JP2005307751A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve provided with a flat plate type movable core and a flat plate type electromagnetic driving part in which a coil is arranged between fixed cores and capable of preventing intrusion of fuel into the coil and preventing the fixed cores from being adversely affected. <P>SOLUTION: This fuel injection valve is constituted in such a way that it is provided with valve parts 12, 30 and the electromagnetic driving part having the movable core 50, the fixed cores 70, and the coil 60, the fixed core 70 has an inner peripheral side core part 71 and an outer peripheral side core part 72 extending in the axial direction across the wound coil 60, both of these core parts 71, 72 are arranged by opposing to the movable core 50 on end faces mutually, and the valve parts shut off and allow fuel injection by being driven by the electromagnetic driving part. This fuel injection valve has a cover 75 covering end faces of both of core parts 71, 72 and the coil 60. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection valve, and is suitably applied to an electromagnetic drive unit in a fuel injection valve that injects fuel into an internal combustion engine, for example.

  As a fuel injection valve, for example, an electromagnetic fuel injection valve that injects fuel directly or indirectly into a combustion chamber of a gasoline engine is known. This type of electromagnetic fuel injection valve includes an electromagnetic drive unit that drives a valve unit that cuts off and allows fuel injection, and the electromagnetic drive unit operates from a fixed core using electromagnetic force generated in a coil. The valve member integrated with the armature as the movable core is driven by the suction force.

For example, there are electromagnetic drive units called plunger type and flat plate type depending on the type of armature, and there is one that proposes a fuel injection valve using a flat type electromagnetic drive unit (see Patent Document 1). In the technique disclosed in Patent Document 1, a coil is sandwiched between an inner peripheral side core and an outer peripheral side core of a fixed core, and both inner peripheral side and outer peripheral side cores are arranged to face a flat plate type armature. Yes. And the technique which prevents the fuel penetration | invasion to a coil by providing the cover which covers the coil between both cores is disclosed. In this technique, both ends of the ring-shaped cover and the fixed core are joined and fixed by laser welding.
JP-A-8-49624

  However, in the conventional configuration, the coil can be isolated from the fuel by covering the cover, but it is difficult to isolate both cores, that is, the fixed core from the fuel.

  In addition, the applicant, as a material of the core, permendur capable of forming a relatively large magnetic force, or an iron-based soft magnetic material such as pure iron in order to improve the attractive force due to restrictions on the mounting space on the engine, etc. We are considering using. However, when such a thing is applied to a thing which covers the coil between both cores with a cover like patent documents 1, since the end face of both cores is not isolated from fuel, there is a possibility that the end faces of both cores may corrode. There is.

  The present invention has been made in view of such circumstances, and includes a flat plate movable core and a flat plate electromagnetic drive unit in which the coil is disposed between the fixed cores. Another object of the present invention is to provide a fuel injection valve having a seal structure that prevents the adverse effects on the fixed core.

  Another object is to provide a flat plate type movable core and a flat plate type electromagnetic drive unit in which the coil is disposed between the fixed cores, and does not adversely affect the fixed core for preventing fuel intrusion into the coil or the like. An object of the present invention is to provide a fuel injection valve that can have a sealing structure and can improve suction force.

  According to claim 1 of the present invention, the inner peripheral side includes a valve portion, a movable core, a fixed core, and an electromagnetic drive portion having a coil, and the fixed core extends in the axial direction across the wound coil. It has a core part and an outer peripheral side core part, these core parts and the movable core are arranged opposite to each other at their end faces, and the valve part blocks fuel injection by being driven by an electromagnetic drive part In addition, the permitted fuel injection valve has a cover that covers both end faces of the core portions and the coil.

  According to this, the fuel injection valve which has what is called a flat-plate type electromagnetic drive part with which the inner peripheral side core part and outer peripheral side core part of a stationary core which pinched | wound the wound coil, and a movable core mutually oppose each other in end surfaces In this embodiment, since the cover that covers the end faces of the inner peripheral side core part and the outer peripheral side core part and the coil is provided, the end face of the coil, the inner peripheral side core part, and the end face of the outer peripheral side core part can be isolated from the fuel. It is possible to prevent the fuel from adversely affecting the end face of the inner peripheral side core part and the end face of the outer peripheral side core part, that is, the fixed core, as compared with the conventional technique that locally covers the coil between both core parts. is there. Therefore, for example, it is possible to form a seal structure that prevents the fuel from entering a coil and a terminal as a terminal of the coil and does not adversely affect the fixed core.

  According to claim 2 of the present invention, the cover is a thin plate-like magnetic member.

  According to this, since the cover is formed as a thin plate-like member and the member is made of a magnetic material, the coil is generated even if the cover is arranged between the core portions facing each other at the end faces and the movable core. The attractive force due to the flow of magnetic flux acting on the movable core from the fixed core is not disturbed by using the electromagnetic force to be applied.

  According to claim 3 of the present invention, the cover is a thin plate-like nonmagnetic member.

  According to this, the cover is formed on a thin plate-like member, and the member is made of a nonmagnetic material. Even if the cover is a non-magnetic member, it is formed in a thin plate shape, so that the magnetic flux flowing in the direction penetrating the thin plate, that is, the direction in which the attractive force that is the flow direction of the magnetic flux acting from the fixed core to the movable core acts, It becomes easy to pass magnetic flux according to the thin thickness of the thin plate. Therefore, the attractive force due to the flow of magnetic flux acting on the movable core from the fixed core using the electromagnetic force generated by the coil is hardly hindered.

  According to a fourth aspect of the present invention, the fuel connector includes a fuel connector through which fuel flows to the valve portion, and the fixed core is disposed on the outer peripheral side of the fuel connector.

  According to this, since the fixed core is disposed on the outer peripheral side of the fuel connector that forms a fuel passage for supplying fuel to the valve portion, the fixed core itself can be reliably cut off from the fuel passage. . Therefore, a soft magnetic material having a relatively large magnetic force, such as an iron-based green compact or permendur which is easily corroded with respect to the fuel, can be used as the fixed core.

  According to claim 5 of the present invention, the cover is a connector portion extending in a substantially radial direction from the fuel connector.

  According to this, for example, a magnetic cover can be formed by the connector portion extending in the substantially radial direction from the fuel connector.

  For example, if the fuel connector, at least the connector part is formed in a thin plate shape, the fuel connector may be formed of a nonmagnetic member.

  According to the sixth aspect of the present invention, the portion of the cover that faces between the inner peripheral core portion and the outer peripheral core portion is a non-magnetic member or a magnetic diaphragm that is thinner than other portions. It is characterized by being.

  According to this, the portion of the cover that faces between the inner peripheral side core portion and the outer peripheral side core portion is a non-magnetic member or a magnetic diaphragm that forms the thickness of this portion thinner than other portions. Magnetic flux flowing in the direction of extending in the cover, so-called transit magnetic flux, can be reduced.

