JP2004162545A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve for atomizing a fuel spray, and improving combustibility of an engine by reducing a collision of fuel in a confluent position becoming a factor of a loss in a fuel flowing speed. <P>SOLUTION: An inner peripheral annular groove 22 is formed on the inner periphery of a first end surface 14 facing a valve seat 7 of a turning body 10, and a turning groove 23 is connected to the inner peripheral annular groove 22 so as to contact from the tangent direction with the outer periphery of the inner peripheral annular groove 22. A seat surface 24 is formed at a first opening angle θ1 on the upstream side of an injection hole 8 of the valve seat 7, and a tapered surface 25 is formed at a second opening angle θ2 on the upstream side of the seat surface 24 of the valve seat 7. An opening diameter A of the tapered surface 25 is constituted larger than an outer diameter B of the inner peripheral annular groove 22, and the second opening angle θ2 of the tapered surface 25 is constituted larger than the first opening angle θ1 of the seat surface 24. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve, and more particularly to a fuel injection valve for in-cylinder injection, and more particularly to a fuel injection valve of a type in which swirling means gives swirling energy to a fuel flow to inject fuel from a fuel injection hole.
[0002]
[Prior art]
In a valve device of a conventional fuel injection valve, a valve seat is disposed at a tip of a valve body, a revolving body is disposed upstream of the valve seat in the valve body, and the valve body is disposed in the axial direction of the valve body. It is arranged so as to be movable and open and close an injection hole formed in a valve seat. An inner circumferential annular groove is formed on the end surface of the revolving structure on the valve seat side, a plurality of axial grooves are formed on the outer peripheral surface of the revolving structure at a constant angular pitch in the circumferential direction, and the revolving grooves are formed on the end surface of the revolving structure on the valve seat side. A plurality of grooves are formed so as to communicate each axial groove and the inner peripheral annular groove.
Then, when the valve body is sucked and the injection hole is opened, fuel flows through the axial groove into the swirl groove, and further flows from the swirl groove into the inner circumferential annular groove. Then, the fuel that has flowed into the inner peripheral annular groove forms a swirling flow, flows from the seat surface of the valve seat into the injection hole, and is sprayed from the outlet at the tip end of the injection hole. At this time, the fuel flowing into the swirl flow path from the swirl groove advances in the swirl flow path in the swirl direction, and collides with the fuel flowing into the swirl flow path from the swirl groove downstream in the swirl direction and merges. Therefore, the side surface of the swirl groove farther from the valve shaft is formed so as to be tangentially connected to the outer periphery of the inner annular groove so as to suppress the collision of the fuel at the fuel merging position. (For example, Patent Document 1)
[0003]
[Patent Document 1]
JP-A-10-47208 (paragraph 0026)
[0004]
[Problems to be solved by the invention]
In this conventional valve device for a fuel injection valve, the side surface of the swirl groove remote from the valve shaft is formed so as to be tangentially connected to the outer periphery of the inner annular groove. Although the matching was suppressed, the suppressing effect was insufficient. Therefore, the collision of the fuel flows causes a decrease (loss) in the fuel flow speed, causing a problem that atomization of the spray deteriorates and engine combustibility decreases.
[0005]
The present invention has been made in order to solve the above-described problem, and a taper surface having an opening angle larger than the seat surface is provided upstream of a seat surface of a valve seat, so that fuel flowing from a swirl groove into a swirl flow path is provided. The fuel flows along the tapered surface and reaches from the swirl groove on the downstream side in the swirl direction to a position where the fuel flows into the swirl flow path, and a collision of the fuel at the merge position that causes a loss of fuel flow velocity It is an object of the present invention to provide a fuel injection valve that reduces the size of the fuel mixture and improves the atomization of the spray and the engine combustion.
