Fuel injection valve

Abstract

The purpose of the present invention is to provide a fuel injection valve 10 having improved reliability of an O-ring 30. The present invention includes: a cylindrical sleeve 25; an O-ring 30 disposed on an outer periphery of the sleeve 25; a backup ring 31 for supporting the O-ring 30; and an orifice member 32. The orifice member 32 has a bottom wall 32B which is arranged on the inner side of the sleeve 25 and in which an orifice hole 32A is formed, a first cylindrical wall 32C which extends from an outer peripheral edge part of the bottom wall 32B and is brought into pressure contact with an inner periphery of the sleeve, and a first flange part 32D which protrudes beyond an outer peripheral surface of the sleeve 25 in a direction orthogonal to an axial direction of the sleeve 25 from the first cylindrical wall 32C. In a state where the orifice member 32 is attached to the sleeve 25, an O-ring groove for holding the O-ring 30 in place is defined by an outer peripheral surface 25D of the sleeve 25, the backup ring 31, and the first flange part 32D.

Description

fuel injection valve

[0001] The present invention relates to a fuel injection valve for use in a fuel supply system.

[0002] 2. Description of the Related Art Conventionally, a fuel injection valve has been known which has a cylindrical fuel inlet sleeve connected to a fuel rail pipe through which fuel pumped from a fuel pump flows.

[0003] In recent years, with the increasing pressure in fuel supply systems, a fuel injection valve has been known which has an O-ring disposed on the outer periphery of the fuel inlet tube and a backup ring for improving the reliability of the O-ring in order to improve the airtightness between the fuel rail pipe and the fuel inlet tube (see, for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2021-039734

[0005] To prevent the O-ring from coming off, it was necessary to provide a protrusion at the end of the fuel inlet tube that protruded beyond the outer periphery of the O-ring in a direction perpendicular to the axial direction of the fuel inlet tube. In this case, due to issues with installation in the fuel inlet tube, it was necessary to use a backup ring with a circumferential notch cut out, i.e., a so-called bias cut.

[0006] Furthermore, even in a high-pressure environment with a fuel pressure of 50 MPa or more, the O-ring is pressurized and pressed against the backup ring with high pressure, which is thought to reduce the possibility of the sealing function being reduced due to breakage caused by the edge created by the bias cut.

[0007] Therefore, an object of the present invention is to provide a fuel injection valve that improves the reliability of the O-ring by making it possible to attach a backup ring that is not bias cut to a sleeve.

[0008] In order to achieve the above object, the fuel injection valve of the present invention comprises a cylindrical sleeve, an O-ring arranged on the outer periphery of the sleeve, a backup ring that supports the O-ring, and an orifice member, wherein the orifice member has a bottom wall that is arranged inside the sleeve and has an orifice hole formed therein, a cylindrical first cylindrical wall that extends from the outer periphery of the bottom wall and is pressed against the inner periphery of the sleeve, and a first flange that protrudes from the first cylindrical wall beyond the outer periphery of the sleeve in a direction perpendicular to the axial direction of the sleeve, and when the orifice member is attached to the sleeve, the outer periphery of the sleeve, the backup ring, and the first flange define an O-ring groove that holds the O-ring in place.

[0009] According to the present invention, it is possible to provide a fuel injection valve with an O-ring having improved reliability.

[0010] Fig. 1 is a cross-sectional view of a fuel injection valve according to one embodiment of the present invention; Fig. 2 is a cross-sectional view showing an enlarged state of a portion of a fuel injection valve according to a first embodiment of the present invention; Fig. 3 is a cross-sectional view showing an enlarged state of a portion of a fuel injection valve according to a second embodiment of the present invention; Fig. 4 is a cross-sectional view showing an enlarged state of a portion of a first flange portion and a second flange portion of a fuel injection valve according to a second embodiment of the present invention;

[0011] [First embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a fuel injection valve 10 according to one embodiment of the present invention.

