JP5880358B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve configured to inject and stop fuel by sliding a needle in an axial direction, and more particularly to a fuel injection valve used in an internal combustion engine.

  For example, as disclosed in Patent Documents 1 to 3, there are fuel injection valves configured to inject and stop fuel by displacing a needle in the axial direction.

  A valve body for opening and closing a fuel injection port provided at the lower end of the cylindrical housing is provided at the lower end of the needle, and a flange is provided at the upper end of the needle. As a drive system for displacing the needle in the axial direction, an electromagnet and an armature (movable core or mover) are used.

  In order to reduce so-called needle bounce, the armature is provided on the outer diameter side of the needle so as to be relatively displaced toward the flange. An electromagnet (coil unit) is fixed to the outer periphery of the housing.

  When a magnetic attractive force is generated by the electromagnet, the armature is attracted upward, and this armature pushes the needle upward, so that the valve body of the needle opens the injection port. On the other hand, in a state where no magnetic attractive force is generated by the electromagnet, the needle and armature are moved downward by the elastic restoring force of a return spring (cylindrical compression coil spring) arranged so as to be coaxially connected above the flange of the needle. When pressed down, the valve body of the needle closes the injection port.

JP 2010-150976 A (see FIG. 1) Japanese translation of PCT publication No. 2002-528672 (see FIG. 1) JP-T-2004-519600 (see FIG. 1)

  In the above conventional example, when the injection port is closed by the valve body of the needle, the upper surface of the armature comes into contact with the lower surface of the flange of the needle. When the contact surface relatively moves, the contact surface comes into frictional contact.

  When such frictional contact is repeated, wear progresses over time, so that when the injection port is opened, the amount of axial displacement of the needle is less than the initial set value, for example, a prescribed fuel injection There is a concern that the amount cannot be obtained.

  In view of such circumstances, the present invention is directed to a temporal change in the axial displacement amount of the needle when the injection port is opened in a fuel injection valve configured to inject and stop fuel by sliding the needle in the axial direction. The goal is to be able to suppress or avoid change.

A fuel injection valve according to the present invention includes a needle provided with a valve body for opening and closing a fuel injection port at one end and a flange provided at the other end, and a side abutting against the flange of the needle to close the injection port. A return spring for urging the needle, an armature provided on the outer diameter side of the needle near the flange so as to be relatively displaceable, and the armature and a flange of the needle provided between the axially opposed members. The needle on the side that opens the injection port by generating a spring for urging the armature in a non-contacting direction and a magnetic attraction force that pulls the armature against the urging force of the return spring. a drive source for displacing in the axial direction, a first stopper for regulating the axial displacement amount when the armature is attracted by the driving source, before Viewed contains a second stopper for limiting the axial displacement amount when the armature is biased by the return spring and the spring when it is not attracted by the driving source, wherein the armature, the magnetic material A region from the end surface on the flange side to the middle in the center axis direction is a large diameter in the center hole, and the return spring is coaxial with the other end side of the needle. The cylindrical compression coil spring is arranged so as to be continuous, and the spring is concentric to the outer diameter side of the needle and has a large diameter of the flange of the needle and the central hole of the armature. A cylindrical compression coil spring disposed between the radial wall and the stepped wall surface in the region where the second stopper is attached to the outer periphery of the needle; Wherein an end face thereof positioned on the valve body side of the needle is a cylindrical member disposed opposite in the axial direction, is characterized in that in said armature.

  In the present invention, the armature and the flange of the needle are not in contact with each other when the armature is not attracted by the magnetic attractive force generated by the drive source.

  As a result, even if the armature and the needle flange move relatively in a state where the injection port is closed by the valve body of the needle, the armature and the needle flange are in frictional contact with each other. Abrasion is avoided.

  As a result, the amount of axial displacement of the needle when the injection port is opened does not change with time, and the fuel injection amount can be kept at the initial set value regardless of the usage progress. It will be possible to contribute to the improvement of reliability.

