetic annular part is provided.

  According to the present invention, even when the movable iron core is inclined, it is possible to prevent the magnetic part of the movable iron core from coming into direct contact with the fixed iron core and receiving a direct load from the fixed iron core, thereby improving the wear resistance of the movable iron core. be able to.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a longitudinal cross-sectional view which shows the longitudinal cross-section in alignment with a valve shaft center (center axis line) 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 IC arrow view which looked at the nozzle plate 21n shown in FIG. 2 from IC arrow direction. FIG. 2 is a cross-sectional view illustrating the drive unit 9 of the fuel injection valve 1 shown in FIG. It is a perspective view of the movable iron core 27a shown in FIG. FIG. 3 is a cross-sectional view showing a drive unit 9 in an enlarged manner according to a second embodiment of the drive unit 9 applicable to the fuel injection valve 1 shown in FIG. 1. FIG. 6 is a cross-sectional view showing a drive unit 9 in an enlarged manner according to a third embodiment of the drive unit 9 applicable to the fuel injection valve 1 shown in FIG. 1. It is an expanded sectional view showing the state where axis 1a 'of mover 27 inclines to central axis 1a about drive part 9 of the 1st example. It is a figure explaining the relationship between the area S and the magnetic flux amount which oppose the fixed iron core 25 of the movable iron core 27a.

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

  A fuel injection valve according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5, 8 and 9.

  First, the overall configuration of the fuel injection valve 1 will be described with reference to FIGS. 1 to 3. FIG. 1 is a longitudinal sectional view showing a longitudinal section along a valve axis (center axis) in an embodiment of a fuel injection valve according to the present invention. FIG. 2 is an enlarged sectional view showing the vicinity of the nozzle portion 8 shown in FIG. 3 is a III arrow view of the nozzle plate 21n shown in FIG. 2 as viewed from the III arrow direction. The center axis 1a coincides with the axis (valve axis) of a mover 27 provided integrally with a valve body 17 which will be described later, and coincides with the center axis of a cylindrical body 5 which will be described later.

  The fuel injection valve 1 is constituted by a cylindrical body 5 made of a metal material so that the fuel flow path 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. In FIG. 1, the large diameter portion 5 a formed on one end side is drawn to be above the small diameter portion 5 b formed on the other end side.

  In FIG. 1, the upper end portion (upper end side) is referred to as a base end portion (base end side), and the lower end portion (lower end side) is 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. Further, the vertical relationship described in this specification is based on FIG. 1 and is not related to the vertical direction when the fuel injection valve 1 is mounted on the internal combustion engine.

  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 fuel filter 13 includes a cylindrical metal core 13a, a resin material frame 13b, and a mesh-shaped filter body 13c. The resin material of the frame 13b is, for example, nylon, fluororesin or the like, and is molded integrally with the core metal 13a. The filter main body 13c is attached to the frame 13b, and is fixed to the base end portion of the cylindrical body 5 by press-fitting the cored bar 13a inside the large diameter portion 5a of the cylindrical body 5.

  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 17 and a valve seat member 15 is configured at the distal end portion of the cylindrical body 5. The valve seat member 15 is formed with a through hole 15a penetrating in a direction along the central axis 1a. A conical surface whose diameter decreases toward the downstream side is formed in the middle of the through hole 15a, and the through hole 15a is formed in a stepped shape by the conical surface. The valve seat 15b is formed on the conical surface, and the fuel passage is opened and closed by the valve body 17 coming into contact with the valve seat 15b. The entire conical surface on which the valve seat 15b is formed may be referred to as a valve seat surface.

  The inner peripheral surface on the upper side from the conical surface in the through-hole 15 a constitutes a valve body accommodation hole for housing the valve body 17. A guide surface 15c for guiding the valve body 17 in the direction along the central axis 1a is formed on the inner peripheral surface of the through hole 15a constituting the valve body accommodation hole. 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 17 and serves to enlarge the fuel passage cross section. On the other hand, the lower end portion of the valve body accommodating hole 15a opens to the tip surface 15t of the valve seat member 15, and this opening constitutes a fuel introduction hole 15e.