[0012] As shown in FIG. 1 , a fuel injection valve 10 of the first embodiment includes a valve housing 13 in which a fuel injection hole 11 and a valve seat 12 are formed, a valve element 15 that enables fuel to be injected from the fuel injection hole 11 by lifting the valve element 15 from a valve-closed position in contact with the valve seat 12 to a valve-open position in response to excitation of a coil 14, and a return spring 16 that returns the valve element 15 to the valve-closed position in contact with the valve seat 12.

[0013] The valve element 15 is lifted to the valve open position by settling the overshoot and overshoot return that occur during the lift. The valve element 15 has a valve portion 17 that cooperates with the valve seat 12 and a rod 18 that is connected to the valve portion 17. The rod 18 is formed in a cylindrical shape that extends in the axial direction.

[0014] The fuel injection valve 10 also includes a hollow fixed core 19 that is part of a sleeve 25 connected to the upstream end of the valve housing 13, a movable core 21 that faces an attraction surface 20 of the fixed core 19 and is slidably fitted on the rod 18, and a valve-opening side stopper 22 that is fixed to the rod 18 and comes into contact with the movable core 21 that is attracted to the attraction surface 20 when the coil 14 is energized, thereby opening the valve body 15.

[0015] A valve-closing stopper 23 is fixed to the rod 18, closer to the valve seat 12 than the valve-opening stopper 22. An auxiliary spring 24 is provided between the valve-opening stopper 22 and the movable core 21. The auxiliary spring 24 exerts a spring force that moves the movable core 21 away from the valve-opening stopper 22 and brings it into contact with the valve-closing stopper 23 when the coil 14 is not energized.

[0016] In this configuration, when the coil 14 is not energized, the valve portion 17 of the valve element 15 is seated on the valve seat 12 by the biasing force of the return spring 16, and the valve is in a closed state, as shown in Figure 1. The movable core 21 is brought into contact with the valve-closing stopper 23 by the biasing force of the auxiliary spring 24, and a predetermined gap is maintained between the movable core 21 and the fixed core 19.

[0017] When the coil 14 is energized in this state, the magnetic force generated thereby first attracts the movable core 21 to the fixed core 19 , compressing the auxiliary spring 24 , which is weaker than the return spring 16 , and the movable core 21 comes into contact with the valve-opening stopper 22 .

[0018] When the movable core 21 comes into contact with the valve-opening stopper 22, it quickly moves the valve-opening stopper 22 against the biasing force of the return spring 16, and then collides with the suction surface 20 to stop it. During this time, the rod 18 moves together with the valve-opening stopper 22, so that the valve portion 17 at the tip of the rod 18 lifts off the valve seat 12, and the valve is opened.

[0019] When the valve portion 17 opens, fuel is pressure-fed into a cylindrical sleeve 25 connected to a fuel pump and a fuel rail pipe (not shown). The fuel passes through the inside of a pipe-shaped retainer 26, the hollow portion 27 of the fixed core 19, the side surface around the valve-opening stopper 22, the through hole 28 of the movable core 21, the inside of the valve housing 13, and the flat surface 29 around the valve portion 17, and is then injected directly into the combustion chamber of the internal combustion engine from the fuel injection hole 11.

[0020] As shown in FIG. 2 , the fuel injection valve 10 of this embodiment has a cylindrical sleeve 25, an O-ring 30 arranged on the outer periphery of the other end (upper end) of the sleeve 25, a backup ring 31 arranged on the outer periphery of the sleeve 25 closer to one end (lower end) than the O-ring 30 and supporting the O-ring 30, and an orifice member 32 attached to the other end of the sleeve 25.

[0021] The sleeve 25 is a connecting portion to a fuel rail pipe (not shown), and one end (lower end) thereof extends toward the movable core 21. The O-ring 30 is for ensuring airtightness with the fuel rail pipe.

[0022] Next, a detailed description will be given of the structure of the other end (upper end) side of the sleeve 25. Fig. 2 is an enlarged cross-sectional view showing the other end of the sleeve 25 of the fuel injection valve 10 according to the first embodiment of the present invention.

[0023] 2, the sleeve 25 has a fuel path 25A therein, a first opening 25B communicating with the fuel path 25A formed at one end thereof, and a second opening 25C communicating with the fuel path 25A formed at the other end thereof. A filter 33 is inserted into the fuel path 25A of the sleeve 25, and the filter 33 is supported by a filter holding member 34.

