Gas fuel injector

Abstract

The present invention provides a gas fuel injector having a normally closed on-off valve, which can prevent fuel leakage when the valve is closed even when the pressure in a cylinder for injecting fuel is too high or the valve body is inclined. An injector (1A) for gaseous fuel, comprising a main body (10) that forms a fuel passage (11), an on-off valve (20A) that is disposed within the main body (10), and a solenoid (30) that drives the on-off valve (20A) to open, the on-off valve (20A) comprising a valve shaft (19), a valve body (21A), and a valve seat member (22). The valve seat member (22) has a valve hole (24) formed through the center of the valve seat member (22), and an annular seat surface (23) formed at the tip of a peripheral wall formed so as to protrude toward the outer periphery of the valve hole (24), and the valve body (21A) has a tapered, arched or spherical seal surface (211A) that comes into contact with the seat surface (23) when the valve is closed.

Description

TECHNICAL FIELD

[0001] The present application relates to a gas fuel injector of a normally closed type, for example, for directly injecting a gas fuel of a required flow rate for an engine driven by a gas fuel such as hydrogen, LPG (Liquefied Petroleum Gas), CNG (Compressed Natural Gas), or the like, into a cylinder. BACKGROUND

[0002] Conventionally, widely known is an electromagnetic drive type injector that injects a fuel of a required flow rate for an engine into a cylinder by operating an on-off valve by energizing an electromagnetic coil to excite it.

[0003] The on-off valve (solenoid valve) is classified into a normally open type and a normally closed type, and is classified into a type that pushes a valve body against a valve seat to close the valve as shown in Patent Document 1, and a type that pulls a valve body toward a valve seat to close the valve as shown in Patent Document 2, for example.

[0004] The valve structure shown in Patent Document 2 is a structure in which an inner annular surface of a valve seat (port) and an outer annular surface of a valve body are in sealing contact while closing a nozzle, but in a case where the valve body is tilted, for example, when the valve shaft swings or the like during an on-off operation, a gap is easily formed between the valve seat and the valve body, and thus, there is a problem in that it is difficult to ensure the internal and external air tightness.

[0005] PRIOR ART DOCUMENT PATENT DOCUMENT Patent Document 1: Japanese Patent Application Laid-Open No. 2005-256638 Patent Document 2: Japanese Patent Application Laid-Open No. Hei 11-280605 SUMMARY PROBLEMS TO BE SOLVED BY THE INVENTION The present application solves the above-described problems, and aims to provide a gas fuel injector having an on-off valve of a normally closed type, which can prevent fuel leakage at the time of closing the valve even in a case where the pressure in a cylinder in which a fuel is injected is excessively high or the valve body is tilted.

[0006] MEANS FOR SOLVING THE PROBLEMS Therefore, the present application is a gas fuel injector, which is a normally closed electromagnetic drive type gas fuel injector directly injecting gas fuel into a cylinder of an engine, having a main body in which a fuel passage is formed, an opening and closing valve disposed in the main body to open and close the fuel passage, and a solenoid disposed in the main body to drive the opening and closing valve to open when energized, characterized in that the opening and closing valve includes a valve shaft fixed at a base end side to a plunger constituting the solenoid, a valve body provided at a front end side of the valve shaft, and a valve seat member disposed in the main body so as to face the valve body, the valve seat member has a valve hole formed through the center of the valve seat member, a peripheral wall protruding in a circular ring shape at a prescribed height along the outer periphery of the opening of the valve hole, and a circular ring-shaped seat surface formed at a front end portion of the peripheral wall, the valve body contacts or separates from the seat surface, the valve body has a sealing surface which contacts the seat surface at the time of closing, and the sealing surface is conical or dome-shaped or spherical.

