JP5482272B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve that injects fuel from an injection hole provided in a valve housing to an internal combustion engine.

  In recent years, for a valve member that opens and closes an injection hole by reciprocating movement and intermittently injects fuel, a protrusion is protruded from a shaft portion that is slidably inserted into an axial hole of the movable core, and the protrusion is made movable core For example, Patent Document 1 proposes a fuel injection valve that can be contacted from the fixed core side.

  In this type of fuel injection valve, when the movable core moves to the fixed core side due to the action of magnetic attraction, the axial end surface of the movable core on the fixed core side comes into contact with the protrusion of the valve member, so that the valve member Moves with the movable core. As a result, the movable core that collided with the fixed core bounces to the opposite side of the fixed core due to the action of the collision reaction force, but the valve member that receives the inertial force is against the axial hole of the movable core. The movement toward the fixed core can be continued while sliding the shaft portion. As a result, the protruding portion of the valve member is separated from the axial end surface of the movable core and hardly receives a collision reaction force, so that bounce of the valve member that causes variation in the fuel injection amount is suppressed.

  Patent Document 1 discloses that a hard plating is applied to the axial end surface of the movable core on the fixed core side as a desirable form of the fuel injection valve as described above. In the movable core, the end surface in the axial direction on the fixed core side repeats the collision not only with the fixed core but also with the protrusion of the valve member. By plating in this way, the wear resistance of the end surface is improved. Thus, durability can be ensured.

JP 2007-218204 A

  Here, in the fuel injection valve disclosed in Patent Document 1, with respect to the plating layer 3 forming the axial end surface 2 of the movable core 1 as shown in FIG. 9, the inner periphery of the axial hole 4 penetrating the movable core 1 in the axial direction. There is a concern that it may protrude further to the inner peripheral side than the surface 5. In particular, in the case of the electrolytic plating layer 3 formed by electrolytically depositing metal, the plating layer 3 is caused by the fact that current tends to concentrate on the edge portion 6 between the axial end face 2 and the axial hole 4. The possibility of protruding from the edge portion 6 toward the inner peripheral side increases.

  When the plating layer 3 protrudes in this manner, the fuel injection valve disclosed in Patent Document 1 inserts and assembles the shaft portion 8 of the valve member 7 into the straight cylindrical hole-shaped axial hole 4. The protruding portion 3a may interfere with the shaft portion 8 and cause an assembly failure. Moreover, even if it can be inserted and assembled, for the plating layer 3 in the protruding state, the slidability of the shaft portion 8 with respect to the axial hole 4 is hindered, and the behavior of the valve member 7 becomes unstable, There is also a possibility that the protruding portion 3a, which is concentrated by the sliding of the shaft portion 8, is worn violently and the durability is lowered.

  As shown in FIG. 10 (a), a method of grinding the protruding portion 3a of the plating layer 3 by polishing the inner peripheral surface 5 of the axial hole 4 with a reamer 9a is conceivable. At the edge portion 6 close to the axial hole 4 in the direction end face 2, even the plating layer 3 covering the edge portion 6 is easily peeled off. On the other hand, as shown in FIG. 10B, a method of masking the axial hole 4 with a straight cylindrical jig 9b at the time of forming the plating layer 3 is also conceivable. In the edge portion 6 that is in the immediate vicinity of the jig 9b, formation failure of the plating layer 3 is likely to occur. Such peeling or poor formation of the plating layer 3 is not desirable because it leads to a decrease in durability.

  Accordingly, an object of the present invention is to provide a fuel injection valve that solves the problems described above.

According to a first aspect of the present invention, a valve housing having an injection hole for injecting fuel to an internal combustion engine, a fixed core fixed to the valve housing, an axial hole penetrating in the axial direction, and a plating layer are formed. A movable core that moves toward the fixed core by the action of magnetic attraction, a shaft that is slidably inserted into the axial hole, and an axial end surface of the movable core that protrudes from the shaft And a valve member that opens and closes the injection hole by reciprocating movement to interrupt fuel injection, and the plating layer has a metal electrodeposited on the end face in the axial direction. In the fuel injection valve, which is an electroplated layer, the movable core further has an annular recess that is recessed from the inner peripheral surface of the axial hole to the outer peripheral side and opens to the axial end surface on the fixed core side. The plating layer should not protrude to the inner periphery of the axial hole. It is characterized in that it is housed in the annular recess.