[0024] The outer peripheral surface of the other end of the sleeve 25 is continuously formed with a narrow surface 25D extending parallel to the axis of the sleeve 25 from the other end of the sleeve 25 toward the first opening 25B, a tapered surface 25E gradually increasing in a direction perpendicular to the axial direction of the sleeve 25, an orthogonal surface 25F extending in a direction perpendicular to the axial direction of the sleeve 25, and a wide surface 25G extending parallel to the axis of the sleeve 25.

[0025] The O-ring 30 has an inner periphery that fits the narrow surface 25D, which is the outer periphery of the sleeve 25, and is formed in a circumferentially continuous annular shape (circular ring shape).

[0026] The backup ring 31 is disposed on the narrow surface 25D, which is the outer periphery of the sleeve 25, closer to the first opening 25B (one end) than the O-ring 30.

[0027] The backup ring 31 is an annular (circular ring) shape that is continuous in the circumferential direction with no cuts. In other words, the backup ring 31 is not bias cut. Here, bias cut refers to an annular shape with an oblique cut surface formed on a portion of the ring.

[0028] The cross-sectional shape of the backup ring 31 is a trapezoid with a shorter bottom side on the first opening 25B side. The bottom surface 31A of the backup ring 31 is a flat surface extending in a direction perpendicular to the axial direction of the sleeve 25, and the bottom surface 31A of the backup ring 31 abuts against the perpendicular surface 25F of the outer peripheral surface of the sleeve 25, thereby restricting the movement of the backup ring 31 toward the first opening 25B side.

[0029] Furthermore, the entire inner peripheral surface 31B of the backup ring 31 abuts against the tapered surface 25E on the outer peripheral surface of the sleeve 25, thereby restricting movement of the sleeve 25 in a direction perpendicular to the axial direction.

[0030] Furthermore, the top surface 31C of the backup ring is a flat surface extending in a direction perpendicular to the axial direction of the sleeve 25. This top surface 31C forms the "contact surface" of the present invention that comes into contact with the O-ring 30. In other words, the backup ring 31 supports the O-ring 30 by means of the top surface 31C of the backup ring, with movement toward the first opening 25B and in a direction perpendicular to the axial direction of the sleeve 25 being restricted.

[0031] Therefore, for example, it is possible to prevent problems such as the O-ring protruding when the fluid pressure of the fuel passing through the fuel path 25A of the sleeve 25 exceeds a certain value.

[0032] The orifice member 32 has a bottom wall 32B arranged inside the second opening 25C of the sleeve 25, a cylindrical first cylindrical wall 32C extending from the outer peripheral edge of the bottom wall 32B, and a first flange portion 32D protruding from the first cylindrical wall 32C in a direction perpendicular to the axial direction of the sleeve 25.

[0033] The bottom wall 32B of the orifice member 32 is formed in a circular flat plate shape and has a size that fits the inner circumference of the fuel path 25A of the sleeve 25. An orifice hole 32A that communicates with the fuel path 25A is formed in the center of the bottom wall 32B. Fuel supplied from the fuel rail pipe flows into the fuel path 25A of the sleeve 25 through the orifice hole 32A.

[0034] The first cylindrical wall 32C extends from the outer peripheral edge of the bottom wall 32B toward the second opening 25C. Therefore, the first cylindrical wall 32C is pressed against the inner peripheral surface of the second opening 25C of the sleeve 25. This limits movement of the orifice member 32 in the axial direction of the sleeve 25 and in a direction perpendicular to the axial direction of the sleeve 25.

[0035] The first flange 32D protrudes from the other end of the first cylindrical wall 32C in a direction perpendicular to the axial direction of the sleeve 25 beyond the narrow surface 25D of the sleeve 25 (the outer peripheral surface of the other end of the sleeve 25). In addition, the first flange 32D abuts against the other end of the sleeve 25, thereby restricting movement of the orifice member 32 toward the first opening 25B.