[0006]
[Means for Solving the Problems]
The fuel injection valve according to the present invention includes a plurality of outer peripheral surfaces that are in contact with the inner peripheral surface of the valve main body and define a position with respect to the valve main body, and a plurality of flows that are provided between the outer peripheral surface portions and form an axial flow path. A path portion, an annular swirl flow path formed on the inner periphery of an axial end face facing the valve seat, and one end connected to each of the plurality of flow path portions, and the other end tangential to the swirl flow path Body having a plurality of swirling grooves connected to the swirling flow path, a seat surface formed at a first opening angle on the upstream side of the injection hole, and the valve body is brought into contact with and separated from the swirl body; A valve seat having a tapered surface formed at a second opening angle on the upstream side of the surface. The opening diameter of the tapered surface is larger than the outer diameter of the swirling flow path, and the second opening angle is larger than the first opening angle.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a sectional view showing the overall structure of a direct injection fuel injection valve according to Embodiment 1 of the present invention, and FIG. 2 is a sectional view of a valve device in the direct injection fuel injection valve according to Embodiment 1 of the present invention. FIG. 3 is an enlarged sectional view showing the vicinity of the valve seat, FIG. 3 is a sectional view taken along the line III-III of FIG. 2, and FIG. 4 shows a valve seat of a valve device in the in-cylinder fuel injection valve according to the first embodiment of the present invention. It is an expanded sectional view.
[0008]
In FIG. 1, the in-cylinder fuel injection valve 1 includes a housing main body 2 and a valve device 3 fixed to one end of the housing main body 2 by caulking or the like. The fuel filter 57 is mounted on the other end of the housing body 2.
[0009]
The valve device 3 includes a stepped hollow cylindrical valve body 4 having a small-diameter cylindrical portion 5 and a large-diameter cylindrical portion 6, a valve seat 7 fixed to a tip of a center hole in the valve body 4 and having a fuel injection hole 8. A needle valve 9 serving as a valve body that opens and closes the fuel injection hole 8 by being brought into contact with and separated from the valve seat 7 by a solenoid device 50 to be described later. The needle valve 9 is guided in the axial direction, and the valve seat 7 is moved radially inward. A revolving body for imparting a revolving motion to the fuel to flow into the fuel injection holes; The valve body 4 of the valve device 3 forms a housing of the in-cylinder fuel injection valve 1 in cooperation with the housing body 2.
[0010]
The housing body 2 includes a first housing 30 having a flange 30a for mounting the in-cylinder fuel injection valve 1 to a cylinder head (not shown) of an internal combustion engine, and a second housing 40 to which a solenoid device 50 is mounted. Have. The solenoid device 50 includes a bobbin 52 around which a coil 51 is wound, and a core 53 provided on an inner peripheral portion of the bobbin 52. The winding of the coil 51 is connected to a terminal 56. The core 53 has a hollow cylindrical shape so that the inside thereof becomes a fuel passage, and a spring 55 is contracted between the sleeve 54 and the needle valve 9 in the hollow portion.
[0011]
The movable armature 31 is attached to the other end of the needle valve 9 so as to face the distal end side of the core 53, and the needle valve 9 is attached to the inner peripheral surface of the valve body 4 in the middle of the needle valve 9. A guide 9a that slides along the guide 9a and a needle flange 9b that is provided on the first housing 30 and abuts on the spacer 32 are provided.
[0012]
2 to 4, the revolving body 10 of the valve device 3 is formed in a substantially hollow cylindrical shape having a center hole 13 which supports the needle valve 9 at the center and slidably supports in the axial direction. When assembled in the valve device 3, the first end face 14 in contact with the valve seat 7, the second end face 15 opposite to the valve seat 7, and between the first and second end faces 14, 15 and inside the valve body 4. And a peripheral surface 16 in contact with the peripheral surface 17.
[0013]
The revolving superstructure 10 is supported such that a peripheral portion of the second end surface 15 is in contact with a shoulder 18 of an inner peripheral surface 17 of the valve body 4. A radially extending passage groove 21 is formed in the second end face 15 of the revolving structure 10 so that fuel flows from the inner peripheral part to the outer peripheral part of the second end face 15.
