JP6779143B2 - 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. When the valve body comes into contact with the valve seat surface, fuel leakage is prevented, and when the valve body separates from the valve seat surface, injection is performed. Regarding the fuel injection valve to be performed.

In a fuel injection valve used in an automobile engine, if fuel droplets scattered during injection or coarse fuel droplets generated after injection adhere to the tip of the fuel injection valve, a deposit is generated due to incomplete combustion. Problems such as changes in spraying performance and factors that generate unburned particulate matter have become issues.

On the other hand, in Patent Document 1, a technique of suppressing fuel adhesion to the outer wall surface and suppressing the generation of deposit by forming the outer wall surface so as to keep the outer wall surface of the spray and the fuel injection hole opening away from each other. Is disclosed.

Japanese Patent No. 5696901

In the above-mentioned conventional technique, a technique relating to a wall surface shape for avoiding fuel adhesion to the tip of a fuel injection valve is disclosed. On the other hand, no consideration has been given to the optimum spray forming method for reducing the amount of fuel adhering to the tip of the fuel injection valve.

Therefore, an object of the present invention is to provide a fuel injection valve capable of forming a spray that reduces the amount of fuel adhering to the tip of the fuel injection valve.

In order to achieve the above object, the present invention presents the present invention downstream of the valve body, the seat member on which the valve seat surface on which the valve body is seated is formed, and the contact portion where the valve body and the valve seat surface abut. The first injection hole formed on the side and the angle formed by the valve body axis and the injection hole axis is the first angle θa, and the angle formed by the valve body axis and the injection hole axis is from the first angle θa. In a fuel injection valve provided with a second injection hole having a small second angle θb, a flow in which the flow path area increases between the seat member and the valve body on the downstream side of the contact portion. A path expansion structure is formed, and the flow path expansion structure is formed so as to overlap the downstream end of the first injection hole and the upstream end of the second injection hole.

According to the present invention, it is possible to reduce the amount of fuel adhering to the tip of the fuel injection valve by increasing the stability of spraying. The configuration, action, and effect of the present invention other than those described above will be described in detail in the following examples.

It is sectional drawing which shows the Example of the fuel injection valve which concerns on 1st Example of this invention. It is sectional drawing which shows the tip structure of the fuel injection valve which concerns on 1st Example of this invention. It is a figure for demonstrating the arrangement of the fuel injection hole and fuel flow which concerns on 1st Example of this invention. It is a figure for demonstrating the shape of the fuel injection hole and the fuel flow in the case where the injection hole inclination angle which concerns on 1st Embodiment of this invention is large. It is a figure for demonstrating the shape of the fuel injection hole and the fuel flow in the case where the injection hole inclination angle which concerns on 1st Embodiment of this invention is small. It is a figure for demonstrating the fuel injection valve tip structure which does not apply this Example for comparison with 1st Example of this invention. It is a figure for demonstrating the arrangement of the fuel injection hole which does not apply this Example for comparison with 1st Example of this invention. It is sectional drawing which shows the tip structure of the fuel injection valve which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the arrangement of the fuel injection hole and the fuel flow which concerns on 2nd Embodiment of this invention.

Hereinafter, examples according to the present invention will be described. The fuel injection valve of this embodiment is formed on the downstream side of the valve body, the valve seat surface that comes into contact with the valve body and seats fuel, and the position where the valve seat surface and the valve body come into contact with each other. It has a fuel injection hole, and at least two or more central axes of the fuel injection holes (injection hole axes) have different angles (injection hole inclination angles) with respect to the central axis (valve body axis) of the valve body. ) Is tilted. The fuel injection valve has a pressure loss on the valve body shaft side of the inflow side opening in the fuel injection hole having a large injection hole inclination angle, and on the anti-valve shaft side of the inflow side opening in the fuel injection hole having a small injection hole angle. It is configured to have a flow path expansion structure that reduces the number of fuels. The details will be described below.