  The valve seat member 15 is inserted inside the front end side of the cylindrical body 5 and is fixed to the cylindrical body 5 by laser welding. 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.

  As shown in FIG. 2, a nozzle plate 21 n is attached to an end surface (hereinafter referred to as a front end surface) 15 t on the front end side of the valve seat member 15. The nozzle plate 21n is fixed to the valve seat member 15 by laser welding. The laser welded portion 23 surrounds the injection hole forming region where the fuel injection holes 110-1 to 110-10 (see FIG. 3) are formed, and makes a round around the injection hole forming region.

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. The radius r _21a of the fuel chamber 21a is larger than the radius r _15e of the fuel introduction hole 15e.

A plurality of fuel injection holes 110-1 to 110-10 are formed in the protruding portion 21na. Fuel injection holes 110-1～110-10, the inlet opening is formed in the radially outward than the radius r _15e, the outlet opening is formed further radially outward than the inlet opening. Therefore, as shown in FIG. 2, the central axes 110-3a and 110-8a of the fuel injection holes 110-3 and 110-8 are inclined with respect to the central axis 1a of the fuel injection valve 1. The central axes of the fuel injection holes 110-1, 110-2, 110-4 to 110-7, 110-9 and 110-10 are also inclined with respect to the central axis 1 a of the fuel injection valve 1. However, the inclination direction and the inclination angle of each central axis are different for each fuel injection hole in order to inject fuel in a direction to be described later.

  In the present embodiment, the fuel injected from the fuel injection holes 110-1 to 110-5 is injected in the direction indicated by the arrow A on the plane of FIG. 3, and the fuel injection holes 110-6 to 110- The inclination angle of the central axis of each of the fuel injection holes 110-1 to 110-10 is set so that the fuel injected from 10 is injected in the direction indicated by arrow B. Thereby, in a present Example, the two-way spray in which a fuel is divided and injected in two directions is formed. The form of the fuel spray is not limited to the two-way spray, and the spray may be formed in more than one direction, or may be formed in only one direction. Hereinafter, when it is not necessary to distinguish between the fuel injection holes 110-1 to 110-10, the fuel injection holes 110-1 to 110-10 are simply described as “fuel injection holes 110”.

  The nozzle plate 21n described above constitutes the fuel injection unit 21 that determines the form of fuel spray. In the present embodiment, the fuel injection holes 110-1 to 110-10 for injecting the rod-shaped fuel are provided in the fuel injection portion 21, but the swirling chambers for rotating the fuel are provided in the fuel injection holes 110-1 to 110-10. The swirling fuel may be injected in a cone shape from the fuel injection holes 110-1 to 110-10 provided on the upstream side.

  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 17, 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 body 17 uses a ball valve having a spherical shape. For this reason, a plurality of notch surfaces 17a are provided at intervals in the circumferential direction at a portion of the valve body 17 facing the guide surface 15c, and a fuel passage is configured by the notch surfaces 17a. It is also possible to constitute the valve body 17 other than the ball valve. For example, a needle valve may be used.

  A drive unit 9 for driving the valve body 17 is disposed in the middle part 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 movable element (movable member) 27 movable in the direction along the axis 1a, and the fixed iron core 25 and the movable iron core 27a formed on the movable element 27 face each other with a minute gap δ. 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 and a movable iron core 27a are accommodated inside the cylindrical body 5, and the cylindrical body 5 constitutes a housing that faces the outer peripheral surface of the movable iron core 27a and surrounds the movable iron core 27a.