Thus, in the movable core, the annular recess that is recessed from the inner peripheral surface of the axial hole penetrating in the axial direction to the outer peripheral side over the entire circumference opens to the axial end surface on the fixed core side, and thus forms the end surface. Even if the plating layer protrudes into the annular recess, it does not easily protrude from the inner peripheral surface of the axial hole. Therefore, when the shaft portion of the valve member is inserted and assembled into the axial hole in which the plating layer does not protrude from the inner peripheral surface, the plating layer interferes with the shaft portion and causes poor assembly. Can be avoided. In addition, even after the shaft portion is inserted and assembled, the protruding portion of the plating layer obstructs the slidability of the shaft portion with respect to the axial hole and makes the behavior of the valve member unstable. A situation in which the portion is worn violently by sliding contact with the shaft portion and the durability is lowered can be avoided.
Moreover, according to the electroplating layer formed by electrolytically depositing metal on the axial end surface of the movable core on the fixed core side, a hard plating layer having excellent wear resistance can be realized. Durability can be ensured over a long period of time, even if it repeatedly collides with the protrusion of the member or the fixed core. In addition, in the case of the electrolytic plating layer, the current concentrates on the edge portion between the annular end portion of the movable core in the axial direction, so that the plating layer protrudes from the edge portion to the inner peripheral side. Even if formed, the protruding portion can be securely stored in the annular recess. Therefore, problems caused by the electrolytic plating layer protruding from the inner peripheral surface of the axial hole can be solved at once.

According to the second aspect of the invention, the plating layer formed on the inner surface of the annular recess is limited to the edge portion between the inner surface and the axial end surface .

  According to the invention described in claim 3, the movable core is formed by polishing the inner peripheral surface of the axial hole. Thus, even if the inner peripheral surface of the axial hole in the movable core is polished, the plating layer that protrudes into the annular recess recessed from the inner peripheral surface is removed from the axial hole in the axial end surface of the movable core. It becomes difficult to peel off at the edge part between the separated annular recesses. Therefore, the durability ensuring effect by the plating layer can be obtained regardless of the polishing of the axial hole.

  According to the invention described in claim 4, the movable core has the inner peripheral surface of the axial hole exposed from the plating layer. According to this, the plating layer that exposes the inner peripheral surface of the axial hole in the movable core can be formed, for example, in a state where the axial hole is masked by a straight cylindrical jig. Here, even if such masking is performed, the edge part between the annular concave part of the axial end surface of the movable core is separated from the cylindrical jig, so that the formation failure of the plating layer at the edge part is avoided and the durability is maintained. Can be secured.

It is sectional drawing which shows the fuel injection valve by 1st embodiment of this invention. It is sectional drawing which expands and shows the principal part of FIG. It is a schematic diagram for demonstrating regarding manufacture of the movable core of FIG. It is sectional drawing which shows the fuel injection valve by 2nd embodiment of this invention. It is a schematic diagram for demonstrating regarding manufacture of the movable core of FIG. It is sectional drawing which shows the fuel injection valve by 3rd embodiment of this invention. It is a schematic diagram for demonstrating manufacture of the movable core of FIG. It is sectional drawing which shows the fuel injection valve by 4th embodiment of this invention. It is a schematic diagram for demonstrating the conventional problem. It is a schematic diagram for demonstrating the conventional problem.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment.

(First embodiment)
FIG. 1 shows a fuel injection valve 10 according to a first embodiment of the present invention. The fuel injection valve 10 is installed in a gasoline engine as an internal combustion engine, and injects fuel into a combustion chamber (not shown) of the engine. In addition to this application form, for example, the fuel injection valve 10 may inject fuel into an intake passage communicating with a combustion chamber of a gasoline engine, or fuel into a combustion chamber of a diesel engine as an internal combustion engine. May be used.

(Constitution)
First, the structure of the fuel injection valve 10 by 1st embodiment is demonstrated based on FIG. The fuel injection valve 10 includes a valve housing 11, a fixed core 20, a movable core 30, a valve member 40, elastic members 50 and 52, and a drive unit 60.

