Fuel injection valve

Abstract

In a fuel injection valve (I), when a valve body (13) is open and fuel that has passed through a valve seat (8) flows into a fuel collection chamber (49), eddies are not generated and pressure loss in the fuel flow is eliminated. The bottom surface of the fuel collection chamber (49) is constituted of a concave curved surface (49a) formed along a virtual spherical surface B of which a center Bo is placed on a center line Y of the valve seat (8) and an intersection point P with the center line Y is positioned in a valve hole (7).

Description

Technical Field

[0001] The present invention mainly relates to a fuel injection valve used in a fuel supply system of an engine.

Background Art

[0002] Conventionally, as a fuel injection valve for an engine, there is provided a valve seat member having a conical valve seat and a valve hole penetrating the center thereof at the front end, a valve body having a spherical valve portion at the front end that cooperates with the valve seat to open and close the valve hole, and an injector plate joined to the front end face of the valve seat member and having a plurality of fuel injection holes arranged radially outward from the valve hole and communicating with the valve hole. A fuel collecting chamber for collecting fuel that has passed through the valve seat and guiding it to the valve hole is provided between the valve seat and the valve hole. On the other hand, a flat fuel diffusion chamber for radially diffusing the fuel that has passed through the valve hole and guiding it to the plurality of fuel injection holes is provided between the opposing surfaces of the valve seat member and the injector plate. As disclosed in Patent Document 1 below, it is known.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the fuel injection valve disclosed in Patent Document 1 above, the peripheral wall of the fuel collecting chamber stands up from its bottom surface, forming a stepped portion from the valve seat to the bottom surface of the fuel collecting chamber. This stepped portion causes a vortex in the flow of fuel flowing from the valve seat into the fuel collecting chamber when the valve body opens, which increases the pressure loss of the fuel flow and reduces the fuel injection amount.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a fuel injection valve that prevents vortices from being generated in the fuel flow when fuel passing through the valve seat flows into the fuel collecting chamber when the valve element opens the valve.

Means for Solving the Problems

[0006] In order to achieve the above object, the present invention includes a valve seat member having a conical valve seat and a valve hole penetrating the center thereof at the front end, a valve element having a spherical valve portion at the front end that cooperates with the valve seat to open and close the valve hole, and an injector plate joined to the front end face of the valve seat member, disposed radially outward from the valve hole, and having a plurality of fuel injection holes communicating with the valve hole. In a fuel injection valve, A fuel collecting chamber connecting between the valve seat and the valve hole is provided in the valve seat member. On the other hand, , before the bottom surface of the fuel collecting chamber is centered on the center line of the valve seat, and the intersection with the center line is formed by a concave surface following a spherical zone of a virtual spherical surface located within the valve hole. , a flat fuel diffusion chamber (50) that communicates between the valve hole (7) and the plurality of fuel injection holes (11) is formed integrally with the valve seat member between the opposing surfaces of the valve seat member and the injector plate, the inner peripheral surface of the valve hole (7) is provided with a convex curved surface (7a) so as to be smoothly continuous with the bottom surface of the fuel collecting chamber (49) and the ceiling surface of the fuel diffusion chamber (50), the valve seat member (3) has a guide hole (9) with a polygonal cross-section formed by arranging three or more planes (9a) of the same width that guide the opening and closing operation of the spherical valve portion (14) so as to surround the center line (Y), a plurality of fuel passages (37) connected to the valve seat (8) are defined between the plurality of inner corner portions (9b) of the guide hole (9) and the spherical valve portion (14), by providing a communication recess (38) that connects the adjacent fuel passages (37) between the valve seat (8) and each plane (9a), the outer edge portion of the valve seat (8) has a star shape having the number of corner portions adapted to the inner corner portions (9b) when viewed in the direction along the center line (Y), matters characteristic characterize.