The peripheral surface 16 of the revolving unit 10 has six flat surfaces extending in the axial direction formed at equal intervals in the circumferential direction, and each corner between the flat surfaces is cut out in an arc shape to form a substantially regular hexagon. It is made square. Accordingly, the outer peripheral surface 16 abuts against the inner peripheral surface 17 of the valve element 9 to define the position with respect to the valve element 9, and the flat surface flow path provided between the outer peripheral surface parts 16 a A portion 16b is formed. The flow path portion 16b and the inner peripheral surface 17 constitute an axial flow path 20 for fuel.
[0014]
An axial end face of the revolving body 10 facing the valve seat 7, that is, a first end face 14, has an inner circumferential annular groove 22 having a predetermined width formed at an opening edge of the center hole 13 of the first end face 14, and one end. A turning groove 23 is provided, which is connected to the flow path portion 16 b of the peripheral surface 16, extends substantially radially inward therefrom, and is connected at the other end to the inner peripheral annular groove 22.
The turning groove 23 is offset from the center of the center hole 13 by a predetermined amount L, and the side surface far from the center hole 13 has the outer periphery of the inner peripheral annular groove 22 (indicated by a dashed line in FIG. 3). Connected tangentially to Further, six turning grooves 23 are formed at an equal angular pitch in the circumferential direction. At this time, the annular space formed between the inner peripheral annular groove 22 and the outer peripheral surface of the needle valve 9 becomes the fuel swirl flow path 29.
[0015]
A fuel injection hole 8 having the hole direction as an axial direction is formed at the center of the valve seat 7, and a seat surface 24 with which the needle valve 9 comes and goes is formed on the fuel injection hole 8 of the valve seat 7 on the revolving body 10 side, Further, a tapered surface 25 is formed on the revolving body 10 side of the seat surface 24 of the valve seat 7. The seat surface 24 and the tapered surface 25 are formed on the outer peripheral surface of a truncated cone with the axis of the fuel injection hole 8 as the center axis, and the apex angle (second opening angle) θ2 of the tapered surface 25 is determined by the sheet. The surface 24 is formed to be larger than the apex angle (first opening angle) θ1. The extension of the sheet surface 24 coincides with the inner peripheral surface of the center hole 13 at the first end surface 14. Further, the opening of the tapered surface 25 is located radially outside the inner peripheral annular groove 22 of the first end surface 14. That is, when the opening diameter of the tapered surface 25 is A and the outer diameter (the swirling width) of the swirling channel 29 is B, A> B.
[0016]
Next, the operation of the in-cylinder fuel injection valve 1 will be described.
Although not shown, the in-cylinder fuel injection valve 1 has a distal end inserted into an injection valve insertion hole of a cylinder head of a fuel engine, and is sealed and attached with a wave washer or the like. Then, a fuel supply pipe is attached to the other end of the housing body 2, and high-pressure fuel is supplied from the fuel supply pipe through the fuel filter 57 into the in-cylinder fuel injection valve 1.
When the coil 51 of the solenoid device 50 is energized from the outside via the terminal 56, a magnetic flux is generated in a magnetic path formed by the movable armature 31, the core 53 and the housing main body 2. It is sucked toward the core 53 against the force. Then, the needle valve 9 integrated with the movable armature 31 moves upward in FIG. 1 until the needle flange 9b contacts the spacer 32. As a result, the tip end of the needle valve 9 is separated from the seat surface 24 of the valve seat 7, and the fuel injection hole 8 is opened.
Further, when the energization of the coil 51 is stopped, the force for magnetically attracting the movable armature 31 toward the core 53 is lost, and the movable armature 31 moves downward in FIG. The distal end of the needle valve 9 integral with the movable armature 31 contacts the seat surface 24 of the valve seat 7. Thereby, the fuel injection hole 8 is closed.
The needle valve 9 is guided and held on the inner peripheral surface of the valve body 4 by a guide 9a.
