JP3572044B2 - Fuel injection device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection device, and more particularly to a fuel injection device for giving swirling energy to fuel and supplying it to a combustion chamber of an internal combustion engine such as an automobile engine.
[0002]
[Prior 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 Application Laid-Open No. 10-103194, etc., 3 is a valve device, 4 is a swirler, and 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 cylindrical body having a bore through which the valve body 32 is inserted. The swirler 4 includes a plurality of, for example, six fuel passages 41 penetrating the thick wall in the axial direction, and It has a swirler groove 43 connected to the fuel passage 41. The valve seat 5 is composed of a seat portion 51 on the surface facing the swirler 4, on which the tip of the valve element 32 is detached and seated, and a fuel passage 52 for injecting fuel to the outside, following the seat portion 51. The fuel supplied from the outside flows from the fuel passage 41 of the swirler 4 to the space between the opposing surfaces of the swirler 4 and the valve seat 5, and then passes through the swirler groove 43 and the fuel reservoir 44 to the fuel provided in the valve seat 5. It reaches the passage 52 and is injected from the outlet 53 thereof and supplied to the cylinder of the engine.
[0003]
As shown in FIG. 6, the fuel passage 52 in Japanese Patent Application Laid-Open No. 10-103194 extends coaxially with the axis of the valve body 32. Recently, the swirling energy given to the fuel by the swirler 4 has been used as the fuel. For the purpose of effectively utilizing the atomization of fuel, proposals have been made to incline the fuel passage 52 with respect to the axis as shown in FIGS. Among them, FIG. 7 is disclosed in JP-A-10-184496. 7 and 8 are denoted by the same reference numerals as in FIG. 6, and FIG. 8 shows the injection of fuel injected from the fuel passage 52 of the valve seat 5. A sectional view of the shape is added. However, the inclined fuel passage 52 has the following problem.
[0004]
That is, in the in-cylinder injection type fuel injection device, 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 of the present inventors, the spray shape of the fuel is a very important factor from the viewpoint of combustion stability and combustion efficiency, and specifically, the fuel is the length of the slope of the cone. That is, the fuel injection distance is as uniform as possible over the circumferential direction of the bottom surface of the cone, and in the example of FIG. 8, the injection distances T1 and T2 are preferably symmetric with respect to the central axis of the cone. .
[0005]
By the way, in FIG. 7, the angle of change in the flow direction of the fuel is different between the left side passage 521 and the right side passage 522 in the figure of the fuel passage 52. That is, in the fuel storage chamber 44, the fuel moves in the axial direction as a whole while turning, and changes its direction in the direction inclined with respect to the axis at the entrance of the fuel passage 52. In the left side passage 521, the angle of change 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 FIG. As a result, as shown in FIG. 8, the injection shape from the inclined fuel passage 52 is such that the injection distance T1 of the fuel injected from the left passage 521 due to the fuel flow velocity difference between the left and right passages is as follows. It becomes smaller than the injection distance T2 of the fuel injected from the right passage 522. Note that the satin portion in FIG. 8 indicates fuel, and the fuel injected from the fuel passage 52 to the outside has a mist state.
[0006]
As described above, in the prior art shown in FIGS. 7 and 8, the injection distances T1 and T2 are asymmetric, and therefore, the variation in combustion between the cylinders of the engine becomes large due to the variation in the spray shape of each fuel injection device, and the engine There are serious issues that can adversely affect operation.
[0007]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION In view of the problems in the prior art, the present invention makes it possible to distribute fuel from an outlet of a fuel passage provided in a valve seat in a direction inclined with respect to an axis and as uniformly as possible over a circumferential direction of the outlet. It is an object to provide a fuel injection device capable of injecting outward.
[0008]
[Means for Solving the Problems]
The 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, a swirler for supplying swirling energy to the fuel and supplying the fuel to the fuel passage, and a bore of the swirler. A fuel injection device provided with a valve body that slides in the axial direction inside and separates and seats the seat portion of the valve seat, wherein the fuel passage is provided on an inlet side of the fuel passage and has a center axis. It is characterized by comprising a straight passage portion at the center and a curved passage portion connected to the straight passage portion .
[0009]
The fuel injection system according to claim 2 of the present invention, at least a portion of the upper Symbol fuel passage in the first aspect is formed by inserting a tube into a through hole provided in the valve seat, and the tube A curved passage portion for injecting the fuel in a direction inclined with respect to a central axis of the valve body is provided on an outlet side of the body.
