Injector for gaseous fuel

Abstract

To prevent fuel leakage when a valve is closed, even when the inside of a cylinder for injecting fuel becomes excessively high pressure or a valve element is inclined, in an injector for gaseous fuel having a normally closed opening / closing valve.SOLUTION: The injector 20A for gaseous fuel includes a body 10 in which a fuel supply path 11 is formed, an opening / closing valve 20A disposed in the body 10, and a solenoid for opening the opening / closing valve 1A. The on-off valve-side 20A includes a valve-stem 19, a valve-body-side 21A, and a valve-seat member 22, the valve-seat member 22 has a valve-hole 24 formed through a center thereof, and an annular seat surface 23 formed at a tip end portion of a peripheral wall protruding from an outer periphery of the valve-hole 24, and the valve-body-side 21A has a tapered, arched, or spherical sealing surface 211A that comes into contact with the seat surface 23 at the time of valve-closing.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a normally closed gas fuel injector for directly injecting gas fuel into a cylinder at a flow rate required by an engine driven by gas fuel such as hydrogen gas, LPG, or CNG. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an electromagnetically driven injector is widely known, which operates an on-off valve by energizing and exciting an electromagnetic coil, thereby injecting fuel into a cylinder at a flow rate required by the engine.

[0003] On-off valves (solenoid valves) are classified into normally open and normally closed types, as well as into types that close by pressing the valve body against the valve seat, as shown in Patent Document 1, for example, and types that close by attracting the valve body to the valve seat, as shown in Patent Document 2, for example.

[0004] In the valve structure shown in Patent Document 2, the inner annular surface of the valve seat (port) and the outer annular surface of the valve body come into sealing contact while closing the nozzle. However, if the valve body tilts due to, for example, the valve stem swinging during opening and closing operations, a gap is likely to form between the valve seat and the valve body, making it difficult to ensure internal and external airtightness. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-256638 [Patent Document 2] Japanese Patent Application Publication No. 11-280605 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to solve the above-mentioned problems, and has as its object to prevent fuel leakage when the valve is closed in a gas fuel injector equipped with a normally closed on-off valve, even if the pressure inside the cylinder into which fuel is injected becomes excessively high or the valve body is tilted. [Means for solving the problem]

[0007] Therefore, the present invention provides a normally closed, electromagnetically driven gaseous fuel injector that directly injects gaseous fuel into a cylinder of an engine, the normally closed, electromagnetically driven gaseous fuel injector comprising: a main body having a fuel passage formed therein; an on-off valve disposed within the main body for opening and closing the fuel passage; and a solenoid disposed within the main body for driving the on-off valve to open when energized. The on-off valve comprises a valve stem having a base end fixed to a plunger constituting the solenoid, a valve body provided at a tip end of the valve stem, and a valve seat member disposed in the main body opposite the valve body, the valve seat member has a valve hole formed through the center, a peripheral wall formed to protrude in an annular shape at a predetermined height along the outer periphery of the opening of the valve hole, and an annular seat surface formed at the tip of the peripheral wall with which the valve element comes into contact and separates, The valve body has a tapered, arched or spherical sealing surface that contacts the seat surface when the valve is closed.

[0008] In this way, with respect to the valve seat member and valve body that constitute the on-off valve in a normally closed gaseous fuel injector, the seat surface of the valve seat member is formed at the tip of the peripheral wall that protrudes in an annular shape, and the sealing surface of the valve body is formed in a tapered, arched or spherical shape with the central axis of the valve stem as its center line. Therefore, even if the valve stem oscillates and the valve body tilts when the valve is closed, the shapes of the seat surface and seal surface can be used to correct and align the valve body as the valve closes, thereby preventing the occurrence of a gap with the seat surface and preventing fuel leakage when the valve is closed.

[0009] In the present invention, if the seat surface is formed at the tip of a peripheral wall that protrudes in an annular shape at a predetermined height along the outer periphery of the valve hole opening, and the tip is chamfered on the outer and inner edge sides to form a semicircular vertical cross section, then when the inclined seal surface of the valve disc is aligned while contacting the seat surface during valve closing, the inclined seal surface slides smoothly over the chamfered seat surface to perform the alignment operation, and the combination of these curved surfaces makes it easy to always ensure close contact between the seat surface and the seal surface.

