JP2003161229A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device capable of uniformly injecting fuel over the circumferential direction of an outlet in the direction oblique to a shaft from an outlet of a fuel passage of a valve seat. <P>SOLUTION: The fuel passage 52 of the valve seat 5 is composed of a linear passage 523 positioned at the lower part of a fuel reserving chamber 44, and a curved passage 524 continued from the linear passage 523 for injecting the fuel in the direction oblique to a central shaft 324 of a valve element 32. The fuel passage 52 is formed by inserting a tubular body 8 into a through hole formed on the valve seat 5, and the curved passage 524 is formed at an outlet side of the tubular body 8 to inject the fuel in the oblique direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device, and more particularly to a fuel injection device for giving swirl energy to fuel and supplying it to a combustion chamber of an internal combustion engine such as an automobile engine.

[0002]

2. Description of the Related Art FIG. 6 is a cross-sectional view of a valve seat and its vicinity in a conventional fuel injection device disclosed in Japanese Patent Laid-Open No. 10-103194, etc., 3 being a valve device, 4 a swirler, 5 Is a valve seat. The valve device 3 includes a valve body 31, a valve body 32, a swirler 4, and a valve seat 5. The swirler 4 is a thick-walled cylindrical body having an inner hole through which the valve body 32 is inserted, and includes a plurality of, for example, six fuel passages 41 that axially penetrate through the thick-walled wall, and these fuel passages 41. The swirler groove 43 is connected to the fuel passage 41.
The valve seat 5 is composed of a seat portion 51 on which a front end portion of the valve element 32 is seated on the surface facing the swirler 4, and a fuel passage 52 for injecting fuel to the outside, following the seat portion 51. The fuel supplied from the outside reaches the space between the facing surfaces of the swirler 4 and the valve seat 5 from the fuel passage 41 of the swirler 4, and then passes through the swirler groove 43 and the fuel storage chamber 44 and is provided on the valve seat 5. It reaches the passage 52, is injected from the outlet 53, and is supplied to the cylinder of the engine.

The fuel passage 52 in JP-A-10-103194 extends coaxially with the axis of the valve element 32 as shown in FIG. 6, but recently, the swirl imparted to the fuel by the swirler 4 has occurred. For the purpose of effectively utilizing energy for atomizing the fuel, it has been proposed to incline the fuel passage 52 with respect to the axis as shown in FIGS. 7 and 8. Of these, FIG. 7 is disclosed in Japanese Patent Laid-Open No. 10-184496. The parts in FIGS. 7 and 8 corresponding to the parts in FIG. 6 are designated by the same reference numerals as in FIG.
A cross-sectional view of the injection shape of the fuel injected from the fuel passage 52 of the valve seat 5 is additionally shown in FIG. However, the inclined fuel passage 52 has the following problems.

That is, in the in-cylinder injection type fuel injector, the fuel is generally directly injected into the engine cylinder in a conical or trumpet shape. In the case of such direct injection, according to the study by the present inventors, the spray shape of the fuel is an extremely important factor from the viewpoint of combustion stability and combustion efficiency. Specifically, the fuel is the length of the slope of the cone. That is, it is preferable that the fuel injection distance is as uniform as possible in the circumferential direction of the cone bottom surface, and in the example of FIG. 8, the injection distances T1 and T2 are symmetrical with respect to the central axis of the cone. .

In FIG. 7, the left passage 521 and the right passage 522 of the fuel passage 52 in the drawing have different change angles in the fuel flow direction. That is, in the fuel storage chamber 44, the fuel swirls and generally progresses in the axial direction and changes its direction at the inlet of the fuel passage 52 in a direction inclined with respect to the axis. In the left side passage 521, the change angle in the flow direction is larger than that in the right side passage 522, so that the degree of decrease in the flow velocity of the fuel is larger than that in the right side passage 522. The same applies to the case of FIG. As a result, the injection shape from the inclined fuel passage 52 is, as shown in FIG. 8, the injection distance T1 of the fuel injected from the left passage 521 due to the above-mentioned difference in the flow velocity of the fuel between the left and right passages. It becomes smaller than the injection distance T2 of the fuel injected from the right passage 522. The satin portion in FIG. 8 indicates the fuel, and the fuel injected from the fuel passage 52 to the outside has a mist state.

