JP6591597B2 - Fuel injection valve - Google Patents

Description

  The present invention is a fuel injection valve used in an internal combustion engine such as a gasoline engine, wherein the valve body is in contact with the valve seat to prevent fuel leakage, and injection is performed by the valve body separating from the valve seat. The present invention relates to a fuel injection valve.

  2. Description of the Related Art A fuel injection valve that diffuses spray by causing a deviation in the fuel flow by decentering the central axis direction of the nozzle hole with respect to the central axis of the nozzle body is known (see Patent Document 1). In this fuel injection valve, when the direction of the central axis of the nozzle hole is eccentric with respect to the central axis of the nozzle body, the shape of the inlet part of the nozzle hole that appears on the inner wall surface of the nozzle body is an elliptical shape and is close to a perfect circle Compared with, it is possible to generate a drift in the flow of fuel entering the nozzle hole. The drifted fuel becomes a swirl flow in the nozzle hole, and the spray shape of the fuel at the outlet part of the nozzle hole can be in a diffusion state.

JP 2007-107459 A

  Particulate matter such as HC (hydrocarbon) and soot contained in the exhaust gas, the fuel that collides and adheres to the wall surface of the cylinder and the intake valve becomes unburned in a situation where the flame is difficult to propagate, Occurs by becoming locally rich. To suppress these, the spray itself is shortened so that the spray does not collide with the wall surface in the cylinder, and the spray shape is configured so that the spray can be laid out so that the spray does not collide with the intake valve or the like. A high degree of freedom is required.

  In the fuel injection valve disclosed in the above-mentioned Patent Document 1, the flow of the fuel is caused to drift by decentering the central axis direction of the nozzle hole with respect to the central axis of the nozzle body, thereby diffusing the spray. It is possible. However, there is no sufficient description of the effect of eccentricity on fuel flow and spraying. In addition, since the spray layout in the cylinder is not sufficiently studied and the spray diffused around the fuel injection valve is configured, the spray may collide and adhere to the wall surface and the intake valve in the cylinder.

  An object of the present invention is to reduce the amount of fuel adhering to the intake valve and the inner wall surface of the cylinder when the fuel is directly injected into the cylinder. It is to provide an injection valve.

In the fuel injection valve according to the present invention, the valve seat surface having a conical surface, the fuel injection hole in which an inlet opening is formed on the conical surface on the downstream side of the valve seat surface, and the valve seat surface are in contact with and separated from each other. And a valve body that opens and closes the flow of fuel to the fuel injection hole, wherein the fuel injection hole is an injection hole that connects the center of the inlet opening and the center of the outlet opening of the fuel injection hole. The shaft is formed so as to be on a plane different from the plane including the center axis of the valve body and the center of the inlet opening of the fuel injection hole, and the fuel injection hole extends from the inlet side of the fuel injection hole. The fuel injection hole is formed so that the inner diameter thereof decreases toward the outlet side.

  According to the present invention, it is possible to shorten the spray reach distance, and at the same time, improve the spray layout and eliminate the adhesion to the intake valve or the like in the cylinder, thereby realizing an internal combustion engine with improved exhaust performance. A fuel injection valve can be provided.

It is a longitudinal cross-sectional view parallel to the center axis | shaft of a fuel injection valve which shows the Example of the fuel injection valve which concerns on this invention. It is the longitudinal cross-sectional view which expanded the vicinity of the nozzle tip of the fuel injection valve which concerns on 1st Example of this invention. It is AA sectional drawing of FIG. 2 which concerns on 1st Example of this invention. It is the enlarged view which showed one of the fuel injection holes which concern on 1st Example of this invention. It is the figure which showed the spray shape of the fuel injection valve which concerns on 1st Example of this invention. It is a figure explaining the side surface of the virtual cone which the direction of a fuel injection hole axis | shaft forms in the fuel injection valve which concerns on 1st Example of this invention. It is a figure for demonstrating the effect of the fuel injection hole twist angle which concerns on 1st Example of this invention. It is the figure shown about the structure of the fuel injection hole of the fuel injection valve which concerns on 2nd Example of this invention. It is the figure shown about the spray shape of the fuel injection valve which concerns on 2nd Example of this invention.