[0036] The filter 33 removes foreign matter contained in the fuel passing through the fuel injection valve 10. The filter 33 has a cylindrical expanded diameter portion 33A and a cylindrical reduced diameter portion 33B extending from the expanded diameter portion 33A toward the first opening 25B. The reduced diameter portion 33B has a smaller diameter than the expanded diameter portion 33A.

[0037] The filter holding member 34 has a pair of upper and lower walls 34A, 34A that engage with the outer peripheral edge of the expanded diameter portion 33A of the filter 33, and a cylindrical wall 34B that covers the outer periphery of the expanded diameter portion 33A of the filter 33 and connects the pair of upper and lower walls 34A.

[0038] Of the pair of upper and lower walls 34A, 34A, one of the upper and lower walls 34A formed on the second opening 25C side is clamped between the bottom wall 32B of the orifice member 32 and the above-mentioned expanded diameter portion 33A, and the cylindrical wall 34B of the filter holding member 34 is pressed against the inner surface of the sleeve 25, thereby restricting the axial movement of the filter 33 with respect to the sleeve 25.

[0039] As described above, the backup ring 31 is arranged on the outer periphery of the sleeve 25 closer to the first opening 25B than the O-ring 30, and with the O-ring 30 supported by the backup ring 31, the orifice member 32 is attached to the other end of the sleeve 25 where the second opening 25C is formed.

[0040] Therefore, when the orifice member 32 is attached to the other end of the sleeve 25, the narrow surface 25D (the outer surface of the other end) of the sleeve 25, the backup ring 31, and the first flange portion 32D define an O-ring groove that holds the O-ring 30 in place.

[0041] In other words, an O-ring 30 and a backup ring 31 having an inner circumference that fits the outer circumference of the sleeve 25 are attached to the sleeve 25, and then an orifice member 32 having a first flange portion 32D that is larger in diameter than the outer circumference of the sleeve 25 (narrow surface 25D) is attached to the sleeve 25, thereby defining an O-ring groove that holds the O-ring 30 in place.

[0042] Next, a description will be given of the operation and effect of the fuel injection valve 10 configured as described above. As described above, in the fuel injection valve 10 of this embodiment, with the orifice member 32 attached to the other end of the sleeve 25, an O-ring groove that holds the O-ring 30 in place is defined by the outer circumferential surface of the other end of the sleeve 25, the backup ring 31, and the first flange 32D.

[0043] Therefore, it is possible to mount a backup ring 31 that is continuous in the circumferential direction and has no notches on the sleeve 25, and the O-ring 30 is supported by this backup ring 31, thereby improving the reliability of the O-ring 30.

[0044] Furthermore, the backup ring 31, which is a continuous ring with no cuts in the circumferential direction, is more durable than a backup ring with a bias cut, and can improve the reliability of the O-ring 30.

[0045] Therefore, even in a high-pressure environment where the fuel pressure is, for example, 50 MPa or more, the O-ring 30 is pressurized and pressed against the backup ring at high pressure, thereby preventing deterioration of the sealing function due to breakage caused by the edges created by the bias cut.

[0046] Therefore, according to the present invention, it is possible to provide a fuel injection valve 10 in which the reliability of the O-ring 30 is improved.

[0047] Furthermore, by using the backup ring 31 that is continuous in the circumferential direction and has no notches, processing steps for the backup ring, such as cutting, are not required, and the cost of manufacturing the fuel injection valve 10 can be reduced.

[0048] Second Embodiment A second embodiment will be described below, with the same configuration as that of the fuel injection valve 10 according to the first embodiment of the present invention being omitted where appropriate.

[0049] FIG. 3 is an enlarged cross-sectional view of the other end of the sleeve 25 of the fuel injection valve 10 according to the second embodiment of the present invention.

[0050] The fuel injection valve 10A of the second embodiment differs from the first embodiment in that it has an assembly in which a filter 33, an orifice member 32, and a collar member 35 are integrated together. The filter 33 inserted into the fuel path 25A of the sleeve 25 is supported by the collar member 35.