  According to claim 7 of the present invention, the total magnetic path area of the magnetic path end face in the inner peripheral side core part is formed larger than the total magnetic path area of the magnetic path end face in the outer peripheral side core part.

  According to this, among the fixed cores, the total magnetic path area of the magnetic path end face in the inner peripheral side core portion is formed larger than that in the outer peripheral side core portion, so the flow of magnetic flux is biased in one core portion. Without increasing the density of the magnetic flux flowing through the entire cores. Therefore, it is possible to maximize the attractive force due to the flow of magnetic flux acting on the movable core from the fixed core.

  According to claim 8 of the present invention, the ratio Si / So between the total magnetic path area Si of the magnetic path end face in the inner peripheral side core portion and the total magnetic path area So of the magnetic path end face in the outer peripheral side core portion is 1. It is 1 or more.

  As a result, it is possible to draw out the maximum suction force within the range of the predetermined outer dimensions in the mounting space of the limited fuel injection valve, that is, the electromagnetic drive unit.

  According to the ninth aspect of the present invention, at least one of the end surfaces of the inner peripheral side core portion, the outer peripheral side core portion, and the movable core facing each other has a protruding portion that can contact and separate from the other end surface. It is characterized by.

  According to this, it is preferable that at least one of the end surfaces facing each other has a protruding portion that can contact and separate from the other end surface. For example, even when the movable core is attracted to and collided with the fixed core, a gap corresponding to a step with respect to the protruding portion is generated between the end surfaces, so that the adhering by a liquid pressure such as a negative pressure generated when the end surfaces collide with each other. Can be avoided. As a result, it is possible to improve the responsiveness on the separation side in which the movable core is separated from the fixed core, that is, the valve closing responsiveness.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments in which the fuel injection valve of the present invention is applied to a fuel injection valve for injecting and supplying fuel to an internal combustion engine will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a sectional view showing a fuel injection valve of the present embodiment. FIG. 2 is a partially enlarged cross-sectional view of the electromagnetic drive unit in FIG. FIG. 3 shows the relationship between the ratio of the magnetic path area of the inner peripheral side core portion and the outer peripheral side core portion in the fixed core of the electromagnetic drive unit in FIG. 2 and the magnitude of the magnetic flux density in the magnetic path in the outer peripheral side core portion. It is a graph. FIG. 4 is a schematic diagram showing distribution of magnetic flux density in each magnetic path of the inner peripheral side core portion and the outer peripheral side core portion in FIG. 3, and FIG. 4 (a) shows the inner peripheral side and the outer peripheral side. FIG. 4B is a schematic diagram showing a case where the ratio Si / So of the magnetic path area on the side is 0.92 and FIG. 4B is 1.06.

  As shown in FIG. 1, a fuel injection valve (hereinafter referred to as an injector) is used in an internal combustion engine (engine), particularly a gasoline engine. The injector is attached to, for example, an intake pipe of a multi-cylinder (for example, 4-cylinder) engine, and fuel pressurized by a fuel pump (not shown) is supplied via a fuel distribution pipe (not shown). The injector is substantially cylindrical and receives fuel from one end and injects fuel from the other end. The injector is an electromagnetic fuel injection valve, and includes a valve portion that blocks and allows fuel injection, an electromagnetic drive portion that drives the valve portion, and an injection hole plate 20 that has an injection hole 21 that forms spray. Has been. The nozzle hole plate 20 is fuel spray forming means for atomizing the fuel to form a spray. You may make it equip the downstream of the seat part 14 of the valve body 12 of the valve part mentioned later with a fuel spray formation means. An inner hole is formed in the fuel inlet portion 48 of the injector and communicates with a fuel passage for supplying fuel to a valve portion in the injector. A filter 80 is attached to the inner hole to remove foreign matter. When the engine is a direct injection engine, an injector is provided in each cylinder and directly supplies fuel to a combustion chamber (not shown) of the cylinder. In this case, in order to set the pressure of the fuel supplied to the combustion chamber to about 2 MPa or more, a predetermined low pressure (for example, 0.2 MPa) fuel sucked up from the fuel tank by the fuel pump is further applied by a high pressure pump (not shown). The pressurized predetermined high pressure fuel (for example, a predetermined pressure fuel within a range of 2 to 13 MPa) is supplied to the injector through the fuel distribution pipe. The fuel discharged from the fuel pump and the fuel discharged after being further pressurized from the high-pressure pump are regulated to a predetermined pressure by a pressure regulator as a fuel pressure regulator (not shown).

  The engine described in this embodiment is a gasoline direct injection engine, and the injector is a gasoline direct injection injector that directly injects into the combustion chamber.

  As shown in FIG. 1, the electromagnetic drive unit includes a coil 60, a fixed core 70, a movable core (hereinafter referred to as an armature) 50, a fuel connector (hereinafter referred to as a fuel pipe) 40, and a spring 58. It is configured. As shown in FIG. 1, the fuel pipe 40 is formed in a substantially stepped cylindrical body, and has a fuel inlet portion 48, a large diameter cylindrical portion 46, and a small diameter cylindrical portion 42. A fuel passage through which fuel flows is formed. The fuel pipe 40 is made of a magnetic material having corrosion resistance against fuel (gasoline fuel in this embodiment), and is made of, for example, electromagnetic stainless steel. The small-diameter cylindrical portion 42 has a smaller outer diameter than the large-diameter cylindrical portion. A fixed core 70 is mounted on the outer peripheral side of the small diameter cylindrical portion 42. A coil 60 wound around a spool 62 is mounted in the fixed core 70. The large-diameter cylindrical portion 46 is disposed at the upper end portion 73 of the fixed core 70, and an accommodation hole for accommodating the terminal 63 provided in the spool 62 is formed.

  The coil 60 is directly wound around a resin spool 62, and the outer peripheral side of the spool 62 and the coil 60 is covered with a resin mold. After the outer periphery of a coil (hereinafter also referred to as a winding coil) 60 wound by a winding device is coated with a resin mold (not shown), the coated winding coil 60 is subjected to secondary resin molding and integrated with the spool 62. It may be molded into. The terminal 65 is joined to the terminal 63 on the coil 60 side and is electrically connected to the coil 60. When the coil 60 is energized, a magnetic attractive force acts between the fixed core 70 and the armature 50, and the armature 50 is attracted toward the fixed core 70 against the biasing force of the spring 58. The terminals 63 and 65 are insert-molded in the connector 64.