  The valve housing 11 includes a main body member 12, an inlet member 13, a nozzle member 14, and the like. The main body member 12 is formed in a cylindrical shape, and has a first magnetic portion 12a, a nonmagnetic portion 12b, and a second magnetic portion 12c in order from one end portion side to the other end portion side in the axial direction. The magnetic parts 12a and 12c made of a magnetic material and the nonmagnetic part 12b made of a nonmagnetic material are coupled by, for example, laser welding. With such a coupling structure, the nonmagnetic portion 12b prevents the magnetic flux from being short-circuited between the first magnetic portion 12a and the second magnetic portion 12c.

  A cylindrical inlet member 13 is fixed to the axial end of the second magnetic portion 12c opposite to the nonmagnetic portion 12b. The inlet member 13 forms a fuel inlet 15 to which fuel is supplied from a fuel pump (not shown). In this embodiment, a fuel filter 16 is accommodated on the inner peripheral side of the inlet member 13 in order to filter the fuel supplied to the fuel inlet 15.

  A nozzle member 14 is fixed to the axial end of the first magnetic portion 12a opposite to the nonmagnetic portion 12b. The nozzle member 14 is formed in a bottomed cylindrical shape, and forms a fuel passage 17 through which fuel flows in cooperation with the main body member 12. The nozzle member 14 is provided with a nozzle hole 18 and a valve seat 19. A plurality of nozzle holes 18 communicating with the fuel passage 17 are provided at equal intervals around the central axis of the nozzle member 14 and are each formed in a cylindrical hole shape. The valve seat 19 is formed around the fuel passage 17 on the fuel upstream side of each nozzle hole 18.

  The fixed core 20 is formed in a cylindrical shape by a magnetic material, and is coaxially fixed to the inner peripheral surfaces of the nonmagnetic portion 12 b and the second magnetic portion 12 c of the main body member 12 of the valve housing 11. The fixed core 20 is formed with a through hole 21 penetrating in the axial direction in a cylindrical hole shape in the central portion in the radial direction. The through hole 21 communicates with the fuel inlet 15 of the inlet member 13, and the supplied fuel flows into the inlet 15. A first elastic member 50 is accommodated in the inner peripheral side of the through hole 21 so as to be elastically deformable, and an adjusting pipe 22 for adjusting a set load of the elastic member 50 is fixed by press-fitting.

  The movable core 30 is formed in a cylindrical shape by a magnetic material, and is coaxially accommodated on the inner peripheral side of the main body member 12 of the valve housing 11 so that one axial end face 32 faces the fixed core 20. The movable core 30 is slidably guided on both sides in the axial direction by the nonmagnetic portion 12 b of the main body member 12 of the valve housing 11. Thereby, the axial end surface 32 of the movable core 30 can contact | abut to the said core 20 by the axial direction movement to the fixed core 20 side.

  The movable core 30 is formed with an axial hole 34 penetrating in the axial direction in the shape of a cylindrical hole in the central portion in the radial direction. In such a movable core 30, the axial hole 34 is open to an axial end face 32 on the fixed core 20 side and an axial end face 33 on the opposite side to the fixed core 20.

  The valve member 40 is formed in a needle shape having a circular cross section by a nonmagnetic material, and is accommodated coaxially on the inner peripheral side of the main body member 12 and the nozzle member 14 of the valve housing 11. The valve member 40 has a seat portion 41 that faces the valve seat 19 of the nozzle member 14 at the end in the axial direction on the nozzle member 14 side. The valve member 40 opens each nozzle hole 18 with respect to the fuel passage 17 by moving the seat portion 41 away from the valve seat 19 by moving in the axial direction toward the fixed core 20. On the other hand, the valve member 40 closes each injection hole 18 with respect to the fuel passage 17 by seating the seat portion 41 on the valve seat 19 by moving in the axial direction opposite to the fixed core 20. Thus, the valve member 40 can open and close the injection holes 18 by reciprocating movements on both sides in the axial direction, thereby intermittently injecting fuel from the injection holes 18 to the combustion chamber.

  The valve member 40 has a columnar shaft portion 42 extending in the axial direction from the seat portion 41 toward the fixed core 20 side as a main body portion of the member 40. As shown in FIGS. 1 and 2, the shaft portion 42 is coaxially inserted into the axial hole 34 of the movable core 30 and is slidable on both axial sides with respect to the inner peripheral surface 35 of the hole 34. . In addition, although the size of the sliding clearance 340 between the axial part 42 and the axial hole 34 can be set suitably according to the specification etc. which are requested | required, in this embodiment, it sets to about 5-40 micrometers, for example. .

