fuel injection valve

Abstract

Provided is a fuel injection valve in which the variation in fuel injection performance caused by distortion in an orifice is suppressed. The fuel injection valve comprises: a fuel passage (1) through which fuel is introduced; and an orifice member (3) press-fitted into the inner wall of the fuel passage (1). The orifice member (3) is provided with a cylindrical part (6) fixed to the inner wall of the fuel passage (1) through press-fitting, an end wall (7) which covers one end of the cylindrical part (6) and to which an orifice (2) is provided, and an annular stress absorption part (8) that is interposed between one end of the cylindrical part (6) and the outer circumference of the end wall (6) to absorb stress caused by the press-fitting.

Description

[Technical Field]

[0001] The present invention relates to a fuel injection valve having an orifice member having an orifice in a fuel passage. [Background technology]

[0002] Conventionally, a fuel injection valve equipped with an orifice member having an orifice in a fuel passage inside a housing has been known (see, for example, Patent Document 1). This fuel injection valve has a fuel inlet tube connected to a fuel distribution cap branched from a fuel rail pipe connected to a discharge port of a fuel pump, and an orifice member is attached to the inlet of the fuel inlet tube.

[0003] The orifice member is composed of a cylindrical mounting tube and a metal diaphragm that covers the upstream end of the mounting tube. An orifice is provided in the center of the metal diaphragm. The fuel inlet tube, which is connected to the fuel distribution cap, has a cylindrical fitting recess on its inner circumferential surface at its inlet, and an annular step that connects to the downstream end.

[0004] The mounting flange of the fuel filter is placed on this annular step, and the fuel filter is attached.Then, the mounting cylindrical portion of the orifice member is press-fitted into the fitting recess of the fuel inlet tube, and the downstream end of the mounting cylindrical portion is brought into close contact with the flange of the fuel filter, thereby attaching the orifice member to the fuel inlet tube. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2022-139378 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the fuel injection valve of Patent Document 1, the orifice member is attached to the fuel inlet tube by press-fitting the mounting cylindrical portion of the orifice member into the fitting recess of the fuel inlet tube, so the orifice member may be deformed by the tension applied to the mounting cylindrical portion during press-fitting, and this deformation may be transmitted to the orifice, causing distortion in the orifice. This distortion may cause variations in the fuel injection performance of the fuel injection valve.

[0007] SUMMARY OF THE INVENTION In view of the above problems of the prior art, an object of the present invention is to provide a fuel injection valve that suppresses variations in fuel injection performance due to distortion of the orifice. [Means for solving the problem]

[0008] The fuel injection valve of the present invention comprises: A fuel injection valve including a fuel passage through which fuel to be injected is introduced, and an orifice member having an orifice and press-fitted into an inner wall of the fuel passage, The orifice member is a cylindrical portion fixed to the inner wall by the press-fitting; a flange portion extending radially outward from an upstream end of the cylindrical portion by a diameter greater than an inner diameter of the fuel passage; Covering one end of the cylindrical portion, Located downstream of the cylindrical portion an end wall portion in which the orifice is provided; The pressure-reducing member is characterized by comprising an annular stress absorbing portion interposed between the one end of the cylindrical portion and the outer periphery of the end wall portion to absorb stress caused by the press-fitting.

[0009] According to the present invention, the cylindrical portion of the orifice member, which is press-fitted into the inner wall of the fuel passage, is subject to distortion due to stress received from the inner wall during press-fitting. However, this distortion is absorbed by the annular stress-absorbing portion between the cylindrical portion and the end wall, and transmission of the distortion to the orifice in the end wall is suppressed. Therefore, the orifice maintains its designed dimensions as much as possible, thereby providing a fuel injection valve with suppressed variation in fuel injection performance.

[0010] In the present invention, the annular stress-absorbing portion may be connected to the one end of the cylindrical portion and the end wall portion via bent portions, respectively. This allows the bent portions to control the transmission of stress during press-fitting from the cylindrical portion to the annular stress-absorbing portion and from the annular stress-absorbing portion to the end wall portion, thereby suppressing stress concentration at both end edges of the annular stress-absorbing portion. This, combined with the stress absorption effect of the annular stress-absorbing portion, makes it possible to more effectively avoid distortion of the orifice.