Effects of the Invention

[0008] According to the first feature of the present invention, the bottom surface of the fuel collecting chamber connecting between the valve seat and the valve hole is formed in a spherical belt-shaped concave surface following a virtual spherical surface centered on the center line of the valve seat and with the intersection point with the center line located inside the valve hole. As a result, no step portion is formed between the bottom surface of the fuel collecting chamber and the valve seat, and moreover, the distance from the spherical valve portion gradually increases toward the valve hole. Therefore, when the valve body opens and fuel flows from the valve seat into the fuel collecting chamber, generation of vortices can be prevented, and in the fuel collecting chamber, fuel can be guided to the valve hole without restricting its flow rate. Thereby, the pressure loss of the fuel flow can be reduced, and a decrease in the fuel injection amount from each fuel injection hole of the injector plate can be suppressed, contributing to improvement of the low fuel consumption and output performance of the engine.

[0009] Also, according to the second feature of the present invention, by forming a guide hole for guiding the opening and closing operation of the spherical valve portion in a polygonal cross-section on the valve seat member, a plurality of fuel flow paths can be provided around the spherical valve portion without performing flat processing on the spherical valve portion. Moreover, since the guide hole with a polygonal cross-section can be formed on the valve seat member together with the valve seat by forging, production costs can be reduced.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0011] Embodiments of the present invention will be described below based on the accompanying drawings. In the fuel injection valve I of the present invention, the fuel injection side is in the front and the fuel inlet side is in the rear.

[0012] First, in FIG. 1, a mounting hole 41 that opens into the combustion chamber 42 is provided in the cylinder head 40 of the engine E, and a fuel injection valve I capable of injecting fuel into the combustion chamber 42 is mounted in this mounting hole 41. At that time, a cushion member 43 is interposed between the fuel injection valve I and the cylinder head 40.

[0013] The valve housing 2 of the fuel injection valve I is composed of a cylindrical valve seat member 3, a magnetic cylindrical body 4 that fits and is liquid-tightly welded to the outer peripheral surface of the rear end portion of the valve seat member 3, a non-magnetic cylindrical body 6 that abuts against the rear end of the magnetic cylindrical body 4 and is liquid-tightly welded, a hollow cylindrical fixed core 5 that fits and is liquid-tightly welded to the inner peripheral surface of the non-magnetic cylindrical body 6 with its small-diameter front end portion 5a, and a fuel inlet cylinder 26 that fits and is liquid-tightly welded to the outer periphery of the rear end portion of the fixed core 5.

[0014] The valve seat member 3 has a conical valve seat 8, a valve hole 7 that penetrates the center portion of the valve seat 8, and a guide hole 9 that continues to the large-diameter portion of the valve seat 8.

[0015] At the front end portion of the non-magnetic cylindrical body 6, a portion that does not fit with the fixed core 5 is left, and from that portion to the magnetic cylindrical body 4, a hollow cylindrical movable core 12 that faces the front end surface of the fixed core 5 is fitted, and a valve body 13 is connected to this movable core 12.

[0016] This valve body 13 is composed of a spherical valve portion 14 that can slide in the guide hole 9 so as to cooperate with the valve seat 8 to open and close the valve hole 7, and a valve stem 15 that is welded and joined to the front end portion of the valve portion 14. The rear end portion of this valve stem 15 is press-fitted and welded to the inner peripheral surface of the movable core 12. Therefore, the valve body 13 can move up and down in the valve housing integrally with the movable core 12.

[0017] The valve stem 15 is made of a pipe material with a slit 15a, and its interior communicates with the hollow portion of the movable core 12, and the inside and outside of the valve stem 15 communicate with each other through the slit 15a.

[0018] In the hollow portion of the fixed core 5, a retainer 20 made of a grooved pipe material is press-fitted and fixed in the middle portion thereof, and the front end portion thereof becomes the first spring seat 21. On the other hand, the rear end portion of the valve stem 15 ends in the middle of the hollow portion of the movable core 12, and the upper end portion thereof becomes the second spring seat 22. A valve spring 23 is provided between these first and second spring seats 21 and 22, and the movable core 12 is biased in a direction away from the fixed core 5, that is, in the valve closing direction of the valve body 13, by the set load of this valve spring 23. The set load of this valve spring 23 is adjusted by the fitting depth of the retainer 20 into the fixed core 5.