Preferably, the drive source is an electromagnet for generating a magnetic attraction force due to the feeding, the spring constant of the front Symbol spring is set smaller than the spring constant of the return spring. Here, the driving source, back Shibane and specifies the configuration of the spring.

Preferably, the first stopper is disposed in a non-contact surrounding manner on the outer diameter side of the return spring and the flange of the needle, and is disposed in the armature so as to face the end face located on the flange side of the needle in the axial direction. It is part of Jo member. Here, it is more specifically identify the structure of the first scan stopper.

  In the fuel injection valve configured to inject and stop the fuel by sliding the needle in the axial direction, the present invention suppresses or avoids the temporal change in the axial displacement amount of the needle when the injection port is opened. Is possible. As a result, the fuel injection amount can be maintained at the initial set value regardless of the progress of use, thereby contributing to improvement in reliability.

1 is a cross-sectional view showing an overall schematic configuration of an embodiment of a fuel injection valve according to the present invention. FIG. 2 is a partially enlarged view of FIG. 1 and shows a state when the fuel injection valve is closed. FIG. 3 is a diagram showing an initial stage when the fuel injection valve is opened in FIG. 2. It is a figure which shows a state when pushing up a needle further from the state of FIG. FIG. 3 is a view corresponding to FIG. 2 in another embodiment of the fuel injection valve according to the present invention.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  1 to 4 show an embodiment of the present invention. In the figure, 1 indicates the entire fuel injection valve. The fuel injection valve 1 is a high-pressure injection valve used to inject fuel such as gasoline into a combustion chamber of an internal combustion engine.

  As shown in FIG. 1, the housing 2 of the fuel injection valve 1 has a configuration in which an upper housing 2a made of a magnetic material and a lower housing 2b made of a magnetic material are connected via a relay ring 2c made of a nonmagnetic material. Yes.

  The upper housing 2a, the relay ring 2c, and the lower housing 2b are connected by, for example, laser welding. The outer diameter and inner diameter of the upper housing 2a are set larger than the outer diameter and inner diameter of the lower housing 2b, respectively. However, the outer diameter and inner diameter of the upper part of the lower housing 2b are set to be substantially the same as the outer diameter and inner diameter of the upper housing 2a.

  The non-magnetic relay ring 2c is provided to prevent a magnetic short circuit between the magnetic upper housing 2a and the magnetic lower housing 2b.

  A fuel introduction pipe 3 is attached to the upper opening of the upper housing 2a, and a cylindrical nozzle body 4 is fixed to the lower opening of the lower housing 2b by, for example, press-fitting or welding.

  In the center of the nozzle body 4, a hole 4a whose lower end in the axial direction is closed is provided, and on the lower side of the nozzle body 4, a protruding portion that protrudes outward is formed on the lower closed portion of the hole 4a. 4b is provided. The projecting portion 4b is provided with a plurality of fuel injection ports 4c. A mortar-shaped valve seat 4 d is provided on the base side of the lower protrusion of the nozzle body 4.

  The housing 2 contains a fixed core 5, an armature (also referred to as a movable core) 6, a needle 7, a return spring 8, and the like, and an electromagnet unit 9 is attached to the outer diameter side of the housing 2. ing.

  The fixed core 5 is made of a long cylindrical member made of a magnetic material, and is fitted and fixed to an area occupying most of the internal space of the upper housing 2a so as to be immovable in the axial direction and the circumferential direction. The central hole of the fixed core 5 serves as a fuel supply passage.

  The lower surface of the fixed core 5 is used as a first stopper for restricting the amount of axial displacement (amount of increase) when the armature 6 is attracted by the electromagnet unit 9 as described below.

  The armature 6 is made of a short cylindrical member made of a magnetic material, and is housed in the lower region of the inner space of the upper housing 2a so as to be vertically displaceable. Around the central hole of the armature 6, a plurality of holes (fuel passages) 6a penetrating in the axial direction are provided.