The fuel injection valve according to the first embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 is a cross-sectional view 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 a cross-sectional view showing an embodiment of the tip structure of the fuel injection valve according to the present invention. FIG. 3 is a diagram for explaining the arrangement of fuel injection holes and the fuel flow of the fuel injection valve according to the present embodiment. 4 and 5 are diagrams for explaining the shape of the fuel injection hole and the fuel flow according to the present embodiment. FIG. 6 is a diagram for explaining a fuel injection valve tip structure to which the present embodiment is not applied for comparison with the present embodiment. FIG. 7 is a diagram for explaining the arrangement of fuel injection holes to which this embodiment is not applied for comparison with this 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 type gasoline engine, but the effect of the present invention is an electromagnetic type for a port injection type gasoline engine. It is also effective in a fuel injection valve and a fuel injection valve driven by a piezo element or a magnetic strain element.

[Explanation of basic operation of injection valve]
In FIG. 1, fuel is supplied from the fuel supply port 112 and is supplied to the inside of 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 designed to be sealed. The valve body 101 can be displaced in the axial direction of the fuel injection valve 100. At this time, in the in-cylinder injection type fuel injection valve that injects fuel directly into the cylinder of the engine, the supplied fuel pressure is in the range of about 1 MPa to 50 MPa.

FIG. 2 is an enlarged cross-sectional view of the tip of the fuel injection valve. The nozzle body 104 is a member arranged on the outer peripheral side of the valve body 101 and forming a fuel flow path. The outer peripheral portion of the sheet member 102 is joined to the nozzle body 104 by welding with a welding beam from the downstream direction. The method of fixing the sheet member 102 to the nozzle body 104 is not limited to welding, and may be screwed or press-fitted. A conical valve seat surface 203 is formed on the surface of the seat member 102 facing the valve body 101.

When the electromagnetic fuel injection valve 100 is in the closed state, the tip end portion of the valve body 101 comes into contact with the valve seat surface 203 of the seat member 102 to keep the fuel sealed. A fuel injection hole 201 is provided at the tip of the seat member 102. More specifically, the seat member 102 is provided with the fuel injection hole 201 on the downstream side of the contact portion (contact position) with the valve body 101. The fuel injection hole 201 of this embodiment is punched to form a fuel injection hole 201 having a substantially cylindrical shape, and a counterbore 202 having a diameter larger than that of the fuel injection hole 201 is punched on the downstream side of the fuel injection hole 201. The length of the fuel injection hole 201 in the longitudinal direction is adjusted by being formed by processing. In the following, 202 is referred to as a counterbore, but it may be simply referred to as a recessed portion or a hole forming portion. In the present embodiment, the method of forming the fuel injection hole 201 by punching has been described, but the present invention is not limited to this, and may be formed by, for example, laser machining.

When the coil 108 is energized via the connector 111 shown in FIG. 1, a magnetic flux density is generated in the core (fixed core) 107, the yoke 109, and the anchor 106 that form the magnetic circuit of the solenoid valve. Then, a gap is formed between the core 107 and the anchor 106 when the power is not applied, and a magnetic attraction force is generated so that the anchor 106 is attracted to the core 107. The urging force of the spring 110 and the urging force due to the fuel pressure described above are applied to the anchor 106 in the downstream direction, but when the magnetic attraction force due to energization becomes larger than these urging forces, the anchor 106 heads toward the core 107. And move.

The valve body 101 is guided by the guide member 103 in the downstream portion, and is guided by the valve body guide 105 formed separately from the guide portion 103 in the upstream portion. The guide member 103 and the valve body guide 105 are also fixedly supported by the inner peripheral portion of the nozzle body 104. The anchor 106 is formed separately from the valve body 101 and is configured independently, and the rod portion of the valve body 101 is inserted into the valve body insertion hole formed on the inner peripheral side. Further, a brim portion having an outer diameter larger than that of the rod portion is formed in the upstream portion of the valve body 101, and this brim portion comes into contact with the valve body support portion of the anchor 106 when the valve is closed in a non-energized state. The anchor 106 is urged to form a gap between the anchor 106 and the core 107.