[0019] A ring-shaped stopper member 35 made of a non-magnetic material that slightly protrudes from the rear end surface is embedded in the inner peripheral surface of the movable core 12. This stopper member 35 abuts against the fixed core 5 when the fixed core 5 attracts the movable core 12, and maintains a constant gap between the two cores 5 and 12.

[0020] A coil assembly 28 is fitted on the outer periphery of the valve housing 2 corresponding to the two cores 5 and 12. This coil assembly 28 is composed of a synthetic resin bobbin 29 that is fitted on the outer peripheral surfaces of the magnetic cylindrical body 4 from the rear end portion to the fixed core 5, and a coil 30 wound around the bobbin 29. A terminal support arm 29a that supports the base end portion of a power supply terminal 33 that protrudes to one side thereof is integrally formed at the rear end portion of the bobbin 29, and the terminal of the coil 30 is connected to the power supply terminal 33. A yoke 31 is disposed on the outer periphery of the coil assembly 28.

[0021] A coating layer 27 made of synthetic resin that covers the outer peripheral surfaces of the magnetic cylindrical body 4 and the fuel inlet cylinder 26 and encapsulates the coil assembly 28 is injection-molded. At this time, a coupler 34 that houses and holds the power supply terminal 33 and protrudes to one side of the coil assembly 28 is integrally formed with the coating layer 27.

[0022] A fuel filter 36 is attached to the inlet of the fuel inlet cylinder 26. Further, a fuel cap 46 is fitted to the outer periphery of the upper end of the fuel inlet cylinder 26 via a seal member 47. This fuel cap 46 is one of a plurality of fuel distribution caps branched from a fuel rail 45 connected to the discharge port of a fuel pump (not shown).

[0023] Next, the structure of the valve seat member 3 will be described in detail with reference to FIGS. 2 and 3. The guide hole 9 provided in the valve seat member 3 has a polygonal cross-section (hexagonal in the illustrated example) and is formed to extend rearward along the center line Y of the conical valve seat 8 from the large-diameter portion of the valve seat 8. That is, this guide hole 9 has a polygonal cross-section (hexagonal in the illustrated example) in which three or more planes 9a of the same width are arranged so as to surround the center line, and the plurality of planes 9a guide the lifting, that is, the opening and closing operation of the spherical valve portion 14. Further, a plurality of fuel passages 37 connected to the valve seat 8 are defined between the plurality of inner corner portions 9b of the guide hole 9 and the spherical valve portion 14.

[0024] Furthermore, a communication recess 38 for connecting between the adjacent fuel passages 37 is provided between the valve seat 8 and each plane 9a. As a result, as shown in FIG. 3, the large-diameter portion of the conical valve seat 8 has a star shape in plan view.

[0025] Further, the valve seat member 3 is provided with a guide hole 16 that extends in a tapered manner and widens rearward from the guide hole 9. This guide hole 16 has a function of guiding the spherical valve portion 14 into the guide hole 9 during the assembly of the fuel injection valve I.

[0026] Furthermore, the valve seat member 3 is provided with a fuel collecting chamber 49 that connects between the valve seat 8 and the valve hole 7. The bottom surface of this fuel collecting chamber 49 is constituted by a concave curved surface 49a formed as follows.

[0027] That is, first, as shown in FIG. 2, the center Bo of the virtual spherical surface B with a radius R2 smaller than the radius R1 of the spherical valve portion 14 is offset forward (downward in the illustrated example) from the center O of the spherical valve portion 14 along the center line Y of the valve seat 8 by a certain distance S, so that the virtual spherical surface B passes through the small-diameter side edge of the conical valve seat 8 and intersects the center line Y at the intersection point P within the valve hole 7. On such a virtual spherical surface B, the concave curved surface 49a is formed following the spherical zone portion from the small-diameter side edge of the valve seat 8 to the rear edge (the upper edge in the illustrated example) of the valve hole 7.