As described above, in the conventional techniques shown in FIGS.
The injection distances T1 and T2 are asymmetrical, which causes a large variation in combustion between the cylinders of the engine due to variations in the spray shape of each fuel injection device, which causes a serious problem that adversely affects the operation of the engine.

[0007]

SUMMARY OF THE INVENTION In view of the above problems in the prior art, the present invention is directed to a direction in which fuel is directed from an outlet of a fuel passage provided in a valve seat in a direction inclined with respect to an axis and a circle of the outlet. An object of the present invention is to provide a fuel injection device capable of injecting outward as uniformly as possible in the circumferential direction.

[0008]

A fuel injection device according to claim 1 of the present invention is a valve seat having a fuel passage for injecting fuel to the outside, and imparts swirling energy to the fuel and supplies it to the fuel passage. And a valve element that axially slides in a middle hole of the swirler to separate and seat the seat portion of the valve seat, wherein the fuel passage is at least the fuel passage. A curved passage portion for injecting the fuel in a direction inclined with respect to the central axis of the valve body is provided near the outlet.

A fuel injection device according to claim 2 of the present invention is
A valve seat having a fuel passage for injecting fuel to the outside, a swirler for giving swirling energy to the fuel to supply the fuel passage to the fuel passage, and a swirler axially sliding inside the bore of the swirler to form a valve seat A fuel injection device including a valve body for seating a seat portion, wherein at least a part of the fuel passage is formed by inserting a pipe body into a through hole provided in the valve seat, and the pipe body. Is provided with a curved passage portion for injecting the fuel in a direction inclined with respect to the central axis of the valve body.

A fuel injection device according to claim 3 of the present invention is
In the second aspect, the curved passage portion of the tubular body is exposed to the outside from the end surface of the valve seat.

The fuel injection device according to claim 4 of the present invention is
The fuel passage according to any one of claims 1 to 3, wherein the fuel passage is provided on an inlet side of the fuel passage and is connected to the straight passage portion centered on the central axis and the straight passage portion. It is characterized by comprising a curved passage portion.

A fuel injection device according to claim 5 of the present invention is
In the above claim 4, the value Ls / D of the length Ls of the straight passage portion to the diameter D of the fuel passage is about 0.5 to 5, and the diameter of the axially projected length Lr of the curved passage portion is the diameter. The value Lr / D for D is about 1 to 10, and the value R / D for the radius D of the radius R of the bending center line of the bending passage portion.
Is about 5-10.

A fuel injection device according to claim 6 of the present invention is
In the first aspect, the curved passage portion is formed by electric discharge machining.

A fuel injection device according to claim 7 of the present invention is
In the sixth aspect, the inner surface of the curved passage portion is smoothed by fluid polishing.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 for explaining the following embodiment.
In FIG. 5, parts corresponding to the parts in FIGS. 6 to 8 are designated by the same reference numerals as those in FIGS.
Description of some parts will be omitted in the description of the embodiment.

Embodiment 1. 1 to 3 are views for explaining a first embodiment of a fuel injection device of the present invention, FIG. 1 is a sectional view of the first embodiment, FIG. 2 is an enlarged view of a valve seat of FIG. 3 is a sectional view of a valve seat and a fuel injection shape.

1 to 3, 1 is a fuel injection device,
2 is a valve actuating device, 3 is a valve device, 4 is a swirler, 5 is a valve seat, 6 is a fuel supply pipe, and 7 is a cylinder of an engine. The valve device 3 includes a valve body 31, a valve body 32, a stopper 33, a swirler 4, and a valve seat 5. Valve actuating device 2
Has a function of operating the valve element 32 by forming a magnetic circuit, and includes a housing 21 that is a yoke portion of the magnetic circuit, a core 22 that is a fixed iron core portion of the magnetic circuit, a coil 23, and a magnetic circuit. Amateur 2 which is a movable iron core
It is composed of 4. The amateur 24 and the valve body 32
And have an integrated structure. The valve body 31 is caulked after being inserted into the inner wall of the housing 21. After the swirler 4 and the valve seat 5 are press-fitted into the inner wall of the valve body 31,
The valve seat 5 is welded to the valve body 31. 44 is a fuel storage chamber.

The swirler 4 cannot be shown in detail in FIG. 1, but is a thick-walled cylinder having an inner hole through which the valve element 32 is inserted, as in FIG. Has a plurality of, for example, six fuel passages penetrating in the axial direction, and a swirler groove connected to these fuel passages. Valve seat 5
Is composed of a seat portion 51 on which the front end portion of the valve element 32 is seated on the surface facing the swirler 4, and a fuel passage 52 for injecting fuel to the outside, following the seat portion 51.

