JP2017025927A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a fuel injection amount.SOLUTION: A fuel injection valve is provided with: a valve member 40 for opening and closing an injection hole 18 of a valve housing 10 by reciprocating movement; a stationary core 220 fixed to the valve housing 10; a movable core 30 provided movably forward and backward together with the valve member 40, and moved to a valve opening side by generation of magnetic force between the stationary core 220 and the movable core; a valve closing spring 50 held by the stationary core 220 and pressure-driving the valve member 40 to a valve closing side; and a bush 270 fixed to the stationary core 220. The stationary core 220 has a holding hole 26 for holding the valve closing spring 50 inserted therein to a valve opening side, and the bush 270 has a hole 72 in which the valve member 40 is reciprocated, at a valve closing side with respect to the holding hole 26. The stationary core 220 has a loose insertion hole 74 having an inner diameter larger than both of the hole 72 in which the valve member 40 is reciprocated and the holding hole 26, so that the valve closing spring 50 is loosely inserted therein. The bush 270 has a stopper face 70a for locking the movable core 30 moved to the valve opening side with the valve member 40.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fuel injection valve that injects fuel into an internal combustion engine.

  2. Description of the Related Art Conventionally, there is known a fuel injection valve that opens and closes a nozzle hole of a valve housing by reciprocating a valve member from the valve opening side to the valve closing side in the axial direction. As a kind of such fuel injection valve, the one disclosed in Patent Document 1 generates a magnetic force between a fixed core fixed to the valve housing and a movable core that can reciprocate, thereby opening the movable core together with the valve member. It is moved to the valve side to realize fuel injection from the nozzle hole. Further, in the fuel injection valve disclosed in Patent Document 1, when the magnetic force between the fixed core and the movable core disappears, the valve member is pressed and driven to the valve closing side together with the movable core by the coil spring held by the fixed core, The fuel injection from the nozzle hole is stopped. Therefore, the fluctuation of the restoring force generated by the coil spring affects the fuel injection amount from the nozzle hole.

  Now, in recent years, the requirement for split injection that divides fuel injection into a plurality of times in one combustion cycle is increasing in the fuel injection valve as exhaust gas regulations become stronger. In such divided injection, since the absolute amount of the fuel injection amount is small, the influence of individual variation, injection-to-injection (between-shot) variation, and secular change increases.

JP 2011-241701 A

  However, in the fuel injection valve disclosed in Patent Document 1, variation between individuals, variation between injections, and secular change are likely to occur in the fuel injection amount. This is because not only the valve member but also the coil spring is easily slidable with respect to the bush which is fixed to the fixed core and slidably supports the valve member from the outer peripheral side. The specific reason will be described below.

  In the fuel injection valve disclosed in Patent Document 1, in the holding hole formed in the fixed core, the coil spring fitted coaxially is held on the valve opening side, and in the sliding hole formed in the bush. The valve member slides coaxially on the valve closing side with respect to the holding hole. In such a configuration, the coil spring is coaxially inserted in the loose insertion hole formed in the bush and the fixed core with an inner diameter larger than the holding hole between the holding hole and the sliding hole. A gap in the radial direction is narrow between the loose insertion hole having the same inner diameter as the moving hole and the coil spring. Therefore, when the coil spring is pressed by the valve member on the valve closing side in the holding state on the valve opening side to bend, the possibility of sliding with the bush on the outer peripheral side increases. Here, since the coil spring causes fluctuations in the restoring force due to sliding with the bush, there is a concern of causing variation among individuals, variation between injections, and aging in the fuel injection amount.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a fuel injection valve having a stable fuel injection amount.