[0017]
When the distal end of the needle valve 9 moves away from the seat surface 24 of the valve seat 7, the high-pressure fuel introduced from the fuel supply pipe flows from the passage between the valve body 4 and the needle valve 9 to the second It flows into the axial flow path 20 on the peripheral surface through the passage groove 21 of the end face 15. Next, the fuel flows into the swirl groove 23 of the first end surface 14 of the swirl body 10, flows radially inward, flows into the inner circumferential annular groove 22 from its tangential direction, and forms a swirl flow from the seat surface 24. The fuel enters the fuel injection hole 8 and is sprayed from the outlet at the tip.
At this time, the fuel flowing from the swirl groove 23 into the swirl flow path 29 (the inner circumferential annular groove 22) flows in the swirl flow path 29 along the tapered surface 25 to the downstream side in the swirl direction, and the downstream in the swirl direction. The fuel flowing into the swirling flow channel 29 from the swirling groove 23 on the side flows into the lower layer side. Therefore, the collision of the fuel flow at the junction of the fuel flowing into the swirl flow channel 29 from the swirl groove 23 and the fuel flowing into the swirl flow channel 29 from the downstream swirl groove 23 is suppressed.
[0018]
As described above, in the first embodiment, when the opening diameter of the tapered surface 25 is A and the outer diameter (turning width) of the swirling flow path 29 is B, A> B. The collision of the fuel flow at the confluence of the fuel flowing into the swirl flow path 29 and the fuel flowing into the swirl flow path 29 from the swirl groove 23 on the downstream side in the swirl direction is suppressed. As a result, the fuel flow loss due to the collision of the fuel flow in the swirl flow path 29 is reduced, the fuel flow speed is improved, the atomization becomes finer, and the combustibility of the engine is improved. it can.
Further, since the inner peripheral annular groove 22 is formed on the inner periphery of the first end face 14 of the revolving body 10 to constitute the swirl flow path 29, the offset amount L of the swirl groove 23 can be adjusted, and the fuel spray angle can be designed. The degree of freedom increases.
[0019]
Here, as a valve structure for reducing the loss of the fuel flow in the swirl flow path 29, for example, as shown in FIG. 5, a single seat surface 24a is provided upstream of the fuel injection hole 8 of the valve seat 7A. It is conceivable to increase the opening angle of the seat surface 24a so that the opening diameter C of the seat surface 24a is larger than the outer diameter B of the swirl flow path 29. In this structure, the center spray amount is determined by the sum of the volume V1 of the swirl flow path 29 and the volume V2 formed by the needle valve 9 and the seat surface 24a on the downstream side of the swirl flow path 29.
However, in the valve structure of this comparative example, the opening angle C of the single seat surface 24a is increased to make the opening diameter C of the seat surface 24a larger than the outer diameter B of the swirl flow path 29, so that the volume V2 The lower limit is determined by the outer diameter B of the swirl flow path 29, and the volume V2, that is, the degree of freedom in designing the central spray amount is restricted. Further, since the opening angle of the single sheet surface 24a is changed, the change amount of the volume V2 with respect to the opening angle of the sheet surface 24a is large, and it is difficult to finely adjust the center spray amount.
Further, as the offset amount L of the turning groove 23 increases, the turning speed of the fuel increases, and the fuel spray angle increases. However, in the valve structure of the comparative example, when the offset amount L of the turning groove 23 is increased, the opening diameter C of the seat surface 24a increases, that is, the lower limit value of the volume V2 increases. As a result, the degree of freedom in designing the fuel spray angle and the center spray amount is reduced.
[0020]
In the first embodiment, since the tapered surface 25 having the second opening angle θ2 larger than the first opening angle θ1 of the seat surface 24 is formed on the upstream side of the seat surface 24, compared with the valve structure of the comparative example. Thus, the lower limit of the volume V2 can be reduced, and the amount of change in the volume V2 can be finely adjusted by adjusting the second opening angle θ2 and the opening diameter A of the tapered surface 25.