[0010] In the present invention, if the on-off valve is an outward-opening type, the valve element is arranged to protrude outside the valve hole, and the sealing surface side is shaped to protrude toward the base end of the valve stem, then even if the internal cylinder pressure rises excessively due to the structure of the outward-opening on-off valve, the biasing force in the valve closing direction caused by the high pressure inside the cylinder, combined with the inclined surface of the sealing surface of the valve element, will result in further increased contact with the seat surface, making it even easier to prevent fuel leakage. [Effects of the Invention]

[0011] According to the present invention, the centering property and sealing property of the valve body can be improved, and fuel leakage when the valve is closed can be effectively prevented. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a longitudinal sectional view showing a first embodiment of a gaseous fuel injector according to the present invention; [Figure 2] 2 is an enlarged longitudinal cross-sectional view of an on-off valve portion in the embodiment shown in FIG. 1. [Figure 3] 2 is an enlarged perspective partial cross-sectional view of an on-off valve portion in the embodiment shown in FIG. 1. [Figure 4] FIG. 3 is a longitudinal sectional view showing a second embodiment of the gaseous fuel injector according to the present invention. [Figure 5] FIG. 4 is a vertical cross-sectional view showing a third embodiment of the gaseous fuel injector according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In the present invention, the term "gas fuel" refers to a fuel such as LPG, CNG, LNG, or hydrogen gas that is supplied to an engine in a gaseous state and burned.

[0014] First Embodiment FIG. 1 is a vertical cross-sectional view showing a first embodiment of a gaseous fuel injector according to the present invention in a valve-closed state.

[0015] The gaseous fuel injector 1A of this embodiment is provided with a cylindrical body 10 having a fuel passage 11 continuing from a fuel inlet 13 on the base end side, an on-off valve 20A for opening and closing the fuel passage 11, and a solenoid 30 for driving the on-off valve 20A to open when energized, and is a device for supplying gaseous fuel, the pressure of which has been reduced and adjusted to a predetermined level, into a cylinder of an engine (not shown) at a flow rate required by the engine.

[0016] When the gas fuel injector 1A is in use, the electromagnetic coil 31 of the solenoid 30 is energized to excite it, causing the fixed iron core 32 to attract the plunger (movable iron core) 33 and open the on-off valve 20A, and the gas fuel that has passed through the on-off valve 20A is injected directly into the cylinder of the engine from the injection hole 42 opening at the tip 41 of the nozzle 40, making it a normally closed, electromagnetically driven injector.

[0017] The main body 10 comprises a cylindrical inlet body 12 having a fuel inlet 13 and an outlet body 14 having a valve seat member holding portion 15, both of which are made of a magnetic material such as metal.

[0018] The inlet body 12 and the outlet body 14 each have a collar member 16 inside thereof for positioning and sealing, which is used in combination with an O-ring 17 .

[0019] The on-off valve 20A is a poppet type valve that includes a valve element 21A formed as a separate part from the main body 10 and a valve seat member 22, and the valve element 21A is driven in a direction perpendicular to the valve seat member 22.

[0020] The valve body 21A is provided at the tip end side of a valve shaft 19 whose base end 191 side is fixed to the plunger 33, and both of them reciprocate in the axial direction.

[0021] The valve body 21A is made of metal and is formed integrally with the valve shaft 19.

[0022] The valve seat member 22 is held and arranged by the valve seat member holding portion 15 so as to face the valve body 21A, and has a seat surface 23 that contacts and is separated from the seal surface 211A of the valve body 21A, a valve hole 24 that passes through the center, and an orifice 25 for flow rate measurement that is narrowed and formed at the middle position of the valve hole 24.

[0023] The valve seat member 22 has an O-ring 27 fitted in a recessed groove 26 formed on the outer circumferential surface, and the outer circumferential side is in airtight contact with the main body 10 .

[0024] The valve seat member 22 is made of a polymer material, and a resin material is particularly suitable.

[0025] The solenoid 30 comprises the electromagnetic coil 31, the fixed iron core 32 located inside the electromagnetic coil 31, the plunger 33 arranged opposite the fixed iron core 32, a spring guide 34, and a coil spring 35, and all of these components constituting the solenoid 30 are arranged coaxially.

[0026] As described above, in this embodiment, the valve element 21A, which reciprocates in the axial direction, is provided at the tip end of the valve shaft 19, the base end 191 of which is fixed to the plunger 33 constituting the solenoid 30, and the annular seat surface 23, which comes into contact with and separates from the seal surface 211A formed on the base end side of the valve element 21A, is provided on the outer periphery of the opening of the valve hole 24 which passes through the valve seat member 22, and these together constitute the on-off valve 20A.