  A valve body 7a for opening and closing the injection port 4c is provided at the lower end (one axial direction) of the needle 7, and a flange 7b projecting radially outward is provided at the upper end (the other axial end) of the needle 7. Is provided.

  The upper portion of the needle 7 is formed in a hollow shape, and a lateral hole 7c penetrating in the radial direction is provided at a predetermined position of the hollow portion. Further, a large diameter portion 7d having a large outer diameter is provided in the vicinity of the valve body 7a of the needle 7. The large diameter portion 7d is fitted into the hole 4a of the nozzle body 4 so as to be relatively displaceable, and is provided to guide the axial displacement of the needle 7.

  Furthermore, a flanged sleeve 10 is fixed to the outer diameter side of the needle 7 in the middle in the longitudinal direction (intermediate in the axial direction) by, for example, welding, adhesion or press fitting.

  As will be described below, the sleeve 10 is a first for restricting the amount of axial displacement (lowering amount) when the armature 6 is not attracted by the electromagnet unit 9 and is urged by the return spring 8 and the spring 12 below. 2 Used as a stopper.

  The valve body 7 a of the needle 7 is formed in a tapered shape so as to match and abut the mortar-shaped valve seat 4 d of the nozzle body 4. When the valve body 7a comes into contact with the valve seat 4d of the nozzle body 4, the injection port 4c of the nozzle body 4 is closed, and when the valve body 7a is separated from the valve seat 4d, the injection port 4c of the nozzle body 4 is opened. Open state.

  The flange 7b of the needle 7 is disposed in a non-contact manner in the center hole of the fixed core 5 so as to be relatively displaceable.

  The body of the needle 7 is inserted into the center hole of the armature 6 so as to be capable of relative displacement, and the reason why the needle 7 and the armature 6 can be relatively displaced is to reduce so-called needle bounce. is there. An annular gap is provided in a portion where the body of the needle 7 and the inner space of the lower housing 2b are opposed to each other. This annular facing gap becomes a fuel supply passage.

  The return spring 8 is a cylindrical compression coil spring, and is disposed so as to be coaxially connected to the upper end side of the flange 7 b of the needle 7 by being housed in the center hole of the fixed core 5.

  Specifically, the return spring 8 is compressed by being sandwiched between the flange 7 b of the needle 7 and the adjusting pipe 11 fitted and fixed to the upper part of the center hole of the fixed core 5. The return spring 8 urges the needle 7 toward the side (lower side) for closing the injection port 4c of the nozzle body 4 by an elastic restoring force from the compressed state.

  The electromagnet unit 9 displaces the needle 7 in the axial direction toward the opening side of the injection port 4c of the nozzle body 4 by generating a magnetic attractive force that pulls the armature 6 against the elastic restoring force (biasing force) of the return spring 8. It is something to be made.

  In the electromagnet unit 9, a coil 9c wound around a spool 9b is installed on the inner periphery of a cylindrical case 9a made of a magnetic material. Further, a connector 9e having a power supply terminal 9d for the coil 9c is provided on the case 9a. It is attached.

  By supplying power to the coil 9c of the electromagnet unit 9, a magnetic field is generated by the magnetic field generated in the coil 9c and flows to the upper housing 2a, the fixed core 5, the armature 6, the lower housing 2b, and the case 9a to form a magnetic circuit. In order to make this possible, as described above, the upper housing 2a, the lower housing 2b, the fixed core 5, the armature 6, and the case 9a are made of a magnetic material.

  By the way, the high-pressure fuel introduced from the fuel introduction pipe 3 passes through the center hole of the fixed core 5, the lateral hole 7 c of the needle 7, the gap between the fixed core 5 and the armature 6, and the gap between the lower housing 2 b and the needle 7. Introduced and filled. When the injection port 4c of the nozzle body 4 is opened, the high-pressure fuel filled in the facing gap between the lower housing 2b and the needle 7 is injected to the outside from the injection port 4c of the nozzle body 4.