Further, even if the offset amount L of the swirl groove 23 is increased, by increasing the second opening angle θ2 of the tapered surface 25, the increase in the volume V2 is suppressed and the opening diameter A of the tapered surface 25 is reduced. It can be larger than the outer diameter B.
As a result, according to the first embodiment, the center spray amount can be set with high accuracy by adjusting the second opening angle θ2 and the opening diameter A of the tapered surface 25, and further, the center spray amount and the fuel spray angle can be adjusted. The degree of freedom in design is increased.
[0021]
Embodiment 2 FIG.
FIG. 6 is an enlarged sectional view showing the vicinity of a valve seat of a valve device in a direct injection fuel injection valve according to Embodiment 2 of the present invention, and FIG. 7 is a sectional view taken along the line VII-VII of FIG.
[0022]
6 and 7, an axial end face of the revolving body 10A facing the valve seat 7, that is, the first end face 14, is connected at one end to the flow passage portion 16b of the peripheral surface 16 and substantially radially inward from the end. And a swivel groove 23 is provided which extends tangentially to the center hole 13 at the other end. Here, an annular space formed between the inner peripheral surface of the center hole 13 that is in contact with the side surface of the respective swirl grooves 23 farther from the central hole 13 and the outer peripheral surface of the needle valve 9 becomes a fuel swirl flow path. Further, the opening diameter A of the tapered surface 25 is larger than the diameter B1 of the center hole 13 (outer diameter of the swirling flow path). Further, the second opening angle of the tapered surface 25 is larger than the first opening angle of the seat surface 24.
The other configuration is the same as that of the first embodiment.
[0023]
In the second embodiment, the gas flows from the passage between the valve body 4 and the needle valve 9 into the axial flow path 20 on the peripheral surface through the passage groove 21 of the second end face 15 of the revolving body 10A. Next, the fuel flows into the swirl groove 23 of the first end surface 14 of the swirl body 10 and flows radially inward, and the center hole 13 is formed in the swirl flow path formed between the center hole 13 and the needle valve 9. Flows from the tangential direction of the fuel injection hole 8 into a swirling flow, enters the fuel injection hole 8 from the seat surface 24 and is sprayed from the outlet at the leading end.
[0024]
At this time, since the opening diameter A of the tapered surface 25 is larger than the diameter B1 of the center hole 13 (the outer diameter of the swirl flow path), the fuel flowing from the swirl groove 23 into the swirl flow path is The fuel flows downstream in the swirling direction along the tapered surface 25 and flows into the lower layer of the fuel flowing into the swirling flow path from the swirling groove 23 on the downstream side in the swirling direction. Therefore, collision of the fuel flow at the confluence of the fuel flowing into the swirl flow channel from the swirl groove 23 and the fuel flowing into the swirl flow channel from the swirl groove 23 on the downstream side in the swirl direction is suppressed. .
[0025]
Thus, also in the second embodiment, similarly to the first embodiment, the loss of the fuel flow due to the collision of the fuel flow in the swirl flow path is reduced, and the fuel flow speed is improved. This leads to finer spraying and improves the combustibility of the engine.
Further, in the second embodiment, since the inner peripheral annular groove is omitted, the volume V1 of the swirl flow path that determines the central spray amount is minimized. Further, since the tapered surface 25 is formed on the upstream side of the seat surface 24, the lower limit of the volume V2 can be reduced and the amount of change in the volume V2 can be finely adjusted, as in the first embodiment. As a result, the center spray amount can be set with high precision when designing the in-cylinder injection fuel injection valve having a small design target value of the center spray amount.
[0026]
In each of the above-described embodiments, the extension line of the seat surface 24 coincides with the inner peripheral surface of the center hole 13 on the first end surfaces 14 of the revolving units 10 and 10A. The extension line of 24 does not necessarily need to coincide with the inner peripheral surface of the center hole 13 at the first end surface 14, and may be appropriately set according to, for example, a target value of the center spray amount. That is, the first opening angle θ1 of the seat surface 24 may be set to be smaller than the target value of the volume V2, and the volume V2 may be finely adjusted to the target value by the second opening angle θ2 of the tapered surface 25. .
