JP5222253B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve used in an internal combustion engine, and more particularly to a fuel injection valve suitable for reducing the minimum injection amount that can control the fuel injection amount.

  2. Description of the Related Art Conventionally, a fuel injection valve used in an internal combustion engine supplies a magnetic flux to a magnetic path including a movable core (anchor) of a mover and a fixed core by flowing a current through a coil. The valve element is opened and closed by generating a magnetic attractive force in the magnetic attractive gap between the end face and attracting the mover toward the fixed core. Specifically, the fixed core is fixed inside the metal cylinder, and the mover is arranged in the metal cylinder so that it can be attracted to or separated from the fixed core, and the coil and housing are arranged outside the metal cylinder. To supply magnetic flux to the movable core and the fixed core.

  Here, by obtaining a magnetic attractive force with a small magnetomotive force, to obtain a good magnetic attractive force and reduce the minimum injection amount (controllable minimum injection amount) that can control the fuel injection amount, the fixed core and the movable core It is known that the magnetic attraction gap portion on the end surface has a facing surface (see, for example, Patent Document 1).

  In addition, as what has the structure similar to this invention, what provided the inner protrusion and the outer protrusion on the end surface of the needle | mover which opposes a fixed core is known (for example, refer patent document 2).

  As another example, there is known one in which three convex portions are provided on the end face of the mover facing the fixed core (see, for example, Patent Document 3).

JP 2008-19785 A JP 2003-106236 A JP 2007-205234 A

  However, in the thing of patent document 1, since both a movable core and a plunger rod part can cooperate, the attitude | position which a movable core contacts the fixed core which is an opposing surface is plunger rod itself. The inclination angle / movable core and the inclination angle generated by the sliding clearance of the plunger rod have a very high possibility of contact. As described above, as an adverse effect due to the one-sided contact, the gap facing surface of the magnetic attraction portion set in the initial stage is repeatedly distorted and deformed by repeatedly receiving the operation due to the collision. In particular, the possibility increases by using a soft magnetic material for the movable core and the fixed core in order to obtain a magnetic attractive force. As a result, the valve body stroke of the fuel injection valve becomes excessive, so that the valve body responsiveness is deteriorated, and there is a possibility that the initial controllable minimum injection amount obtained may change.

  In the case of the one described in Patent Document 2, a concave portion is provided on the end face of the movable element facing the fixed core, and an outer projection is provided to obtain a damper action by the concave portion. The difference in height between the inner protrusions is higher when the damper effect is higher.

  Moreover, in the thing of patent document 3, since three protrusions are provided in the end surface of a needle | mover in order to increase the quantity of the magnetic flux which flows between a fixed core and a needle | mover, these protrusions The height should be the same.

  The objective of this invention is providing the fuel injection valve which can reduce the change of the minimum injection quantity which can control fuel injection quantity.

(1) In order to achieve the above object, the present invention provides a fixed core, a nozzle body having a seat portion at the tip, and a movable valve body that can reciprocate within the nozzle body and abuts against the seat portion. A magnetic flux is supplied to a magnetic path including the movable core of the mover and the fixed core, and a magnetic attraction gap between the movable core end surface of the mover and the fixed core end surface is provided. A fuel injection valve that generates a magnetic attractive force to attract the mover toward the fixed core, and opens the fuel passage by pulling the valve element away from the seat portion. The fuel injection valve is formed on a surface facing the movable core or the fixed core. An annular first protrusion provided on one side and an annular second protrusion provided on the outer peripheral side of the first protrusion, the height of the second protrusion being The height of the first protrusion is lower than the first protrusion. In the core, with respect to the angle that the sum of the inclination angle of the inclination angle and the movable core itself of the movable valve body with respect to the central axis of the nozzle body cylindrical alpha, the said first projecting portion of the movable core first An angle θ ° formed by a line connecting the two protrusions in the radial direction of the movable core with respect to a reference plane (a surface where the protrusion is formed; a plane in a portion where there is no protrusion) is large , and the angle θ The angle α difference (θ−α) is 0.1 ° to 1.5 ° .
With this configuration, it is possible to reduce a change in the minimum injection amount that can control the fuel injection amount.