  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 δ, in order to reduce the leakage magnetic flux flowing through the cylindrical body 5 at the portion of the minute gap δ, the nonmagnetic portion or the cylindrical body is located at a position corresponding to the minute gap δ of the cylindrical body 5. 5 is provided with a weak magnetic portion 5c that is weaker than other portions. 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. Further, a hardening process for increasing the hardness of the nonmagnetic portion 5c is also performed by heat treatment or cold working. Or you may connect the nonmagnetic cylindrical body 5c to the cylindrical body 5 which has magnetism. In this case, the non-magnetic cylindrical body 5 c is preferably a material having higher hardness than the cylindrical body 5. 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. A coil device 70 is constituted by the electromagnetic coil 29, the bobbin 31, the terminal 43, and the like. 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 movable element 27 has a large-diameter portion 27 a formed on the base end side, and the large-diameter portion 27 a constitutes a movable iron core 27 a that faces the fixed iron core 25. A small diameter portion 27b is formed on the distal end side with respect to the movable iron core 27a of the movable element 27, and the valve element 17 is fixed to the distal end of the small diameter portion 27b by welding. The small diameter portion 27b constitutes a connection portion 27b that connects the movable iron core 27a and the valve body 17. In this embodiment, the movable iron core 27a and the connecting portion 27b are integrally formed (one member made of the same material), but two members may be joined. In this embodiment, the valve element 17 is a separate component from the movable element 27, but the valve element 17 may be included in a part of the movable element 27.

  As described above, in this embodiment, the movable iron core 27 a is a member that is connected to the valve body 17 and drives the valve body 27 in the opening / closing valve direction by the magnetic attractive force acting between the fixed iron core 25.

  Moreover, when the outer peripheral surface of the movable iron core 27a contacts the inner peripheral surface of the cylindrical body 5, the mover 27 is guided to move in the direction along the central axis 1a (the on-off valve direction). In this case, the hardness of the nonmagnetic portion 5c described above may be increased by a demagnetization process. Or it is good to comprise the nonmagnetic part 5c using the nonmagnetic member (cylindrical body) whose hardness is higher than the other part of the cylindrical body 5. FIG. And it is good to comprise the guide surface (support surface) which guides the outer peripheral part of the movable iron core 27a with this nonmagnetic part 5c. Thereby, the abrasion resistance of the sliding surface by the side of the cylindrical body 5 which the outer peripheral part of the movable iron core 27a slides can be improved.

  The movable iron core 27a is formed with a recess 27c that opens in the end surface facing the fixed iron core 25 in the direction of the central axis 1a. An annular surface 27e serving as a spring seat of a spring (coil spring) 39 is formed on the bottom surface of the recess 27c. A through hole 27f is formed on the inner peripheral side of the annular surface 27e so as to penetrate the distal end side end of the small diameter portion (connecting portion) 27b along the central axis 1a. The small diameter portion 27b has an opening 27d on the side surface. A back pressure chamber 37 is formed between the outer peripheral surface of the small diameter portion 27 b and the inner peripheral surface of the cylindrical body 5. The through hole 27f opens at the bottom surface of the recess 27c, and the opening 27d opens at the outer peripheral surface of the small diameter portion 27b, so that the base end side of the mover 27 and the side surface portion of the mover 27 are formed inside the mover 27. The fuel flow path 3 is formed to communicate with the back pressure chamber 37 formed in the above.

  A coil spring 39 is disposed in a compressed state across the through hole 25a of the fixed iron core 25 and the recess 27c of the movable iron core 27a. The coil spring 39 functions as a biasing member that biases the movable element 27 in a direction (valve closing direction) in which the valve element 17 contacts the valve seat 15b.

  An adjuster (adjuster) 35 is disposed inside the through-hole 25 a of the fixed iron core 25, and the proximal end side end portion of the coil spring 39 is in contact with the distal end side end surface of the adjuster 35. By adjusting the position of the adjuster 35 in the through hole 25a in the direction along the central axis 1a, the urging force of the movable element 27 (that is, the valve body 17) 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. After flowing through the fuel flow path 3 of the adjuster 35, the fuel 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 then flows into the fuel flow path 3 configured in the mover 27.

  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 closed magnetic path at this facing portion is reduced.

  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. The yoke 33 has a distal end side end located on the distal end side with respect to the proximal end side end of the valve seat member 15. For this reason, the yoke 33 and the valve seat member 15 are provided in an overlapping range in the direction along the central axis 1a, and the tip of the cylindrical body 5 is reinforced. Note that the laser welding portion 19 of the valve seat member 15 is located further to the front end side than the end portion on the front end side of the yoke 33 so that the assembly order of the valve seat member 15 and the yoke 33 is not restricted. .