On the other hand, when the coil 108 is energized, the anchor 106 is attracted to the core 107 side by the magnetic attraction force, and at this time, the valve body support portion of the anchor 106 and the brim portion of the valve body 101 engage with each other, and the valve body 101 Is urged to the side of the core 107, so that the valve can be opened.

When the valve is opened, a gap (stroke) is formed between the valve seat surface 203 and the valve body 101, and fuel injection is started. When the injection of fuel is started, the energy given as the fuel pressure is converted into kinetic energy to reach the fuel injection hole 201, which is injected into the cylinder of the engine (not shown).

[Structure and Features of Examples]
The configuration of this embodiment will be described with reference to FIGS. 2 to 5.
FIG. 2 is an enlarged cross-sectional view of the tip of the fuel injection valve. Each fuel injection hole is provided with the injection hole shaft 211 having an injection hole inclination angle (for example, θa, θb) with respect to the valve body shaft 210 according to the target position of the fuel spray. In the figure, the one having a large injection hole inclination angle is θa, and the one having a small injection hole inclination angle is θb. In the actual design, the injection hole inclination angle of each fuel injection hole is determined depending on the target spray shape. The valve body 101 is provided with a flow path expanding structure 212 in the circumferential direction so as to be axisymmetric with respect to the valve body shaft 210.

FIG. 3 is a diagram illustrating the arrangement of the fuel injection holes provided in the seat member 102 as viewed from the inlet side of the fuel injection holes. The fuel injection hole 201a is arranged on the circumference of the radius Ra, and the fuel injection hole 201b is arranged on the circumference of the radius Rb.

4 and 5 are cross-sectional views of the vicinity of the fuel injection hole. The length of the fuel injection hole 201 provided in the seat member 102 is adjusted by the counterbore 202 provided on the downstream side (outlet side) of the fuel injection hole. The length of the injection hole of the fuel injection hole 201 is defined by the length of the line connecting the center of the inlet surface and the center of the outlet surface of the fuel injection hole 201. FIG. 4 shows the vicinity of the fuel injection hole having the injection hole inclination angle θa, and the intersection with the valve body 101 when a line segment is extended in the normal direction from the downstream end of the fuel injection hole 201a toward the valve body 101. The distance La2 to is larger than the distance La1 to the intersection with the valve body 101 when the line segment is extended in the direction direction from the upstream end of the fuel injection hole 201a toward the valve body 101. It is configured in.
FIG. 5 shows the vicinity of the fuel injection hole having the injection hole inclination angle θb, and the intersection with the valve body 101 when a line segment is extended in the normal direction from the downstream end of the fuel injection hole 201b toward the valve body 101. The distance Lb2 to is smaller than the distance Lb1 to the intersection with the valve body 101 when the line segment is extended in the normal direction from the upstream end of the fuel injection hole 201b toward the valve body 101. It is configured in. The flow path expansion structure 212 is formed on the valve body 101 by, for example, cutting. Further, the flow path expansion structure 212 may be formed on the seat member (nozzle plate 102) instead of the valve body 101.

Next, the features of this embodiment will be described. As shown in FIG. 2, the valve body 101 is provided with a flow path expansion structure 212 in the vicinity of the inlet of the fuel injection hole 201. At this time, the shape of the flow path expansion structure 212 is formed so that La1, La2, Lb1, and Lb2 shown in FIGS. 4 and 5 satisfy the condition of La1 <La2 or Lb1> Lb2. In this embodiment, as shown in FIG. 3, the fuel injection holes are arranged on different circumferences so as to satisfy both of the above conditions in combination with the shape of the flow path expansion structure 212.

At this time, it is effective to gradually reduce the height of the flow path formed by the flow path expansion structure 212 and the valve seat surface 203 from the flow path expansion structure 212 to the sack 205.