[0028] This concave curved surface 49a is formed by forging on the valve seat member 3 together with the valve seat 8, the guide hole 9, and the induction hole 16.

[0029] An injector plate 10 made of a steel plate having a plurality of fuel injection holes 11 communicating with the valve hole 7 is liquid-tightly welded to the front end surface of the valve seat member 3.

[0030] And between the opposing surfaces of these valve seat member 3 and injector plate 10, a flat fuel diffusion chamber 50 that spreads radially outward from the valve hole 7 and diffuses the fuel passing through the valve hole 7 radially outward is formed. In the illustrated example, this fuel diffusion chamber 50 is formed as a recess on the front end surface of the valve seat member 3. A plurality of fuel injection holes 11 that open into the fuel diffusion chamber 50 are formed in the injector plate 10 at positions radially outward from the valve hole 7. Therefore, the valve hole 7 and each fuel injection hole 11 communicate with each other through the fuel diffusion chamber 50.

[0031] Furthermore, the inner peripheral surface of the valve hole 7 is configured by a convex curved surface 7a so as to be smoothly continuous with the bottom surface of the fuel collecting chamber 49 and the ceiling surface of the fuel diffusion chamber 50.

[0032] In the above, the hollow portions of the fuel inlet cylinder 26, the fixed core 5, the valve stem 15, and the valve housing 2, as well as the split 15a of the valve stem 15, the fuel passage 37 around the spherical valve portion 14, and the communication recess 38 constitute a series of fuel flow paths 18 from the inlet of the fuel inlet cylinder 26 to the valve seat 8.

[0033] Next, the operation of this embodiment will be described. In the non-energized state of the coil 30, the movable core 12 and the valve body 13 are pressed forward by the set load of the valve spring 22, and the spherical valve portion 14 of the valve body 13 is seated on the valve seat 8. Therefore, the fuel pumped from a fuel pump (not shown) into the fuel inlet cylinder 26 fills the series of fuel flow paths 18 and waits.

[0034] When the coil 30 is energized, the magnetic flux generated by the coil 30 sequentially passes through the fixed core 5, the coil housing (yoke) 31, the magnetic cylindrical body 4, and the movable core 12. Due to the magnetic force, the movable core 12 is attracted to the fixed core 5 against the set load of the valve spring 23, and the spherical valve portion 14 of the valve body 13 is separated from the valve seat 8. Therefore, the high-pressure fuel in the fuel flow path 18, after passing through the valve seat 8, is collectively guided to the valve hole 7 by the fuel collecting chamber 49, the flow is reversed at the valve hole 7, moves to the fuel diffusion chamber 50, diffuses radially, and is injected from the plurality of fuel injection holes 11 of the injector plate 10 to form a plurality of spray forms F.

[0035] By the way, the bottom surface of the fuel collecting chamber 49 connecting between the valve seat 8 and the valve hole 7 is configured by a concave curved surface 49a formed following a spherical zone of a virtual spherical surface B with the center Bo placed on the center line Y of the valve seat 8 and the intersection point P with the center line Y located inside the valve hole 7. Thus, a step portion is not formed at the connection portion of the bottom surface of the fuel collecting chamber 49 with the valve seat 8. Therefore, when the valve body 13 opens and fuel flows from the valve seat 8 into the fuel collecting chamber 49, the generation of vortices can be prevented, and the pressure loss of the fuel flow can be reduced.

[0036] Moreover, since the distance between the bottom surface of the fuel collecting chamber 49 and the spherical valve portion 14 gradually increases toward the valve hole 7, the fuel is guided to the valve hole 7 without being throttled in the fuel collecting chamber 49, and the pressure loss of the fuel flow can also be reduced here.