  The fixed core 70 is formed in a substantially cylindrical shape, and includes an inner peripheral side core portion 71, an outer peripheral core portion 72, and an upper end portion 73 connected to both the core portions 71 and 72 at both ends. The inner peripheral side core part 71 and the outer peripheral core part 72 are each formed in a substantially cylindrical body, and the coil 60 is sandwiched between these substantially cylindrical bodies. The fixed core 70 is formed of a soft magnetic material. For example, permendur (in this embodiment, the material composition is represented by main elements: Fe: 49 to 50%, Co: 49 to 50%, V: 2%. Below). The soft magnetic material may be pure iron (Fe) formed of, for example, a green compact. The fixed core 70 is installed on the side opposite to the injection hole with respect to the armature 50 and faces the armature 50. The inner peripheral side core portion 71 and the outer peripheral side core portion 72 and the armature 50 face each other at their end faces. Using the electromagnetic force generated in the coil 60 by supplying an electric current, each end surface of the inner peripheral side core portion 71 and the outer peripheral side core portion 72 (hereinafter referred to as an inner peripheral side magnetic path end surface and an outer peripheral side magnetic path end surface, respectively). ) To the flat plate portion 51 of the armature 50, and an attractive force corresponding to the magnetic flux density acts on the armature 50. Here, the inner peripheral side core portion 71 and the outer peripheral side core portion 72 constitute magnetic paths through which the magnetic flux flows in the direction of the fuel injection valve shaft 108, respectively. This is called a passage. The total magnetic path area of the armature side end face of the inner peripheral side core part 71, that is, the inner peripheral side magnetic path end face is represented by Si, and the total magnetic path area of the armature side end face of the outer peripheral side core part 72, that is, the outer peripheral side magnetic path end face, This is represented as So.

  Furthermore, in this embodiment, the total magnetic path surface Si of the inner peripheral side magnetic path end face in the fixed core 70 is formed larger than the total magnetic path area So of the outer peripheral side magnetic path end face. The ratio Si / So between the total magnetic path surface Si of the inner peripheral side magnetic path end face and the total magnetic path area So of the outer peripheral side magnetic path end face is preferably set to 1.1 or more. When the predetermined outer dimensions and the ratio Si / So are the same, depending on the magnitude of the magnetic force of the soft magnetic material itself forming the fixed core 50 (specifically, the magnitude Is of the magnetic flux density that can be increased by the material itself). The maximum magnetic attractive force is determined.

  The armature 50 has a flat plate portion 51 formed in a substantially flat plate shape, and the upper end surface of the flat plate portion 51 is disposed to face the end surfaces of the inner peripheral side magnetic passage 71 and the outer peripheral side magnetic passage 72. Yes. The armature 50 is made of a soft magnetic material, and is made of, for example, permendur. A cylindrical body portion 52 is provided on the valve member (hereinafter referred to as a nozzle needle) 30 side of the flat plate portion 51. The cylindrical body portion 52 is a portion indicated by a broken wedge in FIG. The upper end of 30 is fixed by welding such as laser welding (hereinafter referred to as laser welding). Here, the wedge of the broken line shows the joint part by welding. The armature 50 can cooperate with the nozzle needle and reciprocates in the axial direction. Further, the armature 50 forms a fuel passage inside. More specifically, a stepped inner hole is formed through the flat plate portion 51 and the cylindrical body portion 52 in the substantially axial direction, and an accommodation hole 53 for locking the spring 58 is formed in the inner hole. The fuel communication hole 54 penetrates the inner hole in the substantially radial direction. Furthermore, it is preferable that the flat plate portion 51 is provided with a through-hole penetrating in the moving direction of the armature 50, that is, in the axial direction. In the fuel disposed on both sides of the armature 50, the space volume for storing each fuel changes as the armature 50 moves, so that the fuel is transferred from one fuel side to the other fuel side with the armature 50 in between. When a flow occurs, this fuel flow is smoothed to prevent a damper effect due to the fuel. Furthermore, as shown in FIG. 1, the upper end surface of the flat plate portion 51 is not a uniform plane, but has protrusions that can come into contact with and separate from the end surfaces of the inner peripheral magnetic path 71 and the outer peripheral magnetic path 72. It is preferable. Even when the armature 50 is attracted to and collides with the fixed core 70, a gap corresponding to a step with respect to the protruding portion is formed between the end surfaces of the armature 50 and the fixed core 70. Therefore, negative pressure generated when the end surfaces collide with each other. Adherence due to fluid pressure such as is avoided.

  The adjusting pipe 56 is press-fitted into the inner periphery of the fuel pipe 40 and forms a fuel passage therein. The spring 58 is locked to the adjusting pipe 56 at one end and is locked to the armature 50 at the other end. By adjusting the press-fitting amount of the adjusting pipe 56, the load of the spring 58 biased to the armature 50 is changed. The armature 50 and the nozzle needle 30 are urged toward the valve seat 14 described later by the urging force of the spring 58.

  Here, a seal structure for preventing fuel intrusion into the fixed core 70 and the coil 60 will be described below with reference to FIGS. 1 and 2. The fixed core 70 and the coil 60 are disposed on the outer peripheral side of the fuel pipe 40 and are covered with a cup-shaped cover 75. The cover 75 is made of a magnetic material (for example, electromagnetic stainless steel) and is formed in a thin plate shape. Both end portions of the shaft of the cover are welded to the small-diameter cylindrical portion 42 and the large-diameter cylindrical portion 46 all around by laser welding. Specifically, the lower end portion of the small-diameter cylindrical portion 42 of the fuel pipe 40 extends from the inner peripheral side magnetic path end surface and the outer peripheral side magnetic path end surface of the fixed core 70 toward the nozzle needle 30 side. As shown in FIGS. 1 and 2, the outer periphery of the lower end portion of the small-diameter cylindrical portion 42 and the outer periphery of the large-diameter cylindrical portion 46 and the shaft end portion of the cover 75 are each laser-welded. As a result, the internal space defined by the cover 75 and the fuel pipe 40 is joined in an airtight manner, so that fuel can be prevented from entering the fixed core 70 and the coil 60 disposed in the internal space.

  Note that it is preferable that the lower end portion of the small-diameter cylindrical portion 42 is formed so that the extension amount extending from the inner peripheral side magnetic path end surface and the outer peripheral side magnetic path end surface of the fixed core 70 is small or not extended. When this lower end extends, in order to avoid interference between the small diameter cylindrical portion 42 joined to the flat plate portion 51 and the cover 75, a step portion 54 having an inner circumference larger than the accommodation hole 54 of the flat plate portion 51 is formed. Need to form.

  In this embodiment, as shown in FIGS. 1 and 2, the cover 75 includes an upper end portion of the valve housing 16 and a fixed core 50 (specifically, the outer peripheral side core portion 72) disposed opposite to the upper end portion. It is sandwiched and accommodated between the large-diameter cylindrical portion 46. As an assembly method, as shown in FIG. 1, the fixed core 70 and the coil 60 are accommodated, and the cover 75, the large-diameter cylindrical portion 46, and the small-diameter cylindrical portion 42 are entirely welded by laser welding. Thereafter, the valve housing 16 is inserted through the opening on the upper end side, and the valve housing 16, the cover 75, and the large-diameter cylindrical portion 46 are welded from the outer peripheral side of the valve housing 16 by laser welding.

