JP2003155965A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device improving fuel atomization. SOLUTION: This fuel injection device has a disc-shaped fuel cavity 14d between a nozzle hole plate member 17 drilled with a plurality of nozzle holes 18 and a valve seat 14. In this fuel injection device, at least one outer periphery 14f of the fuel cavity 14d is formed into a tapered shape in which an axial height tapers down toward an outer-periphery end. The fuel cavity 14d has a central section 14e and an outer periphery section 14i which is positioned at its outside and has an axial height shorter than that of the central section 14e.

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 for atomizing 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 As an example of the above fuel injection device,
There is known a structure in which a liquid fuel is sprayed in a mist state from a nozzle plate member having a plurality of nozzles. FIG. 7 is a cross-sectional view of the nozzle plate member and its vicinity in the fuel injection device disclosed in JP 2001-46919 A, and FIG. 8 is a plan view seen from the nozzle outlet side of FIG. is there.

In FIGS. 7 to 8, reference numeral 20 designates four nozzles 2
1, a valve sheet 30 having a valve seat 31 and a fuel passage 32 communicating with the nozzle 21 and 40 a nozzle plate member 20 and a valve sheet 30.
Is a disc-shaped fuel cavity that is provided between the fuel passage 32 and the injection port 21, and 50 is a valve member that is seated on and off the valve seat 31 to open and close the fuel passage 32. The fuel supplied from the outside reaches the fuel cavity 40 from the fuel passage 32 when the valve member 50 is separated from the valve seat 31 and the fuel passage 32 is in an open state, and then from each injection port 21 of the internal combustion engine. It is injected into a combustion chamber (not shown). In the meantime, it is atomized by the mechanism described below and sprayed in the form of mist.

That is, the fuel flowing into the fuel cavity 40 flows radially from the center of the fuel cavity 40 having a disk shape or in the vicinity thereof, in other words, toward the outer periphery of the fuel cavity 40. At this time, a part of the fuel does not reach the outer periphery and flows out into the combustion chamber from the nozzle 21 provided on the nozzle plate member 20 on the way. Further, a part of the fuel passes through between the nozzles 21 to reach the outer circumference, then reverses and flows from the outer circumference toward the center, and then flows out from the nozzle 21 to the combustion chamber on the way. Therefore, at the injection port 21, the flow A coming from the central direction and the flow B coming from the outer periphery collide with each other to generate a turbulent flow. As a result, the fuel flowing out from the injection port 21 is atomized by the turbulent flow.

However, in the conventional disc-shaped fuel cavity 40, the flow A coming from the central area has a larger flow velocity than the flow B coming from the outer circumference, and therefore the collision between the two flows does not occur uniformly, There is a big problem that the atomization of fuel is still insufficient.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems in the prior art and to provide a fuel injection device with improved fuel atomization.

[0007]

According to a first aspect of the present invention, there is provided a fuel injection device having an injection port plate member having a plurality of injection ports, a fuel sheet communicating with the injection port and a valve sheet having a valve seat, and the injection port. A disc-shaped fuel cavity provided between the plate member and the valve sheet to connect the fuel passage and the injection port, and a valve member that is seated on and off the valve seat to open and close the fuel passage. In the above fuel injection device, at least the outer peripheral portion of the fuel cavity is tapered so that the height in the axial direction gradually decreases toward the outer peripheral end.

A fuel injection device according to claim 2 of the present invention is
In the above claim 1, the fuel cavity is composed of a central portion having a substantially constant axial height and the tapered outer peripheral portion connected to the central portion. .

A fuel injection device according to claim 3 of the present invention is
In the above-mentioned claim 2, the plurality of injection holes are arranged concentrically with respect to the center of the fuel cavity,
In addition, each of the injection ports is provided so as to face at least a part of the tapered outer peripheral portion.

A fuel injection device according to claim 4 of the present invention is
In the above-mentioned claim 1, the entire fuel cavity is tapered so that the height in the axial direction gradually decreases toward the outer peripheral end.

A fuel injection device according to claim 5 of the present invention is
A nozzle plate member having a plurality of nozzles, a fuel passage communicating with the nozzle and a valve seat having a valve seat, and the fuel passage and the nozzle provided between the nozzle plate member and the valve sheet. In a fuel injection device including a disc-shaped fuel cavity communicating with the valve seat and a valve member that is seated on and off the valve seat to open and close the fuel passage, the fuel cavity includes a central portion of the fuel cavity and a central portion of the fuel cavity. It is characterized in that it has an outer peripheral portion located outside and having a height in the axial direction lower than that of the central portion.