As described above, in the fuel injection valve of this embodiment, the valve body 101, the seat member (nozzle plate 102) on which the valve seat surface 203 on which the valve body 101 is seated is formed, and the valve body 101 and the valve seat surface 203 are formed. The first injection hole 201a, which is formed on the downstream side of the abutting portion and has the angle formed by the valve body shaft 210 and the injection hole shaft 211a as the first angle θa, and the valve body shaft 210 and the injection hole shaft 211b. It is provided with a second injection hole 201b whose second angle θb is smaller than the first angle θa. Then, on the downstream side of the contact portion of the fuel injection valve, a flow path expanding structure 212 having a large flow path area is formed between the seat member (nozzle plate 102) and the valve body 101. The flow path expansion structure 212 overlaps the downstream end of the first injection hole 201a (the central end in FIG. 3) and is located on the upstream end of the second injection hole 201b (on the side away from the center in FIG. 3). It is formed so as to overlap with the end).

As shown in FIG. 3, the flow path expansion structure 212 described above is formed on the circumference of the seat member (nozzle plate 102) or the valve body 101 when viewed in the direction of the valve body shaft 210. Further, the flow path expansion structure 212 is formed on the circumference when the seat member (nozzle plate 102) or the valve body 101 is viewed in the valve body axial direction, and the upstream end portion of the first injection hole 201a (FIG. It is formed in a region downstream of the end portion on the side away from the center in No. 3) and upstream side of the downstream end portion (central side end portion in FIG. 3) of the second nozzle hole 201b.

Further, as shown in FIG. 4, in the direction normal to the first injection hole orthogonal to the entrance surface of the first injection hole from the downstream end portion of the first injection hole 201a (the end on the tip center side of the nozzle plate 102 in FIG. 4). The distance La2 to the intersection with the valve body 101 is the distance La1 from the upstream end (seat side end in FIG. 4) of the first injection hole 201a to the intersection with the valve body 101 in the normal direction of the first injection hole. Is formed to be larger than. Although FIG. 4 shows a state in which the valve is opened, this relationship is the same when the valve is opened and when the valve is closed. Further, as shown in FIG. 5, in the direction normal to the second injection hole orthogonal to the entrance surface of the second injection hole from the downstream end portion of the second injection hole 201b (the end on the tip center side of the nozzle plate 102 in FIG. 5). The distance Lb2 to the intersection with the valve body 101 is the distance Lb1 from the upstream end (seat side end in FIG. 5) of the second injection hole 201b to the intersection with the valve body 101 in the normal direction of the second injection hole. Is formed to be smaller than. Although FIG. 5 shows a state in which the valve is opened, this relationship is the same when the valve is opened and when the valve is closed.

Further, as shown in FIGS. 4 and 5, a part of the flow path from the flow path expansion structure 212 to the tip end portion of the sheet member (nozzle plate 102) is formed so as to be gradually reduced. As shown in FIG. 2, a gap is formed between the center of the tip of the valve body and the center of the tip of the seat member facing the center of the tip of the valve body in the valve body axial direction. When the valve is closed, it is desirable that the distance of this gap is formed to be smaller than the maximum distance in the flow path expansion structure 212.

In this embodiment, the arrangement diameter of the injection hole differs depending on the magnitude of the injection hole inclination angle θ. The arrangement diameter is the distance from the center to the center of the inlet surface when the seat member (nozzle plate 102) or the valve body 101 is viewed in the direction of the valve body shaft 210 as shown in FIG. 3, and is a PCD (Pitch Circle Diameter). ) May be called. As shown in FIG. 4, in the first injection hole 201a of θa having a large injection hole inclination angle θ, the flow path expansion structure 212 is formed so that a large inflow area is formed on the sack side of the entrance of the injection hole. Further, as shown in FIG. 5, the second injection hole 201b of θb having a small injection hole inclination angle θ is formed with a flow path expansion structure 212 so that a large inflow area is formed on the sheet side of the injection hole. The flow path expansion structure 212 may be formed on either the valve body 101 or the seat member (nozzle plate 102).

In addition, each fuel injection hole may be arranged on a different circumference as in this embodiment. On the contrary, when all the fuel injection holes are arranged on the same circumference, in order to satisfy the above condition of La1 <La2 or Lb1> Lb2, the flow path expansion structure is not axisymmetric as in this embodiment. The shape may be adjusted according to the position of each fuel injection hole. Further, if two or more injection holes having different injection hole inclination angles satisfy the condition of La1 <La2 or Lb1> Lb2, the effect of the invention in those injection holes can be exhibited.