  Furthermore, the opening on the upper end side of the valve housing and the shaft end of the cover are resin-molded together with the large-diameter cylindrical portion 46 through which the terminal 63 is inserted, and are integrally formed with the connector 64. Here, the cover 75 includes, in order from the downstream side of the fuel flow, the first fixing portion 75a joined and fixed to the lower end portion of the small diameter cylindrical portion 42, and the armature side of both core portions 71 and 72 of the fixed core 70. A flat plate portion 75b that supports the end surface, and a cylindrical portion 75c that extends in the axial direction along the outer periphery of the fixed core 70 (specifically, the outer peripheral side core portion 72 and the upper end portion 73) and the outer periphery of the large-diameter cylindrical portion 46. Has been.

  As shown in FIG. 1, the valve portion includes a valve body 12, a nozzle needle 30, and a housing 16. The valve body 12 is fixed to the inner wall of the end portion of the fuel injection side of a housing (hereinafter referred to as a valve housing) 16 by welding. The valve body 12 has a conical surface 13 as an inner peripheral surface that is reduced in diameter toward the nozzle hole plate 20 side in the fuel flow direction. The nozzle needle 30 can be separated from and seated on the conical surface 13. Here, the conical surface 13 constitutes a valve seat 14 on which the nozzle needle 30 can be separated and seated. Specifically, the contact portion 31 of the nozzle needle 30 is separated from and seated on the valve seat 14. The nozzle needle 30 is formed in a substantially shaft shape, and can reciprocate in the valve body 12 in the axial direction. For example, it is preferable that the guide member 15 is accommodated in the inner periphery of the valve body 12, and the nozzle needle 30 is supported by the inner periphery of the guide member 15 so as to be able to reciprocate. A fuel groove through which fuel flows is provided on the outer peripheral side of the guide member 15. Further, for example, the fuel groove may be formed on the inner peripheral side instead of the outer peripheral side of the guide member 15. In this case, a swirl is formed in the flow of the fuel flowing into the nozzle hole 21 by forming the fuel groove in a spiral shape. The guide member 15, the valve body 12, and the nozzle hole plate 20 are welded all around by laser welding at the bottom side of the valve body. Here, the valve seat 14 and the contact portion 31 constitute a seat portion that functions as an oil tight function for the valve portion to block fuel injection.

  The armature 50 and the nozzle needle 30 are accommodated in the inner periphery of the valve housing 16 so as to be able to reciprocate, and a fuel passage for guiding the fuel flowing in from the fuel pipe 40 to the valve seat 14 is formed. As shown in FIG. 1, a support member that movably supports the nozzle needle is preferably provided at an intermediate portion of the fuel passage on the armature 50 side. The guide member 15 or the supporting member prevents the nozzle needle 30 and the armature 50 from being misaligned or tilted. A plurality of fuel holes penetrates between the inner periphery and the outer periphery of the support member. The support member is inserted into the inner periphery of the valve housing 16 and is press-fitted and fixed.

  As shown in FIG. 1, the nozzle hole plate 20 is formed in a bottomed cylindrical shape, and is sandwiched between the inner wall at the bottom of the valve housing 16 and the inner wall at the bottom of the valve body 12. As shown in FIG. 1, a plurality of nozzle holes 21 are arranged in the nozzle hole plate 20. The size of the nozzle hole 21, the direction of the nozzle hole axis, the nozzle hole arrangement, and the like are determined in accordance with the required fuel spray shape, direction, number, and the like. The opening area of the nozzle hole defines the flow rate when the valve is opened. Therefore, the fuel injection amount of the injector is measured by the opening area of the injection hole and the valve opening period. When the nozzle needle 30 is seated on the valve seat 14, fuel injection from the nozzle hole 21 is cut off, and when the nozzle needle 30 is separated from the valve seat 14, fuel injection from the nozzle hole 21 is allowed and fuel is injected.

  The fuel inlet portion 48 is formed in a substantially cylindrical shape, and includes an O-ring 91 as a seal member and a backup ring 92. The fuel inlet 48 is assembled by being inserted into a distribution port (not shown) of the fuel distribution pipe. The O-ring 91 seals between the fuel inlet 48 and the distribution port. As shown in FIG. 1, a resin ring is attached to the front end side of the fuel inlet portion 48 to prevent the O-ring 91 movable along the outer periphery of the fuel inlet portion 48 from being detached. ing. The backup ring 92 has a backup function for ensuring the sealing performance of the O-ring 91 when the fuel inlet 48 is attached to the fuel distribution pipe and predetermined high-pressure fuel is supplied from the distribution port to the injector.

  Next, the operation of the fuel injection valve of the present embodiment having the above-described configuration will be described. When the vehicle engine key is set to the IG position and an ignition switch (not shown) is turned on, the fuel pump is driven and the fuel is sucked into the fuel tank by the fuel pump. The sucked fuel is regulated by a pressure regulator, and a predetermined low pressure fuel is supplied to the high pressure pump. The predetermined low pressure fuel is pressurized by the high pressure pump, and the pressurized fuel is supplied to the fuel distribution pipe. The fuel supplied to the fuel distribution pipe is regulated to a predetermined high-pressure fuel by a pressure regulator, and is supplied to each injector from each distribution port in the fuel distribution pipe. When the injector is opened, current is supplied to the coil 60 of the injector to control the lift of the nozzle needle 30. When the nozzle needle 30 starts to lift, the nozzle portion is opened and fuel is supplied to the engine. On the other hand, when the injector is closed, the current supply to the coil 60 is stopped, and the lift of the nozzle needle 30 is reduced by the biasing force of the spring 58. Then, when the nozzle needle 30 is seated, the injection is finished.