[0010]
A fuel injection device according to a third aspect of the present invention is the fuel injection device according to the second aspect, wherein the curved passage portion of the pipe is exposed to the outside from an end face of the valve seat.
[0011]
The fuel injection system according to claim 4 of the present invention, the value Ls / D to the diameter D of the fuel passage length Ls of Oite the straight path portion to the first aspect, in the order of 0.5 to 5 The value Lr / D of the axial projection length Lr of the curved passage portion with respect to the diameter D is approximately 1 to 10, and 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 characterized by being about 5 to 10 .
[0012]
A fuel injection device according to a fifth aspect of the present invention is the fuel injection device according to the first aspect, wherein the curved passage portion is formed by electric discharge machining .
[0013]
A fuel injection device according to a sixth aspect of the present invention is the fuel injection device according to the fifth aspect, wherein the curved passage portion is formed using an electrode rod having the same curved shape as the curved passage portion. .
[0014]
A fuel injection device according to a seventh aspect of the present invention is the fuel injection device according to the fifth aspect, wherein the inner surface of the curved passage portion is made smooth by fluid polishing.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
In FIGS. 1 to 5 for describing the following embodiments, portions corresponding to the portions in FIGS. 6 to 8 are denoted by the same reference numerals as those in FIGS. In this case, description of some parts will be omitted.
[0016]
Embodiment 1 FIG.
1 to 3 illustrate a first embodiment of a fuel injection device according to the present invention. FIG. 1 is a sectional view of the first embodiment, FIG. 2 is an enlarged view of a valve seat in FIG. 3 is a sectional view of a valve seat and a fuel injection shape.
[0017]
1 to 3, reference numeral 1 denotes a fuel injection device, 2 denotes a valve operating device, 3 denotes a valve device, 4 denotes a swirler, 5 denotes a valve seat, 6 denotes a fuel supply pipe, and 7 denotes a cylinder of the 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. The valve actuating device 2 has a function of forming a magnetic circuit and operating the valve element 32, and includes a housing 21 which is a yoke portion of the magnetic circuit, a core 22 which is a fixed core portion of the magnetic circuit, and a coil 23. , An armature 24 which is a movable core portion of a magnetic circuit. Note that the armature 24 and the valve body 32 have an integral structure. After the valve body 31 is inserted into the inner wall of the housing 21, it is connected by caulking. After the swirler 4 and the valve seat 5 are pressed 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.
[0018]
Although the detailed structure of the swirler 4 cannot be shown in FIG. 1, similarly to FIG. 6, the swirler 4 is a thick-walled cylindrical body having a hollow hole through which the valve body 32 is inserted, and the inside of the thick-walled wall extends in the axial direction. , A plurality of, for example, six fuel passages, and a swirler groove connected to these fuel passages. The valve seat 5 is composed of a seat portion 51 on the surface facing the swirler 4, on which the tip of the valve element 32 is detached and seated, and a fuel passage 52 for injecting fuel to the outside, following the seat portion 51.
[0019]
The fuel passage 52 is provided on the inlet side of the fuel passage 52 and includes a straight passage portion 523 centered on the central axis 324 of the valve body 32 and a curved passage portion 524 connected to the straight passage portion 523. The outlet of the curved passage portion 524 is the outlet 53 of the fuel passage 52. Reference numerals 521 and 522 denote a left passage and a right passage, respectively, through a straight passage portion 523 and a curved passage portion 524 in the fuel passage 52.
[0020]
The fuel that has passed through the swirler 4 travels in the direction of the central axis 324 as a whole while turning in the fuel storage chamber 44 as described with reference to FIG. The straight passage portion 523 in the present invention functions to maintain the flow of the fuel flow in the fuel storage chamber 44 in the direction of the central axis 324 and guide the flow to the curved passage portion 524. On the other hand, the curved passage portion 524 gradually changes the flow direction based on the curved shape without causing the rapid flow direction change observed in the inclined fuel passage 52 in FIGS. As shown in FIG. 3, the fuel is injected in a direction inclined with respect to the central shaft 324 without substantially causing a flow velocity difference between the passages 521 and 522.
[0021]
Hereinafter, the operation of the first embodiment will be described. 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 to generate a magnetic flux in the magnetic circuit, and the armature 24 is attracted to the core 22 side, and the armature 24 is And the valve body 32, which is an integral structure, is separated from the valve seat 5 to form a gap between them. At this time, the high-pressure fuel is injected into the cylinder 7 of the engine from the outlet 53 of the fuel passage 52 through the fuel passage, the swirler groove, and the fuel storage chamber 44 in the swirler 4. A turning force is applied while passing through the swirler groove.