A fuel injection device according to claim 6 of the present invention is
In the above claim 5, a step portion is provided at a boundary between the central portion and the outer peripheral portion, and the plurality of injection holes are dispersed concentrically with respect to the center of the fuel cavity and the step portion or the vicinity thereof. It is characterized by being provided in.

A fuel injection device according to claim 7 of the present invention is
In claim 5 or 6, the step between the central portion and the outer peripheral portion in the step portion is 10 to 50% of the height of the central portion.

A fuel injection device according to claim 8 of the present invention is
In any one of claims 5 to 7, the outer peripheral portion is tapered so that its axial height gradually decreases toward the outer peripheral end.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 to 3 are views for explaining Embodiment 1 of the fuel injection device of the present invention, and FIG. 1 is a cross-sectional view of Embodiment 1 and FIG.
2 is an enlarged view of the C portion in FIG. 1, and FIG. 3 is K- in FIG.
It is the top view seen from the K direction. In addition, the arrow in FIG.
5 shows the direction of fuel flow in the fuel cavity.

1 to 3, the fuel injection device 1 is
An electromagnetic coil 3 and a fixed iron core 4 inside the resin housing 2.
And the metal plate 5 constituting the magnetic path is arranged and integrally molded. The electromagnetic coil 3 is a resin bobbin 3
It is composed of a, a coil 3b wound around its outer circumference, and a terminal 6 provided for connection to the outside, and is integrally molded with the resin housing 2.

An adjuster 8 for adjusting the load of the compression spring 7 is fixed inside the fixed iron core 4. One end of the metal plate 5 forming the magnetic path is welded to the fixed iron core 4, and the other end is welded to the magnetic pipe 9 forming the magnetic path. The non-magnetic pipe 11 is fixed to the fixed iron core 4 and the magnetic pipe 9 so that the movable iron core 10 arranged inside the magnetic pipe 9 is axially movable.

A needle pipe 12 is welded to one end of the movable iron core 10. An end of the needle pipe 12 on the movable iron core 10 side is in contact with the compression spring 7, and a ball 13 as an example of the valve member is welded to the other end. The valve sheet 14 arranged inside the magnetic pipe 9 has an inclined surface 14 a that serves as a valve seat of the ball 13 and a fuel passage 14 c. The ball 13 has a pentagonal outer peripheral portion which is guided by the guide portion 14b of the valve sheet 14 by the pentagon and axially moves back and forth to form an inclined surface 14a.
It is arranged so that it can be seated on and taken off.

The nozzle plate member 17 includes a fuel passage 14c.
Alternatively, it has a plurality of (eight in FIG. 3) injection holes 18 which are concentrically arranged with respect to the center of the fuel cavity 14d and are equally spaced from each other, and the liquid sheet is provided at the lower end of the valve sheet 14 in the figure. It is tightly fixed. As shown in FIG. 2, each injection port 18 has its center line inclined at an angle θ with respect to a line parallel to the axis. Injection plate member 17 and valve sheet 14
The fuel cavity 14d provided between and has a disk shape, and has a function of connecting the fuel passage 14c and the plurality of injection holes 18 to each other. At this time, since a part of the surface 14h of the valve sheet 14 facing the nozzle plate member 17 is a taper surface, the fuel cavity 14d has an outer peripheral portion 14f because of the taper surface. Has a taper shape in which the axial height (hereinafter, cavity height) gradually decreases toward the outer peripheral wall 14g.

Next, the operation of the fuel injection device 1 will be described. When the coil 3 is energized from the outside through the terminal 6, the fixed iron core 4, the metal plate 5, the magnetic pipe 9, the movable iron core 1
A magnetic flux is generated in the magnetic path composed of
Is attracted to the fixed iron core 4 by an electromagnetic attraction force, and is joined to the movable iron core 10 to form an integral middle pipe 12.
And a ball 1 welded and fixed to the needle pipe 12.
3 operates, and the ball 13 makes the inclined surface 1 of the valve sheet 14
When separated from 4a, the fuel passage 14c is opened.