  While fuel is supplied from the fuel pump, fuel of a predetermined pressure is supplied to the valve portion through the fuel passage inside the injector, that is, the inner periphery of the fuel pipe 40. The fixed core 70 and the coil 60 are disposed on the outer peripheral side of the fuel pipe 40. Since the cover 75 is joined to the fuel pipe 40 (specifically, the small-diameter cylindrical upper part 42 and the large-diameter cylindrical part 46) by laser welding, the fixed core 70 and the coil 60 are formed by the cover 75 and the fuel pipe 40. In the space which divides, it is accommodated airtight with respect to the supply fuel. Therefore, fuel intrusion into the coil 60 or fuel intrusion from the coil 60 into the terminals 63 and 65 is prevented. It is not necessary to install an O-ring or the like as a seal member on the terminal 63 installed on the spool 62 and seal it. Therefore, for example, it may be about a resin mold for forming the connector 64, and the sealing structure of the terminals 63 and 65 is simplified. In the case of the O-ring seal structure of the prior art, when assembling the injector, it is not necessary to pay attention to ensuring reliability such as O-ring breakage or foreign object biting, reducing the product cost by eliminating the O-ring, and assembling. Management costs for ensuring reliability in the process can be reduced. Moreover, compared with the case where the coil 60 existing between the armature side end surfaces of the inner peripheral side core portion 71 and the outer peripheral side core portion 72 is locally covered, the armature side end surfaces of the inner peripheral side core portion 71 and the outer peripheral side core portion 72. Since the entire coil 60 is covered, at least the armature side end surfaces of the inner peripheral side core portion 71 and the outer peripheral side core portion 72 can be isolated from the fuel. Therefore, since the inner peripheral side core portion 71 and the outer peripheral side core portion 72, that is, the fixed core 70, are isolated from the fuel, adverse effects (for example, rusting) due to the fuel on the fixed core 70 can be prevented.

  Further, when the cover 75 is joined for sealing, portions other than the armature side end surfaces of the inner peripheral side core portion 71 and the outer peripheral side core portion 72 {for example, relatively far from the armature side end surfaces such as the upper end portion 73 of the fixed core. It can be joined to a remote part or a member different from the fixed core 70 (in this embodiment, the fuel pipe 40)} by laser welding or the like. In joining by welding such as laser welding in which a heat load at which the welding temperature exceeds the melting temperature is applied to the joint, deterioration of the magnetic characteristics of the fixed core 70 due to welding is prevented, and influence on the magnetic characteristics of the fixed core 50 can be prevented.

  Next, in the present embodiment, the total magnetic path surface Si of the inner peripheral side magnetic path end face in the fixed core 70 is formed larger than the total magnetic path area So of the outer peripheral side magnetic path end face. The magnetic flux density flowing through both the core portions 71 and 72 can be increased without being biased. Therefore, it is possible to maximize the attractive force due to the flow of magnetic flux acting on the armature 50 from the fixed core 70. In this embodiment, since the total magnetic path area of the inner peripheral core portion 71 is larger than that of the outer peripheral core portion 72, a magnetic flux flows in the inner peripheral core portion 71 as shown in FIGS. The magnetic flux density of the magnetic flux flowing in the outer peripheral side magnetic passage 71 and the inner peripheral side magnetic passage 72 can be increased without being biased.

  Details will be described below with reference to FIGS. 3 and 4. FIG. 4A shows an example in which the total magnetic path surface Si of the inner peripheral magnetic path end face is set smaller than the total magnetic path area So of the outer peripheral magnetic path end face (ratio Si / So = 0.92). FIG. 4B shows an example, and the total magnetic path surface Si of the inner peripheral magnetic path end face is set larger than the total magnetic path area So of the outer peripheral magnetic path end face (ratio Si / So = 1.06). An example of the case is shown. In FIGS. 4A and 4B, the flow of magnetic flux, that is, the magnitude of the magnetic flux contour component is increased as it is changed from blank to thin hatching and darker hatching. Here, for convenience of explanation, the magnitude level of the magnetic flux contour component is shown in four stages as shown on the right side of FIG. 4, and the first level, the second level, and the third level from the smaller magnetic flux contour component level. This is called the fourth level. As shown in FIG. 4A, in the case where Si / So = 0.92, the total magnetic path surface Si of the inner peripheral side magnetic path end face is smaller than the outer peripheral side magnetic path end face, the inner peripheral side magnetic path 71 is passed through. Compared with the magnetic flux flowing in the third level range, the magnetic flux flowing in the outer magnetic path 72 is lower than the second level range, and the magnetic force that can be generated in the outer magnetic path 72 is sufficiently extracted. No. On the other hand, as shown in FIG. 4B, when Si / So = 1.06, the total magnetic path surface Si of the inner peripheral side magnetic path end face is larger than the outer peripheral side magnetic path end face, the inner peripheral side The magnetic flux flowing in the magnetic path 71 and the magnetic flux flowing in the outer peripheral magnetic path 72 both reach the third level range, and the ratio Si / So is set so as to extract the maximum attractive force. FIG. 3 is a graph in which the inventor investigated the magnetic flux density in the outer magnetic path by changing the numerical value of the ratio Si / So. The horizontal axis represents the ratio Si / So, and the vertical axis represents the magnetic flux in the outer magnetic path. Indicates density. As shown in FIG. 3, when Si / So = 0.75 or Si / So = 0.92 where the ratio Si / So is less than 1, the smaller the Si / So, the smaller the magnetic flux density of the outer peripheral magnetic path. Become. In other words, when the total magnetic path area So of the outer peripheral magnetic path end surface is ensured larger than the total magnetic path surface Si of the inner peripheral magnetic path end surface, the density of the magnetic flux flowing in the inner peripheral magnetic path 71 is a predetermined level. The magnetic flux density in the outer peripheral magnetic path 72 cannot be increased as much as the magnetic flux density in the inner peripheral magnetic path 71. As a result, even if the total magnetic path area of the outer peripheral magnetic path 72 is increased within the range of the predetermined outer dimensions of the fixed core 70, the maximum magnetic attraction force cannot be obtained. On the other hand, in the case of Si / So = 1.06 in which the total magnetic path surface Si at the inner peripheral side magnetic path end face is secured to be larger than the total magnetic path area So at the outer peripheral side magnetic path end face, Since both the magnetic flux density and the magnetic flux density in the outer peripheral magnetic path 72 reach the third level range, a substantially maximum magnetic attractive force can be obtained. In the present embodiment, the ratio Si / So is preferably 1.1 or more. As a result, as shown in FIG. 3, the magnetic flux density in the outer peripheral magnetic path 72 can be made almost uniform in the third level range as well as the magnetic flux density in the inner peripheral magnetic path 71. . Therefore, in the range of Si / So ≧ 1.1, the magnetic flux density in the outer peripheral magnetic path 72 is increased within a predetermined range and homogenized regardless of the size of the ratios Si and So. Can be pulled out.

  Next, the operation and effect of this embodiment will be described. (1) The inner peripheral side core portion 71 and the outer peripheral side core portion 72 of the fixed core 70 sandwiching the wound coil 60 and the armature 50 are end surfaces. In a fuel injection valve having so-called flat-plate type electromagnetic drive parts that face each other, the cover 75 covering the end faces of the inner peripheral side core part 71 and the outer peripheral side core part 72 and the coil 60 is provided. It is possible to prevent adverse effects on the units 71 and 72.