[0007] Thus, in the normally closed gas fuel injector, the seat surface of the valve seat member is formed at the front end portion of the peripheral wall protruding in a circular ring shape, and the sealing surface of the valve body is conical or dome-shaped or spherical with the center axis of the valve shaft as the center line, whereby even in the case where the valve shaft swings and the valve body tilts at the time of closing, the seat surface and the sealing surface are aligned while correcting the tilt of the valve body at the time of closing, a gap between the seat surface and the sealing surface is avoided, and fuel leakage at the time of closing is prevented.

[0008] In the present application, if the seat surface is formed at the front end portion of the peripheral wall protruding in a circular ring shape at a prescribed height along the outer periphery of the opening of the valve hole, the outer edge side and the inner edge side of the front end portion are chamfered, and the longitudinal cross-sectional shape of the front end portion is semicircular, when the tilted sealing surface of the valve body is aligned while contacting the seat surface at the time of closing, the tilted sealing surface is smoothly slid on the chamfered seat surface while being aligned, and the tightness between the seat surface and the sealing surface is easily ensured at all times by the combination of the curved surfaces.

[0009] In the present application, if the opening and closing valve is outward opening type, the valve body is disposed so as to protrude to the outside of the valve hole, and the sealing surface side is protruding toward the base end side of the valve shaft, even in the case where the pressure in the cylinder excessively rises due to the structure of the outward opening type opening and closing valve, the result is that the force in the closing direction generated by the high pressure in the cylinder is combined with the inclined surface of the sealing surface of the valve body, the tightness with the seat surface is further improved, and fuel leakage is further prevented.

[0010] Effects of the Invention According to the present application, the valve body can be improved in terms of alignment and sealing, and fuel leakage at the time of valve closing can be effectively prevented. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a longitudinal sectional view showing a first embodiment of a gas fuel injector according to the present application.

[0012] Figure 2 is a longitudinal sectional view showing a first embodiment of a gas fuel injector according to the present application. Figure 1 is an enlarged longitudinal sectional view of the open / close valve portion in the embodiment shown in Fig. 1.

[0013] Figure 3 is an enlarged longitudinal sectional view of the open / close valve portion in the embodiment shown in Fig. 1. Figure 1 is an enlarged longitudinal sectional view of the open / close valve portion in the embodiment shown in Fig. 1.

[0014] Figure 4 is a longitudinal sectional view showing a second embodiment of a gas fuel injector according to the present application.

[0015] Figure 5 is a longitudinal sectional view showing a third embodiment of a gas fuel injector according to the present application.

[0016] REFERENCE NUMERALS 1A, 1B, 1C: gas fuel injector, 10: main body, 11: fuel passage, 12: inlet body, 13: fuel introduction port, 14: outlet body, 15: valve seat member holding portion, 16: sleeve member, 17: O-ring, 19: valve shaft, 20A, 20B, 20C: open / close 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: fixed core, 33: plunger, 34: spring guide member, 35: coil spring, 40: nozzle, 41: front end, 42: injection hole, 211A, 211B, 211C: sealing surface. DETAILED DESCRIPTION

[0017] Hereinafter, embodiments of the present application will be described with reference to the drawings. In this specification, gas fuel refers to fuel such as LPG, CNG, LNG (Liquefied Natural Gas), hydrogen, and the like, which is supplied to an engine in a gaseous state and combusted.

[0018] <First Embodiment> Figure 1 is a longitudinal sectional view showing a first embodiment of a gas fuel injector according to the present application.

[0019] The gas fuel injector 1A of the present embodiment is a device in which, inside a cylindrical main body 10 that forms a fuel passage 11 continuous with a fuel inlet port 13 on the proximal end side, an on-off valve 20A that opens and closes the fuel passage 11 and a solenoid 30 that drives the on-off valve 20A to open when energized are provided, and gas fuel that has been reduced in pressure to a prescribed pressure is supplied to the cylinder of an engine not shown at a flow rate required by the engine.