  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 and covered 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. The resin cover 47 covers a wiring member that connects the electromagnetic coil 29 and the terminal 43, and the connector 41 is integrally formed by the resin cover 47.

  Next, the operation of the fuel injection valve 1 will be described.

  When the electromagnetic coil 29 is in a non-energized state and no drive current flows through the electromagnetic coil 29, the mover 27 is urged in the valve closing direction by the coil spring 39, and the valve element 17 abuts (seats) the valve seat 15b. Is in a state. In this case, a gap δ exists between the distal end side end surface of the fixed iron core 25 and the proximal end side end surface of the movable iron core 27a. In this embodiment, the gap δ is equal to the stroke of the mover 27 (that is, the valve body 17).

  When the electromagnetic coil 29 is switched to the energized state and a drive current flows through the electromagnetic coil 29, a magnetic flux is generated in a closed magnetic path constituted by the movable iron core 27a, the fixed iron core 25, and the yoke 33. Due to this magnetic flux, a magnetic attractive force is generated between the fixed iron core 25 and the movable iron core 27a facing each other across the gap δ. When this magnetic attraction force overcomes the urging force of the coil spring 39 or the resultant force such as the fuel pressure acting on the mover 27 in the valve closing direction, the mover starts moving in the valve opening direction. When the movable element 27 moves in the valve opening direction by a distance δ equal to the gap δ and comes into contact with the fixed iron core 25, the movable iron core 27a is stopped from moving in the valve opening direction, and is opened to reach a stationary state.

  When the movable element 27 moves in the valve opening direction and the valve body 17 is separated from the valve seat 15b, a gap (fuel flow path) is formed between the valve body 17 and the valve seat 15b, and the fuel chamber is formed through the fuel introduction hole 15e. Fuel flows into 21a. The fuel supplied from the fuel introduction hole 15e to the fuel chamber 21a flows radially outward from the central portion of the fuel chamber 21a, flows into the fuel injection hole 110 from the inlet opening of the fuel injection hole 110, and exits from the outlet opening. The fuel is injected outside the fuel injection valve 1.

  When the energization of the electromagnetic coil 29 is stopped, the magnetic attractive force decreases and eventually disappears. At this stage, when the magnetic attractive force becomes smaller than the biasing force of the coil spring 39, the mover 27 starts to move in the valve closing direction. When the valve element 17 comes into contact with the valve seat 15b, the valve element 17 closes the valve portion 7 and comes to a stationary state.

  The time from when the movable element 27 moves in the valve opening direction and the valve body 17 starts to move away from the valve seat 15b to the time when the movable element 27 moves in the valve closing direction and the valve element 17 contacts the valve seat 15b again is opened. When the valve is closed (valve open state), the time when the valve element 17 is in contact with the valve seat 15b and is closed is called the valve closed time (valve closed state).

  In order to reduce the squeeze force acting between the movable iron core 27a and the fixed iron core 25, a protrusion may be provided on the end surface of the movable iron core 27a facing the fixed iron core 25. In such a case, the moving distance (stroke) of the valve body 17 is a size obtained by subtracting the protrusion height from the gap δ. Moreover, before the movable iron core 27a and the fixed iron core 25 contact, the stopper which restrict | limits the movement to the valve opening direction of the needle | mover 27 may be provided.

  Next, the configuration of the drive unit 9 will be described in detail with reference to FIGS. 4, 5, 8, and 9.

  4 is an enlarged cross-sectional view of the drive unit 9 of the fuel injection valve 1 shown in FIG. In FIG. 4, only the right side from the central axis 1 a is shown, but the left side is configured symmetrically with the central axis 1 a as the target axis.

  As described above, the cylindrical body 5 is provided with the nonmagnetic portion 5c. The nonmagnetic portion 5c is provided so as to surround the periphery of the portion where the suction surface 25b of the fixed iron core 25 and the suction surface 27h of the movable iron core 27a face each other with the gap g interposed therebetween. That is, the nonmagnetic portion 5c is provided so that the inner peripheral surface thereof faces the outer peripheral surface of the fixed iron core 25 on the suction surface 25b side and the outer peripheral surface of the movable iron core 27a on the suction surface 27h side.