  (2) Note that when the cover 75 is joined by welding or the like for sealing, a thermal load exceeding the melting point temperature is applied when joining by welding, so that the magnetic characteristics of the joined portion may deteriorate. is there. On the other hand, in the injector of this embodiment, each end surface of the inner peripheral side core part 71 and the outer peripheral side core part 72 is compared with the conventional one that locally covers the coil 60 between the two cores 71 and 72 parts. It is possible to join other parts by laser welding or the like. Therefore, it is possible to prevent the influence on the magnetic properties exerted on the end surfaces of the inner peripheral side core portion 71 and the outer peripheral side core portion 72 by a thermal load such as laser welding when the cover 75 is joined. As a result, it is possible to prevent the fuel 60 from entering the coil 60 and the terminal 63 serving as the terminal of the coil 60, and to form a seal structure that does not adversely affect the fixed core 70.

  (3) The cover 75 is formed as a thin plate-like member, and the member is made of a magnetic material. Therefore, even if the cover 75 is disposed between the core portions 71 and 72 and the armature 50 that face each other at the end faces. The magnetic force generated by the flow of magnetic flux acting on the armature 50 from the fixed core 70 is not disturbed by using the electromagnetic force generated by the coil 60.

  (4) Since the fixed core 70 is disposed on the outer peripheral side of the fuel pipe 40 that forms a fuel passage for supplying fuel to the valve portion, the fixed core 70 itself can be reliably cut off from the fuel passage. It is. Therefore, for example, a soft magnetic material having a relatively large magnetic force, such as an iron green compact or permendur which is easily corroded with respect to a fuel such as gasoline, can be used as the fixed core 70.

  (5) In the fixed core 70, the total magnetic path area Si of the magnetic path end face in the inner peripheral side core part 71 is formed larger than the total magnetic path area So of the magnetic path end face in the outer peripheral side core part 72. Therefore, the magnetic flux density flowing through the entire cores 71 and 72 is increased without the magnetic flux flowing in one core. Therefore, it is possible to maximize the magnetic attractive force due to the flow of magnetic flux acting on the armature 50 from the fixed core 70.

  (6) One core is formed by forming the total magnetic path area Si of the end surface of the magnetic path in the inner peripheral side core portion 71 larger than the total magnetic path area So of the end surface of the magnetic path in the outer peripheral side core portion 72. Since the magnetic flux density flowing through both the core portions 71 and 72 can be homogenized without the magnetic flux flowing in the portion, for example, the maximum magnetic attraction force can be obtained with the minimum necessary magnetic path area (Si + So). it can.

  (7) Furthermore, the ratio Si / So between the total magnetic path area Si of the magnetic path end face in the inner core portion and the total magnetic path area So of the magnetic path end face in the outer core portion is 1.1 or more. Preferably there is. As a result, when it is desired to improve the magnetic attraction force within the predetermined outer dimensions of the mounting space of the fuel injection valve, that is, the electromagnetic driving unit, where the mounting space on the engine is limited, the electromagnetic driving unit (specifically, the fixed core) 70) within the range of the predetermined outer dimensions, and by setting the ratio Si / So of the fixed core as the magnetic circuit to 1.1 or more, the magnetic circuit is optimized, thereby extracting the maximum magnetic attraction force. be able to.

  (8) In the present embodiment, the upper end surface of the flat plate portion 51 of the armature 50 is not a uniform plane, and can be brought into contact with or separated from the end surfaces of the inner peripheral magnetic path 71 and the outer peripheral magnetic path 72. It is preferable to have a protrusion. Even when the armature 50 is attracted to and collides with the fixed core 70, a gap corresponding to a step with respect to the protruding portion is formed between the end surfaces of the armature 50 and the fixed core 70. Therefore, negative pressure generated when the end surfaces collide with each other. Adherence due to fluid pressure such as is avoided. As a result, it is possible to improve the responsiveness on the side of separating the armature 50 from the fixed core 70, that is, the valve closing responsiveness.

(Second Embodiment)
Hereinafter, other embodiments to which the present invention is applied will be described. In the following embodiments, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

  In the second embodiment, as shown in FIG. 5, the fixed core 70 and the coil 6 described in the first embodiment are replaced with a cover 75 that is accommodated in an internal space partitioned by the fuel pipe 40. The cover 175 covers only the end surfaces of the inner peripheral side core portion 71 and the outer peripheral side core portion 72 of the fixed core 70 and the coil 60. FIG. 5 is a partially enlarged cross-sectional view of the electromagnetic drive unit according to the present embodiment.

  As shown in FIG. 5, the cover 175 is formed in a substantially disc shape, and the inner peripheral end portion and the outer peripheral end portion of the cover 175 are the lower end portion of the small-diameter cylindrical portion 42 and the inner peripheral surface of the valve housing 16, respectively. The entire circumference is joined by laser welding. Thereby, the fixed core 70 and the coil 60 can be cut off from the fuel passage flowing inside the fuel pipe 40. Note that the number of joint portions of the cover 175 is two, which is the same as the number of joint portions described in the first embodiment.

  Even if it is such a structure, the effect similar to 1st Embodiment can be acquired.

  Furthermore, the cover 75 described in the first embodiment is a cup-shaped thin plate-like member, and in order to form a cup shape, a special drawing such as press forming by deep drawing or deep drawing by cold forging is used. It is necessary to perform processing. On the other hand, in this embodiment, since it can be formed by simple processing to the extent that press forming by punching is performed, it can be manufactured at low cost.

(Third embodiment)
In the third embodiment, the cover 175 described in the first embodiment is formed as a separate member from the fuel pipe 40. However, as shown in FIG. FIG. 6 is a partially enlarged cross-sectional view of the electromagnetic drive unit according to the present embodiment.

  As shown in FIG. 6, the fuel pipe 140 has a small-diameter cylindrical portion 142 and a connector portion 141 extending from the lower end portion of the small-diameter cylindrical upper portion 142 in a substantially radial direction. The connector portion 141 is formed in a flat plate shape, and is joined to the upper end portion of the valve housing 116 by laser welding all around. The fixed core 70 and the coil 60 are arranged on the outer peripheral side of the fuel pipe 140, and the armature side end surfaces of both core portions 71 and 72 of the fixed core 70 are in contact with the upper end surface of the connector portion 141. As shown in FIG. 6, the height of the valve housing 116 in the axial direction is formed to be short enough to exceed the armature side end surface of the fixed core 70. The upper end side of the valve housing 116, the fuel pipe 140, and the outer periphery of the fixed core 70 are resin-molded together with the terminals 63 and 65 and are integrally formed with the connector 164.