[0020] In use of the gas fuel injector 1A, by energizing the solenoid 31 of the solenoid 30 and magnetizing it, the fixed core 32 attracts the plunger (movable core) 33 while opening the on-off valve 20A, and gas fuel that has passed through the on-off valve 20A is directly injected from the injection hole 42 that opens at the tip 41 of the nozzle 40 to the cylinder of the engine, and the electromagnetic drive type injector is of the normally closed type.

[0021] The main body 10 includes a cylindrical inlet body 12 that has the fuel inlet port 13 and an outlet body 14 that has a valve seat member holding portion 15, and these members are formed of a magnetic material such as metal.

[0022] In addition, a sleeve member 16 is provided on the inner side of the inlet body 12 and the outlet body 14, and the sleeve member 16 is used in combination with an O-ring 17 for positioning and sealing.

[0023] The on-off valve 20A includes a valve body 21A formed separately from the main body 10 and a valve seat member 22, and is a poppet valve in which the valve body 21A is driven in a direction at right angles to the valve seat member 22 (a direction perpendicular to the valve seat surface of the valve seat member).

[0024] The valve body 21A is provided on the tip side of the valve shaft 19 and reciprocates in the axial direction together with the valve shaft 19, and the proximal end 191 side of the valve shaft 19 is fixed to the plunger 33.

[0025] The valve body 21A is made of metal and is formed integrally with the valve shaft 19.

[0026] The valve seat member 22 is arranged so as to be held by the valve seat member holding portion 15 in a manner facing the valve body 21A, has a seat surface 23 that contacts or separates from the sealing surface 211A of the valve body 21A, a valve hole 24 that penetrates the center portion, and a restriction hole 25 that is formed narrow at an intermediate position of the valve hole 24 for metering the flow rate.

[0027] An O-ring 27 is installed in a groove 26 formed on the outer circumferential surface of the valve seat member 22, and the outer circumferential side of the valve seat member 22 is in airtight (sealed without gas leakage) contact with the main body 10.

[0028] The valve seat member 22 is made of a high molecular material, and a resin material is particularly preferable.

[0029] The solenoid 30 includes the electromagnetic coil 31, the fixed core 32 positioned inside the electromagnetic coil 31, the plunger 33 positioned opposite the fixed core 32, the spring guide member 34, and the coil spring 35, and all of the components that constitute the solenoid 30 are coaxially arranged.

[0030] As described above, in the present embodiment, the valve body 21A that reciprocates in the axial direction is provided on the front end side of the valve shaft 19, the base end 191 side of the valve shaft 19 is fixed to the plunger 33 that constitutes the solenoid 30, the seat surface 23 that is a circular ring is provided on the outer periphery of the opening of the valve hole 24 that penetrates the valve seat member 22, the sealing surface 211A that is formed on the base end side of the valve body 21A is in contact with or separated from the circular ring-shaped seat surface 23, and the on-off valve 20A is constituted by these members.

[0031] Furthermore, as shown in the partial cross-sectional view that partially enlarges the on-off valve 20A of Figure 2 In the valve body 21A, the sealing surface 211A that includes the portion that is in contact with the seat surface 23 at the time of closing is formed in a tapered shape (frustoconical shape) in which the center line coincides with the center axis of the plunger 33 and the valve shaft 19, and even in the case where the valve body 21A is in contact with the seat surface 23 in an inclined state at the time of closing, the valve body 21A is aligned by being guided by the inclination of the tapered sealing surface 211A, and this is a characteristic part of the present application.

[0032] That is, in the gas fuel injector 1A of the present embodiment that is a normally closed type, by forming the sealing surface 211A that includes the portion of the valve body 21A that constitutes the on-off valve 20A and that is in contact with the seat surface 23 in a tapered shape in which the center line coincides with the center axis of the valve shaft 19, a gap between the sealing surface 211A of the valve body 21A and the seat surface 23 of the valve seat member 22 at the time of closing can be avoided, and leakage of fuel can be reliably prevented.