  The present invention opens and closes a nozzle hole by reciprocating a valve housing (10) having a nozzle hole (18) for injecting fuel into an internal combustion engine and a valve opening side and a valve closing side in the axial direction. The valve member (40), the fixed core (220) fixed to the valve housing, and the valve member are provided so as to be able to reciprocate. In a fuel injection valve, comprising: a core (30); a coil spring (50) that is held by the fixed core and drives the valve member to close the valve member; and a bush (270) that is fixed to the fixed core. Has a holding hole (26) for holding the coil spring fitted coaxially inside on the valve opening side, and the bush holds a hole (72) for the valve member to reciprocate coaxially inside. The fixed core is located on the valve closing side of the hole. The coil spring further has a loose insertion hole (74) with an inner diameter larger than both of the reciprocating hole (72) and the holding hole, and the bush has a valve member and a valve opening side. It further has a stopper surface (70a) for locking the movable core moved to the position.

  According to the present invention, the coil spring fitted coaxially is held on the valve opening side in the holding hole of the fixed core, and the valve member is coaxial on the valve closing side of the holding hole in the hole of the bush. Will be going up and down. Under such a configuration, the inner diameter of the loose insertion hole into which the coil spring is coaxially inserted into the fixed core is made larger than both the reciprocating hole and the holding hole of the valve member. As a result, the coil spring having a large radial clearance with the loose insertion hole is fixed on the outer peripheral side even if it is pressed and bent by the valve member on the valve closing side in the holding state on the valve opening side. It becomes difficult to slide with the core. According to this, it is possible to suppress a situation in which the variation in individual force, the variation between injections, and the secular change are caused in the fuel injection amount due to the fluctuation of the restoring force by the sliding of the coil spring with the fixed core. As described above, the present invention can provide a fuel injection valve with a stable fuel injection amount.

  Here, as a further feature of the present invention, the valve member is inserted into the loose insertion hole from the reciprocating hole (72) of the valve member between the moving end on the valve opening side and the moving end on the valve closing side. A spring receiving portion (44) for receiving the restoring force of the coil spring is maintained while maintaining the rushed state.

  According to such a feature, the spring receiving portion that receives the restoring force of the coil spring in the valve member is located in the loose insertion hole from the reciprocating hole of the valve member between the moving end on the valve opening side and the moving end on the valve closing side. The rush state is maintained. As a result, the coil spring is prevented from entering the reciprocating hole of the valve member as a hole having an inner diameter smaller than the loose insertion hole by the spring receiving portion, so that interference with the bush in the hole can be suppressed. . According to this, it is possible to avoid a situation in which the stability of the fuel injection amount decreases due to fluctuations in the restoring force of the coil spring that interferes with the bush.

  As a further feature of the present invention, a valve member having a shaft portion (42) extending in the axial direction and a projection (44) projecting from the shaft portion and the shaft portion penetrate through the inside so as to be relatively movable. The movable core is movable with the valve member by contacting the axial end surface (30a) on the valve opening side, and the movable core is locked to the stopper surface at the moving end on the valve opening side. And a valve closing spring (50) interposed between the fixed core and the valve member as a coil spring, and a valve opening interposed between the valve housing and the movable core to drive the movable core to the valve opening side. A spring (51).

  According to the valve member having such a feature, the projecting portion protruding from the shaft portion contacts the axial end surface of the movable core on the valve opening side while the shaft portion extending in the axial direction penetrates the movable core so as to be relatively movable. By doing so, both the valve member and the movable core can move. Therefore, when the movable core is pressed and driven to the valve opening side by the valve opening spring with the valve housing under such contact state, the valve member is against the valve closing spring with the fixed core. Move to. As a result, when the movable core is locked to the stopper surface of the bush at the moving end on the valve opening side, the valve member continues to move to the valve opening side due to inertia, but the valve member closes. The overshoot can be suppressed by the restoring force of the spring. Here, the valve-closing spring as a coil spring having a wide radial gap between the loose insertion hole and the fixed core on the outer peripheral side is bent by being pressed by the valve member on the valve-closing side. It is difficult to slide. According to this, since the suppression action of the overshoot by the valve closing spring can be surely exhibited, the situation where the stability of the fuel injection amount is lowered due to the overshoot can be avoided.