[0011] In the present invention, the end wall portion may be located downstream of the cylindrical portion, and the orifice member may include a flange portion extending radially outward from the upstream end of the cylindrical portion. With this, when the orifice member is press-fitted into the fuel passage, the flange portion comes into contact with the opening of the fuel passage, making it possible to easily check the position of the orifice member. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing an orifice member of a fuel injection valve according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic view showing a state in which the orifice member of FIG. 1 is formed. [Figure 3] 3A to 3C are schematic diagrams showing how the orifice member of FIG. 1 is press-fitted into the cylindrical fuel inlet portion of the fuel injection valve. [Figure 4] 4A to 4C are schematic diagrams showing how a conventional orifice member not having an annular stress absorbing portion is press-fitted into a cylindrical fuel inlet portion of a fuel injection valve. [Figure 5] 2 is a graph showing the results of measurements of the relationship between the interference [μm] and the deformation amount of the orifice (amount of diameter change [μm]) when the orifice member of FIG. 1 is press-fitted into the cylindrical fuel inlet portion of the fuel injection valve. [Figure 6] 2 is a graph showing the results of measurements of the relationship between the interference [μm] when the orifice member of FIG. 1 is press-fitted into the cylindrical fuel inlet portion of the fuel injection valve and the press-fit load [N] required for press-fitting. [Figure 7]7A is an explanatory diagram for explaining the effect of preventing distortion of the orifice by the orifice member of FIG. 1 in comparison with the conventional orifice member of FIG. 7B. [Figure 8] FIG. 6 is a cross-sectional view showing an orifice member of a fuel injection valve according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a cross-sectional view showing an orifice member of a fuel injection valve according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view showing an orifice member of a fuel injection valve according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 shows an orifice member of a fuel injection valve according to a first embodiment of the present invention. As shown in Fig. 1, this fuel injection valve is provided in its housing and includes a fuel passage 1 into which fuel to be injected is introduced, and an orifice member 3 having an orifice 2 and press-fitted into the inner wall of the fuel passage 1.

[0014] Specifically, the orifice member 3 is press-fitted and fixed into the fuel inlet tube portion 5 on the upstream side of the portion of the fuel passage 1 where the fuel filter 4 is installed.

[0015] The orifice member 3 includes a cylindrical portion 6 that is fixed to the inner wall of the fuel passage 1 by the press-fitting, an end wall portion 7 that covers one end of the cylindrical portion 6 and in which the orifice 2 is provided, and an annular stress absorbing portion 8 that is interposed between the one end of the cylindrical portion 6 and the outer periphery of the end wall portion 7 and absorbs stress due to the press-fitting. In this embodiment, however, the one end of the cylindrical portion 6 is the downstream end.

[0016] The annular stress absorbing portion 8 is connected to one downstream end of the cylindrical portion 6 and to the end wall portion 7 via bent portions 9. The end wall portion 7 is located on the downstream side of the cylindrical portion 6. The orifice member 3 has a flange portion 10 that extends radially outward from the upstream end portion of the cylindrical portion 6. The flange portion 10 contacts the end portion of the fuel inlet cylindrical portion 5.

[0017] Fig. 2 shows how the orifice member 3 is formed. As shown in Fig. 2, the orifice member 3 is formed by pressing a metal plate as a base material using upper and lower dies 11 and 12 having the shape of the orifice member 3 to form an orifice 2. As the metal plate, for example, a stainless steel plate can be used.

[0018] 3A to 3C show how the orifice member 3 is press-fitted into the cylindrical fuel inlet section 5. First, as shown in FIG. 3A, the orifice member 3 is positioned at the opening of the cylindrical fuel inlet section 5 with the orifice 2 facing downstream. Next, as shown in FIG. 3B, the orifice member 3 is pressed downstream by a pressing member 13. At this time, the downstream end of the cylindrical section 6 receives a radially inward force F from the inner wall of the cylindrical fuel inlet section 5, causing stress (strain) S within the cylindrical section 6.

[0019] However, this stress (strain) S is absorbed and suppressed by the annular stress absorbing portion 8 and the bent portions 9 on both sides thereof, and therefore is not transmitted significantly to the end wall portion 7. When the orifice member 3 is further pressed and the flange portion 10 abuts against the end of the cylindrical fuel inlet portion 5 as shown in Figure 3C, the press-fitting is completed, and the attachment of the orifice member 3 to the cylindrical fuel inlet portion 5 is completed.

[0020] Even at this point, the stress (strain) S due to the force F from the inner wall of the tubular fuel inlet portion 5 is absorbed and suppressed by the annular stress absorbing portion 8 and the bent portions 9 on both sides thereof, and is not significantly transmitted to the end wall portion 7. Therefore, in the orifice member 3 after installation is completed, the orifice 2 is maintained as much as possible in its designed shape and position.