  A bush 60 is provided on the outer peripheral surface of the movable iron core 27a on the suction surface 27h side. The bush 60 is an annular member made of a nonmagnetic material or a material that is weaker than the movable iron core 27a. When the bush 60 has weak magnetism, the bush 60 is made of a material that is weaker than the fixed iron core 25.

  The outer peripheral surface of the bush 60 is opposed to the inner peripheral surface of the nonmagnetic portion 5c. In order to provide the bush 60, the outer peripheral surface on the suction surface 27h side of the movable iron core 27a includes a step surface 27ad and a peripheral surface that circulates around the movable iron core 27a at a position that is recessed from the outer peripheral surface of the movable iron core 27a by the step surface 27ad. 27ac is formed. A bush 60 is fitted into a concave portion formed by the step surface 27ad and the peripheral surface 27ac. In this embodiment, the bush 60 is press-fitted and fixed to the movable iron core 27a.

The length dimension l ₆₀ in the direction along the central axis 1a of the bush 60 is shorter than the length dimension in the direction along the central axis 1a of the movable iron core 27a, and the entire range of the outer peripheral surface of the bush 60 is within the nonmagnetic portion 5c. The length is set to face the peripheral surface. In the present embodiment, the yoke 33 transitions from the large diameter portion 33a to the small diameter portion 33b at the lower end position of the bobbin 31, and the inner peripheral surface of the yoke 33 is in contact with the outer peripheral surface of the cylindrical body 5 having magnetism. . The outer peripheral surface of the movable iron core 27a is opposed to the inner peripheral surface of the yoke 33 through the cylindrical body 5 at a position where the inner peripheral surface of the yoke 33 contacts the outer peripheral surface of the cylindrical body 5 having magnetism. Thereby, a magnetic path is formed between the yoke 33 and the movable iron core 27a. For this reason, the lower end of the nonmagnetic part 5c is located above the lower end of the movable iron core 27a. Further, the lower end of the nonmagnetic portion 5 c is located further above the lower end of the bobbin 31.

The width of the suction surface 27h (thickness) dimension W ₂₇ in order to increase the cross-sectional area of the magnetic path, it is necessary to increase. Therefore, the width _{W 60} of the bush 60 is smaller than the width _{W 27} of the suction surface 27h of the movable iron core 27a. Be smaller the width _{W 60} of the bush 60, the width _{W 27} of the suction surface 27h of the movable iron core 27a is reduced. Therefore, the material of the movable iron core 27 a is selected so that the saturation magnetic flux density B ₂₇ is larger than the saturation magnetic flux density B ₂₅ of the fixed iron core 25.

FIG. 9 is a diagram for explaining the relationship between the area S of the movable iron core 17a facing the fixed iron core 25 and the amount of magnetic flux. When the saturation magnetic flux density of the movable iron core 27a is B ₂ (B ₂ > B ₁ ), the amount of magnetic flux necessary for the valve opening attractive force can be obtained with the facing area of S ₁ . B ₁ is the saturation magnetic flux density of the stator core 25. In contrast, the saturation magnetic flux density of the movable iron core 27a is in the case of B ₁ represents, the opposing area can not be obtained the magnetic flux amount necessary for opening the suction force is the value of S _1. The suction surface 27 h of the movable iron core 27 a is narrower than the suction surface 25 b of the stator core 25 by providing the bush 60. Therefore, by selecting the material of the movable core 27a, the saturation magnetic flux density of the movable iron core 27a is set to be larger than the saturation magnetic flux density B ₁ of the stator core 25.

  The bush 60 is made of a high hardness material whose hardness is higher than that of the movable iron core 27a. Further, the nonmagnetic portion 5 c and the fixed iron core 25 are also made of a high hardness material having the same degree of hardness as the bush 60. Therefore, you may comprise the bush 60, the nonmagnetic part 5c, and the fixed iron core 25 with the same material. Alternatively, since the fixed iron core 25 has restrictions on the magnetic characteristics, it is made of a material lower in level than the bush 60 and the nonmagnetic portion 5c, and a protective film is formed on the suction surface 25b with which the movable iron core 27a contacts. Also good.