It is a longitudinal section showing a fuel injection valve by a first embodiment of the present invention. It is a longitudinal cross-sectional view which expands and shows the principal part of FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. It is a longitudinal cross-sectional view which expands and shows the principal part of the fuel injection valve by 2nd embodiment of this invention. It is a schematic diagram which shows the modification of FIG.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description may be abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment. When only a part of the configuration is described in each embodiment, the configuration of the other embodiment described above can be applied to the other part of the configuration. In addition, not only combinations of configurations explicitly described in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined even if they are not explicitly specified unless there is a problem with the combination. .

(First embodiment)
A fuel injection valve 1 shown in FIG. 1 as a first embodiment of the present invention is installed in a gasoline engine which is an “internal combustion engine”, and injects fuel into a combustion chamber (not shown) of the gasoline engine. In addition to this application mode, for example, the fuel injection valve 1 may inject fuel into an intake passage communicating with a combustion chamber of a gasoline engine.

(Constitution)
First, the configuration of the fuel injection valve 1 will be described. The fuel injection valve 1 includes a valve housing 10, a fixed core 20, a bush 70, a movable core 30, a valve member 40, springs 50 and 51, and a solenoid unit 60.

  The valve housing 10 includes a main body member 12, an inlet member 13, a nozzle member 14, and the like. The cylindrical main body member 12 has a first magnetic part 120, a nonmagnetic part 121, and a second magnetic part 122 in this order from the valve closing side to the valve opening side in the axial direction. Each magnetic part 120,122 which consists of metal magnetic bodies, and the nonmagnetic part 121 which consists of metal nonmagnetic bodies are couple | bonded by laser welding etc., for example. With such a coupling structure, the nonmagnetic portion 121 prevents the magnetic flux from being short-circuited between the first magnetic portion 120 and the second magnetic portion 122.

  A cylindrical inlet member 13 is fixed to a portion of the second magnetic portion 122 opposite to the nonmagnetic portion 121. The inlet member 13 forms a fuel inlet 15 that receives fuel supplied from a fuel pump (not shown). In order to filter the fuel flowing into the fuel inlet 15, a fuel filter 16 is accommodated on the inner peripheral side of the inlet member 13.

  The nozzle member 14 is fixed to a part of the first magnetic part 120 opposite to the nonmagnetic part 121. The bottomed cylindrical nozzle member 14 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 around the central axis of the nozzle member 14 and are each formed in a cylindrical hole shape. The valve seat 19 is formed in a conical surface around the fuel passage 17 on the upstream side of each nozzle hole 18.

  The fixed core 20 made of a cylindrical metal magnetic body is coaxially fixed to the inner peripheral surfaces of the nonmagnetic portion 121 and the second magnetic portion 122. A cylindrical adjusting pipe 24 made of metal is press-fitted and fixed on the same axis at the radial center of the fixed core 20. The fixed core 20 forms a communication passage 22 communicating with the upstream fuel inflow port 15 in cooperation with the adjusting pipe 24 and a bush 70 described in detail later. The communication passage 22 guides the fuel flowing in from the fuel inflow port 15 to the downstream side.

  The bush 70 made of a cylindrical metal is press-fitted and fixed on the same axis at a position spaced from the adjusting pipe 24 toward the valve closing side in the radial center of the fixed core 20. As shown in FIG. 2, the bush 70 protrudes toward the valve closing side from the fixed core 20, thereby forming an annular surface-like stopper surface 70 a by the axial end surface 70 a on the valve closing side.

  As shown in FIG. 1, the movable core 30 made of a cylindrical metal magnetic material is accommodated coaxially on the inner peripheral side of the main body member 12 on the valve closing side with respect to the fixed core 20, and is opened in the axial direction. And reciprocating movements are possible. The movable core 30 is locked by bringing the axial end face 30a of FIG. 2 into contact with the stopper face 70a at the moving end on the valve opening side. The movable core 30 is formed with an axial hole 34 extending in the axial direction in the shape of a cylindrical hole at the radial center.