When the fuel passage 14c is in the open state, the fuel supplied from the delivery pipe (not shown) to the fuel injection device 1 passes through the filter 16 and then the adjuster 8 arranged in the fixed iron core 4. And the compression spring 7, the movable iron core 10, the inside of the needle pipe 12, and between the guide portion 14b of the valve sheet 14 and the outer periphery of the ball 13 to sequentially pass through to reach the cylindrical fuel passage 14c. Is further injected from the injection port 18 to the outside (in the intake pipe of the engine, etc.) through the fuel cavity 14d.

The flow of fuel in the fuel cavity 14d will be described in detail with reference to FIGS.
The fuel flowing from c to the central portion 14e of the fuel cavity 14d changes its flow direction in the radial direction of the fuel cavity 14d from the central portion 14e, as in the case of the prior art shown in FIGS. It flows toward the outer peripheral portion 14f, and a part (flow A) thereof flows toward the nozzles 18 and is injected outside, and the remaining fuel passes between the nozzles 18 and reaches the outer peripheral portion 14f, and thereafter. It collides and reflects on the outer peripheral wall 14g of the fuel cavity 14d, changes its direction again, and travels toward the injection port 18 (flow B). At the injection port 18, the injection ports 1 in the state where the flows A and B collide with each other and the fuel flow is disturbed
Outflow from 8.

Regarding the flow velocities of the flows A and B, the difference between the prior art shown in FIGS. 7 to 8 and the first embodiment will be described. The prior art fuel cavity 40 (see FIG. 7), which does not have the tapered outer periphery 14f, has a uniform cavity height. Now, if the height is H, the fuel passage area in the fuel cavity 40 becomes 2πrH, and the passage area also increases as the radius r from the center increases. Therefore, the fuel flow velocity decreases as the fuel flows toward the outer peripheral end, and in particular, the flow velocity of the flow B, which is a reflected flow from the outer peripheral wall, decreases, and the above-mentioned problems occur in the related art. On the other hand, the fuel cavity 14d of the first embodiment has the outer peripheral portion 14f adjacent to the central portion 14e having the cavity height H2 (see FIG. 2), and the cavity height there is toward the outer peripheral wall 14g. Since the fuel flow velocity decreases gradually, the flow velocity of the flow B is reduced to a small extent, and thus the flow velocity difference between the flows A and B at the injection port 18 is small, and the degree of atomization of the fuel is improved.

From the viewpoint of minimizing the flow velocity difference between A and B as described above, it is preferable that the plurality of injection ports 18 are provided facing at least a part of the outer peripheral portion 14f. In other words, φB in FIG. 2 is the inner diameter of the outer peripheral portion 14f having a donut shape in a plan view, that is, the diameter of the circle at the boundary between the outer peripheral portion 14f and the central portion 14e, and φP is the circle connecting the center points of the plurality of injection holes 18. , Φd is the diameter of each injection port 18 (φD is the diameter of the fuel passage 14c), φB is preferably smaller than φP + φd / 2.

The size or size range of each portion in the first embodiment and the following embodiments is the same as that of the fuel injection device 1.
However, if the diameter of the ball 13 of the fuel injection device 1 is 4 mm, then φd is 0.
1 to 0.3 mm, particularly 0.15 mm, φP is 1.0 to
3.0 mm, especially 2.0 mm, angle θ is 0 to 30 degrees, especially 15 degrees, φD is 0.7 to 1.5 mm, especially 1.0 m
m and H2 are 0.1 to 0.3 mm, especially 0.15 mm.

Embodiment 2. FIG. 4 is a view for explaining the second embodiment of the fuel injection device of the present invention, and is an enlarged view of the portion C of FIG. 1 different from FIG. In addition, in FIG. 4 and FIG. 5 described later, the same parts as those shown in FIGS.

The second embodiment differs from the first embodiment in that the entire fuel cavity 14d has a tapered shape in which the axial height gradually decreases toward the outer peripheral end.
Other configurations are the same. In the fuel cavity 14d, the cavity height H2 at the center is the outer peripheral wall 14
Since it gradually decreases toward g, the decrease in the fuel flow velocity is small even in the vicinity of the outer peripheral wall 14g, and thus the flow velocity of the flow B is reduced to a small extent.
The difference in the flow velocity between the two is small, and the degree of atomization of the fuel is improved as in the case of the first embodiment.