  In addition, as a manufacturing method, as shown in FIG. 6, the fuel pipe 140 (specifically, the connector part 142) and the valve housing 116 are welded all around by laser welding. The winding coil 60 is inserted and assembled between the core portions 71 and 72 of the fixed core 70. The assembled fixed core 70 and coil 60 are inserted along the outer periphery of the small diameter cylindrical portion 142 until the armature side end surfaces of the core portions 71 and 72 abut against the upper end surface of the connector portion 141. Resin the terminals 63 and 65 together with the terminals 63 and 65 on the upper end side of the valve housing 116, the fuel pipe 140, and the outer periphery of the fixed core 70 with the armature side end surfaces of the core portions 71 and 72 in contact with the upper end surface of the connector portion 141. Molded and integrally formed with the connector 164.

  Next, operations and effects of the present embodiment will be described. (1) The magnetic cover described in the first embodiment can be formed by the connector portion 141 extending from the fuel pipe 140 in a substantially radial direction. it can. Even if it is such a structure, the effect similar to 1st Embodiment can be acquired.

  (2) Since the fuel pipe 140 is formed of a magnetic material (electromagnetic stainless steel in this embodiment), the fuel pipe 140 is not limited to a thin plate member, but is relatively thick like a structural member that forms a fuel passage inside. Even if it is a member, the attractive force by the flow of the magnetic flux which acts on a movable core from a fixed core is not prevented using the electromagnetic force which the coil 60 generate | occur | produces. The connector portion 141 is disposed between the core portions 71 and 72 and the armature 50 that face each other at their end faces.

  (3) In the present embodiment, the fixed core 70 and the coil 60 are inserted and attached to the small-diameter cylindrical portion 142 and are supported by the upper end surface of the connector portion 141. Therefore, in the first and second embodiments, Like the valve housing 16 described, the valve housing is extended to the upper end side of the fixed core 70 (specifically, the outer peripheral side core portion 72 and the upper end portion 73) and joined to the outer periphery of the large diameter cylindrical portion 46. It is not necessary to have a structure in which the fixed core 70 and the coil 60 are held on the outer periphery of the fuel pipe 40 and the inner periphery of the valve housing 16. Therefore, for example, the fixed core 70 and the coil 60 are simply accommodated in the injector to the extent that a resin mold for integral molding with the connector 164 is performed, so that the configuration for accommodating the fixed core 70 and the coil 60 in the injector is simplified. Can do.

  (4) Since the fixed core 70 and the coil 60 are inserted and mounted along the outer periphery of the small-diameter cylindrical portion 142 and are supported by the upper end surface of the connector portion 141, the fixed core 70 and the injector of the coil 60 are provided. (Specifically, the fuel pipe 140) can be assembled in the axial direction, and the assemblability can be improved.

(Fourth embodiment)
In the fourth embodiment, instead of the cover 75 made of the magnetic material described in the first embodiment, as shown in FIG. 7, the inner peripheral side core portion 71 and the outer peripheral side core portion 72 of the cover 275 A portion (hereinafter referred to as a bridging portion) 275d facing each other is made a nonmagnetic material. FIG. 7 is a partially enlarged cross-sectional view of the electromagnetic drive unit according to the present embodiment. In FIG. 7, a solid line arrow and a broken line arrow indicate the flow of magnetic flux acting on the electromagnetic force generated in the coil 60, and the magnetic flux acting on the electromagnetic force acts between the fixed core 70 and the armature 50. The flow of magnetic flux that is a magnetic attractive force is indicated by an arrow, and the flow of magnetic flux that is a transit magnetic flux that does not contribute to the magnetic attractive force is indicated by a dashed arrow.

  As shown in FIG. 7, the flat plate portion 275 b corresponds to the flat plate portion 75 b of the cover 75 described in the first embodiment, and the inner peripheral side core portion 71 and the outer periphery of the flat plate portion 275 b. A bridging portion 275d facing the side core portion 72 is formed of a nonmagnetic material.

  Even with such a configuration, the same effect as in the first embodiment can be obtained.

  Furthermore, since the bridging portion 275d facing between the inner peripheral side core portion 71 and the outer peripheral side core portion 72 is made nonmagnetic, the magnetic flux flowing in the direction of extending in the bridging portion 275d, so-called transit magnetic flux, can be reduced. .

(Fifth embodiment)
In the fifth embodiment, instead of the cover 75 made of the magnetic material described in the first embodiment, as shown in FIG. 8, among the cover 375, the inner peripheral side core portion 71 and the outer peripheral side core portion 72. The bridging portion 375d facing each other is formed thinner than the other portions. FIG. 8 is a partially enlarged cross-sectional view of the electromagnetic drive unit according to this embodiment.

  Even with such a configuration, the same effect as in the first embodiment can be obtained.

  Furthermore, since the bridging portion 375d facing between the inner peripheral side core portion 71 and the outer peripheral side core portion 72 is a magnetic aperture that is formed thinner than the other portions, the inside of the bridging portion 275d is stretched. Magnetic flux flowing in the direction, so-called transit magnetic flux, can be reduced.

(Sixth embodiment)
In the sixth embodiment, a cover 475 made of a non-magnetic material is used instead of the cover 175 made of a magnetic material described in the second embodiment, as shown in FIG. FIG. 9 is a partially enlarged cross-sectional view of the electromagnetic drive unit according to this embodiment.

  As shown in FIG. 9, the cover 475 is formed as a thin plate-like member, and the member is made of a nonmagnetic material. Even if the cover 475 is a non-magnetic member, it is formed in a thin plate shape, so that a magnetic attractive force that is a flow direction of a magnetic flux flowing in a direction penetrating the thin plate, that is, a magnetic flux acting on the armature 50 from the fixed core 70 acts. The magnetic flux can be easily passed through the gap according to the thickness of the thin plate. Therefore, the magnetic attraction force due to the flow of magnetic flux acting on the armature 50 from the fixed core 70 using the electromagnetic force generated by the coil 60 is hardly hindered. Therefore, even with such a configuration, the same effect as in the second embodiment can be obtained.

(Seventh embodiment)
In the seventh embodiment, in place of the connector part 141 of the fuel pipe 140 made of the magnetic material described in the third embodiment, as shown in FIG. The bridging portion 241d facing the outer core portion 72 is formed thinner than the other portions. FIG. 10 is a partially enlarged cross-sectional view of the electromagnetic drive unit according to this embodiment.

  Even with such a configuration, the same effect as in the third embodiment can be obtained.

  Further, since the bridge portion 241d facing between the inner peripheral side core portion 71 and the outer periphery side core portion 72 is formed to be thinner than the other portions, the bridge portion 241d flows in a direction extending in the bridge portion 241d. Magnetic flux, so-called transit magnetic flux, can be reduced.

(Other embodiments)
In the present embodiment described above, it has been described that permendur is used as the soft magnetic material forming the fixed core 70. However, for example, pure iron (Fe) may be formed of a green compact. In the present embodiment, the covers 75, 175, 275, 375, and 475 or the connector portions 141 and 241 that cover the armature side end surfaces of the inner core portion 71 and the outer core portion 72 of the fixed core 70 are lasers for sealing. Since welding is not performed on the fixed core 70, but on other portions (specifically, fuel pipes, valve housings) other than the fixed core 70, it is difficult to weld the soft magnetic material. Even if it is a powder, it can be applied to the fixed core 70 of the present embodiment.