[0021] 4A to 4C show how a conventional orifice member 3b that does not have an annular stress-absorbing portion 8 is press-fitted into the cylindrical fuel inlet portion 5. In this case, as shown in Fig. 4A, the orifice member 3b is positioned at the opening of the cylindrical fuel inlet portion 5, and as shown in Fig. 4B, when press-fitting is initiated by a pressing member 13, the downstream end of the cylindrical portion 6b receives a radially inward force F from the inner wall of the cylindrical fuel inlet portion 5, causing stress (strain) S inside the cylindrical portion 6b. This stress (strain) S is transmitted as is to the end wall portion 7b.

[0022] 4C, even when the press-fitting is completed, the stress (strain) S due to the force F from the inner wall of the cylindrical fuel inlet portion 5 is transmitted to the end wall portion 7b without being absorbed. Therefore, in the orifice member 3b after the attachment is completed, the orifice 2 has a different shape and position compared to the orifice 2 in the present embodiment shown in FIG.

[0023] Figure 5 shows the results of measurements of the relationship between the interference [μm] when press-fitting the orifice member 3 into the cylindrical fuel inlet portion 5 and the deformation amount (diameter change [μm]) of the orifice 2. The results are shown by the graph curve A in the figure. From these results, it can be seen that the diameter change amount of the orifice 2 is approximately 7 [μm] or less within the assumed range W of interference during mass production.

[0024] In contrast, in the case of a conventional orifice member 3b (see FIGS. 4A to 4C) that does not have an annular stress absorbing portion 8, as shown by point B in the figure, when the interference is 60 μm within the expected range W, the amount of change in diameter of the orifice 2 is 30 μm, which is significantly larger than in the case of this embodiment.

[0025] Figure 6 shows the results of measurements of the relationship between the interference [μm] when press-fitting the orifice member 3 into the fuel inlet tube portion 5 and the press-fit load [N] required for press-fitting. The results are shown by graph curve C. In consideration of equipment requirements, the target press-fit load is 1000 [N] or less.

[0026] As shown by graph curve C in FIG. 6, within the expected range W of interference during mass production, the press-fit load is approximately 400 [N] or less, which is well below the target press-fit load of 1000 [N].

[0027] In contrast, in the case of a conventional orifice member 3b (see FIGS. 4A to 4C) that does not have an annular stress absorbing portion 8, as shown by point D in the figure, the press-fit load when the interference is 60 μm within the expected range W is approximately 750 N, which is smaller than the target press-fit load of 1000 N, but is significantly larger than in the case of this embodiment.

[0028] As described above, according to this embodiment, the cylindrical portion 6 of the orifice member 3 press-fitted into the inner wall of the fuel passage 1 receives strain due to stress from the inner wall when the orifice member 3 is press-fitted, but this strain is absorbed by the annular stress absorber 8, thereby suppressing transmission of the strain to the orifice 2. Therefore, the orifice 2 maintains its designed dimensions as much as possible, making it possible to provide a fuel injection valve that suppresses variations in fuel injection performance.

[0029] Furthermore, since the annular stress absorbing portion 8 is connected to one end of the cylindrical portion 6 and the end wall portion 7 via the bent portion 9, the bent portion 9 controls the transmission of stress during pressing from the cylindrical portion 6 to the annular stress absorbing portion 8 and further to the end wall portion 7, thereby suppressing the concentration of stress at both end edges of the annular stress absorbing portion 8.

[0030] Therefore, according to the orifice member 3 of this embodiment, as shown in Fig. 7A, compared to the conventional orifice member 3b shown in Fig. 7B which does not have the annular stress absorbing portion 8, the force F that the cylindrical portion 6 receives during press-fitting is more effectively avoided by the bent portion 9, in combination with the stress absorption effect of the annular stress absorbing portion 8, thereby making it possible to prevent the orifice 2 from being distorted as much as possible. In addition, the pressing force required for press-fitting can also be reduced.

[0031] Furthermore, the orifice member 3 has a flange 10 extending radially outward from the upstream end of the cylindrical portion 6. Therefore, when the orifice member 3 is press-fitted into the fuel passage 1, the flange 10 comes into contact with the opening of the fuel passage 1, making it easy to check the position of the orifice member 3.

[0032] Fig. 8 shows an orifice member of a fuel injection valve according to a second embodiment of the present invention. This orifice member 3c corresponds to the orifice member 3 of Fig. 1 from which the flange portion 10 has been removed. In other respects, it has the same configuration as the orifice member 3 of Fig. 1 and provides the same effects.