  (2) In the above (1), preferably, the movable core has a plurality of through-holes formed in a direction that coincides with the fuel injection valve body axis at a position that blocks the annular portion of the first protrusion. Is provided.

  According to the present invention, it is possible to suppress the deformation that occurs permanently on the opposed surfaces of the fixed core and the movable core, and to minimize the amount of change in the valve body stroke due to repetitive operation, the minimum injection amount that can control the fuel injection amount. The change can be reduced.

It is a longitudinal section showing the whole fuel injection valve composition by one embodiment of the present invention. It is a partial expanded sectional view which shows the principal part detailed structure of the fuel injection valve by one Embodiment of this invention. It is a top view of the movable core used for the fuel injection valve by one Embodiment of this invention. It is a partial expanded sectional view which shows the principal part detailed structure of a fuel injection valve when there is no outside protrusion part. It is a partial expanded sectional view which shows the principal part detailed structure of the fuel injection valve by one Embodiment of this invention. It is explanatory drawing of the moving amount | distance of the movable core in the fuel injection valve by one Embodiment of this invention. It is explanatory drawing of the dimension of the projection part in the fuel injection valve by one Embodiment of this invention. It is explanatory drawing of the surface pressure reduction effect with respect to the change of the dimension of the projection part in the fuel injection valve by one Embodiment of this invention.

Hereinafter, the configuration and operation of a fuel injection valve according to an embodiment of the present invention will be described with reference to FIGS.
Initially, the whole structure of the fuel injection valve by this embodiment is demonstrated using FIG.
FIG. 1 is a longitudinal sectional view showing the overall configuration of a fuel injection valve according to an embodiment of the present invention.

  The fuel injection valve of the present embodiment is a fuel injection valve that directly injects fuel such as gasoline into an engine cylinder (combustion chamber).

  The fuel injection valve body 1 has a hollow fixed core 2, a yoke 3 that also serves as a housing, a mover 4, and a nozzle body 5. The mover 4 includes a movable core 40 and a movable valve body 41. Here, the fixed core 2, the yoke 3, and the movable core 40 are components of the magnetic circuit.

  The yoke 3, the nozzle body 5, and the fixed core 2 are joined by welding. There are various coupling modes. In this example, the nozzle body 5 and the fixed core 2 are welded and joined in a state where a part of the inner periphery of the nozzle body 5 is fitted to a part of the outer periphery of the fixed core 2. ing. Further, the nozzle body 5 and the yoke 3 are joined by welding so that the yoke 3 surrounds a part of the outer periphery of the nozzle body 5. An electromagnetic coil 6 is incorporated inside the yoke 3. The electromagnetic coil 6 is covered with a yoke 3, a resin cover 23, and a part of the nozzle body 5 while maintaining a sealing property.

  A movable element 4 is incorporated in the nozzle body 5 so as to be movable in the axial direction. An orifice cup 7 which is a part of the nozzle body is fixed to the tip of the nozzle body 5 by welding. The orifice cup 7 has a conical surface 7A including a seat portion 7B.

  Inside the fixed core 2, a spring 8 that presses the movable element 4 against the seat portion 7B, an adjuster 9 that adjusts the spring force of the spring 8, and a filter 10 are incorporated.

  Guide members 11 and 12 that guide the movement of the movable element 4 in the axial direction are provided inside the nozzle body 5 and the orifice cup 7. The guide member 11 is fixed to the nozzle body 5. The guide member 12 is fixed to the orifice cup 7. The mover 4 is guided to move in the axial direction by two guide members 11 and 12 arranged vertically.

  The valve body (valve rod) 41 of this example shows a needle type with a tapered tip, but may be a type with a spherical body at the tip.

  The fuel passage in the fuel injection valve includes an inside of the fixed core 2, a plurality of holes 13 provided in the movable core 40, a plurality of holes 14 provided in the guide member 11, the inside of the nozzle body 5, and the guide member 12. And a conical surface 7A including the sheet portion 7B.

  The resin cover 23 is provided with a connector portion 23A for supplying an exciting current (pulse current) to the electromagnetic coil 6, and a part of the lead terminal 18 insulated by the resin cover 23 is located in the connector portion 23A.