  In the present embodiment described above, the fixed core 70 can be completely isolated from the fuel by the fuel pipe 40 and the covers 75, 175, 275, 375, 475, or the fuel pipes 140, 240 and the resin mold 164. It is possible to prevent corrosion of the fixed core material, which is not limited to green compacts or permendurs, and has relatively low corrosion resistance against fuel properties such as gasoline.

  In the fourth embodiment described above, the bridge portion 275d of the cover 275 made of a magnetic material has been described as a nonmagnetic member. However, as a manufacturing method, the magnetic member and the nonmagnetic member are welded or bonded. It may be formed by any manufacturing method such as a material integrated by joining with a magnetic material or a composite material in which a magnetic member is partially non-magnetic by heat treatment or the like. Note that the non-magnetic portion may be formed of a non-metal.

  In the fourth, fifth, and seventh embodiments described above, the bridging portions 275d, 375d, and 241d facing each other between the inner peripheral core portion 71 and the outer peripheral core portion 72 are nonmagnetic or magnetic diaphragms. The crossing magnetic flux flowing in the direction extending in the bridging portion 275d can be reduced, and the magnetic flux acting by the electromagnetic force generated in the coil 60 can be concentrated on the flow of the magnetic flux from the fixed core 70 to the armature 50. Therefore, since the magnetic flux generated by the electromagnetic force generated in the coil 60 is efficiently concentrated on the magnetic flux that acts on the magnetic attractive force, the magnetic attractive force can be improved.

  In the third embodiment described above, the magnetic cover is formed by the connector portion 141 extending from the fuel pipe 140 in the substantially radial direction. However, the fuel pipe 140 has at least the connector portion 141 as a thin plate. If it is formed in a shape, it may be formed of a nonmagnetic member.

  In the present embodiment described above, the fixed core 70 has been described as being formed by one single member, but a plurality of members may be used such as one that is divided and integrated into one by assembling.

  In the present embodiment described above, the fuel injection valve has been described as an injector for a direct injection engine. However, the fuel injection valve is not limited to the one that directly injects and supplies fuel to the combustion chamber, such as an injector for a direct injection engine, but is injected into an intake pipe or the like. In this way, it may be indirectly supplied to the combustion chamber. In recent years, there has been a growing demand for injectors to increase the flow rate per hour, that is, to increase the flow rate, for the purpose of improving fuel consumption and reducing exhaust gas. In order to meet this demand, there is a demand for an electromagnetic drive unit that has a larger driving force of an electromagnetic drive unit that drives the valve unit than a conventional fuel injection valve, in other words, an attractive force that attracts the armature. By applying this embodiment, the attraction force of the electromagnetic drive unit can be improved, which is advantageous for increasing the flow rate.

It is sectional drawing which shows the fuel injection valve of the 1st Embodiment of this invention. It is sectional drawing which expanded the electromagnetic drive part in FIG. 1 partially. FIG. 3 is a graph showing the relationship between the ratio of the magnetic path areas of the inner peripheral side core part and the outer peripheral side core part in the fixed core of the electromagnetic drive unit in FIG. 2 and the magnitude of the magnetic flux density in the magnetic path in the outer peripheral side core part. is there. FIG. 4 is a schematic diagram showing the distribution of magnetic flux density in each magnetic path of the inner peripheral side core portion and the outer peripheral side core portion in FIG. 3, and FIG. 4A shows the magnetic path area on the inner peripheral side and the outer peripheral side. FIG. 4B is a schematic diagram when the ratio Si / So is 0.92 and FIG. 4B is 1.06. It is sectional drawing which expanded the electromagnetic drive part concerning 2nd Embodiment partially. It is sectional drawing to which the electromagnetic drive part concerning 3rd Embodiment was expanded partially. It is sectional drawing which expanded the electromagnetic drive part concerning 4th Embodiment partially. It is sectional drawing which expanded the electromagnetic drive part concerning 5th Embodiment partially. It is sectional drawing which expanded the electromagnetic drive part concerning 6th Embodiment partially. It is sectional drawing which expanded the electromagnetic drive part concerning 7th Embodiment partially.

Explanation of symbols

12 Valve body 14 Valve seat 16 Valve housing (housing)
30 Nozzle needle (valve member)
31 Abutting part 40 Fuel pipe (fuel connector)
42 Small-diameter cylindrical portion 46 Large-diameter cylindrical portion 48 Fuel inlet 50 Armature (movable core)
51 Flat part 52 Cylindrical body part 58 Spring 60 Coil (winding coil)
62 Spool 63, 65 Terminal 64 Connector (resin mold)
70 Fixed core 71 Inner peripheral core (inner peripheral magnetic path)
72 Outer peripheral core (outer peripheral magnetic path)
73 Upper end 75 Cover

Claims (9)

An inner peripheral side core portion and an outer peripheral side core portion that include a valve portion, a movable core, a fixed core, and an electromagnetic drive portion having a coil, and in which the fixed core extends in the axial direction across the wound coil The two core portions and the movable core are arranged so as to face each other at their end faces, and the valve portion is driven by the electromagnetic drive portion so that the valve portion cuts off and allows fuel injection. In the injection valve,
A fuel injection valve comprising a cover that covers the end faces of both the core portions and the coil. The fuel injection valve according to claim 1, wherein the cover is a thin plate-like magnetic member. The fuel injection valve according to claim 1, wherein the cover is a thin plate-like nonmagnetic member. It has a fuel connector through which fuel flows to the valve part inside,
The fuel injection valve according to any one of claims 1 to 3, wherein the fixed core is disposed on an outer peripheral side of the fuel connector. The fuel injection valve according to claim 4, wherein the cover is a connector portion extending in a substantially radial direction from the fuel connector. A portion of the cover that faces between the inner peripheral core portion and the outer peripheral core portion is a non-magnetic member or a magnetic diaphragm that is thinner than other portions. The fuel injection valve according to any one of claims 1 to 5. The total magnetic path area of the magnetic path end face in the inner peripheral side core part is formed larger than the total magnetic path area of the magnetic path end face in the outer peripheral side core part. The fuel injection valve according to any one of the above. The ratio Si / So between the total magnetic path area Si of the magnetic path end face in the inner peripheral side core portion and the total magnetic path area So of the magnetic path end face in the outer peripheral side core portion is 1.1 or more. The fuel injection valve according to claim 7. At least one of the end faces of the inner peripheral side core part, the outer peripheral side core part, and the movable core that face each other has a protruding part that can contact and separate from the other end face. The fuel injection valve according to any one of claims 1 to 8.

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