  In this embodiment, as shown in FIGS. 1 and 2, a spring 12 is provided for urging the armature 6 and the flange 7 b of the needle 7 in a pulling direction so as not to contact each other.

  This spring 12 is a cylindrical compression coil spring, and is compressed in a state of being concentric with the outer diameter side of the needle 7 and between the upper face of the armature 6 and the lower face of the flange 7b of the needle 7 in the axial direction. Has been placed. The spring constant of the spring 12 is set smaller than the spring constant of the return spring 8.

  The central hole of the armature 6 has a large diameter in the upper half region in the axial direction and a small diameter in the lower half region. The step wall surface 6 b along the radial direction between the large diameter region and the small diameter region is a spring receiving surface that receives the lower end of the spring 12. The lower surface of the flange 7b of the needle 7 is a spring receiving surface that receives the upper end of the spring 12.

  Next, the operation of the fuel injection valve 1 will be described with reference to FIGS.

  First, in a state where power supply to the coil 9c is stopped, the needle 7 is biased downward by the elastic restoring force of the return spring 8, as shown in FIGS. The valve body 7a is in contact with the valve seat 4d of the nozzle body 4, and the injection port 4c of the nozzle body 4 is closed.

  Therefore, when power is supplied to the coil 9c of the electromagnet unit 9, the magnetic field generated by the coil 9c causes the magnetic flux to flow to the upper housing 2a, the fixed core 5, the armature 6, the lower housing 2b, and the case 9a to form a magnetic circuit. Since the armature 6 is attracted to the lower surface side of the fixed core 5, the armature 6 is raised.

  As the armature 6 rises, as shown in FIG. 3, the spring 12 is compressed and the upper surface of the armature 6 contacts the lower surface of the flange 7 b of the needle 7 as an initial stage.

  Subsequently, as shown in FIG. 4, the armature 6 is further pulled upward by the magnetic attraction force generated by the electromagnet unit 9, so that the armature 6 raises the needle 7.

  As a result, the valve body 7a of the needle 7 is separated from the valve seat 4d of the nozzle body 4 to open the injection port 4c of the nozzle body 4, so that the facing gap between the lower housing 2b and the needle 7 is filled. High-pressure fuel is injected outside from the injection port 4c.

  Thereafter, when the power supply to the coil 9c is stopped, the needle 7 is pushed down by the elastic restoring force of the return spring 8, and the valve body 7a of the needle 7 is brought into contact with the valve seat 4d of the nozzle body 4. Thus, the injection port 4c of the nozzle body 4 is closed.

  By the way, when the armature 6 ascends or descends as described above, the fuel present around the armature 6 can move through the hole 6a of the armature 6, so that the fuel present around the armature 6 It is not necessary to have a resistance when raising and lowering 6. Therefore, the movement of the armature 6 is smooth, and the responsiveness of the opening / closing operation of the fuel injection valve 1 is good.

  As is apparent from the above description, in the fuel injection valve 1 according to the embodiment to which the present invention is applied, the axial displacement amount of the needle 7 is set to the distance 20 from the lower surface of the fixed core 5 to the lower surface of the flange 7b of the needle 7. (See FIGS. 2 and 3).

  In this embodiment, the armature 6 and the flange 7b of the needle 7 are not in contact with each other when the fuel injection valve 1 is fully closed. Therefore, slight vibration is generated when the fuel injection valve 1 is fully closed. Even if the armature 6 and the flange 7b of the needle 7 are moved relative to each other, the surfaces where the armature 6 and the flange 7b of the needle 7 are opposed do not come into frictional contact.

  In other words, in this embodiment, the trouble (wear with time of the contact portion) that occurs when the armature 6 and the flange 7b of the needle 7 are always in contact as in the conventional example does not occur. You don't have to.

  Therefore, in the case of the fuel injection valve 1 of this embodiment, it is possible to keep the initial setting value without changing the distance 20 regardless of the progress of use. As a result, it becomes possible to avoid the change, and as a result, it becomes possible to keep the fuel injection amount at the initial set value and contribute to the improvement of reliability.