Embodiment 3. FIG. 5 illustrates a third embodiment of the fuel injection device of the present invention, and is an enlarged view of a portion C of FIG. 1 different from that of FIG.

In the third embodiment, the outer peripheral portion 14 having a cavity height lower than that of the central portion 14e is provided outside the central portion 14e through a step portion 14j instead of the tapered outer peripheral portion 14f.
i is provided. φB is the diameter of the step portion 14j (inner diameter of the outer peripheral portion 14i). The outer peripheral portion 14i is the central portion 14
Since the cavity height is lower than that of e, the fuel passage area is small, and thus the tapered outer peripheral portion 1 in the first embodiment is used.
By performing the same function as 4f, the flow velocity difference between the flows A and B is reduced, and atomization of fuel is improved.

In FIG. 5, when the cavity height of the central portion 14e is H2 and the step between the central portion 14e and the outer peripheral portion 14i in the step portion 14j is H1, it is generally assumed that the step portion 14j is too small. If the step H1 is too large to be provided, the fuel passage area in the outer peripheral portion 14i becomes small and the flow velocity of the flow A becomes too large. Therefore, the step H1 is preferably about 10 to 50% of H2.

Fourth Embodiment FIG. 6 is a diagram for explaining the fourth embodiment of the fuel injection device of the present invention and is an enlarged view of a portion C of FIG. 1 different from that of FIG. In the fourth embodiment, the step portion 14j is different from that of the third embodiment in that
8 is different from that of FIG. 8 in other words, φB is provided at a position close to φP, and the outer peripheral portion 14i is tapered, and other configurations are the same.

In the fourth embodiment, the fuel cavity 1
As described above, the plurality of injection holes 18 concentrically distributed with respect to the center of 4d are provided in the step portion 14j or in the vicinity thereof, particularly within the range where the diameter φB is φP ± φd / 2. Is preferred. Thus, in addition to the effect of reducing the flow velocity difference between the flows A and B described in the third embodiment,
Since the step portion 14j exists at the position facing each nozzle 18 or in the vicinity thereof, in addition to the above-described flows A and B that are lateral flows at the entrance of the nozzle 18, a vertical flow from the top to the bottom along the wall of the step 14j. Therefore, the turbulence of the fuel flow is further increased by the collision of the fuel flows from three directions, and the atomization of the fuel is further advanced. Although the outer peripheral portion 14i of the fourth embodiment has a tapered shape, it does not have to be tapered.

[0033]

As described above, the fuel injection device according to the first aspect of the present invention has the injection port pre-press having a plurality of injection ports.
Member, a valve seat having a fuel passage communicating with the injection port and a valve seat, and a disc-shaped fuel provided between the injection plate member and the valve sheet to communicate the fuel passage with the injection port. In a fuel injection device including a cavity and a valve member that is seated on and off the valve seat to open and close the fuel passage, at least an outer peripheral portion of the fuel cavity has a tapered shape in which an axial height gradually decreases toward an outer peripheral end. Therefore, the atomization of the fuel due to the effective collision of the above-described flows A and B of the fuel is improved at each injection port as compared with the related art. As a result, the fuel combustion efficiency is improved.

Further, in the above-mentioned claim 1, the fuel cavity is composed of a central portion whose axial height is substantially constant, and the tapered outer peripheral portion which is connected to the central portion. 2, the plurality of injection holes are distributed concentrically with respect to the center of the fuel cavity, and the injection holes are provided so as to face at least a part of the tapered outer peripheral portion. , The collision of the above-mentioned streams A and B of fuel occurs more effectively.

Further, in the above-mentioned claim 1, even if the entire fuel cavity has a tapered shape in which the axial height gradually decreases toward the outer peripheral end, the collision of the fuel flows A and B described above Atomization is improved.

A fuel injection device according to claim 5 of the present invention is
As described above, a nozzle plate member having a plurality of nozzles, a valve sheet having a fuel passage communicating with the nozzle and a valve seat, and provided between the nozzle plate member and the valve sheet. In a fuel injection device including a disc-shaped fuel cavity that communicates a fuel passage and the injection port, and a valve member that is seated on and off the valve seat to open and close the fuel passage, the fuel cavity includes a central portion of the fuel cavity. And an outer peripheral portion located outside the central portion and having an axial height lower than that of the central portion, the same effect as the fuel injection device according to claim 1 of the present invention can be obtained. Have.