[0051] The collar member 35 has an engagement wall 35A that engages with the outer peripheral edge portion of the expanded diameter portion 33A of the filter 33 on the first opening 25B side, a cylindrical second wall 35B that extends from the engagement wall 35A and covers the outer periphery of the expanded diameter portion 33A of the filter 33 and the outer periphery of the first cylindrical wall 32C of the orifice member 32, and a second flange portion 35C that protrudes from the second cylindrical wall 35B in a direction perpendicular to the axial direction of the sleeve 25.

[0052] The engagement wall 35A of the collar member 35 is annular (circular ring-shaped) and has a size that fits the inner circumferential surface of the sleeve 25. The inner periphery of the engagement wall 35A, which is annular, has a size that fits the outer diameter of the reduced diameter portion 33B of the filter 33.

[0053] The reduced diameter portion 33B of the filter 33 is inserted into the inside of the annular body of the engagement wall 35A, and the engagement wall 35A engages with the outer peripheral edge portion of the expanded diameter portion 33A of the filter 33 on the first opening 25B side, thereby allowing the collar member 35 to support the filter 33.

[0054] The second cylindrical wall 35B extends from the outer peripheral edge of the engagement wall 35A toward the second opening 25C, and covers the outer periphery of the enlarged diameter portion 33A of the filter 33 and the outer periphery of the first cylindrical wall 32C of the orifice member 32.

[0055] The second cylindrical wall 35B is pressed against the inner peripheral surface of the second opening 25C of the sleeve 25. Therefore, movement of the collar member 35 in the axial direction of the sleeve 25 and in a direction perpendicular to the axial direction of the sleeve 25 is restricted.

[0056] The second flange 35C protrudes from the other end of the second cylindrical wall 35B in a direction perpendicular to the axial direction of the sleeve 25 beyond the narrow surface 25D of the sleeve 25 (the outer peripheral surface of the other end of the sleeve 25) so as to overlap with the first flange 32D of the orifice member 32. In addition, the upper surface of the second flange 35C (the surface facing the first flange 32D) and the lower surface of the first flange 32D of the orifice member 32 (the surface facing the second flange 35C) are in close contact with each other.

[0057] As shown in Figure 3, the expanded diameter portion 33A of the filter 33 is sandwiched between the bottom wall 32B of the orifice member 32 and the engagement wall 35A of the collar member 35, and the first cylindrical wall 32C of the orifice member 32 is pressed against the second cylindrical wall 35B of the collar member 35, thereby forming an assembly in which the filter 33, orifice member 32, and collar member 35 are integrated.

[0058] 4, the thickness t1 of the first flange 32D of the orifice member 32 in the axial direction of the sleeve 25 is thicker than the thickness t2 of the second flange 35C of the collar member 35, and the thickness t1 of the first flange 32D is, for example, 0.3 to 1.0 mm. Furthermore, in consideration of rigidity and formability, the thickness t1 of the first flange 32D is preferably 0.5 to 1.0 mm.

[0059] Furthermore, when the filter 33, orifice member 32, and collar member 35 are integrated, a space R is provided between the boundary (corner) between the first flange 32D of the orifice member 32 and the first cylindrical wall 32C, and between the boundary between the second flange 35C of the collar member 35 and the second cylindrical wall 35B, so that the lower surface of the first flange 32D and the upper surface of the second flange 35C are kept in close contact with each other.

[0060] Next, a description will be given of the effects of the fuel injection valve 10 configured as described above. As described above, in the fuel injection valve 10 of this embodiment, the second flange 35C of the collar member 35 protrudes in a direction perpendicular to the axial direction of the sleeve 25 beyond the narrow surface 25D of the sleeve 25 (the outer peripheral surface of the other end of the sleeve 25) so as to overlap with the first flange 32D of the orifice member 32.

[0061] Therefore, the pressure resistance of the O-ring groove against pressure received from the second opening 25C side can be improved, and the effect of preventing the O-ring 30 from coming off can be further improved.

[0062] Furthermore, because the filter 33, the orifice member 32, and the collar member 35 are integrated, the filter 33, the orifice member 32, and the collar member 35 can be attached to the sleeve 25 in the same procedure as the process of attaching a conventional filter to a sleeve. Therefore, the initial cost for manufacturing the fuel injection valve 10 of this embodiment can be reduced.