  FIG. 5 is a perspective view of the movable iron core 27a. In this embodiment, the side surface of the bush 60 on the suction surface 27h side is formed at the same height as the suction surface 27h and is configured on the same plane as the suction surface 27h. Moreover, the outer peripheral surface of the bush 60 is formed on the same cylindrical surface as the outer peripheral surface 27aa, with the same radius (diameter) as the outer peripheral surface 27aa (see FIG. 5) of the movable iron core 27a. For this reason, when the valve is opened, the suction surface 27 h of the movable iron core 27 a comes into contact with the suction surface 25 b of the fixed iron core 25. Further, when the mover 27 is driven in the on-off valve direction (direction along the central axis 1 a), the outer peripheral surface 27 aa of the movable iron core 27 a is in sliding contact with the inner peripheral surface of the cylindrical body 5.

  However, since the side surface on the suction surface 27h side of the bush 60 abuts on the suction surface 25b of the fixed iron core 25, the load at the time of contact with the suction surface 25b can be borne by the bush 60, and wear of the suction surface 27h is reduced. It can be prevented or suppressed. Further, since the outer peripheral surface of the bush 60 slides on the inner peripheral surface of the nonmagnetic portion 5c, a load acting on the movable iron core 27a during sliding can be borne by the bush 60, and the outer peripheral surface 27aa of the movable iron core 27a. Can be prevented or suppressed.

  Further, the outer peripheral surface of the movable iron core 27a is composed of an upper (suction surface 27h side) outer peripheral surface 27aa and a lower (anti-suction surface 27h side) outer peripheral surface 27ab. The radius (diameter) of the outer peripheral surface 27aa is the same as the radius (diameter) of the bush 60, and the outer peripheral surface 27aa and the outer peripheral surface of the bush 60 constitute one cylindrical surface. The radius (diameter) of the outer peripheral surface 27ab is slightly smaller than the radius (diameter) of the outer peripheral surface 27aa. That is, the outer peripheral surface 27aa and the outer peripheral surface 27ab form a stepped outer peripheral surface. Thereby, the clearance gap between outer peripheral surface 27ab and the internal peripheral surface of the cylindrical part 5c can be enlarged with respect to the clearance gap between outer peripheral surface 27aa and the cylindrical peripheral part 5c, and a movable iron core The viscous resistance received from the fuel acting between the outer peripheral surface of 27a and the inner peripheral surface of the cylindrical portion 5c can be reduced.

In order to prevent wear of the outer peripheral surface 27aa of the movable iron core 27a, the radius (diameter) of the outer peripheral surface of the bush 60 is made slightly larger than the radius (diameter) of the outer peripheral surface 27aa so that the outer peripheral surface of the bush 60 is the outer peripheral surface. It may be slightly protruded radially outward from 27aa. If the radius (diameter) of the outer peripheral surface 27aa is made too small relative to the radius (diameter) of the outer peripheral surface of the bush 60,
Since the gap between the outer peripheral surface 27aa and the inner peripheral surface of the cylindrical body 5 is increased, the magnetic resistance in the magnetic path is increased, which is not preferable.

  FIG. 8 is an enlarged cross-sectional view showing a state in which the axis 1a 'of the mover 27 is inclined with respect to the central axis 1a. When the axis 1a ′ of the mover 27 is tilted with respect to the central axis 1a, the suction surface 27h of the movable iron core 27a cannot abut against the suction surface 25b of the fixed iron core 25 evenly on the entire circumference. To do. In this embodiment, since the bush 60 is provided on the outer peripheral portion of the movable iron core 27a, the bush 60 comes into contact with the suction surface 25b of the fixed iron core 25 as shown in FIG. For this reason, even when the mover 27 comes into contact with the suction surface 25b of the fixed iron core 25 with the axis 1a ′ of the mover 27 inclined with respect to the central axis 1a, wear of the suction surface 27h of the movable iron core 27a is prevented. can do.