Further, in the above-mentioned claim 5, a step portion is provided at a boundary between the central portion and the outer peripheral portion, and the plurality of injection holes are concentrically distributed with respect to a center of the fuel cavity and the step portion is formed. If it is provided in the portion or in the vicinity thereof, in addition to the effect of reducing the flow velocity difference between the flows A and B,
Since the stepped portion exists at the position facing each jet port 18 or in the vicinity thereof, in addition to the flows A and B at the inlet of the jet port, a vertical flow from the top to the bottom along the wall of the stepped portion also occurs, so that there are three directions. Due to the collision of the fuel flow from the above, the turbulence of the fuel flow is further increased, and the atomization of the fuel is further advanced.

Further, in the above-mentioned claim 5, the step between the central portion and the outer peripheral portion in the step portion is 10 to 50% of the height of the central portion, and the outer peripheral portion in the axial direction. When the height is tapered so as to gradually decrease toward the outer peripheral end, the collision of the fuel in the three directions and the atomization due to the collision are further improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is an enlarged view of part C in FIG.

FIG. 3 is a plan view seen from the KK direction in FIG.

FIG. 4 is a second embodiment of the fuel injection device according to the present invention.
FIG. 2 is another enlarged view of the C portion of FIG.

FIG. 5 is a third embodiment of the fuel injection device of the present invention.
FIG. 6 is a further enlarged view of the part C in FIG.

FIG. 6 is a fourth embodiment of the fuel injection device according to the present invention.
FIG. 6 is a further enlarged view of the part C in FIG.

FIG. 7 is an injection port press in a conventional fuel injection device.
FIG. 3 is a cross-sectional view of the tongue member and its vicinity.

FIG. 8 is a plan view seen from the jet outlet side of FIG. 7.

[Explanation of symbols]

1 fuel injection device, 13 balls, 14 valve seal
14c fuel passage, 14d fuel cavity, 14
e central part, 14f outer peripheral part, 14g outer peripheral wall, 14i
Outer peripheral portion, 14j step portion, 17 nozzle plate member, 1
8 nozzles.

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Claims (8)

[Claims] 1. A nozzle plate member having a plurality of nozzles,
A valve seat having a fuel passage communicating with the injection port and a valve seat
A disk-shaped fuel cavity that is provided between the nozzle plate member and the valve sheet and connects the fuel passage and the nozzle, and is seated on and off the valve seat to open and close the fuel passage. A fuel injection device including a valve member, wherein at least an outer peripheral portion of the fuel cavity has a tapered shape in which an axial height gradually decreases toward an outer peripheral end. 2. The fuel cavity comprises a central portion having a substantially constant axial height and a tapered outer peripheral portion connected to the central portion. Fuel injector. 3. The plurality of injection holes are distributed concentrically with respect to the center of the fuel cavity, and the injection holes are provided so as to face at least a part of the tapered outer peripheral portion. The fuel injection device according to claim 2, wherein the fuel injection device is provided. 4. The fuel injection device according to claim 1, wherein the entire fuel cavity has a tapered shape in which the height in the axial direction gradually decreases toward the outer peripheral end. 5. A nozzle plate member having a plurality of nozzles,
A valve seat having a fuel passage communicating with the injection port and a valve seat
A disk-shaped fuel cavity that is provided between the nozzle plate member and the valve sheet and connects the fuel passage and the nozzle, and is seated on and off the valve seat to open and close the fuel passage. In the fuel injection device including the valve member, the fuel cavity includes a central portion of the fuel cavity and an outer peripheral portion having an axial height lower than that of the central portion. A fuel injection device characterized by: 6. A step portion is provided at a boundary between the central portion and the outer peripheral portion, and the plurality of injection holes are dispersed concentrically with respect to a center of the fuel cavity and at or near the step portion. The fuel injection device according to claim 5, wherein the fuel injection device is provided. 7. The fuel injection according to claim 5, wherein a step between the central portion and the outer peripheral portion of the step portion is 10 to 50% of a height of the central portion. apparatus. 8. The fuel injection device according to claim 5, wherein the outer peripheral portion has a taper shape whose axial height gradually decreases toward the outer peripheral end. .