[0063] Furthermore, since the second flange 35C of the collar member 35 and the first flange 32D of the orifice member 32 overlap, the thickness of the entire flange can be increased, thereby enhancing the rigidity of the entire flange. As a result, the flange can further improve the effectiveness of preventing the O-ring 30 from coming off.

[0064] Furthermore, the thickness t1 of the first flange 32D in the axial direction of the sleeve 25 is thicker than the thickness t2 of the second flange 35C, and the thickness t1 of the first flange 32D is 0.3 to 1.0 mm, so that sufficient strength can be ensured to prevent the O-ring 30 from coming loose.

[0065] If the thickness t1 of the first flange 32D is less than 0.3 mm, the strength of the first flange 32D tends to be insufficient, and if the thickness t1 exceeds 1.0 mm, press working becomes difficult, which is undesirable.

[0066] As described above in detail, according to the present invention, it is possible to provide a fuel injection valve 10 in which the reliability of the O-ring 30 is improved.

[0067] REFERENCE SIGNS LIST 10: Fuel injection valve 25: Sleeve 25A: Fuel path 25B: First opening 25C: Second opening 30: O-ring 31: Backup ring 32: Orifice member 32A: Orifice hole 32B: Bottom wall 32C: First cylindrical wall 32D: First flange 33: Filter 33A: Enlarged diameter portion 33B: Reduced diameter portion 35: Collar member 35A: Engagement wall 35B: Second cylindrical wall 35C: Second flange

Claims

1. A cylindrical sleeve having a fuel path therein, a first opening formed at one end, and a second opening formed at the other end communicating with the fuel path, an O-ring arranged on the outer periphery of the other end of the sleeve, a backup ring arranged on the outer periphery of the sleeve closer to the one end than the O-ring and supporting the O-ring, and an orifice member attached to the other end of the sleeve, wherein the orifice member has a bottom wall arranged inside the second opening of the sleeve and having an orifice hole formed therein communicating with the fuel path, a cylindrical first cylindrical wall extending from an outer periphery of the bottom wall and pressed against an inner periphery of the second opening of the sleeve, and a first flange protruding from the first cylindrical wall beyond the outer periphery of the other end of the sleeve in a direction perpendicular to the axial direction of the sleeve, a first flange portion and an outer peripheral surface of the other end of the sleeve, the backup ring, and the first flange portion define an O-ring groove that holds the O-ring in place and prevents it from coming off when the orifice member is attached to the other end of the sleeve.

2. A fuel injection valve as claimed in claim 1, wherein the backup ring is annular and continuous in the circumferential direction with no notches, and has a flat contact surface which comes into contact with the O-ring.

3. A fuel injection valve as claimed in claim 1 or 2, wherein a filter is inserted into the fuel path of the sleeve and is supported by a collar member, the filter having an expanded diameter portion disposed within the second opening of the sleeve and a reduced diameter portion extending from the expanded diameter portion towards the one end of the sleeve and having a smaller diameter than the expanded diameter portion, the collar member having an engagement wall engaging with an outer peripheral edge of the expanded diameter portion of the filter, a cylindrical second cylindrical wall extending from the engagement wall and covering the outer periphery of the expanded diameter portion and the outer periphery of the first cylindrical wall of the orifice member, and a second flange portion protruding from the second cylindrical wall in a direction perpendicular to the axial direction of the sleeve and above the outer periphery of the other end of the sleeve so as to overlap with the first flange portion of the orifice member, A fuel injection valve in which the expanded diameter portion of the filter is sandwiched between the bottom wall of the orifice member and the engagement wall of the collar member, and the first cylindrical wall of the orifice member is pressed against the second cylindrical wall of the collar member, thereby forming an assembly in which the filter, the orifice member, and the collar member are integrated.

4. A fuel injection valve as claimed in claim 3, wherein the thickness of the first flange in the axial direction of the sleeve is thicker than the thickness of the second flange, and the thickness of the first flange is 0.3 to 1.0 mm.