  The valve member 40 has a circular hook-shaped protrusion 44 protruding from the shaft portion 42 toward the outer peripheral side at an axial end portion on the fixed core 20 side. The protrusion 44 formed with a smaller diameter than the through hole 21 of the fixed core 20 is inserted into the hole 21 and is in contact with the first elastic member 50. Further, the protrusion 44 formed with a larger diameter than the axial hole 34 of the movable core 30 can come into contact with the axial end surface 32 of the core 30 from the fixed core 20 side.

  The valve member 40 has a fuel hole 46 across the shaft portion 42 and the protrusion 44. The fuel hole 46 is open to the contact surface of the protrusion 44 with the first elastic member 50 and the outer peripheral surface of the shaft portion 42 exposed from the axial hole 34. The fuel hole 46 communicates between the through hole 21 into which the protrusion 44 is inserted and the fuel passage 17 by such an opening form. Therefore, the fuel that has flowed into the through hole 21 from the fuel inlet 15 reaches the fuel passage 17 via the fuel hole 46.

  As shown in FIG. 1, the first elastic member 50 is made of a metal compression coil spring and is coaxially accommodated on the inner peripheral side of the through hole 21 of the fixed core 20. One end of the first elastic member 50 is locked to the adjusting pipe 22, and the other end of the elastic member 50 is locked to the protrusion 44 of the valve member 40 (see also FIG. 2). With such a locking structure, the first elastic member 50 is compressed between the adjusting pipe 22 and the valve member 40 to be elastically deformed, thereby restoring force that biases the valve member 40 to the side opposite to the fixed core 20. Is generated.

  The second elastic member 52 is made of a metal compression coil spring, and is coaxially accommodated on the inner peripheral side of the first magnetic portion 12a of the main body member 12 of the valve housing 11 and on the outer peripheral side of the shaft portion 42 of the valve member 40. Has been. One end of the second elastic member 52 is locked to the first magnetic portion 12a, and the other end of the elastic member 52 is locked to the axial hole 34 of the movable core 30 (see also FIG. 2). With this locking structure, the second elastic member 52 is compressed between the valve housing 11 and the movable core 30 and elastically deformed, thereby restoring the restoring force that urges the movable core 30 toward the fixed core 20 side. It occurs smaller than the restoring force of the member 50.

  The drive unit 60 includes a coil 61, a resin bobbin 62, a magnetic yoke 63, a connector 64, and the like. The coil 61 is formed by winding a metal wire around a resin bobbin 62, and a magnetic yoke 63 is disposed on the outer peripheral side thereof. The coil 61 is coaxially fixed to the outer peripheral surfaces of the nonmagnetic portion 12 b and the second magnetic portion 12 c on the outer peripheral side of the fixed core 20 of the main body member 12 of the valve housing 11 via a resin bobbin 62. The coil 61 is electrically connected to an external control circuit (not shown) via a terminal 64a provided on the connector 64, and energization is controlled by the control circuit.

  Here, when the coil 61 is excited by energization, magnetic flux flows through a magnetic circuit formed by the magnetic yoke 63, the first magnetic portion 12a, the movable core 30, the fixed core 20, and the second magnetic portion 12c. As a result, a magnetic attraction force that attracts and moves the movable core 30 toward the fixed core 20 is generated between the movable core 30 and the fixed core 20 facing each other. On the other hand, when the coil 61 is demagnetized by stopping energization, magnetic flux does not flow in the magnetic circuit described above, so that the magnetic attractive force disappears between the movable core 30 and the fixed core 20.

  In the valve opening operation of the fuel injection valve 10 configured as described above, a magnetic attractive force acts on the movable core 30 in response to the start of energization of the coil 61. Due to the action of the magnetic attraction force, the movable core 30 receives the restoring force of the first elastic member 50, and the valve member 40 in which the protrusion 44 is in contact with the axial end surface 32 on the fixed core 20 side is used as the restoring force. Press against. As a result, the movable core 30 moves together with the valve member 40 toward the core 20 until the axial end surface 32 collides with the fixed core 20, so that the seat portion 41 moves away from the valve seat 19 and moves to the core 20 side. Fuel is injected from the nozzle hole 18.