  Examples according to the present invention will be described below.

  A fuel injection valve according to a first embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a longitudinal sectional view parallel to the central axis of a fuel injection valve, showing an example of an electromagnetic fuel injection valve as an example of a fuel injection valve according to the present invention. FIG. 2 is an enlarged longitudinal sectional view of the lower end portion of the nozzle body in the fuel injection valve according to the first embodiment. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2, and is an enlarged view for explaining the configuration of the fuel injection hole (positional relationship between the inlet and the outlet). FIG. 4 is an enlarged view of one fuel injection hole in FIG. 3, and is an enlarged view for explaining the flow in the vicinity of the fuel injection hole and the effect thereof. FIG. 5 is a view for explaining the direction of the fuel injection hole axis (also referred to as the injection hole axis) and the spray shape formed when fuel is injected in the fuel injection valve according to the first embodiment. FIG. 6 is a diagram illustrating the side surface of the virtual cone formed by the direction of the fuel injection hole axis in the fuel injection valve according to the first embodiment. FIG. 7 is a diagram for explaining the effect of the fuel injection hole twist angle according to the first embodiment.

  The electromagnetic fuel injection valve 100 shown in FIG. 1 is an example of an electromagnetic fuel injection valve for an in-cylinder direct injection gasoline engine, but the effect of the present invention is intended for a port injection gasoline engine. It is also effective in an electromagnetic fuel injection valve, and a fuel injection valve driven by a piezo element or a magnetostrictive element.

<< Explanation of basic operation of injection valve >>
In FIG. 1, fuel is supplied from a fuel supply port 112 and is supplied into the fuel injection valve. The electromagnetic fuel injection valve 100 shown in FIG. 1 is a normally closed electromagnetic drive type, and when the coil 108 is not energized, the valve body 101 is urged by the spring 110 and pressed against the seat member 102. The fuel is sealed. At this time, in the fuel injection valve for in-cylinder injection, the supplied fuel pressure is in the range of about 1 MPa to 35 MPa.

  FIG. 2 is an enlarged cross-sectional view of the vicinity of the fuel injection hole 201 provided at the tip of the valve body 101. When the fuel injection valve is in the closed state, the valve body 101 keeps the fuel seal by contacting the valve seat surface 203 formed of a conical surface provided on the seat member 102 joined to the nozzle body 104 by welding or the like. It is like that. At this time, the contact portion on the valve body 101 side is formed by the spherical surface 202, and the contact between the conical valve seat surface 203 and the spherical surface 202 is in a substantially line contact state. When the coil 108 shown in FIG. 1 is energized, a magnetic flux density is generated in the core 107, the yoke 109, and the anchor 106 constituting the magnetic circuit of the solenoid valve, and the magnetic attraction force is generated between the core 107 and the anchor 106 having a gap. Produce. When the magnetic attractive force becomes larger than the force of the biasing force of the spring 110 and the aforementioned fuel pressure, the valve body 101 is attracted to the core 107 side by the anchor 106 while being guided by the guide member 103 and the valve body guide 105 to open the valve. It becomes a state.

  When the valve is opened, a gap is created between the valve seat surface 203 and the spherical surface 202 of the valve body 101, and fuel injection is started. When fuel injection is started, the energy given as the fuel pressure is converted into kinetic energy and injected into the fuel injection hole 201.

《Explanation of hole arrangement》
Next, the effect of the fuel injection hole 201 configured in the seat member 102 and the flowing fuel, the spray shape, and the effect will be described in detail with reference to FIGS.

  FIG. 3 is a cross-sectional view taken along the line AA of the seat member 102 shown in FIG. It is a figure to do.