  As shown in FIG. 1, a valve member 40 made of an elongated columnar (needle-like) metal nonmagnetic material is accommodated coaxially on the inner peripheral side of the main body member 12 and the nozzle member 14, and opens and closes the valve. It can be moved back and forth. The valve member 40 has a cylindrical shaft portion 42 extending in the axial direction. The shaft portion 42 is coaxially fitted in the axial hole 34 so as to penetrate the inside of the movable core 30 so as to be relatively movable in the axial direction.

  The valve member 40 has a circular hook-shaped (flange-shaped) protruding portion 44 protruding from the shaft portion 42 toward the outer peripheral side at the proximal end on the valve opening side. As shown in FIG. 2, the protrusion 44 is slidably supported by the bush 70 from the outer peripheral side by being fitted coaxially in the bush 70. The axial end surface 44 a facing the valve closing side in the projection 44 having a diameter larger than that of the axial hole 34 is in contact with the axial end surface 30 a facing the valve opening side in the movable core 30. In such a contact state, the valve member 40 can reciprocate together with the movable core 30.

  As shown in FIG. 1, the valve member 40 has a fuel hole 46 that passes through the shaft portion 42 and the protrusion 44. The fuel hole 46 communicates the opening that opens to the protrusion 44 on the valve opening side with respect to the movable core 30 to the downstream portion of the communication passage 22. At the same time, the fuel hole 46 communicates with the upstream portion of the fuel passage 17 an opening that opens to the shaft portion 42 on the valve closing side with respect to the movable core 30. With such a communication structure, the fuel hole 46 allows the fuel to flow from the communication passage 22 to the fuel passage 17 regardless of the movement position of the valve member 40.

  The valve member 40 has a seat portion 48 that faces the valve seat 19 at the front end on the valve closing side. The valve member 40 opens each nozzle hole 18 to the fuel passage 17 by moving the seat portion 48 away from the valve seat 19 by moving toward the valve opening side. As a result, the fuel in the fuel passage 17 is injected from each nozzle hole 18 into the combustion chamber. On the other hand, the valve member 40 closes each nozzle hole 18 with respect to the fuel passage 17 by seating the seat portion 48 on the valve seat 19 by moving toward the valve closing side. As a result, the injection from each nozzle hole 18 stops. In this way, the valve member 40 can open and close the injection holes 18 by reciprocating movement, thereby enabling the fuel injection from the injection holes 18 to be interrupted.

  The valve closing spring 50 is a compression coil spring made of metal and is coaxially accommodated on the inner peripheral side of the fixed core 20 and the bush 70. As shown in FIG. 2, the valve closing spring 50 is sandwiched between an axial end surface 24 a facing the valve closing side of the adjusting pipe 24 and an axial end surface 44 b facing the valve opening side of the protrusion 44. . With this clamping structure, the valve closing spring 50 generates an elastic restoring force in response to compression between the elements 24 and 44 to drive the valve member 40 to the valve closing side.

  As shown in FIG. 1, the valve opening spring 51 is a compression coil spring made of metal, and is coaxially accommodated on the inner peripheral side of the main body member 12 on the outer peripheral side of the shaft portion 42. The valve closing spring 50 is sandwiched between the concave surface 30 b facing the valve closing side in the movable core 30 and the step surface 120 a facing the valve opening side in the first magnetic part 120. With this clamping structure, the valve-opening spring 51 generates an elastic restoring force in response to compression between the elements 30 and 120, thereby driving the movable core 30 to the valve-opening side.

  The solenoid unit 60 includes a solenoid coil 61, an insulating bobbin 62, a magnetic yoke 63, a connector 64, a terminal 65, and the like. The solenoid coil 61 is formed by winding a metal wire around a resin insulating bobbin 62. The solenoid coil 61 is coaxially fixed to the outer peripheral surfaces of the magnetic portions 120 and 122 and the nonmagnetic portion 121 on the outer peripheral side of the fixed core 20 via an insulating bobbin 62. The magnetic yoke 63 made of a cylindrical metal magnetic body as a whole covers the periphery of the solenoid coil 61 by being coaxially fixed to the outer peripheral surfaces of the magnetic portions 120 and 122 on the outer peripheral side of the cores 20 and 30. Yes. The resin-made connector 64 protrudes to one outside in the circumferential direction through the opening of the magnetic yoke 63. A metal terminal 65 embedded in the connector 64 electrically connects the solenoid coil 61 to an external control circuit (not shown). With this electrical connection, energization of the solenoid coil 61 can be controlled by a control circuit.