The fuel passage 52 is provided on the inlet side of the fuel passage 52 and has a straight passage portion 523 centered on the central axis 324 of the valve body 32 and a curved passage portion 5 connected to the straight passage portion 523.
24, and the outlet of the curved passage portion 524 is the outlet 53 of the fuel passage 52. 521,522
Shows the left passage and the right passage through the straight passage portion 523 and the curved passage portion 524 in the fuel passage 52, respectively.

As described with reference to FIG. 7, the fuel that has passed through the swirler 4 travels in the direction of the central axis 324 while swirling in the fuel storage chamber 44 as a whole. The straight passage portion 523 of the present invention has a function of maintaining the flow of the fuel flow in the fuel storage chamber 44 in the direction of the central axis 324 and guiding the flow to the curved passage portion 524. On the other hand, the curved passage portion 5
24 does not cause the abrupt change in the flow direction seen in the inclined fuel passage 52 of FIGS. 7 and 8, but gradually changes the flow direction based on the curved shape, so that between the left and right passages 521, 522. The function of injecting the fuel in the inclined direction with respect to the central axis 324 as shown in FIG.

The operation of the first embodiment will be described below. When an operation signal is sent from the microcomputer of the engine to the valve operating device 2 of the fuel injection device 1, a current flows through the coil 23 and a magnetic flux is generated in the magnetic circuit, and the armature 24 is attracted to the core 22 side, so that the armature 24 The valve body 32 having an integral structure separates from the valve seat 5 and a gap is formed between the two. At this time, the high-pressure fuel passes through the fuel passage in the swirler 4, the swirler groove, and the fuel storage chamber 44, and then exits from the outlet 5 of the fuel passage 52.
3 is injected into the cylinder 7 of the engine. Further, a turning force is applied while passing through the swirler groove.

As described above, the curved passage portion 524 injects the fuel in the direction inclined with respect to the central axis 324 without substantially causing a flow velocity difference between the left and right passages 521 and 522. As shown, the injection distance T1 of the fuel injected from the left side passage 521 and the injection distance T2 of the fuel injected from the right side passage 522 are substantially equal to each other. Compared with the case of the technology, it is much less, and there is less variation in combustion between cylinders of the engine.

Next, when an operation stop signal is sent from the microcomputer to the valve actuating device 2, the coil 23 is de-energized, and the compression spring 11 is constantly pushing the valve body 32 in the valve closing direction.
As a result, the gap between the valve body 32 and the valve seat 5 is closed,
Fuel injection stops. The valve body 32 includes a valve body portion 321 that slides on the inner wall of the valve body 31, a valve body portion 322 that slides on the inner wall of the swirler 4, and a valve body portion 323. The valve body portion 323 is the stopper 3
It contacts the lower surface of 3. Since the valve body portion 322 is a means for controlling the radial non-coaxiality (deflection) of the valve body 32 with respect to the surface of the valve seat 5, the clearance between the inner wall of the swirler 4 and the valve body portion 322 is set as small as possible. In the first embodiment, in order to keep the durable wear of the valve element 32 within the allowable limit, it is set to 10 μm or less (one-side gap 5 μm or less).

By the way, in FIG. 2, the straight passage portion 523 is formed.
If the length Ls is too small, the above-mentioned function of the straight passage portion 523 becomes poor, and conversely, if the length Ls is too large, the fuel was imparted by the swirler 4 while the fuel passed through the straight passage portion 523. The damping of the swirling energy of the fuel increases. On the other hand, the axial projection length Lr of the curved passage portion 524 and the curved passage portion 5
If the radius R of the curved center line of 24 is too small, the function of injecting fuel in the inclination direction becomes poor. On the contrary, if these values are too large, the left and right passages 521 in the curved passage portion 524,
The flow velocity difference between 522 becomes remarkable. Therefore, in the present invention, the value Ls with respect to the diameter D of the fuel passage 52 having the above length Ls
/ D is about 0.5 to 5, preferably about 0.8 to 3, and the value Lr / D of the length Lr with respect to the diameter D is 1
Is about 10 to 10, preferably about 2 to 5, and the radius R is
The value R / D with respect to the diameter D is about 5 to 10, preferably about 7 to 9.