On the other hand, if the number of the swirl grooves 23 is too small, the fuel flowing from each groove into the swirl flow channel is difficult to be uniformly mixed into the swirl flow, while if the number is too large, the swirl flow is turbulent. At the same time, since the pressure loss affects the flow characteristics, it is desirable to set the number of the swirling grooves 23 to 4 to 8, and particularly to set the number of the swirling grooves 23 to six.
In each of the above embodiments, the in-cylinder fuel injection valve is described. However, the present invention is not limited to the in-cylinder fuel injection valve. Applicable.
[0027]
【The invention's effect】
As described above, according to the present invention, the opening diameter of the tapered surface of the valve seat is larger than the outer diameter of the swirling flow path formed in the rotating body, and the second opening angle of the tapered surface is the first opening angle of the seat surface. , The loss of the fuel flow due to the collision of the fuel flow in the swirl flow path is reduced. As a result, atomization of the spray is promoted, and a fuel injection valve that can improve the combustibility of the engine is realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an overall structure of a direct injection fuel injection valve according to Embodiment 1 of the present invention.
FIG. 2 is an enlarged sectional view showing the vicinity of a valve seat of a valve device in the in-cylinder fuel injection valve according to Embodiment 1 of the present invention;
FIG. 3 is a sectional view taken along the line III-III in FIG. 2;
FIG. 4 is an enlarged sectional view showing a valve seat of a valve device in the in-cylinder fuel injection valve according to Embodiment 1 of the present invention;
FIG. 5 is an enlarged cross-sectional view showing the periphery of a valve seat of a valve device in a direct injection fuel injection valve as a comparative example.
FIG. 6 is an enlarged sectional view showing the vicinity of a valve seat of a valve device in a direct injection fuel injection valve according to Embodiment 2 of the present invention;
7 is a sectional view taken along the line VII-VII in FIG.
[Explanation of symbols]
Reference Signs List 1 fuel injection valve for in-cylinder injection, 3 valve device, 4 valve body, 7 valve seat, 8 injection hole, 9 needle valve (valve element), 10 and 10A revolving body, 14 first end face, 16a outer peripheral face, 16b flow Road, 22 annular inner circumferential groove, 23 turning groove, 24 seat surface, 25 taper surface, 29 turning channel.

Claims (2)

A hollow valve main body, a valve seat provided at one end of the valve main body, provided with an injection hole, and disposed so as to be able to reciprocate in the valve main body in the axial direction, and come into contact with and separate from the valve seat. A valve device having a valve body that opens and closes the injection hole, and a revolving body that is disposed around the valve body, slidably supports the valve body, and gives a swirl to fuel flowing out of the injection hole. In a fuel injection valve provided with
A plurality of outer peripheral surfaces that are in contact with an inner peripheral surface of the valve main body and define a position with respect to the valve main body; and a plurality of flow path units that are provided between the outer peripheral surface portions and form an axial flow path. An annular swirl flow path formed on the inner periphery of an axial end face of the revolving body facing the valve seat; one end connected to each of the plurality of flow path units; A plurality of swirl grooves extending tangentially to the swirl flow path,
The valve seat is formed at a first opening angle on the upstream side of the injection hole, and a seat surface on which the valve element is brought into contact with or separated from the valve body, and a taper formed at a second opening angle on the upstream side of the seat surface. Surface and
A fuel injection valve, wherein an opening diameter of the tapered surface is larger than an outer diameter of the swirl flow path, and the second opening angle is larger than the first opening angle. An annular groove is formed on an inner periphery of an axial end face of the revolving body facing the valve seat so that an outer periphery thereof is in contact with a side surface farther from the axis of the plurality of revolving grooves, and constitutes the revolving flow path. The fuel injection valve according to claim 1, wherein

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