  In the valve opening operation of the fuel injection valve 1 configured as described above, the solenoid coil 61 energized by the control circuit is excited, so that the magnetic yoke 63, the first magnetic portion 120, the movable core 30, the fixed core 20, and the first Magnetic flux is guided to the two magnetic part 122. That is, a magnetic circuit is formed so that the magnetic flux passes through these elements 63, 120, 30, 20, and 122. Then, a magnetic force (magnetic attractive force) is generated between the cores 20 and 30 facing each other so as to attract the movable core 30 toward the fixed core 20 side. When the sum of the magnetic force, the restoring force of the valve opening spring 51 and the fuel pressure closing force (= seat area × fuel pressure) is larger than the restoring force of the valve closing spring 50, the movable core 30 comes into contact with the axial end face 30a. The projecting portion 44 is pressed toward the valve opening side. As a result, the movable core 30 moves to the valve opening side together with the valve member 40, so that the seat portion 48 is separated from the valve seat 19 and fuel is injected from each nozzle hole 18.

  The movable core 30 is locked by colliding with the stopper surface 70a by the movement toward the valve opening side. At this time, since the valve member 40 continues the inertial movement, the protrusion 44 is separated from the axial end surface 30a. Thereby, even if the movable core 30 receives the collision reaction force with the bush 70 and bounces to the valve closing side, the valve member 40 that suppresses the action of the collision reaction force due to the separation from the axial end surface 30a Bounces that erroneously close the nozzle hole 18 and cause variations in the fuel injection amount are less likely to occur. Further, the valve member 40 receives the restoring force of the valve closing spring 50 toward the valve closing side due to the separation from the axial end face 30a, so that an overshoot that is excessive movement toward the valve opening side is less likely to occur.

  In the valve closing operation after such valve opening operation, the solenoid coil 61 that is energized and stopped by the control circuit is demagnetized, so that the magnetic force between the cores 20 and 30 is lost. Due to the disappearance of the magnetic force, the valve member 40 receives a restoring force larger than that of the valve opening spring 51 from the valve closing spring 50, thereby pressing the movable core 30 in contact with the axial end surface 44a to the valve closing side. As a result, the valve member 40 moves to the valve closing side together with the movable core 30, so that the seat portion 48 is seated on the valve seat 19 and fuel injection from each nozzle hole 18 is stopped.

(Feature configuration)
Next, the characteristic configuration of the fuel injection valve 1 will be described in detail.

  As shown in FIG. 2, the fixed core 20 has a holding hole 26 that forms a communication passage 22. The holding hole 26 is a central hole portion adjacent to the valve closing side of the adjusting pipe 24 and the valve opening side of the bush 70 in the radial center of the fixed core 20. The inner diameter of the holding hole 26 is set larger than the inner diameter of the adjusting pipe 24. With this inner diameter setting, the adjusting pipe 24 exposes the axial end face 24 a in the holding hole 26.

  In the present embodiment, the bush 70 shown in FIG. 2 is made of a metal non-magnetic material or a metal magnetic material having a saturation magnetic flux density lower than that of the fixed core 20, and is given rigidity higher than that of the fixed core 20 by, for example, a quenching process. ing. As shown in FIGS. 2 and 3, the bush 70 has a sliding hole 72 and a loose insertion hole 74 that form the communication passage 22.

  As shown in FIG. 2, the sliding hole 72 is a central hole portion located closer to the valve closing side than the holding hole 26 in the radial center of the bush 70, and is held from the stopper surface 70 a on the valve closing side to the valve opening side. It has an axial length that does not reach the hole 26. That is, the sliding hole 72 extends between the peripheral stopper surface 70a and a portion spaced from the holding hole 26 toward the valve closing side. The inner diameter of the sliding hole 72 is set so as to allow the protrusion 44 to reciprocate within the hole 72.