Embodiment 2. FIG. 4 illustrates Embodiment 2 of the fuel injection device of the present invention, and is an enlarged view in the manufacturing process of the valve seat 5. In FIG.
6 is a straight electrode rod, and 7 is an arc-shaped electrode rod.

Hereinafter, the valve seat 5 used in the first embodiment will be described as an example of an object to be manufactured and with reference to FIG. The fuel passage 52 of the valve seat 5 is the straight passage portion 5
23 and a curved passage portion 524, the straight passage portion 523 is formed by the electrode rod 6, and the curved passage portion 524 is formed by the electrode rod 7 by electric discharge machining. At that time, as the electrode rod 7, one having the same curved shape as the value R / D of the curved passage portion 524 is used. The straight passage portion 523 may be formed by machining using an end mill or the like instead of the electric discharge machining using the electrode rod 6.
The inner surface of the fuel passage 52 formed by the above-described processing, and in particular, the inner surface of the curved passage portion 524 is smoothed by fluid polishing. The surface roughness of the electric discharge machining is usually about 6 to 12 μm, but it can be set to about 3 μm by fluid polishing, and by doing so, the curved passage portion 52 can be formed.
4 It has the effect of significantly reducing the amount of carbon adhering to the surrounding area.

Embodiment 3. FIG. 5 illustrates a third embodiment of the fuel injection device of the present invention, and is an enlarged sectional view of a valve seat. In FIG. 5, 8 is a fuel passage 5
It is a tubular body forming a part of 2, and is inserted and fixed in a through hole 525 provided in the valve seat 5 in advance. The through hole 5
The reference numeral 25 is straight, and is bored so that its inner diameter is larger than the inner diameter of the straight passage portion 523 of the fuel passage 52 by the thickness of the wall of the pipe body 8. On the other hand, the tubular body 8 is a J-shaped one composed of a straight portion and a curved portion that follows the straight portion,
Only the straight portion is inserted and fixed in the through hole 525, and the curved portion is exposed to the outside from the end surface of the valve seat 5.

Therefore, the fuel passage 5 in the third embodiment
The second straight passage portion 523 includes a straight portion directly drilled in the valve seat 5 and the inside of the straight portion of the pipe body 8, and the curved passage portion 524 exists in the above-mentioned curved portion of the pipe body 8. Typically,
Since it is much easier to form a straight passage inside a solid body as compared with the formation of a curved passage, the third embodiment is described.
The valve seat 5 used in 1 has the advantage that it can be produced at low cost. In addition, Ls / D of the fuel passage 52 using the pipe body 8,
Regarding the ranges of Lr / D and R / D, what has been described in the first embodiment also applies to the third embodiment.

[0029]

As described above, the fuel injection device according to claim 1 of the present invention has a valve seat having a fuel passage for injecting fuel to the outside, and imparts swirling energy to the fuel to supply the fuel to the fuel passage. A fuel injection device comprising a supply swirler, and a valve body that slides axially in a middle hole of the swirler to separate and seat a seat portion of the valve seat, wherein the fuel passage is the fuel passage of the fuel passage. Since at least the vicinity of the outlet has a curved passage portion for injecting the fuel in a direction inclined with respect to the central axis of the valve body,
When the fuel given the velocity component in the swirling direction by the swirler passes through the fuel passage, only the velocity component in the straight traveling direction can be bent while keeping the velocity component in the swirling direction, so that the symmetry of the fuel spray shape is maintained. There is an effect that the fuel can be injected in a direction inclined with respect to the central axis of the valve body as it is. Also, by adjusting the curved shape of the curved passage,
A desired spray shape can be realized by adjusting the spray direction and spray distance.

The fuel injection device according to claim 2 of the present invention is
A valve seat having a fuel passage for injecting fuel to the outside, a swirler for giving swirling energy to the fuel to supply the fuel passage to the fuel passage, and a swirler axially sliding in the bore of the swirler to form a valve seat of the valve seat. A fuel injection device including a valve body for seating a seat portion, wherein at least a part of the fuel passage is formed by inserting a pipe body into a through hole provided in the valve seat, and the pipe body. A curved passage portion for injecting the fuel in a direction inclined with respect to the central axis of the valve body is provided on the outlet side of the valve.
In addition to the effect of the invention of claim 1, in addition to the effect of the invention of claim 1, the curved passage portion of the pipe body is exposed to the outside from the end surface of the valve seat. Since it is much easier to form a straight passage in the inside than to form a curved passage, the valve seat has an advantage that it can be produced at low cost.