  By the way, in this embodiment, the spring 12 for making the armature 6 and the flange 7b of the needle 7 non-contact is provided between the stepped wall surface 6b provided in the center hole of the armature 6 and the flange 7b of the needle 7 along the radial direction. Since it is made to contact directly with the lower surface, for example, a separate spring support is not used, it is advantageous in suppressing an increase in equipment cost, such as eliminating the need for adding extra parts.

  In addition, this invention is not limited only to the said embodiment, It can change suitably in the range equivalent to the claim and the said range.

  (1) In the above embodiment, for example, the case where the flange 7b is integrally formed at the upper end of the needle 7 is described as an example. However, the present invention is not limited to this. It can be formed separately and fixed to the needle 7 by, for example, welding, adhesion or press fitting.

  (2) In the above embodiment, an example in which the flanged sleeve 10 is attached to the needle 7 as the second stopper for regulating the lower slide position of the armature 6 is described, but the present invention is limited to this. Is not to be done.

  For example, as shown in FIG. 5, by providing a protruding portion 2d extending in the axial direction on the step wall surface portion along the radial direction in the upper diameter-expanded portion of the lower housing 2b, this protruding portion 2d is used as the second stopper. Is possible. In this case, since the existing lower housing 2b is used and it is not necessary to use a separate member such as the flanged sleeve 10, it is advantageous in reducing the equipment cost compared to the above embodiment.

  INDUSTRIAL APPLICABILITY The present invention can be used for a fuel injection valve for injecting fuel into an internal combustion engine. In particular, the invention is used for a fuel injection valve configured to inject and stop fuel by displacing a needle in the axial direction. be able to.

1 Fuel injection valve
2 Housing
2a Upper housing
2b Lower housing
4 Nozzle body
4c injection port
4d valve seat
5 Fixed core
6 Armature
7 Needle
7a Disc
7b Flange
8 Return spring
9 Electromagnet unit
9c Coil 10 Sleeve 12 Spring

Claims (3)

A needle having a valve body for opening and closing the fuel injection port at one end and a flange at the other end;
A return spring that abuts against the needle flange and biases the needle toward the side of closing the injection port;
An armature provided so as to be relatively displaceable on the outer diameter side of the needle near the flange;
A spring provided between the armature and the flange of the needle in the axial direction so as to urge the armature and the needle apart in a non-contacting manner;
A drive source for axially displacing the needle toward the opening side of the injection port by generating a magnetic attractive force that pulls the armature against the urging force of the return spring;
A first stopper for regulating an axial displacement amount when the armature is attracted by the drive source;
Look including a second stopper for limiting the axial displacement amount when the armature is biased by the return spring and the spring when it is not attracted by the drive source,
The armature is formed of a magnetic material in a cylindrical shape, and a region from the end surface on the flange side to the middle in the central axis direction is a large diameter in the center hole,
The return spring is a cylindrical compression coil spring arranged to be coaxial with the other end of the needle,
The spring is arranged concentrically on the outer diameter side of the needle and between the flange of the needle and a step wall along the radial direction in a region where the diameter of the central hole of the armature is large. A cylindrical compression coil spring,
The second stopper is a cylindrical member that is attached to the outer periphery of the needle, and is a cylindrical member that is axially opposed to an end face of the armature located on the valve body side of the needle. valve. The fuel injection valve according to claim 1, wherein
The drive source is an electromagnet that generates a magnetic attraction force with power feeding ;
Fuel injection valve spring constant of the front Symbol spring, the return is set to be smaller than the spring constant of the spring, characterized in that. The fuel injection valve according to claim 1 or 2,
The first stopper is a cylindrical member that is arranged in a non-contact surrounding manner on the outer diameter side of the return spring and the flange of the needle and is axially opposed to an end face located on the flange side of the needle in the armature. A fuel injection valve characterized in that it is a part.

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