  The loose insertion hole 74 is a central hole portion adjacent to the valve closing side of the holding hole 26 and the valve opening side of the sliding hole 72 in the central portion in the radial direction of the fixed core 20, and an axis extending between the holes 26 and 27. Has a directional length. The inner diameter of the loose insertion hole 74 is set larger than both the inner diameter of the holding hole 26 and the inner diameter of the sliding hole 72. With the above configuration, the protruding portion 44 in the sliding hole 72 can maintain the state of protruding into the loose insertion hole 74 between the moving end on the valve opening side and the moving end on the valve closing side. It has become.

  In the present embodiment, a grinding end type compression coil spring made of a metal magnetic material is employed for the valve closing spring 50. The valve closing spring 50 has a predetermined number of turns (two turns in the present embodiment) from the axial end on the valve opening side and the axial end on the valve closing side, respectively, and is a counter winding that does not substantially contribute to the generation of the restoring force. 52, 54.

  The end winding 52 on the valve opening side of the valve closing spring 50 is held by the fixed core 20 by being fitted coaxially into the holding hole 26. Here, in particular, the axial end surface 24 a of the adjusting pipe 24 exposed into the holding hole 26 is in contact with the grinding surface 52 a at the axial end of the end winding 52. At the same time, the axial length of the end winding 52 is set to be substantially equal to the axial length of the holding hole 26. With such a contact configuration and length setting, the holding hole 26 holds only the end winding 52 in the valve closing spring 50.

  As shown in FIGS. 2 and 3, the portion of the valve closing spring 50 extending from the portion adjacent to the valve closing side of the end winding 52 to the end winding 54 opens a radial clearance 74 a coaxially in the loose insertion hole 74. Are loosely inserted. Here, in particular, the axial end surface 44b of the projecting portion 44 in which the state of entry into the loose insertion hole 74 is maintained as shown in FIG. With the above configuration, the valve member 40 receives the restoring force on the valve closing side of the valve closing spring 50 held on the fixed core 20 on the valve opening side by the protrusion 44 as a “spring receiving portion”.

(Function and effect)
The effect of the fuel injection valve 1 demonstrated above is demonstrated below.

  According to the fuel injection valve 1, the valve closing spring 50 fitted coaxially in the holding hole 26 of the fixed core 20 is held on the valve opening side, and in the sliding hole 72 of the bush 70, the holding hole 26. The valve member 40 reciprocates coaxially on the valve closing side. Under such a configuration, the inner diameter of the loose insertion hole 74 through which the valve closing spring 50 is loosely inserted coaxially by straddling between the holding hole 26 and the sliding hole 72 is the same as that of the sliding hole 72 in which the valve member 40 reciprocates. It is made larger than both of the holding holes 26. Thereby, even if the valve closing spring 50 in which the radial clearance 74a is widened with the loose insertion hole 74 is pressed by the valve member 40 on the valve closing side while being held on the valve opening side, the valve closing spring 50 is bent. It becomes difficult to slide with the bush 70 on the outer peripheral side. According to this, the situation in which the valve closing spring 50 fluctuates the restoring force by sliding with the bush 70 and causes the variation between individuals, the variation between injections, and the secular change in the fuel injection amount is suppressed. it can. As described above, the fuel injection valve 1 with a stable fuel injection amount can be provided.

  Here, the protrusion 44 that receives the restoring force of the valve closing spring 50 in the valve member 40 is located in the sliding hole 72 in which the valve member 40 reciprocates between the moving end on the valve opening side and the moving end on the valve closing side. Thus, the rushing state into the loose insertion hole 74 is maintained. As a result, the valve closing spring 50 is prevented from entering the sliding hole 72 having an inner diameter smaller than the loose insertion hole 74 by the projecting portion 44, so that interference with the bush 70 in the sliding hole 72 is suppressed. Can be done. According to this, it is possible to avoid a situation in which the stability of the fuel injection amount decreases due to the restoring force fluctuation of the valve closing spring 50 that interferes with the bush 70.