[0033] In addition, in the present embodiment, as shown in the partial cross-sectional view that partially enlarges the on-off valve 20A of Figure 3 The seat surface 23 is formed on the front end portion of the peripheral wall that protrudes in a circular ring shape at a prescribed height along the opening of the valve hole 24 of the valve seat member 22, the outer edge side and the inner edge side of the front end portion are chamfered, and the longitudinal cross-sectional shape is semicircular, and this is also an important characteristic.

[0034] Thus, when the valve body 21A is tilted and aligned with the seat surface 23 while the sealing surface 211A contacts the seat surface 23, the seat surface 23 is annular and its longitudinal cross-sectional shape is semi-circular.

[0035] Therefore, by combining these curved surfaces, even if the sealing surface 211A slides on the seat surface 23 while its contact angle changes, the two surfaces can maintain a tight fit and achieve smooth self-aligning action, thus improving the sealing performance when the valve is closed.

[0036] Moreover, such as Figure 1 As shown, in the gas fuel injector 1A of this embodiment, when the valve body 21A is provided on the front end side of the valve shaft 19 that passes through the valve hole 24, the valve body 21A is configured to protrude to the outer side of the valve hole 24, and the sealing surface 211A side that contacts the seat surface 23 is formed to protrude in the direction of the base end side of the valve shaft 19, and an externally opening and closing valve structure (check valve structure) is adopted.

[0037] By employing such a check valve structure, even if the internal pressure rises excessively, the valve body 21A only exerts force in the direction of the seat surface 23, thus making it easier to minimize fuel leakage.

[0038] Furthermore, as described above, the valve body 21A is formed such that the sealing surface 211A facing the seat surface 23 protrudes in a frustoconical shape. As a result, the valve body 21A is self-aligned by the force in the valve-closing direction generated by the high pressure inside the cylinder, and the shape of the sealing surface 211A further improves the tightness of contact with the seat surface 23, thereby making it easier to further prevent fuel leakage.

[0039] <Second Implementation> Figure 4 A partially enlarged longitudinal sectional view is shown of the on / off valve 20B in the second embodiment of the gas fuel injector 1B, which is a variation of the gas fuel injector 1A described above. Furthermore, structural elements identical to those in the gas fuel injector 1A are labeled with the same reference numerals, and their descriptions are omitted.

[0040] In this modified example, the sealing surface 211B of the valve body 21B constituting the on / off valve 20B is formed into a spherical shape as a feature.

[0041] More specifically, the seal surface 211B corresponds to a portion of a surface drawn by an arc of a sector that is rotated about the center axis of the valve shaft 19 by a sector that is separated by a prescribed distance from the center axis of the valve shaft 19 in a direction orthogonal to the center axis of the valve shaft 19, one radius of the sector being parallel to the center axis of the valve shaft 19, the arc of the sector facing the seat surface 23 side, and the central angle of the sector being 90 degrees.

[0042] Thus, as with the conical seal surface 211A described above, the surface side that contacts the seat surface 23 is tapered in the protruding direction and is inclined, and thus, even in the case where the valve body 21B contacts the seat surface 23 in an inclined state at the time of valve closing, the valve body 21B can be aligned by being guided by the inclination of the spherical seal surface 211B thereof.

[0043] Further, the seal surface 211B of the valve body 21B is spherical, and thus, when the valve body 21B that is inclined due to the swing of the valve shaft 19 is aligned, the seat surface 23 can be brought into close contact with the seal surface 211B, and the valve body 21B can correct the inclination of the valve shaft 19 while rotating.

[0044] Further, in the present embodiment, the longitudinal cross-sectional shape of the annular seat surface 23 is semicircular, and thus, the structure is configured such that the spherical surface of the seal surface 211B of the valve body 21B contacts the curved surface of the seat surface 23.

[0045] Thus, the alignment action is smoother by the sliding that occurs by the contact of these curved surfaces with each other, and the wear of the contact surfaces is easily suppressed to a minimum.