[Flow, effect explanation]
The action and effect of configuring the fuel injection hole and the valve body as described above will be described with reference to FIGS. 3 to 5.

The arrows 301a and 301b in FIGS. 3 to 5 represent the fuel flow. As shown in FIG. 3, with respect to the fuel injection holes arranged on the circumference of the radius Ra represented by the fuel injection holes 201a, the fuel is mainly from the center side (sack side) of the nozzle plate 102. There is a large amount of inflow. As shown in FIG. 4, since the flow path expansion structure 212 is provided in the fuel injection hole 201a so that La1 <La2, the pressure loss in the flow path on the La2 side is smaller than that on the La1 side. This is because the amount of fuel that has flowed from the outer peripheral side of the fuel directly flows into the fuel injection hole is reduced, and the amount that reaches the center of the nozzle plate and flows into the fuel injection hole from the sack side like the fuel flow 301a is increased. Therefore, the amount of water flowing into the fuel injection hole from the sack side is relatively large.

Similarly, a large amount of fuel flows mainly from the outer peripheral side of the nozzle plate 102 into the fuel injection holes arranged in a circumferential shape having a radius Rb represented by the fuel injection holes 201b. As shown in FIG. 5, since the flow path expansion structure 212 is provided in the fuel injection hole 201b so that Lb1> Lb2, the pressure loss in the flow path on the Lb1 side is smaller than that on the Lb2 side. The amount of water flowing from the outer peripheral side of the plate is relatively large.
The reason for controlling the fuel flow in this way is to adjust the inflow direction of the fuel into the fuel injection hole according to the magnitude of the injection hole inclination angle (θa or θb) and reduce the peeling at the time of inflow. By reducing the peeling, the fluctuation of the spray can be reduced, and the adhesion of minute droplets generated during the spray to the wall surface of the fuel injection valve tip can be reduced. Therefore, it is possible to provide a fuel injection valve that realizes an internal combustion engine with improved exhaust performance.

[Comparison with other structures]
6 and 7 are diagrams for explaining the configuration of other structures and the flow of fuel for comparison with the present embodiment. As shown in FIG. 6, the other structure does not have a flow path expansion structure, and the flow path of the sack 206 is wide. As a result, the fuel easily flows from the sack side toward the fuel injection holes 201c and 201d, and it is difficult to adjust the inflow direction to the fuel injection holes as in the present embodiment. Therefore, in this embodiment, the height of the flow path composed of the valve body 101 and the sack 205 is configured to be smaller than the maximum height of the flow path formed by the valve seat surface and the valve body at least in the flow path expansion structure.

FIG. 7 shows the arrangement of fuel injection holes in other structures. In other structures, all fuel injection holes are arranged on the same circumference, so that the ease of fuel flow into each fuel injection hole is almost the same. For example, when the flow path on the center side is wider than the outer peripheral side of the nozzle plate 102, the amount of water flowing into the fuel injection hole from the center side such as 301c and 301d is large, and when the injection hole inclination angle is small, the nozzle plate Peeling is likely to occur on the center side of 102. Therefore, in order to reduce the peeling in all the fuel injection holes, it is necessary to control the direction in which the fuel easily flows into each fuel injection hole as in this embodiment.

The fuel injection valve according to the second embodiment of the present invention will be described below with reference to FIGS. 8 and 9. FIG. 8 is a cross-sectional view showing the configuration of the fuel injection valve tip in the present embodiment, and those assigned the same numbers as those in FIG. 2 have the same or the same functions as those in the first embodiment. FIG. 9 is a diagram for explaining the arrangement of the fuel injection holes provided in the seat member 102 as viewed from the inlet side of the fuel injection holes in the present embodiment, and has the same or the same function as that of the first embodiment. ..