[0033] 9 shows an orifice member of a fuel injection valve according to a third embodiment of the present invention. In this orifice member 3d, an annular stress-absorbing portion 8d has a truncated cone shape whose diameter decreases toward the upstream side. The diameter of the end wall portion 7d is approximately half that of the end wall portion 7 of the orifice member 3 shown in FIG. 1.

[0034] Therefore, the cylindrical portion 6d is longer than the cylindrical portion 6 of the orifice member 3 in Fig. 1. The bending angle of the bent portion 9d between the cylindrical portion 6d and the annular stress absorbing portion 8d is approximately 45°. The bending angle of the bent portion 9d between the annular stress absorbing portion 8c and the end wall portion 7d is approximately 135°.

[0035] In the case of the orifice member 3d, the force F that is applied to the cylindrical portion 6 when press-fitted into the tubular fuel inlet portion 5 is more effectively suppressed by the bent portion 9d, in combination with the stress absorption effect of the annular stress absorption portion 8d, to generate stress (strain) S in the end wall portion 7d, thereby minimizing distortion of the orifice 2. In other respects, the orifice member 3d has the same configuration as the orifice member 3 in Fig. 1 and achieves the same effects.

[0036] The analytically predicted value for the deformation of the diameter of the orifice 2 due to press-fitting is, for example, 0.008 mm for the orifice member 3 in Fig. 1, and approximately 0.01 mm for the orifice member 3d. Also, the analytically predicted value for the press-fitting load when press-fitting into the tubular fuel inlet portion 5 is 419.1 N for the orifice member 3 in Fig. 1, and approximately 707.3 N for the orifice 2 of the orifice member 3d.

[0037] 10 shows an orifice member 3e of a fuel injection valve according to a fourth embodiment of the present invention. In this orifice member 3e, an annular stress-absorbing portion 8e, bent portions 9e on both sides of the annular stress-absorbing portion 8e, and an end wall portion 7e are located on the upstream side of a cylindrical portion 6e. The lower end of the cylindrical portion 6e is formed with a tapered guide portion 14 whose diameter decreases toward the downstream side to serve as a guide when the cylindrical portion 6e is press-fitted into the cylindrical fuel inlet portion 5.

[0038] That is, excluding the guide portion 14, the orifice member 3e has a configuration in which the upstream side and downstream side of the orifice member 3c in Fig. 8 are reversed. Except for the effect of the flange portion 10, the orifice member 3e also exhibits the same effects as the orifice member 3 in Fig. 1.

[0039] The analytically predicted value of the deformation of the diameter of the orifice 2 due to press-fitting is, for example, 0.008 [mm] for the orifice member 3 in Fig. 1, and approximately 0.017 [mm] for the orifice member 3e. Also, the analytically predicted value of the press-fitting load when press-fitting into the tubular fuel inlet portion 5 is 419.1 [N] for the orifice member 3 in Fig. 1, and approximately 547.4 [N] for the orifice member 3e.

[0040] Although the embodiment of the present invention has been described above, the present invention is not limited to this. For example, the bent portions on both sides of the annular stress absorbing portion may be omitted. [Explanation of symbols]

[0041] 1...fuel passage, 2...orifice, 3, 3b, 3c, 3d, 3e...orifice member, 4...fuel filter, 5...fuel inlet cylindrical portion, 6, 6b, 6c, 6d, 6e...cylindrical portion, 7, 7b, 7c, 7d, 7e...end wall portion, 8, 8c, 8d, 8e...annular stress absorption portion, 9, 9c, 9d, 9e...bent portion, 10...flange portion, 11...die, 12...die, 13...pressing member, 14...guiding portion, A...graph curve, B...point, C...graph curve, D...point, F...force, S...stress (strain), W...expected range of interference.

Claims

1. A fuel injection valve including a fuel passage through which fuel to be injected is introduced, and an orifice member having an orifice and press-fitted into an inner wall of the fuel passage, The orifice member is a cylindrical portion fixed to the inner wall by the press-fitting; a flange portion extending radially outward from an upstream end of the cylindrical portion by a diameter greater than an inner diameter of the fuel passage; an end wall portion covering one end of the cylindrical portion, positioned downstream of the cylindrical portion, and having the orifice provided therein; a ring-shaped stress absorbing portion disposed between the one end of the cylindrical portion and an outer periphery of the end wall portion, the ring-shaped stress absorbing portion absorbing stress caused by the press-fitting;

2. 2. The fuel injection valve according to claim 1, wherein the annular stress absorbing portion is connected to the one end of the cylindrical portion and the end wall portion via bent portions, respectively.

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