  When the electromagnetic coil 6 housed in the yoke 3 is excited by an external drive circuit (not shown) via the lead terminal 18, the fixed core 2, the yoke 3 and the movable core 40 form a magnetic circuit, and the mover 4 is It is magnetically attracted against the force of the spring 8 on the fixed core 2 side. At this time, the movable element 4 is moved upward by the movable gap 200 between the movable core 40 and the fixed core 2, and the valve element 41 is separated from the seat portion 7B to be opened, and an external high-pressure pump (not shown). The fuel in the fuel injection valve body 1 that has been previously pressurized (1 MPa or more) is injected from the injection hole 7C. A plurality of, for example, six nozzle holes 7C are provided.

  When the excitation of the electromagnetic coil 6 is turned off, the valve element 41 is pressed against the seat portion 7B side by the force of the spring 8, and the valve is closed.

Next, the detailed configuration of the main part of the fuel injection valve according to the present embodiment will be described with reference to FIGS. 2 and 3.
FIG. 2 is a partially enlarged cross-sectional view showing a detailed configuration of a main part of the fuel injection valve according to the embodiment of the present invention. FIG. 3 is a top view of the movable core used in the fuel injection valve according to the embodiment of the present invention. 2 is a cross-sectional view taken along the line AA in FIG. 2 and 3, the same reference numerals as those in FIG. 1 denote the same parts.

  As shown in FIG. 2, by providing an inner protrusion 40A on the upper surface of the movable core 40 on the opposite surface of the fixed core 2 and the movable core 40, the magnetic circuit is optimized and the responsiveness of the valve body is ensured. Yes. In this example, an inner protrusion 40A that directly collides with the fixed core is provided on the end surface of the movable core 40, and an outer protrusion 40B is provided so as to surround the inner protrusion 40A. Here, the height of the outer protruding portion 40B is set lower than the height of the inner protruding portion 40A, and in the initial dimension setting, only the inner protruding portion 40A is set to a dimension that collides with the fixed core 2. The heights of the inner protrusion 40A and the outer protrusion 40B will be described later with reference to FIG.

  Further, as shown in FIG. 3, the inner protrusion 40A is an annular protrusion. However, as shown in FIG. 3, four holes 13 through which the fuel passes are formed in the axial direction of the fuel injection valve main body so as to block the ring of the inner protrusion 40A. This is a structure necessary to prevent the movable core 40 from sticking to the fixed core 2 due to a squeeze effect when the movable core 40 collides with the fixed core 2 and to secure a fuel passage.

  The outer protrusion 40B is an annular protrusion that is concentric with the inner protrusion 40A so as to surround the inner protrusion 40A.

  In FIG. 3, a portion illustrated as a semicircular arc around the hole 13 is a chamfered portion 40 </ b> C also illustrated in FIG. 2.

Next, the operation | movement at the time of the one-sided contact in the fuel injection valve by this embodiment is demonstrated using FIG.4 and FIG.5.
FIG. 4 is a partial enlarged cross-sectional view showing the detailed configuration of the main part of the fuel injection valve when there is no outer protrusion. FIG. 5 is a partial enlarged cross-sectional view showing a detailed configuration of a main part of the fuel injection valve according to the embodiment of the present invention. 4 and 5, the same reference numerals as those in FIGS. 1 to 3 denote the same parts.

  The operation of the movable core 40 when colliding with the fixed core 2 is limited by the sliding part size (clearance / clearance length) of the movable element 4, and the opposing surfaces do not necessarily collide vertically. . In other words, when the movable core 40 collides with the fixed core 2, the movable core 40 hits one side at a certain inclination angle α ° due to the limitation of the clearance of the movable element 4. The angle α ° is an angle obtained by adding the falling angle of the mover 4 and the falling of the movable core itself.