  Further, the movable core 30 that has moved to the valve opening side together with the valve member 40 is locked to the stopper surface 70 a around the sliding hole 72 in the bush 70 having a hardness higher than that of the fixed core 20. Here, around the sliding hole 72 having an inner diameter smaller than the loose insertion hole 74, the area of the stopper surface 70a, that is, the collision area of the movable core 30 against the bush 70 increases as much as possible toward the inner peripheral side. Can be done. According to this, it is possible to avoid a situation in which the stability of the fuel injection amount decreases due to the collision wear of the bush 70 and the movable core 30.

  Furthermore, the predetermined number of turns from the axial end on the valve opening side of the valve closing spring 50 does not substantially contribute to the generation of the restoring force as the end turn 52. Therefore, even if the predetermined number of turns as the end turn 52 is fitted and held in the holding hole 26, the portion of the valve closing spring 50 adjacent to the valve closing side of the predetermined winding number is adjacent to the valve closing side of the holding hole 26. By freely inserting into the loose insertion hole 74, a desired restoring force can be stably generated without sliding with the bush 70. Therefore, it is possible to avoid a situation in which the stability of the fuel injection amount is lowered due to fluctuations in the restoring force of the valve closing spring 50 that slides on the bush 70.

  In addition, according to the valve member 40, the projecting portion 44 protruding from the shaft portion 42 has the axial end surface 30 a of the movable core 30 with the shaft portion 42 extending in the axial direction penetrating through the movable core 30 so as to be relatively movable. The valve member 40 and the movable core 30 can move together by making contact with each other on the valve opening side. Therefore, when the movable core 30 is pressed and driven to the valve opening side by the valve opening spring 51 between the movable housing 30 and the valve housing 10 under the contact state, the valve member 40 is moved to the valve closing spring 50 between the fixed core 20 and the valve member 40. Move to the valve opening side. As a result, when the movable core 30 is locked to the stopper surface 70a of the bush 70 at the moving end on the valve opening side, the valve member 40 continues to move toward the valve opening side due to inertia and tries to overshoot. However, the overshoot can be suppressed by the valve closing spring 50. Here, the valve-closing spring 50 having a wide radial gap 74a between the loose insertion hole 74 and the bush 70 on the outer peripheral side is bent by being pressed by the valve member 40 on the valve-closing side. It is difficult to slide. According to this, since the suppression action of the overshoot by the valve closing spring 50 can be surely exhibited, the situation where the stability of the fuel injection amount is lowered due to the overshoot can be avoided.

(Second embodiment)
As shown in FIG. 4, the second embodiment of the present invention is a modification of the first embodiment. The bush 270 of the second embodiment has an axial length that forms only the sliding hole 72. Accordingly, the fixed core 220 straddles between the holes 26 and 72 by a central hole portion adjacent to the valve closing side of the holding hole 26 and the valve opening side of the sliding hole 72 (bush 270) in the central portion in the radial direction. A loose insertion hole 74 is formed.

  Here, since the loose insertion hole 74 of the second embodiment also has an inner diameter larger than both the inner diameter of the holding hole 26 and the inner diameter of the sliding hole 72, the same effect as the first embodiment is exhibited. be able to.

(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 various embodiments and combinations can be made without departing from the scope of the present invention. Can be applied.

  Specifically, in Modification 1, as shown in FIG. 5 (this is a modification of the first embodiment), the bushes 70 and 270 do not protrude from the fixed cores 20 and 220 toward the valve closing side, but are opened. A protrusion 32 that can come into contact with the stopper surface 70a by protrusion toward the valve side may be provided on the movable core 30.

  In the second modification, the end winding 52 of the valve closing spring 50 may be inserted from the holding hole 26 into the loose insertion hole 74 in the loose insertion state. Alternatively, in the third modification, a portion of the valve closing spring 50 adjacent to the valve closing side of the end winding 52 may be fitted and held in the holding hole 26.