  The fuel injection hole inlet 304a and the fuel injection hole outlet 305a on the valve seat surface 203 are characterized by having the following relationship. A plane including a straight line 303a connecting the center point 302a at the fuel injection hole inlet 304a and the apex 301 of the valve seat surface 203 and the vertical center axis 204 of the fuel injection valve is a center point 302a at the fuel injection hole inlet 304a. And a plane parallel to the vertical central axis 204 of the fuel injection valve including a straight line 307a connecting the center point 306a at the fuel injection hole outlet 305a with an angle greater than 0 degrees (having a twist angle 308a Cross) The vertical center axis 204 of the fuel injection valve coincides with the central axis of the nozzle body 104. In the above description, 302a to 307a have been described as typical examples, but 302b to 307b, 302c to 307c, 302d to 307d, 302e to 307e, and 302f to 307f in the present embodiment are also the same. A plane that includes the straight line connecting the center point and the apex of the valve seat surface and the central axis in the vertical direction of the fuel injection valve forms a straight line connecting the center point of the fuel injection hole inlet and the center point of the fuel injection hole outlet. The fuel injection valve intersects with a plane parallel to the central axis in the vertical direction at an angle larger than 0 degrees.

  In this embodiment, a fuel injection hole having a fuel injection hole inlet 304b and a fuel injection hole outlet 305b, a fuel injection hole having a fuel injection hole inlet 304d and a fuel injection hole outlet 305d, a fuel injection hole inlet 304f, and a fuel The fuel injection hole having the injection hole outlet 305f constitutes the first spray, the fuel injection hole having the fuel injection hole inlet 304a and the fuel injection hole outlet 305a, the fuel injection hole inlet 304c, and the fuel injection hole outlet 305c. And a fuel injection hole having a fuel injection hole inlet 304e and a fuel injection hole outlet 305e are injected so as to form a second spray. The second spray is injected around the first spray so as to surround the first spray. That is, the second spray constitutes the outer spray of the second spray.

  In this embodiment, the first spray and the second spray are both composed of a plurality of sprays injected from a plurality of fuel injection holes, and each spray is independently distributed in the circumferential direction. . At this time, the fuel injection holes for injecting each of the sprays constituting the first spray have a twist angle, thereby shortening the spray reach and suppressing adhesion to the intake valve and the cylinder inner wall surface. can do.

  In this embodiment, since all the fuel injection holes have a twist angle, the twist angle has been described for the fuel injection hole having the fuel injection hole inlet 304a. However, the fuel injection hole inlet where the spray reach distance is desired to be shortened is described. Each fuel injection hole having 304b, 304d, and 304f is provided with a twist angle, and the effect thereof is the same as that of the fuel injection hole having the fuel injection hole inlet 304a.

《Flow, effect explanation》
The operation and effect of configuring the fuel injection hole as described above will be described with reference to FIGS. FIG. 4 (a) is an enlarged view of one of the fuel injection holes, illustrating the fuel flow at the fuel injection hole inlet 304a and the fuel flow toward the fuel injection hole outlet 305a (upper left direction not shown). . For comparison with FIG. 4A, FIG. 4B is a diagram illustrating the flow when the fuel injection holes are configured in a form other than the present embodiment. FIG. 5 is a diagram illustrating fuel spray injected by the fuel injection valve according to the present embodiment. FIG. 6 is a diagram illustrating a virtual conical surface formed by the fuel injection hole shaft according to the present embodiment. FIG. 7 is a diagram for explaining the influence of the twist angle on the reach of the fuel spray.