  FIG. 4 shows a case where only the inner protrusion 40A exists on the movable core 40, and the movable core 40 hits one side. In the transient region at the time of collision with the fixed core 2, the inner projection 40 </ b> A does not collide uniformly, so that the collision surface slightly deforms. By repeating the collision, the slight deformation of the collision surface becomes permanent. Therefore, the movable gap 200 (FIG. 1) increases from the initially set gap. As a result, since the gap between the seat portion 7B and the mover 4 also increases, the flow rate of fuel injected from the injection hole 7C also increases with respect to the initial stage.

  On the other hand, as shown in FIG. 5, in this embodiment, the end surface of the movable core 40 is provided with an outer protrusion 40B in addition to the inner protrusion 40A. Here, when the angle connecting the inner protrusion 40A and the outer protrusion 40B is θ °, the angle is set to be larger than the angle α ° to which the clearance of the movable element 4 is restricted. The angle θ ° is an angle formed by a line connecting the inner protrusion 40A and the outer protrusion 40B with respect to a reference surface (a surface where the protrusion is formed; a plane where there is no protrusion). As a result, the outer protrusion 40B collides with the fixed core 2 only in the region where the inner protrusion 40A undergoes a transient deformation at the time of collision, but the surface pressure at the time of collision is reduced compared to the case of only the inner protrusion 40A. The amount of deformation at the time of collision can be reduced. Therefore, the movable gap 200 may slightly increase from the initially set gap, but the amount can be controlled.

  In the region where the inner protrusion 40A does not undergo a transitional deformation at the time of collision, the inner protrusion 40A collides with the fixed core 2, and the initially set gap can be substantially maintained.

Next, the movement amount of the movable core 40 in the fuel injection valve according to the present embodiment will be described with reference to FIG.
FIG. 6 is an explanatory diagram of the moving amount of the movable core in the fuel injection valve according to the embodiment of the present invention.

  In FIG. 6, the vertical axis represents the amount of movement of the movable core 40, and the horizontal axis represents time.

  The characteristic indicated by the dotted line A indicates the amount of movement of the movable core 40 when the inner projection 40A is provided with only the inner projection 40A on the end face of the movable core 40 and the inner projection 40A undergoes a transient deformation at the time of collision. . As shown in the figure, in the transition region, the slight deformation amount greatly overshoots the initial set movable gap.

  The characteristic indicated by the solid line B is the case where the outer protrusion 40B is provided in addition to the inner protrusion 40A in the present embodiment. Here, by setting the angle θ ° connecting the inner protrusion 40A and the outer protrusion 40B and the dimensions of the inner and outer protrusions 40A and 40B to predetermined values, overshoot can be reduced. The angle θ ° connecting the inner protrusion 40A and the outer protrusion 40B is an angle uniquely determined by the clearance formed by the movable element 4 (an angle obtained by adding the inclination angle of the movable element 4 and the inclination of the movable core itself) α °. On the other hand, θ> α.

Next, the dimensions of the protrusions and the effect of reducing the surface pressure at the time of collision in the fuel injection valve according to the present embodiment will be described with reference to FIGS.
FIG. 7 is an explanatory diagram of the dimensions of the protrusions in the fuel injection valve according to the embodiment of the present invention. FIG. 8 is an explanatory diagram of the effect of reducing the surface pressure with respect to the change in the dimension of the protrusion in the fuel injection valve according to the embodiment of the present invention.

  As shown in FIG. 7, the protrusion is defined by the protrusion width t and the protrusion start position d. The inner protrusion 40A has a protrusion width t1 and a protrusion start position d1, and the outer protrusion 40B has a protrusion width t2 and a protrusion start position d2.

The protrusion area A is expressed by the following (Formula 1).

A = (π / 4) ((d + 2t) ² −d ² ) (1)

Further, when the surface pressure reduction rate n at the time of collision by the outer protrusion 40B is n (n <100% is arbitrary), (Expression 2) is established.

(A1 / (A1 + A2)) = n (2)


Here, when d1, d2, t1, and t2 are arranged, (Expression 3) is obtained.

1 = n × (1 + ((d2 × t2 + t2 ² ) / (d1 × t1 + t1 ² ))) (3)

FIG. 8 shows the relationship between the dimensions of the inner protrusion 40A and the outer protrusion 40B when the horizontal axis is d2 / d1 and the vertical axis t2 / t1. Here, as the surface pressure decrease rate n at the time of collision, 30% to 60% is illustrated.