  When the movable core 30 collides with the fixed core 20 in the process of fuel injection, the valve member 40 continues to move by the action of inertial force, thereby separating the protrusion 44 from the axial end surface 32 of the core 30. Therefore, even if the movable core 30 bounces to the opposite side to the fixed core 20 due to the action of the collision reaction force, the nozzle hole 18 is erroneously closed for the valve member 40 that is difficult to receive the collision reaction force on the protrusion 44. Thus, bounce that causes variations in the fuel injection amount is suppressed.

  In the valve closing operation of the fuel injection valve 10 after the valve opening operation described above, the magnetic attractive force acting on the movable core 30 disappears in response to the stop of energization to the coil 61. Due to the disappearance of the magnetic attractive force, the valve member 40 that receives a restoring force larger than that of the second elastic member 52 from the first elastic member 50 causes the projecting portion 44 to abut against the axial end surface 32 to fix the movable core 30 to the fixed core. 20 is pressed to the opposite side. As a result, when the seat portion 41 is seated on the valve seat 19, the movement of the valve member 40 is stopped and the fuel injection from each nozzle hole 18 is also stopped. At this time, the movable core 30 continues to move against the restoring force of the second elastic member 52 by the action of the inertial force, thereby separating the axial end face 32 from the protrusion 44. However, since the inertial force is attenuated by the restoring force of the second elastic member 52, the movable core 30 that receives the restoring force of the second elastic member 52 moves toward the fixed core 20 after the damping, Finally, it stops in the contact state between the axial end face 32 and the protrusion 44.

(Feature)
Next, features of the fuel injection valve 10 according to the first embodiment will be described with reference to FIGS.

  For example, in a cylindrical movable core 30 formed of a magnetic material such as stainless steel, a plating layer 36 is formed on the surface including the axial end surface 32 on the fixed core 20 side and the inner peripheral surface 35 of the axial hole 34. Has been. Here, in particular, the first plating layer 360 that forms the axial end face 32 in the plating layer 36 is a thin-film electrolytic plating layer 360 formed by electrolytic deposition of a high-hardness metal such as chromium. The film thickness of the first plating layer 360 can be appropriately set according to the size of the magnetic gap required between the cores 20 and 30, but is set to, for example, about 2 to 30 μm in this embodiment.

  On the other hand, the second plating layer 362 that forms the inner peripheral surface 35 of the axial hole 34 in the plating layer 36 is a thin-film electroless plating obtained by chemically reducing and depositing a metal such as a nickel-phosphorus alloy. Layer 362. In the present embodiment, the second plating layer 362 is secured not only on the inner peripheral surface 35 of the axial hole 34 but also on the entire surface of the movable core 30. Therefore, in the movable core 30 of the present embodiment, the second plating layer 362 is a base film of the first plating layer 360 that forms the axial end surface 32, but the second plating is applied only to the surface portion excluding the axial end surface 32. The layer 362 may be secured. The film thickness of the second plating layer 362 can be appropriately set according to the size of the sliding clearance 340 required between the shaft portion 42 and the axial hole 34, but in this embodiment, for example, about 2 to 35 μm. Set to

  A cylindrical hole-shaped axial hole 34 through which the shaft portion 42 of the valve member 40 passes in the movable core 30 is partially enlarged by an annular groove-shaped annular recess 38. Specifically, the annular recess 38 is recessed from the inner peripheral surface 35 forming the second plating layer 362 to the outer peripheral side in the axial hole 34 over the entire circumference, and the first plating layer 360 is formed on the axial end surface 32. It opens and extends to the other end surface 33 side by a predetermined length. Here, since the axial end surface 32 needs to contact the protrusion 44 of the valve member 40 as described above, at least the end surface of the inner surface 39 of the annular recess 38 that surrounds the shaft portion 42 of the member 40. The inner diameter in the vicinity of 32 is set smaller than the outer diameter of the protrusion 44. In the present embodiment, the second plating layer 362 is also secured from the inner peripheral surface 35 of the axial hole 34 to the inner surface 39 of the annular recess 38. In addition, although the amount of depressions of the annular recess 38 with respect to the inner peripheral surface 35 of the axial hole 34 can be appropriately set according to the film thickness of the plating layers 360, 362, etc., in this embodiment, it is set to, for example, about 30 to 300 μm. Is done.