  In Modification 4 with respect to the valve member 40, the protrusion 44 extends from the sliding hole 72 into the loose insertion hole 74 in a part of the moving range between the moving end on the valve opening side and the moving end on the valve closing side. You may employ | adopt the structure which does not rush into. Further, in the modified example 5, a hole into which the valve member 40 (projection 44) is loosely inserted with an inner diameter larger than the sliding hole 72 is formed adjacent to the valve closing side of the sliding hole 72 in the bushes 70 and 270, A stopper surface 70a may be formed around the periphery.

  In the modified example 6, the valve member 40 is fixed so as not to move relative to the movable core 30, and the valve opening spring 51 may not be provided. In this case, the projecting portion 44 is not provided, and the shaft portion is not provided. 42 may be slidably supported by bushes 70 and 270. Moreover, in the modification 7, you may form the loose insertion hole 74 ranging over both a bush and a fixed core.

DESCRIPTION OF SYMBOLS 1 Fuel injection valve, 10 Valve housing, 18 Injection hole, 20, 220 Fixed core, 26 Holding hole, 30 Movable core, 30a Axial end surface, 32 Protrusion, 34 Axial hole, 40 Valve member, 42 Shaft part, 44 Projection, 50 Valve closing spring, 51 Valve opening spring, 52 End winding, 70, 270 Bush, 70a Axial end surface / stopper surface, 72 Sliding hole, 74 Free insertion hole, 74a Radial clearance

Claims (5)

A valve housing (10) having a nozzle hole (18) for injecting fuel into the internal combustion engine;
A valve member (40) for opening and closing the nozzle hole by reciprocating between the valve opening side and the valve closing side in the axial direction;
A stationary core (220) secured to the valve housing;
A movable core (30) that is provided so as to be reciprocally movable together with the valve member, and that moves to the valve-opening side by generating a magnetic force with the fixed core;
A coil spring (50) held by the fixed core and driving the valve member to the valve closing side;
A fuel injection valve comprising a bush (270) fixed to the fixed core,
The fixed core is
A holding hole (26) for holding the coil spring fitted coaxially inside on the valve opening side;
The bush
A hole (72) in which the valve member reciprocally coaxially reciprocates inside, on the valve closing side from the holding hole;
The fixed core is
The valve member further has a loose insertion hole (74) into which the coil spring is coaxially inserted with a larger inner diameter than both the reciprocating hole (72) of the valve member and the holding hole,
The bush
The fuel injection valve according to claim 1, further comprising a stopper surface (70a) for locking the movable core moved to the valve opening side together with the valve member. The valve member is
The coil spring is maintained between the moving end on the valve-opening side and the moving end on the valve-closing side, while maintaining a state where the valve member has entered from the reciprocating hole (72) into the loose insertion hole. The fuel injection valve according to claim 1, further comprising a spring receiving portion (44) for receiving the restoring force of the fuel. The coil spring is
While having a predetermined number of turns from the axial end on the valve opening side as an end turn (52) fitted into the holding hole,
3. The fuel injection valve according to claim 1, further comprising a loose insertion portion that is loosely inserted into the loose insertion hole, adjacent to the valve closing side of the end winding.   The fuel injection valve according to any one of claims 1 to 3, wherein the bush having a hardness higher than that of the fixed core has the stopper surface. The valve member having a shaft portion (42) extending in the axial direction and a protrusion (44) projecting from the shaft portion;
The shaft portion penetrates through the inside so as to be relatively movable, and the projecting portion comes into contact with the axial end surface (30a) on the valve opening side, whereby the movable core is movable with the valve member, The movable core locked to the stopper surface at the moving end on the valve opening side;
A valve closing spring (50) interposed between the fixed core and the valve member as the coil spring;
The fuel injection according to claim 4, further comprising: a valve opening spring (51) interposed between the valve housing and the movable core and pressing the movable core toward the valve opening side. valve.

Images