[0046] <Third Embodiment> Figure 5 A longitudinal sectional view showing a portion of the on-off valve 20C in a gas fuel injector 1C that is a modified example of the above-described gas fuel injector 1A of the third embodiment is shown. Further, the same reference numerals are affixed to the same structural elements as those of the gas fuel injector 1A, and the description thereof is omitted.

[0047] In this modified example, as a feature, the seal surface 211C of the valve body 21C that constitutes the on-off valve 20C is formed in a spherical shape.

[0048] More specifically, the seal surface 211C corresponds to a portion of a surface drawn by an arc of a sector that is rotated about the center axis of the valve shaft 19 by a sector that is separated by a prescribed distance from the center axis of the valve shaft 19 in a direction orthogonal to the center axis of the valve shaft 19, one radius of the sector being parallel to the center axis of the valve shaft 19, the arc of the sector facing the seat surface 23 side, and the central angle of the sector being 90 degrees.

[0049] Thus, similarly to the tapered seal surface 211A described above, the surface side that contacts the seat surface 23 is tapered in the protruding direction, and thus, even in the case where the valve body 21C contacts the seat surface 23 in a tilted state at the time of closing the valve, the valve body 21C can be aligned by the tilt of the spherical seal surface 211C.

[0050] In addition, the seal surface 211C of the valve body 21C is spherical, and thus, when the valve body 21C tilted due to the swing of the valve shaft 19 is aligned, the seat surface 23 can be brought into close contact with the seal surface 211C, and the valve body 21C can correct the tilt of the valve shaft 19 while rotating.

[0051] In addition, in the present embodiment, the longitudinal cross-sectional shape of the circular ring-shaped seat surface 23 is semicircular, and thus, the structure is configured such that the spherical surface of the seal surface 211C of the valve body 21C contacts the curved surface of the seat surface 23.

[0052] Thus, the alignment action is smoother by the sliding generated by the contact of these curved surfaces with each other, and the wear of the contact surfaces is easily suppressed to a minimum.

[0053] Further, the shape of the seal surface can be an axisymmetric shape that converges toward the center axis of the valve shaft 19 with the direction of the valve seat member 22 as the apex. In the first embodiment, it is conical (frustoconical), and in the second and third embodiments, it is spherical, but other than this, for example, it can be an arched shape.

[0054] As described above, for the gas fuel injector having the open / close valve of the normally closed type, according to the present application, even in the case where the pressure in the cylinder is excessively high or the valve body is tilted, fuel leakage at the time of closing the valve can be reliably prevented.

Claims

1. A gas fuel injector, a normally closed, electromagnetically driven gas fuel injector that directly injects gas fuel into the cylinder of an engine, comprising: The main body has internal fuel passages. An on / off valve, disposed within the main body, opens and closes the fuel passage, and A solenoid, disposed within the main body, drives the on / off valve to open when energized; Its features are, The on / off valve includes: The valve shaft is fixed at its base end to the plunger that forms the solenoid. The valve body is located on the front end side of the valve shaft, and A valve seat component is disposed within the main body facing the valve body; The valve seat component has: A valve hole is formed through the center of the valve seat component. The peripheral wall is formed by protruding in a circular shape at a predetermined height along the outer periphery of the valve hole opening, and A circular seat surface is formed at the front end of the peripheral wall, and the valve body is in contact with or separate from the seat surface; The valve body has a sealing surface, which contacts the seat surface when the valve is closed. The sealing surface is conical, arched, or spherical.

2. The gas fuel injector according to claim 1, characterized in that, The outer and inner edges of the seat surface are chamfered, and the longitudinal cross-section of the seat surface is semi-circular.

3. The gas fuel injector according to claim 1, characterized in that, The valve seat component is made of resin.

4. The gas fuel injector according to any one of claims 1 to 3, characterized in that, The valve is an outward-opening type, the valve body is configured to protrude to the outside of the valve hole, and the sealing surface side is shaped to protrude towards the base end of the valve shaft.

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