[0022]
As described above, the curved passage portion 524 injects fuel in a direction inclined with respect to the central axis 324 without substantially causing a flow velocity difference between the left and right passages 521, 522. The injection distance T1 of the fuel injected from the left side passage 521 is substantially equal to the injection distance T2 of the fuel injected from the right side passage 522. And the variation in combustion between the cylinders of the engine is also reduced.
[0023]
Next, when a stop signal of the operation is sent from the microcomputer to the valve operating device 2, the energization of the coil 23 is stopped, and the valve body 32 and the valve seat 5 are pressed by the compression spring 11 which always pushes the valve body 32 in the valve closing direction. Is closed, and the fuel injection stops. The valve element 32 includes a valve element portion 321 that slides on the inner wall of the valve body 31, a valve element part 322 that slides on the inner wall of the swirler 4, and a valve element part 323. The valve body portion 323 contacts the lower surface of the stopper 33. Since the valve body portion 322 is means for restricting the radial non-coaxiality (runout) 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, the thickness is set to 10 μm or less (a gap on one side is 5 μm or less) in order to keep the durable wear of the valve body 32 within an allowable limit.
[0024]
In FIG. 2, if the length Ls of the straight passage portion 523 is too small, the above-described function of the straight passage portion 523 becomes poor. Conversely, if the length Ls is too large, the fuel passes through the straight passage portion 523. Attenuation of the swirling energy of the fuel provided by the swirler 4 during the passage increases. On the other hand, if the axial projection length Lr of the curved passage portion 524 or the radius R of the curved center line of the curved passage portion 524 is too small, the function of injecting fuel in the inclined direction becomes poor, and conversely, those values become too large. If there is, the flow velocity difference between the left and right passages 521 and 522 in the curved passage portion 524 becomes remarkable. Therefore, in the present invention, the value Ls / D of the length Ls with respect to the diameter D of the fuel passage 52 is about 0.5 to 5, preferably about 0.8 to 3, and the length Lr with respect to the diameter D. The value Lr / D is about 1 to 10, preferably about 2 to 5, and the value R / D of the radius R with respect to the diameter D is about 5 to 10, preferably about 7 to 9.
[0025]
Embodiment 2 FIG.
FIG. 4 is a view for explaining Embodiment 2 of the fuel injection device of the present invention, and is an enlarged view in a process of manufacturing the valve seat 5. In FIG. 4, reference numeral 6 denotes a straight electrode rod, and reference numeral 7 denotes an arc-shaped electrode rod.
[0026]
Hereinafter, the valve seat 5 used in the first embodiment will be described as an example to be manufactured and with reference to FIG. The fuel passage 52 of the valve seat 5 includes a straight passage portion 523 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. Is formed. At this time, the electrode rod 7 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 electric discharge machining using the electrode rod 6. The inner surface of the fuel passage 52 formed by the above processing, particularly, the inner surface of the curved passage portion 524 is made smooth by fluid polishing. The surface roughness of the electric discharge machining is usually about 6 to 12 μm, but it can be reduced to about 3 μm by fluid polishing, so that the amount of carbon attached around the curved passage portion 524 is greatly increased. Has the effect of reducing.
[0027]
Embodiment 3 FIG.
FIG. 5 is a view for explaining Embodiment 3 of the fuel injection device of the present invention, and is an enlarged sectional view of a valve seat. In FIG. 5, reference numeral 8 denotes a tube forming a part of the fuel passage 52, which is inserted and fixed in a through hole 525 provided in the valve seat 5 in advance. The through hole 525 has a straight shape, and is formed so that the inner diameter thereof is larger than the inner diameter of the straight passage portion 523 of the fuel passage 52 by the thickness of the tube wall of the tube 8. On the other hand, the tubular body 8 is a J-shaped one including a straight portion and a curved portion following the straight portion. Only the straight portion is inserted through and fixed to the through hole 525, and the curved portion is an end face of the valve seat 5. From the outside.
[0028]
Thus, the straight passage portion 523 of the fuel passage 52 in the third embodiment includes a straight portion formed by directly drilling the valve seat 5 and the inside of the straight portion of the tube 8. Exists in the above-mentioned curved portion. In general, since it is much easier to form a straight passage inside a solid body than to form a curved passage, the valve seat 5 used in the third embodiment can be manufactured at low cost. There is. Note that the ranges of Ls / D, Lr / D, and R / D of the fuel passage 52 using the tube 8 are the same as those described in the first embodiment.