[0027] As shown in the partially enlarged longitudinal cross-sectional view of the on-off valve 20A in FIG. 2, the valve body 21A has a sealing surface 211A, including a portion that comes into contact with the seat surface 23 when the valve is closed, formed in a tapered shape (frustum shape) whose center line coincides with the central axes of the plunger 33 and the valve shaft 19. Even if the valve body 21A comes into contact with the seat surface 23 in an inclined state when the valve is closed, the valve body 21A is guided by the inclination of the tapered sealing surface 211A and is centered, which is a characteristic feature of the present invention.

[0028] That is, in the gaseous fuel injector 1A of the present embodiment, which is of a normally closed type, the sealing surface 211A, including the portion that contacts the seat surface 23 of the valve body 21A constituting the on-off valve 20A, is formed in a tapered shape whose center line coincides with the central axis of the valve stem 19. This makes it possible to reliably prevent fuel leakage while avoiding the occurrence of a gap between the sealing surface 211A of the valve body 21A and the seat surface 23 of the valve seat member 22 when the valve is closed.

[0029] Furthermore, in this embodiment, as shown in the enlarged perspective partial cross-sectional view of the on-off valve 20A in FIG. 3, the seat surface 23 is formed at the tip of a peripheral wall that protrudes in an annular shape at a predetermined height along the outer periphery of the opening of the valve hole 24 of the valve seat member 22, and the tip is chamfered on both the outer and inner edge sides to form a semicircular vertical cross section, which is also an important feature.

[0030] As a result, when the valve body 21A, which is tilted when the valve is closed, is aligned with the sealing surface 211A in contact with the seat surface 23, the seat surface 23 is annular and its vertical cross-sectional shape is semicircular.

[0031] Therefore, by combining these curved surfaces, even if the contact angle changes as the sealing surface 211A slides on the seat surface 23, it is possible to achieve smooth alignment operation while maintaining a tight contact state between the two, and also to achieve high sealing performance when the valve is closed.

[0032] Furthermore, in the gas fuel injector 1A of this embodiment, as shown in FIG. 1, the valve element 21A is provided on the tip side of the valve stem 19 that passes through the valve hole 24, and the valve element 21A is arranged to protrude outward from the valve hole 24, and the sealing surface 211A side that contacts the seat surface 23 is shaped to protrude toward the base end of the valve stem 19, thereby adopting an outward-opening type opening / closing valve structure (reverse valve structure).

[0033] By employing such a check valve structure, even if the cylinder internal pressure rises excessively, the valve body 21A is only biased toward the seat surface 23, making it even easier to minimize fuel leakage.

[0034] Furthermore, as described above, the valve body 21A is formed so that the sealing surface 211A side facing the seat surface 23 protrudes in a truncated cone shape. As a result, the biasing force in the valve closing direction due to the high pressure inside the cylinder aligns the valve body 21A, and in combination with the shape of the sealing surface 211A, this further increases the degree of adhesion with the seat surface 23, making it even easier to prevent fuel leakage.

[0035] Second Embodiment 4 is an enlarged longitudinal cross-sectional view of a portion of an on-off valve 20B in a gaseous fuel injector 1B according to a second embodiment, which is a modification of the gaseous fuel injector 1A described above. Note that the same components as those in the gaseous fuel injector 1A are denoted by the same reference numerals, and the description thereof will be omitted.

[0036] This modification is characterized in that the seal surface 211B of the valve element 21B constituting the on-off valve 20B is formed in a spherical shape.

[0037] More precisely, the sealing surface 211B corresponds to the surface of a rotating body that is a sector with a central angle of 90 degrees, one chord of which is parallel to the central axis of the valve shaft 19 and the arc of which faces the seat surface 23, and is spaced a certain distance perpendicular to the central axis of the valve shaft 19, and that is rotated around the central axis of the valve shaft 19 as an axis.

[0038] As a result, similar to the tapered sealing surface 211A described above, the surface side that contacts the seat surface 23 is inclined while reducing in diameter in the protruding direction, so that even if the valve body 21B contacts the seat surface 23 in an inclined state when the valve is closed, the valve body 21B is guided by the inclination of the spherical sealing surface 211B and is centered.

[0039] Furthermore, since the sealing surface 211B of the valve body 21B is spherical, when the valve body 21B, which has been tilted due to the swinging of the valve shaft 19, is aligned, the seat surface 23 and the sealing surface 211B are in close contact with each other, and the valve body 21B rotates, thereby correcting the tilt of the valve shaft 19.

[0040] Also in this embodiment, the annular seat surface 23 has a semicircular cross-sectional shape, so that the spherical surface of the seal surface 211B of the valve body 21B and the curved surface of the seat surface 23 come into contact with each other.