  In FIG. 4A, a straight line 303a connecting the apex 301 of the valve seat surface (lower right direction not shown) and the center point 302a at the fuel injection hole inlet 304a and the fuel injection valve, such as the fuel injection hole inlet 304a. The plane including the central axis in the vertical direction includes a straight line 307a connecting the center point 302a at the fuel injection hole inlet 304a and the center point 306a (upper left direction not shown) at the fuel injection hole outlet 305a. When intersecting with a twist angle 308a in a plane parallel to the central axis of the fuel, the fuel flows as follows. The fuel flow 410 toward the fuel injection hole inlet 304a forms a flow 411 twisted in the direction of the straight line 307a at the fuel injection hole inlet 304a, and flows toward a fuel injection hole outlet 305a (not shown) as a flow 412 in the fuel injection hole. Flowing. At the fuel injection hole entrance 304a, when the fuel is twisted, the fuel is pressed in the fuel injection hole to change the flow velocity distribution, so that the flow velocity distribution 410 'having no deviation becomes a flow velocity distribution 412' having deviation. The flow having this bias is injected from the fuel injection hole outlet 305a to constitute the spray 501a shown in FIG. When the fuel is injected from the fuel injection hole 201, the fuel having the bias in the flow velocity distribution due to the twist is twisted as compared with the case where the fuel is not twisted and the flow velocity distribution is not biased (422 ′ described below). As a result, a velocity component is also present in the direction 413 in which the flow velocity distribution is biased, and it is easy to spread after being injected from the fuel injection hole, and a lot of air around the fuel injection hole outlet 305a is entrained in the spray. This increases the shear resistance of the fuel spray and shortens the reach of the fuel spray.

  For example, like the fuel injection hole 404 shown in FIG. 4B, the fuel injection and the straight line 403 connecting the apex 301 of the valve seat surface (lower right direction not shown) and the center point 402 at the inlet of the fuel injection hole. A plane including a central axis 204 in the vertical direction of the valve includes a straight line 407 connecting a center point 402 at the inlet of the fuel injection hole and a center point (upper left direction not shown) at the outlet of the fuel injection hole. When it coincides with a plane parallel to the central axis 204 in the vertical direction (that is, the twist angle is 0 degree), the flow velocity distribution 420 ′ of the inflowing fuel 420 becomes the flow 422 flowing in the fuel injection hole, but the flow velocity distribution. 422 'does not change. In this case, since the fuel flow is not biased, the injected fuel is difficult to spread, and even after injection, the air around the outlet of the fuel injection hole is not engulfed and the shearing force with the air is small, so the arrival of the fuel spray The distance will be longer.

  FIG. 7 shows a relationship line 701 with the twist angle as the horizontal axis and the spray reach distance as the vertical axis. The effect obtained in this embodiment is due to a phenomenon that occurs because the flow velocity distribution is biased by the twist at the inlet of the fuel injection hole. Therefore, even if there is a difference in the fuel injection hole perforation position error, a fine twist angle is formed in the fuel injection hole in terms of structure, but the effect is not obtained with the small disturbance that occurs. After a region 702 where the reaching distance does not change and a twist angle is set to a certain value or more, the spray reaching distance becomes shorter as indicated by 703. It has been found that this twist angle is preferably 5 degrees or more.

  The above description relates to the fuel injection hole inlet 304a. However, the same effect can be obtained at each of the fuel injection hole inlets 304b to 304f. The sprays 501b to 501f from the fuel injection hole outlets 305b to 305f also have a spray reach distance. It is getting shorter.

  In this embodiment, straight lines 307a to 307f connecting the center of the inlet and the center of the outlet of the fuel injection hole are configured as follows. Straight lines 307a, 307c, 307e connecting the center of the inlet and the outlet of the fuel injection hole are arranged along a virtual conical surface 602 having a vertex on the central axis 204 of the fuel injection valve, Straight lines 307b, 307d, and 307f that connect the center of the inlet and the outlet of the fuel injection hole are arranged along a virtual conical surface 601 that has a vertex on the center axis 204 of the fuel injection valve, Each straight line connecting the center of the inlet and the center of the outlet of each fuel injection hole is configured to be along one of the two virtual conical surfaces. As a result, various spray shapes can be formed, and the layout is excellent when fuel is injected into the internal combustion engine. In this embodiment, the number of virtual conical surfaces is two, but each straight line connecting the center of the inlet and the center of the outlet of each fuel injection hole (hereinafter also referred to as the fuel injection hole axis or simply the injection hole axis). May be configured so as to be along any one of the three or more virtual conical surfaces. Further, the apexes of the virtual conical surfaces 601 and 602 may be appropriately shifted from the center axis 204 of the fuel injection valve, thereby further improving the fuel spray layout.

  In this embodiment, by making the twist angles 308b and 308f and 308c and 308e for the sprays 501b and 501f and 501c and 501e that are paired with respect to the spray symmetry axis 502 of FIG. Further, the symmetry of the spray shape is improved, which is even better.