  Furthermore, in this embodiment, since the bush 60 is provided on the outer peripheral portion on the suction surface 27h side of the movable iron core 27a, an effect of reducing the leakage magnetic flux toward the nonmagnetic portion 5c side can be expected. Even if the nonmagnetic part 5c is provided, the magnetic flux (leakage magnetic flux) passing through the nonmagnetic part 5c may not be eliminated. By providing the bush 60, the magnetic flux is brought close to the central portion of the attracting surface 27h of the movable iron core 27a, and the leakage magnetic flux passing through the nonmagnetic portion 5c can be reduced. In particular, when the nonmagnetic portion 5c is formed of the above-described thin portion, a great effect can be expected.

  In the present embodiment, since the radius (diameter) of the outer peripheral surface 27ab is smaller than the radius (diameter) of the outer peripheral surface 27aa, the outer peripheral surface 27ab is a cylindrical body even when the mover 27 is inclined as shown in FIG. 5 becomes difficult to contact. Thereby, when the needle | mover 27 inclines, the bush 60 can be made to contact the nonmagnetic part 5c reliably.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a second embodiment of the drive unit 9 applicable to the fuel injection valve 1 shown in FIG. 1, and is a cross-sectional view showing the drive unit 9 in an enlarged manner. As the basic configuration of the fuel injection valve 1, the configuration described in the first embodiment can be used as it is. The same reference numerals are used for the same components as in the first embodiment, and differences from the first embodiment will be described below.

In this embodiment, the bush (annular member) 60 side of the suction surface 27h of the movable iron core 27a of, and a suction surface 27h at the height of h ₂₇ so as to project upward. Thus, when the valve is opened, the side surface on the suction surface 27h side of the bush (annular member) 60 contacts the suction surface 25b of the fixed iron core 25, and a gap is maintained between the suction surface 27h and the suction surface 25b. For this reason, the adsorption | suction phenomenon of the suction surface 27h and the suction surface 25b by a fuel can be prevented or suppressed, and the delay of the valve closing operation | movement of the needle | mover 27 can be prevented or suppressed. Further, according to the present embodiment, demagnetization can be accelerated and the valve closing delay can be suppressed.

  Except for the configuration in which the side surface on the suction surface 27h side of the bush (annular member) 60 is configured to protrude upward from the suction surface 27h, the configuration is the same as that of the first embodiment. The same effect can be obtained.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a third embodiment of the drive unit 9 applicable to the fuel injection valve 1 shown in FIG. As the basic configuration of the fuel injection valve 1, the configuration described in the first embodiment can be used as it is. The same reference numerals are used for the same components as in the first embodiment, and differences from the first embodiment will be described below.

  In this embodiment, instead of providing the bush 60, the portion (magnetic part) of the movable iron core 27a in which the bush 60 is arranged in the first embodiment is demagnetized and the hardness is increased (hardness increasing). The performed high hardness nonmagnetic part 60 'is provided. The demagnetization process is a process for making the portion 60 'nonmagnetic or weaker than the movable iron core 27a. Such demagnetization treatment and high hardness treatment can be performed by heat treatment. Alternatively, when heat treatment for increasing the hardness is performed, the magnetic properties are lowered and the magnetic properties are reduced. Further, in this embodiment, in order to realize the same configuration as that of the second embodiment, a protrusion is formed on the outer peripheral portion of the suction surface 27h of the movable iron core 27a, and the non-magnetization is performed including this protrusion. You may perform a process and a hardening process.

  In this embodiment, the annular member constituting the bush 60 becomes unnecessary, and the number of parts can be reduced. Moreover, since the sliding part which slides with the nonmagnetic part 5c is comprised with the movable iron core 27a, the precision in the shape of the sliding part which slides with the nonmagnetic part 5c can be improved.

  In each embodiment according to the present invention, the bush 60 or the high hardness nonmagnetic portion 60 ′ is nonmagnetic or weaker than the movable iron core 27a on the outer peripheral portion of the movable iron core 27a facing the fixed iron core 25. And the annular parts 60 and 60 'comprised more highly than the movable iron core 27a are comprised.