[0041] Therefore, the sliding caused by the contact between these curved surfaces not only makes the alignment operation smoother, but also makes it easier to minimize wear on the contact surfaces.

[0042] Third Embodiment 5 is an enlarged longitudinal cross-sectional view of a portion of an on-off valve 20C in a gaseous fuel injector 1C according to a third embodiment, which is a modification of the gaseous fuel injector 1A described above. Note that the same components as those in the gaseous fuel injector 1A are denoted by the same reference numerals, and the description thereof will be omitted.

[0043] This modification is characterized in that a sealing surface 211C of a valve body 21C constituting the on-off valve 20C is formed in a spherical shape.

[0044] More precisely, the sealing surface 211C corresponds to a part of the surface of a rotating body that rotates a sector with a central angle of 90 degrees, one of whose chords coincides with the central axis of the valve shaft 19 and whose arc faces the seat surface 23, around the central axis of the valve shaft 19 as its axis.

[0045] As a result, similar to the tapered sealing surface 211A described above, the surface side that contacts the seat surface 23 is inclined while reducing in diameter in the protruding direction, so that even if the valve body 21C contacts the seat surface 23 in an inclined state when the valve is closed, the valve body 21C is guided by the inclination of the spherical sealing surface 211C and is centered.

[0046] Furthermore, since the sealing surface 211C of the valve body 21C is spherical, when the valve body 21C, which has tilted due to the swinging of the valve shaft 19, is aligned, the seat surface 23 and the sealing surface 211C are in close contact with each other, and the valve body 21C can rotate to correct the tilt of the valve shaft 19.

[0047] Also in this embodiment, the annular seat surface 23 has a semicircular cross-sectional shape, so that the spherical surface of the sealing surface 211C of the valve body 21C and the curved surface of the seat surface 23 come into contact with each other.

[0048] Therefore, the sliding caused by the contact between these curved surfaces not only makes the alignment operation smoother, but also makes it easier to minimize wear on the contact surfaces.

[0049] The shape of the sealing surface may be any shape as long as it is axially symmetrical, with the valve seat member 22 as the apex and converging toward the central axis of the valve shaft 19. In the first embodiment, the sealing surface is tapered (frustum-shaped), and in the second and third embodiments, the sealing surface is spherical, but it may also be arch-shaped, for example.

[0050] As described above, with respect to a gas fuel injector equipped with a normally closed on-off valve, the present invention makes it possible to reliably prevent fuel leakage when the valve is closed, even if the pressure inside the cylinder becomes excessively high or the valve body is tilted. [Explanation of symbols]

[0051] 1A, 1B, 1C gas fuel injector, 10 main body, 11 fuel passage, 12 inlet body, 13 fuel inlet, 14 outlet body, 15 valve seat member holder, 16 collar member, 17 O-ring, 19 valve stem, 20A, 20B, 20C on-off valve, 21A, 21B, 21C valve body, 22 valve seat member, 23 seat surface, 24 valve hole, 25 orifice, 26 groove, 27 O-ring, 30 solenoid, 31 electromagnetic coil, 32 stationary core, 33 plunger, 34 spring guide, 35 coil spring, 40 nozzle, 41 tip, 42 injection hole, 211A, 211B, 211C sealing surface

Claims

1. a main body having a fuel passage formed therein; an on-off valve disposed in the main body for opening and closing the fuel passage; a solenoid disposed in the main body for driving the on-off valve to open when energized, A normally closed, electromagnetically driven gas fuel injector that directly injects gas fuel into an engine cylinder, The on-off valve is a valve stem having a base end fixed to a plunger constituting the solenoid; a valve body provided at the tip side of the valve shaft; a valve seat member disposed in the main body opposite the valve body, The valve seat member is a valve hole formed through the center; a peripheral wall formed in a circular shape and protruding to a predetermined height along the outer periphery of the opening of the valve hole; an annular seat surface formed at a tip end of the peripheral wall with which the valve element comes into contact and separates, The valve body is The valve has a tapered, arched or spherical seal surface that contacts the seat surface when the valve is closed.

1. A gaseous fuel injector comprising:

2. 2. The gaseous fuel injector according to claim 1, wherein the seat surface has outer and inner edge sides chamfered to form a semicircular vertical cross section.

3. 2. The gaseous fuel injector according to claim 1, wherein the valve seat member is made of resin.

4. 4. A gaseous fuel injector according to claim 1, 2 or 3, wherein the on-off valve is an outward-opening type, the valve body is arranged to protrude outside the valve hole, and the sealing surface side is shaped to protrude toward the base end side of the valve stem.

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