  Further, in this embodiment, when it is assumed that fuel is injected into the internal combustion engine, the internal combustion engine parts are configured by making the distance between the inner cylinder upper and lower surfaces and the side surfaces and the twist angles 308a to 308f proportional to each other. When the distance to the fuel is short, increasing the twist angle of the target fuel injection hole makes the spray reach distance shorter than others, and sprays the internal combustion engine without colliding with parts. Is possible and even better.

  In the present embodiment, the case where the fuel injection hole 201 is cylindrical has been described. However, even when the fuel injection hole is linearly or curved with a curvature toward the outlet, the same effect can be obtained. The effect of the example is not impaired. Further, in this embodiment, the fuel injection hole inlets 304a to 304f on the seating surface are configured to be equidistant from the central axis 204 of the fuel injection valve. Even if the distance from the shaft 204 and the interval between the fuel injection holes are different, the operational effects of the present embodiment are not impaired. In this embodiment, the number of fuel injection holes is six. However, even when the number of fuel injection holes is different, the same effect is obtained and the effect is not impaired. Similarly, even when different spray shapes are formed with the same number of fuel injection holes, the effects obtained by the present invention are not impaired.

  A fuel injection valve according to a second embodiment of the present invention will be described below with reference to FIGS. FIG. 8 is a longitudinal sectional view showing the structure of the fuel injection hole of the fuel injection valve in the present embodiment, and those assigned the same numbers as those in FIG. 3 have the same or equivalent functions as those in the first embodiment. Therefore, explanation is omitted. FIG. 9 is a diagram showing a spray shape constituted by the present embodiment.

  The difference from the first embodiment is that the spray 901a corresponding to the straight line 307a ′ connecting the inlet center and the outlet center of the fuel injection hole is injected to the center side, and at the center point and the outlet at the inlet of the other fuel injection holes. That is, sprays 901b to 901g respectively corresponding to straight lines 307b 'to 307g' connecting the center point are sprayed so as to surround the outer edge. That is, the sprays 901b to 901g constitute an outer spray of the spray 901a.

  With such a configuration, since the spray 901a is surrounded by the sprays 901b to 901g on the outer edge, it is difficult to receive air resistance, and the reach of the spray may be extended. However, according to the present embodiment, the center 302a ′ of the fuel injection hole inlet has a distance from the plane including the fuel spray symmetry axis 903 and the fuel injection valve central axis 204 (extending in the direction penetrating the paper surface). ing. As a result, a plane including a straight line 303a ′ connecting the center point 302a ′ at the inlet of the fuel injection hole and the apex 301 of the valve seat surface 203 and the central axis 204 in the vertical direction of the fuel injection valve is the surface of the fuel injection hole. In order to configure the twist angle 308a ′ in a plane that includes a straight line 307a ′ connecting the center point 302a ′ at the inlet and the center point 306a ′ at the outlet of the fuel injection hole and is parallel to the central axis 204 in the vertical direction of the fuel injection valve, The reach of the spray can be shortened by a mechanism similar to that of the first embodiment. Since the number of fuel injection holes is larger than that in the first embodiment, it is possible to reduce the diameter of the fuel injection holes when the fuel flow rate equivalent to that in the first embodiment is injected, and to promote atomization of the fuel spray. It becomes possible.

  In this embodiment, the spray 901a constitutes the first spray, and the sprays 901b, 901c, 901d, 901e, 901f, and 901g constitute the second spray. In this embodiment, the first spray is composed of one spray injected from one fuel injection hole, and the second spray is composed of a plurality of sprays injected from a plurality of fuel injection holes, The sprays are independently distributed in the circumferential direction. At this time, the fuel injection hole for injecting the spray 901a constituting the first spray has a twist angle, thereby shortening the reach (penetration) of the spray 901a and preventing the fuel from adhering to the intake valve or the cylinder inner wall surface. Can be suppressed.