  The angle α °, which is the sum of the tilt angle of the mover 4 and the tilt of the movable core itself, varies depending on the sliding part dimensions (clearance and clearance length) and the tilt angle of the movable core itself.

  Here, the outer dimensions of the fuel injection valve whose overall shape is shown in FIG. 1 are substantially constant. Further, as shown in FIG. 1, in the structure in which the movement of the mover 4 in the axial direction is guided by the two guide members 11 and 12, the tilt angle of the mover 4 is considerably small and almost constant. In addition, the tilt angle of the movable core itself is almost constant although it depends on the work accuracy. In the actual measurement by the present inventors, the angle α ° was 0.5 °.

  On the other hand, the angle θ ° connecting the inner protrusion 40A and the outer protrusion 40B needs to be larger than the angle α °. However, if the angle is too large, the inner protrusion 40A may be deformed transiently during a collision. The outer projection 40B will not collide with the fixed core 2, and the effect will not be exhibited. The difference (θ−α) between the angle θ and the angle α is suitably 0.1 ° to 1.5 °. That is, when the angle α is 0.5 °, the angle θ is set to 0.6 ° to 2.0 °.

  Here, a specific example will be described. The projection width t1 of the inner projection 40A is 0.35 mm, the projection start position d1 is 6.4φ, the projection height h1 is 0.02 mm, and the projection width of the outer projection 40B. When t2 is 0.35 mm, the protrusion start position d2 is 8.0φ, and the protrusion height h2 is 0.015 mm, d2 / d1 is 1.25 and t2 / t1 is 1.0. The surface pressure reduction rate at the time of collision is about 40%. At this time, the angle θ is 0.8 °.

  In the above description, the protrusions 40A and 40B are provided on the surface of the movable core 40 facing the fixed core, but may be provided on the surface of the fixed core 2 facing the movable core. However, since the movable core 40 generally requires cutting with high machining accuracy, it is preferable in terms of machining work to form the protrusions 40A and 40B when the movable core 40 is cut.

The movable core 40 is configured separately from the movable element 4, but the present invention can also be applied to a configuration in which both are integrated.

DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve main body 2 ... Fixed core 3 ... Yoke 3
4 ... movable element 5 ... nozzle body 6 ... electromagnetic coil 7 ... orifice cup 8 ... spring 9 ... adjuster 10 ... filter 11, 12 ... guide members 13, 14 ... hole 15 ... side groove 18 ... lead terminal 23 ... resin cover 40 ... movable Core 40A ... inner projection 40B ... outer projection 40C ... chamfer 41 ... movable valve element 200 ... movable gap

Claims (2)

A fixed core, a nozzle body having a seat portion at the tip, and a movable element having a movable valve body that can reciprocate inside the nozzle body and abuts against the seat portion;
Magnetic flux is supplied to a magnetic path including the movable core of the mover and the fixed core, and a magnetic attraction force is generated in a magnetic attraction gap between the movable core end face of the mover and the fixed core end face. A fuel injection valve that opens a fuel passage by attracting a child to the fixed core side and pulling the valve body away from the seat part,
An annular first protrusion provided on one of the opposing surfaces of the movable core or the fixed core, and an annular second protrusion provided on the outer peripheral side of the first protrusion. ,
The height of the second protrusion is lower than the height of the first protrusion,
In the movable core, the first protrusion of the movable core with respect to an angle α obtained by summing a tilt angle of the movable valve body with respect to a central axis of the cylindrical nozzle body and a tilt angle of the movable core itself; An angle θ ° formed by a line connecting the second protrusion in the radial direction of the movable core with respect to a reference surface (a surface where the protrusion is formed; a plane in a portion where there is no protrusion) is large , and the angle A fuel injection valve characterized in that a difference between θ and angle α (θ−α) is 0.1 ° to 1.5 ° . The fuel injection valve according to claim 1, wherein
The movable core includes a plurality of through holes formed in a direction that coincides with a fuel injection valve body axis at a position where the annular portion of the first protrusion is blocked.

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