  And in order to manufacture the movable core 30 of 1st embodiment as mentioned above, first, the metal material which provided the annular recessed part 38 in the axial direction hole 34 as a base material of the movable core 30 is immersed in an electroless bath. . As a result, an oxidation-reduction reaction occurs, so that the metal in the electroless bath is deposited on the entire surface of the movable core 30 to form the second plating layer 362 as shown in FIG. Thereafter, the base material of the movable core 30 is immersed in an electrolytic bath, and direct current electrolysis or pulse electrolysis is performed using the axial end face 32 of the base material as a cathode. As a result, the metal in the electrolytic bath is deposited on the axial end face 32 by the electrochemical reaction, and the first plating layer 360 of the plating layer 36 is also formed as shown in FIG.

  In the manufacture of the movable core 30, the first plating layer 360 on the axial end face 32 may protrude to the inner peripheral side through which the axial hole 34 penetrates, as indicated by reference numeral 360 a in FIG. 3. Here, in particular, in the present embodiment in which the first plating layer 360 is formed by electrolytic deposition, the current during electrolysis concentrates on the edge portion 320 between the axial end surface 32 and the annular recess 38. The protruding portion 360a that protrudes from the edge portion 320 to the inner peripheral side is easily generated.

  However, in the present embodiment in which the annular recess 38 is provided on the axial end face 32 side of the axial hole 34, even if the first plating layer 360 protrudes into the recess 38, the inner peripheral side of the recess 38. It is difficult to protrude from the axial hole 34. In other words, the protruding portion 360 a of the first plating layer 360 can be securely stored in the annular recess 38 on the outer peripheral side of the inner peripheral surface 35 of the axial hole 34 and can be released from the hole 34. is there.

  Therefore, when the shaft portion 42 of the valve member 40 is inserted and assembled in the axial hole 34 as shown in FIG. 3 after the plating layer 36 is formed, a sliding clearance 340 (see FIG. 2) between the elements 42 and 34 is provided. Even in the case of management, it is possible to avoid a situation in which the protruding portion 360a of the first plating layer 360 interferes with the shaft portion 42 and causes assembly failure. In addition, after assembly, the protruding portion 360a of the first plating layer 360 hinders the slidability of the shaft portion 42 with respect to the axial hole 34 and makes the behavior of the valve member 40 unstable. It is also possible to avoid a situation in which the protruding portion 360a is worn violently by sliding contact with the shaft portion 42 and causes a decrease in durability. Moreover, according to the first plating layer 360 formed by metal electrolytic deposition, it is possible to realize a hard plating layer having excellent wear resistance, so that the axial end surface 32 has the protrusion 44 of the valve member 40. Even if it repeatedly collides with the fixed core 20, durability can be ensured over a long period of time.

(Second embodiment)
As shown in FIG. 4, the second embodiment of the present invention is a modification of the first embodiment. In the movable core 2030 of the second embodiment, the second plating layer 362 is removed by polishing in the axial direction hole 34, and is secured only on the surface portion excluding the inner peripheral surface 35 of the hole 34. Therefore, in this embodiment, the inner peripheral surface 35 of the axial hole 34 is exposed from the first plating layer 360 on the axial end surface 32 and the second plating layer 362 on the inner surface 39 of the annular recess 38. .

  In order to manufacture the movable core 2030 according to the second embodiment, the second plating layer 362 and the first plating layer 360 are sequentially formed in the same manner as in the first embodiment, and the shaft is then rotated by the reamer 2034 as shown in FIG. The inner peripheral surface 35 of the direction hole 34 is polished. As a result, the second plating layer 362 that is likely to cause uneven plating and film thickness variations due to reduction deposition remains in the annular recess 38 on the outer peripheral side of the inner peripheral surface 35, but the inner peripheral surface 35. Therefore, the inner diameter accuracy of the axial hole 34 can be improved. Further, even if the protruding portion 360a of the first plating layer 360 to the annular recess 38 protrudes to the inner peripheral side from the inner peripheral surface 35 of the axial hole 34, the polishing as shown in FIG. It can be ground by machining. Moreover, since the first plating layer 360 is hardly peeled off at the edge portion 320 away from the inner peripheral surface 35 of the axial hole 34 in the axial end surface 32 during the polishing, the quality of the first plating layer 360 is improved. Durability can be ensured without causing damage.