[0029]
【The invention's effect】
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, a swirler that gives swirling energy to the fuel and supplies the fuel to the fuel passage, and A fuel injection device comprising a valve body that slides in an axial direction in a bore of the swirler and detaches and seats a seat portion of the valve seat, wherein the fuel passage is provided on an inlet side of the fuel passage. And a curved passage portion connected to the straight passage portion around the central axis. When the fuel passes through the fuel passage, only the velocity component in the straight traveling direction is bent without changing the velocity component in the turning direction, so that the fuel is maintained with respect to the central axis of the valve body while maintaining the symmetry of the spray shape. Spray in an inclined direction There is an effect that can be. Further, by adjusting the curved shape of the curved passage portion, the direction of the spray and the spray distance can be adjusted, and a desired spray shape can be realized.
[0030]
In the first aspect, at least a portion of the upper Symbol fuel passage is formed by inserting a tube into a through hole provided in the valve seat and the valve body the fuel to the outlet side of the tube Wherein the curved passage portion of the tubular body in the above-mentioned claim 2, wherein the curved passage portion of the tubular body is provided from the end face of the valve seat to the outside. It is characterized in that it is exposed, and in addition to the effect of the above-mentioned claim 1, in general, forming a straight passage in a solid body is more difficult than forming a curved passage. Since it is much easier, the valve seat has the advantage that it can be produced at low cost.
[0031]
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. A 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; The value Lr / D of the axial projection length Lr of the curved passage portion with respect to the diameter D is about 1 to 10, and 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 When the diameter is about 5 to 10, the straight passage portion has an effect of maintaining the flow of the fuel flow in the fuel storage chamber in the direction of the central axis and guiding this flow to the curved passage portion. On the other hand, the curved passage portion gradually changes the flow direction based on the curved shape without causing the rapid flow direction change observed in the conventional inclined fuel passage. This has the effect of injecting fuel in a direction inclined with respect to the central axis without substantially causing a flow velocity difference.
[0032]
In the first aspect, the curved passage portion is formed by electric discharge machining, and the inner surface of the curved passage portion is smoothened by fluid polishing. This has the effect of greatly reducing the amount of carbon adhering.
[Brief description of the drawings]
FIG. 1 is a sectional view of a fuel injection device according to a first embodiment of the present invention.
FIG. 2 is an enlarged view of the valve seat of FIG. 1;
FIG. 3 is a sectional view of a valve seat and a fuel injection shape according to the first embodiment;
FIG. 4 is a view for explaining Embodiment 2 of the fuel injection device of the present invention, and is an enlarged view in a process of manufacturing a valve seat.
FIG. 5 is an enlarged sectional view of a valve seat for explaining a third embodiment in the fuel injection device of the present invention.
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 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 reservoir, 5 valve seat, 52 fuel passage, 523 straight passage portion,
524 Curved passage, 6 straight electrode rods, 7 arc-shaped electrode rods, 8 tubes.

Claims (7)

A valve seat having a fuel passage for injecting fuel to the outside, a swirler for supplying swirling energy to the fuel and supplying the fuel to the fuel passage, and a valve seat that slides in a bore of the swirler in an axial direction to axially slide the fuel. A fuel injection device provided with a valve body for detaching and seating a seat portion, wherein 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 curved passage portion connected to the fuel injection device. At least a portion of the upper Symbol fuel passage is formed by inserting a tube into a through hole provided in the valve seat, and tilt the fuel to the outlet side of the tube with respect to the central axis of the valve body 2. The fuel injection device according to claim 1, further comprising a curved passage portion for injecting the fuel in a predetermined direction. 3. The fuel injection device according to claim 2, wherein the curved passage portion of the tube is exposed to the outside from an end surface of the valve seat. 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 value Lr / D of the axial projection length Lr of the curved passage portion with respect to the diameter D. 2. The fuel injection according to claim 1, wherein D is about 1 to 10, and a value R / D of a radius R of the curved center line of the curved passage portion with respect to the diameter D is about 5 to 10. apparatus.   The fuel injection device according to claim 1, wherein the curved passage portion is formed by electric discharge machining.   The fuel injection device according to claim 5, wherein the curved passage portion is formed using an electrode rod having the same curved shape as the curved passage portion. 6. The fuel injection device according to claim 5, wherein the inner surface of the curved passage portion is made smooth by fluid polishing.

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