[0037] Furthermore, the inner peripheral surface (convex curved surface) 7a of the valve hole 7 is formed of a convex curved surface so as to be continuous with the bottom surface of the fuel collecting chamber 49 and the ceiling surface of the fuel diffusion chamber 50. Therefore, the reversal of the fuel flow in the valve hole 7 is extremely smoothly guided by the inner peripheral surface 7a, and the generation of vortices at the reversal point can be prevented. Accordingly, the pressure loss of the fuel flow can also be reduced here.

[0038] Thus, it is possible to suppress a decrease in the fuel injection amount from each fuel injection hole 11, promote atomization of the injected fuel, and stabilize the spray form F, which can contribute to improving the fuel efficiency and output performance of the engine.

[0039] In addition, by forming the guide hole 9 for guiding the opening and closing operation of the spherical valve portion 14 into a polygonal cross-section, a plurality of fuel passages 37 can be provided around the spherical valve portion 14 without performing flat processing on the spherical valve portion 14. Moreover, since the guide hole 9 with a polygonal cross-section can be formed by forging together with the valve seat 8 and the valve seat member 3, the manufacturing cost can be reduced.

[0040] The present invention is not limited to the above-described embodiments, and various design changes are possible without departing from the gist thereof.

Explanation of Reference Numerals

[0041] I ····· Fuel injection valve B ····· Virtual spherical surface Bo ···· Center of the virtual spherical surface P ····· Intersection point 3 ····· Valve seat member 7 ····· Valve hole 8 ····· Valve seat 9 ····· Guide hole 10 ····· Injector plate 11 ····· Fuel injection hole 13 ····· Valve body 14 ····· Spherical valve portion 37 ····· Fuel passage 49 ····· Fuel collecting chamber 49a ··· Concave curved surface (bottom surface of the fuel collecting chamber) 50 ···· Fuel diffusion chamber

Claims

【Claim 1】 a valve seat member (3) having a conical valve seat (8) and a valve hole (7) penetrating the center thereof at the front end; a valve body (13) having a spherical valve portion (14) at the front end for opening and closing the valve hole (7) in cooperation with the valve seat (8); In a fuel injection valve comprising an injector plate (10) joined to the front end face of the valve seat member (3) and having a plurality of fuel injection holes (11) arranged radially outward from the valve hole (7) and communicating with the valve hole (7), a fuel collecting chamber (49) connecting between the valve seat (8) and the valve hole (7) is provided in the valve seat member (3), while the bottom surface of the fuel collecting chamber (49) has a center (Bo) on the center line (Y) of the valve seat (8), and the intersection point (P) with the center line (Y) is constituted by a concave curved surface (49a) formed following a spherical zone of a virtual spherical surface (B) located within the valve hole (7), a flat fuel diffusion chamber (50) communicating between the valve hole (7) and the plurality of fuel injection holes (11) is integrally formed with the valve seat member between the opposing surfaces of the valve seat member (3) and the injector plate (10), the inner peripheral surface of the valve hole (7) is provided with a convex curved surface (7a) so as to be smoothly continuous with the bottom surface of the fuel collecting chamber (49) and the ceiling surface of the fuel diffusion chamber (50), the valve seat member (3) has a guide hole (9) with a polygonal cross-section formed by arranging three or more planes (9a) of the same width for guiding the opening and closing operation of the spherical valve portion (14) so as to surround the center line (Y), a plurality of fuel passages (37) connected to the valve seat (8) are defined between a plurality of inner corner portions (9b) of the guide hole (9) and the spherical valve portion (14), A fuel injection valve, characterized in that a communication recess (38) connecting between the adjacent fuel passages (37) is provided between the valve seat (8) and each plane (9a), and thus the outer edge portion of the valve seat (8) has a star shape having the number of corner portions adapted to the inner corner portions (9b) when viewed in the direction along the center line (Y).

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