In this embodiment, the flow path expansion structure 213 is provided on the valve seat surface 203 of the seat member 102. At this time, although detailed description in this embodiment is omitted, it is sufficient that the relationship between the fuel injection hole shape and the valve body satisfies the condition of La1 <La2 or Lb1> Lb2 shown in Example 1. The definitions of La1, La2, Lb1, and Lb2 are defined by the distance from the injection hole inlet end to the valve body, as in the first embodiment. As a result, the effect of the flow path expansion structure 213 is the same as that of the first embodiment, and it is possible to control the direction in which the fuel flows into the fuel injection hole.

Unlike the first embodiment, the shape of the valve body does not need to be changed in this embodiment, and not only the needle valve shown in the present embodiment but also the ball valve can be used.

The flow path expansion structure of this embodiment is provided as concentric recesses as shown in FIG. 9, but even when the fuel injection holes are arranged on the same circumference, the injection holes of each fuel injection hole are inclined. By providing the flow path expansion structure so as to satisfy the condition of La1 <La2 or Lb1> Lb2 according to the angle, the flow direction into the fuel injection hole can be controlled.

100 ... Electromagnetic fuel injection valve 101 ... Valve body 102 ... Seat member 103 ... Guide member 104 ... Nozzle body 105 ... Valve body guide 106 ... Anchor 107 ... Core 108 ... Coil 109 ... Yoke 110 ... Spring 111 ... Connector 112 ... Fuel supply Ports 201a, 201b ... Fuel injection holes 202a, 202b ... Counterbore 203 ... Valve seat surface 205, 206 ... Sack 210 ... Central axis of fuel injection valve (valve body shaft)
211a, 211b ... Central axis of fuel injection hole (injection hole axis)
212, 213 ... Flow channel expansion structure 301a, 301b, 301c, 301d, 301e, 301f ... Fuel flow

Claims (9)

The valve body, the seat member on which the valve seat surface on which the valve body is seated are formed, and the valve body shaft and the injection hole are formed on the downstream side of the contact portion where the valve body and the valve seat surface come into contact with each other. The first injection hole formed by the angle formed by the shaft is the first angle θa, and the angle formed by the valve body shaft and the injection hole shaft is the second angle θb smaller than the first angle θa. In a fuel injection valve equipped with an injection hole,
On the downstream side of the contact portion, a flow path expanding structure in which the flow path area is increased is formed between the seat member and the valve body.
The flow channel expanding structure, the together first injection hole overlaps with only the downstream end of the second injection hole fuel injection valve is formed so as to overlap with only the upstream end of the. In the fuel injection valve according to claim 1, the flow path expansion structure is a fuel injection valve formed on the circumference of the seat member or the valve body when viewed in the valve body axial direction. In the fuel injection valve according to claim 1, the flow path expansion structure is formed on the circumference of the seat member or the valve body when viewed in the valve body axial direction, and is formed in the first injection hole. A fuel injection valve formed in a region downstream of the upstream end and upstream of the downstream end of the second injection hole. In the fuel injection valve according to claim 1, the distance from the downstream end of the first injection hole to the intersection with the valve body in the normal direction of the first injection hole orthogonal to the inlet surface of the first injection hole is determined. A fuel injection valve formed so as to be larger than the distance from the upstream end of the first injection hole to the intersection with the valve body in the normal direction of the first injection hole. In the fuel injection valve according to claim 1, the distance from the downstream end of the second injection hole to the intersection with the valve body in the normal direction of the second injection hole orthogonal to the inlet surface of the second injection hole is determined. A fuel injection valve formed so as to be smaller than the distance from the upstream end of the second injection hole to the intersection with the valve body in the normal direction of the second injection hole. The fuel injection valve according to claim 1, wherein a part of the flow path from the flow path expansion structure to the tip end portion of the seat member is gradually reduced. In the fuel injection valve according to claim 6, the distance between the center of the valve body tip and the center of the seat member tip facing the center of the valve tip in the valve body axial direction is the maximum in the flow path expansion structure. A fuel injection valve formed so as to be smaller than a distance. In the fuel injection valve according to claim 1, the flow path expansion structure is a fuel injection valve formed on the valve body by cutting. In the fuel injection valve according to claim 1, the flow path expansion structure is a fuel injection valve formed on the seat member.

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