  In each of the above embodiments, the bush 60 or the high-hardness non-magnetic portion 60 ′ slides with the non-magnetic portion 5c. Therefore, the movable iron core 27a does not need to be considered for wear resistance, and gives priority to the magnetic characteristics. Therefore, it is possible to select and use a material having excellent magnetic properties.

  Further, it is preferable that the hardness of the bush 60 or the high hardness nonmagnetic portion 60 ′, the hardness of the fixed iron core 25, and the hardness of the nonmagnetic portion 5 c (nonmagnetic or weak magnetic portion of the housing portion) be approximately the same. For this reason, the hardness of the bush 60 or the high-hardness nonmagnetic part 60 ′ is larger than the hardness of the movable iron core 27a, and the hardness of the fixed iron core 25 and the nonmagnetic part 5c (nonmagnetic or weakly magnetic part of the housing part). It is good to secure the above height.

  In each of the embodiments described above, as the material of the movable iron core 27a, for example, a ferrite-based or martensitic-based magnetic material or permalloy can be used, and as the material of the fixed core 25, for example, a ferrite-based or A martensitic high-hardness magnetic material or the like can be used, and as the material of the nonmagnetic part 5c and the bush 60, for example, austenitic stainless steel or the like can be used.

  The present invention is not limited to the above-described embodiments, and some components can be deleted or other components not described can be added.

  DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve, 5 ... Cylindrical body, 5c ... Non-magnetic part, 9 ... Drive part, 25 ... Fixed iron core, 25b ... Suction surface, 27a ... Movable iron core, 27h ... Suction surface, 27aa, outer peripheral surface 27ab ... Movable The outer peripheral surface of the iron core, 27ac ... the peripheral surface of the movable iron core, 27ad ... the stepped surface of the movable iron core, 60 ... the bush, 60 '... the high hardness nonmagnetic part.

Claims (4)

A valve seat and a valve body that open and close the fuel passage in cooperation with each other, and an electromagnetic drive unit that drives the valve body. The fixed core and the fixed iron core connected to the valve body are connected to the electromagnetic drive unit. A magnetic core that drives the valve element in the direction of the on-off valve by a magnetic attractive force acting between the magnetic core and a magnetic path that is energized to generate a magnetic flux between the fixed iron core and the movable iron core. An electromagnetic coil , a housing member that has magnetism and surrounds the movable iron core, and a non-magnetic part or a weak magnetic part provided in an outer peripheral side portion of the housing member facing the fixed iron core and the movable iron core, In a fuel injection valve equipped with
An annular portion that is nonmagnetic or weaker than the movable iron core and has a higher hardness than the movable iron core is provided on the outer peripheral portion of the movable iron core that faces the fixed iron core,
It said annular portion, prior together to face the inner peripheral surface of the KIHA Ujingu member, adapted to said fixed iron core and the contact when the valve is opened,
Further, the annular portion has a length dimension in the direction along the central axis of the fuel injection valve is shorter rather than the length of the movable core in a direction along the central axis, and the entire range of the outer peripheral surface of the annular portion A fuel injection valve characterized in that it is set to a length that opposes the inner peripheral surface of the non-magnetic part or the weak magnetic part . The fuel injection valve according to claim 1, wherein
The fuel injection valve according to claim 1, wherein a saturation magnetic flux density of the movable iron core is higher than a saturation magnetic flux density of the fixed iron core. The fuel injection valve according to claim 2,
A portion surrounding the movable iron core of the housing member is nonmagnetic or weaker than other portions of the housing member, and the annular portion is an inner peripheral surface of the nonmagnetic or weak magnetic portion of the housing member. A fuel injection valve configured to guide the outer peripheral surface of the fuel in the direction of the on-off valve. The fuel injection valve according to claim 3,
The fuel injection valve according to claim 1, wherein a hardness of the annular portion is equal to or higher than a hardness of the non-magnetic or weakly magnetic portion of the fixed iron core and the housing member.

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