(Third embodiment)
As shown in FIG. 6, the third embodiment of the present invention is a modification of the first embodiment. In the movable core 3030 of the third embodiment, the plating layer 362 is not formed, and only the plating layer 360 forming the axial end surface 32 is formed. Therefore, in this embodiment, the inner peripheral surface 35 of the axial hole 34 and the inner surface 39 of the annular recess 38 are exposed from the plating layer 360.

  In order to manufacture such a movable core 3030 of the third embodiment, the axial hole 34 polished in advance is masked by a straight cylindrical jig 3034 as shown in FIG. A plating layer 360 is formed by electrolytic deposition of metal. Even if such masking is performed, the edge portion 320 between the axial end face 32 and the annular recess 38 is separated from the cylindrical jig 3034, so that the formation failure of the plating layer 360 in the edge portion 320 is avoided. Durability.

(Fourth embodiment)
As shown in FIG. 8, the fourth embodiment of the present invention is a modification of the first embodiment. In the movable core 4030 of the fourth embodiment, the axial end surface 4032 on the fixed core 20 side is fixed so as to protrude beyond the end surface portion 4032a on the inner peripheral side capable of contacting the protrusion 44 of the valve member 40 and the end surface portion 4032a. It is formed from an outer peripheral end surface portion 4032b capable of contacting the core 20. Therefore, the annular recess 38 of the present embodiment has a shape opened to the inner peripheral side end surface portion 4032a of the axial end surface 4032 formed by laminating the first and second plating layers 360, 362.

  Even in the fourth embodiment, since the protruding portion 360a of the first plating layer 360 can be released from the axial hole 34 by the annular recess 38, the same effect as the first embodiment can be obtained. It is.

(Other embodiments)
Although a plurality of embodiments of the present invention have been described above, the present invention is not construed as being limited to these embodiments, and can be applied to various embodiments without departing from the scope of the present invention. .

  Specifically, as the plating layer 360 that forms the axial end face 32 in the movable cores 30, 2030, 3030, and 4030 of the first to fourth embodiments, instead of an electrolytic plating layer by electrolytic deposition of metal, for example, An electroless plating layer or the like by metal reduction deposition may be employed. In the movable cores 2030 and 3030 of the second and third embodiments, a stepped surface axial end surface 4032 such as the movable core 4030 of the fourth embodiment is employed instead of the flat surface axial end surface 32. May be.

DESCRIPTION OF SYMBOLS 10 Fuel injection valve, 11 Valve housing, 18 Injection hole, 19 Valve seat, 20 Fixed core, 30, 2030, 3030, 4030 Movable core, 32, 4032 Axial end surface, 34 Axial hole, 35 Inner peripheral surface, 36 Plating Layer, 38 annular recess, 39 inner surface, 40 valve member, 41 seat portion, 42 shaft portion, 44 protrusion, 50 first elastic member, 52 second elastic member, 60 driving portion, 320 edge portion, 360 first plating layer 360a protrusion part, 2034 reamer, 3034 cylindrical jig, 362 second plating layer, 4032a, 4032b end face part

Claims (4)

A valve housing having nozzle holes for injecting fuel into the internal combustion engine;
A fixed core fixed to the valve housing;
A movable core having an axial hole penetrating in the axial direction and an axial end face formed with a plating layer, and moving to the fixed core side by the action of magnetic attraction;
A shaft portion that is slidably inserted into the axial hole, and a protrusion that protrudes from the shaft portion and can abut on the axial end surface of the movable core from the fixed core side; A valve member that opens and closes the injection hole to intermittently inject fuel;
Wherein the plating layer is the fuel injection valve metal is electroless plating layer formed by electrolytic deposition on the axial end face,
The movable core, an annular recess open to the axial end face an inner circumferential surface recess over the entire circumference to the outer peripheral side from the axial bore, and further organic,
The fuel injection valve according to claim 1, wherein the plating layer is accommodated in the annular recess so as not to protrude toward the inner peripheral side of the axial hole . 2. The fuel injection valve according to claim 1, wherein the plating layer formed on the inner surface of the annular recess is limited to an edge portion between the inner surface and the axial end surface .   The fuel injection valve according to claim 1 or 2, wherein the movable core is formed by polishing an inner peripheral surface of the axial hole.   The fuel injection valve according to any one of claims 1 to 3, wherein the movable core has an inner peripheral surface of the axial hole exposed from the plating layer.

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