  In the present embodiment, the case where the fuel injection hole has a cylindrical shape has been described. However, even when the fuel injection hole is linearly or curved with a curvature toward the outlet, the same effect can be obtained. The effect is not impaired. Further, in the present embodiment, the inlets of the fuel injection holes on the seat surface are configured at equal distances from the central axis of the fuel injection valve at substantially equal intervals. Even if the distance and the interval between the fuel injection holes are different, the operational effects of the present embodiment are not impaired. Moreover, even if the spray shape comprised in a present Example differs, the effect obtained by this invention is not impaired.

DESCRIPTION OF SYMBOLS 101 Valve body 102 Sheet member 103 Guide member 104 Nozzle body 105 Valve body guide 106 Anchor 107 Magnetic core 108 Coil 109 Yoke 110 Energizing spring 111 Connector 112 Fuel supply port 201 Fuel injection hole 202 Valve body spherical surface 203 Valve seat surface 204 Fuel Center axis 301 of injection valve in the vertical direction Apex 302a to 302f of valve seat surface Fuel injection hole inlet center points 303a to 303f Straight lines 304a to 304f connecting the fuel injection valve central axis and fuel injection hole inlet center Fuel injection hole inlets 305a to 305f Fuel injection hole outlets 306a to 306f Fuel injection hole outlet center points 307a to 307f Straight lines 308a to 308f connecting the fuel injection hole inlet center and the outlet center Twist angles 410, 420 Fuel flow 411, 421 before fuel injection hole inflow Fuel injection hole inlet Fuel at the department Is fuel stream 501a to 501f, 901a to 901g spray 502 spray axis of symmetry 601 and 602 imaginary conical surface 701 twist angle and the spray reaching distance relationship line in the 412 and 422 fuel injection hole

Claims (7)

A valve seat surface comprising a conical surface;
A fuel injection hole having an inlet opening formed on the conical surface on the downstream side of the valve seat surface;
A fuel injection valve comprising: a valve body that opens and closes the flow of fuel to the fuel injection hole by contacting and separating from the valve seat surface;
The fuel injection hole is a plane in which an injection hole axis connecting the center of the inlet opening of the fuel injection hole and the center of the outlet opening includes the center axis of the valve element and the center of the inlet opening of the fuel injection hole. Formed to be on different planes,
The fuel injection hole is formed so that an inner diameter of the fuel injection hole decreases from an inlet side to an outlet side of the fuel injection hole. The fuel injection valve according to claim 1,
The plane including the nozzle hole axis of the fuel injection hole and parallel to the central axis of the valve body is 5 with respect to the plane including the central axis of the valve body and the center of the inlet opening of the fuel injection hole. A fuel injection valve configured to intersect with an inclination angle larger than the degree. The fuel injection valve according to claim 1 or 2,
A plurality of the fuel injection holes are provided such that the fuel injection holes are arranged symmetrically with respect to a symmetry plane including the central axis of the valve body. The fuel injection valve according to claim 3,
A fuel injection valve comprising a fuel injection hole formed separately from the plurality of fuel injection holes such that an injection hole axis is closer to the symmetry plane than an injection axis of the plurality of fuel injection holes . The fuel injection valve according to any one of claims 1 to 4,
A plurality of the fuel injection holes are provided,
When each of the plurality of fuel injection holes is divided into two regions by a plane including the center of the inlet opening of the fuel injection hole and the central axis of the valve body, a predetermined point on the valve seat surface is included. A fuel injection valve in which the center of the outlet opening of the fuel injection hole is arranged in a region on the side. The fuel injection valve according to claim 5,
Of the plurality of fuel injection holes, a fuel injection hole disposed at a position away from the one point in the circumferential direction includes a plane parallel to the central axis of the valve body including the injection hole axis of the fuel injection hole. The fuel injection valve formed so that an angle formed between the central axis of the valve body and a plane including the center of the inlet opening of the fuel injection hole is increased. The fuel injection valve according to any one of claims 1 to 6,
A fuel injection valve in which a recess having an inner diameter larger than a hole diameter at an outlet opening of the fuel injection hole is formed on an outlet side of the fuel injection hole.

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