Further, in any one of claims 1 to 3, the fuel passage is provided on an inlet side of the fuel passage and has a straight passage portion centered on the central axis and the straight passage portion. And a value Ls / D with respect to the diameter D of the fuel passage of the length Ls of the straight passage portion is 0.
The value Lr / D of the axially projected length Lr of the curved passage portion with respect to the diameter D is about 1 to 10;
If the value R / D of the radius R of the curved center line of the curved passage portion with respect to the diameter D is about 5 to 10, the straight passage portion has a flow in the direction of the central axis of the fuel flow in the fuel reservoir. Is maintained and this flow is effectively guided to the curved passage portion. On the other hand, the curved passage portion gradually changes the flow direction based on its curved shape without causing the abrupt flow direction change seen in the conventional inclined fuel passage. There is an effect that fuel is injected in a direction inclined with respect to the central axis without causing a flow velocity difference.

According to the first aspect of the present invention, the curved passage portion is formed by electric discharge machining, and the inner surface of the curved passage portion is made smooth by fluid polishing. This has the effect of significantly reducing the amount of carbon adhering to the surrounding area.

[Brief description of drawings]

FIG. 1 is a first embodiment of a fuel injection device according to the present invention.
Sectional view of.

FIG. 2 is an enlarged view of the valve seat of FIG.

FIG. 3 is a sectional view of the valve seat and the fuel injection shape according to the first embodiment.

FIG. 4 is a second embodiment of the fuel injection device according to the present invention.
FIG. 7 is an enlarged view of the valve seat in the manufacturing process.

FIG. 5 is a third embodiment of the fuel injection device of the present invention.
FIG. 6 is an enlarged cross-sectional view of the valve seat.

FIG. 6 is a sectional view of a valve seat and its vicinity in a conventional fuel injection device.

FIG. 7 is an enlarged sectional view of a valve seat in a conventional fuel injection device.

FIG. 8 is an enlarged cross-sectional view of another valve seat in the conventional fuel injection device.

[Explanation of symbols]

1 fuel injection device, 3 valve device, 32 valve body, 4 swirler, 44 fuel storage chamber, 5 valve seat, 52 fuel passage, 5
23 straight passage parts, 524 curved passage parts, 6 straight electrode rods, 7 arc-shaped electrode rods, 8 tubular bodies.

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Claims (7)

[Claims] 1. A valve seat having a fuel passage for injecting fuel to the outside, a swirler for giving swirling energy to the fuel to supply the fuel to the fuel passage, and a swirler slidably in an inner hole of the swirler. A fuel injection device including a valve element for seating a seat portion of the valve seat.
A fuel injection device comprising a curved passage portion for injecting the fuel in a direction inclined with respect to a central axis of the valve body at least near an outlet of the fuel passage. 2. A valve seat having a fuel passage for injecting fuel to the outside, a swirler for giving swirling energy to the fuel to supply the fuel to the fuel passage, and an axial slide in a bore of the swirler. In the fuel injection device, a valve body for seating and detaching a seat portion of the valve seat is provided, wherein at least a part of the fuel passage is formed by inserting a pipe into a through hole provided in the valve seat. A fuel injection device having a curved passage portion for injecting the fuel in a direction inclined with respect to a central axis of the valve body, on the outlet side of the pipe body. 3. The fuel injection device according to claim 2, wherein the curved passage portion of the pipe body is exposed to the outside from an end surface of the valve seat. 4. The fuel passage includes a straight passage portion provided on an inlet side of the fuel passage and having the center axis as a center, and the curved passage portion connected to the straight passage portion. The fuel injection device according to any one of claims 1 to 3. 5. The value Ls / D of the length Ls of the straight passage portion with respect to the diameter D of the fuel passage is about 0.5 to 5, and the diameter of the axially projected length Lr of the curved passage portion is the diameter. The value Lr / D for D is about 1 to 10, and the value R / D for the radius D of the radius R of the bending center line of the bending passage portion is
It is about 5-10, The fuel injection device of Claim 4 characterized by the above-mentioned. 6. The fuel injection device according to claim 1, wherein the curved passage portion is formed by electric discharge machining. 7. The fuel injection device according to claim 6, wherein an inner surface of the curved passage portion is smoothed by fluid polishing.