GB2636790A

GB2636790A - Gas injector

Info

Publication number: GB2636790A
Application number: GB2319787.4A
Authority: GB
Inventors: Enters Richard; Lesieur Cyrille; Didier François; Calonne Jerome
Original assignee: Phinia Delphi Luxembourg SARL
Current assignee: Phinia Delphi Luxembourg SARL
Priority date: 2023-12-21
Filing date: 2023-12-21
Publication date: 2025-07-02
Also published as: GB202319787D0; WO2025132068A1

Abstract

A gas injector 10 for an internal combustion engine, extending along injector axis A. The injector comprises an armature 32 with an armature cavity 38 in fluid communication with an inlet portion 14. An elongate shaft 44 is partially inserted in the armature via a proximal bore 40, wherein the shaft lies within the armature cavity. The armature comprises at least one distal bore 42 which enables flow through the armature when the injector is in the open position. The armature or the injector body 12 comprises first sealing means 52.1 surrounding the at least one proximal bore of the armature. The armature or the elongate shaft comprises second sealing means 52.2 surrounding the at least one distal bore of the armature. The first and second sealing means are each configured to prevent flow between the armature cavity and the outlet around/through the armature when a pintle 26 is in the closed position. The pintle has a pintle shaft 28 comprising a hollow length 28.1 extending from the armature to the distal side of the injector. A fuel delivery system using the gas injector is also claimed.

Description

GAS INJECTOR

Technical field

The present invention generally relates to a gas injector for injection of gaseous fuel.

Background Art

For automotive applications, hydrogen engines are considered as a promising alternative to gasoline or diesel engines. Indeed, emissions from hydrogen internal combustion engines consist mainly of water and do not comprise nearly as much pollutants as those from traditional engines. When designing hydrogen engine components, inspiration is naturally drawn from those of currently available thermal engines, which are typically powered by liquid fuel such as gasoline or diesel.

In their simplest form, the fuel delivery systems of such liquid fueled combustion engines typically comprise a liquid fuel tank with a low-pressure pump, a high-pressure pump connected thereto, a fuel rail and a plurality of gas injectors.

However, the components of liquid fueled engines cannot be carelessly used in gaseous fueled internal combustion engines and must instead be adapted to meet specific technical requirements. In particular, when designing gaseous fuel delivery systems, care must be taken to anticipate possible fuel leaks and/or excessive pressure drops, which occur much more frequently with gaseous fuels than with their liquid counterparts.

Technical problem It is an object of the present invention to provide a gas injector suitable for injection of gaseous fuel, which overcomes the aforementioned drawbacks.

This object is achieved by a gas injector as claimed in claim 1.

General Description of the Invention

In order to overcome the above-mentioned problem, the present invention provides a gas injector for injection of gaseous fuel in an internal combustion engine, extending along an injector axis from a proximal side to a distal side. The gas injector comprises an injector body defining an injector channel extending from a proximal inlet portion to a distal outlet portion having an outlet opening surrounded by a valve seat and a pintle having a pintle shaft and pintle head.

The pintle is movable along the injector axis between a closed position, in which the pintle head engages the outlet valve seat to prevent gas flow through the outlet opening, and an open position, in which the pintle head is distally spaced from the valve seat to enable flow of gas through the outlet opening.

A magnetic armature is mechanically coupled to the pintle shaft to be axially moveable therewith, and a solenoid is configured to selectively generate a magnetic field, thereby displacing the magnetic armature and forcing the pintle into its open position.

The armature comprises an armature cavity in fluid communication with the inlet portion. An elongate shaft is partially inserted in the armature via a proximal bore, such that an end of the shaft lies within the armature cavity. The armature or the injector body comprises first sealing means surrounding the at least one proximal bore of the armature, the first sealing means being configured to prevent flow between the armature cavity and the outlet portion around the armature when the pintle is in the closed position.

According to the invention, the armature comprises at least one distal bore which enables flow through the armature when the pintle is in the open position. The pintle shaft comprises a hollow length extending from the distal bore of the armature to the distal side of the injector body, and the pintle comprises a proximal aperture and a distal aperture, thereby defining an axial gas passage between the armature cavity and the outlet portion. The armature or the elongate shaft comprises second sealing means surrounding the at least one distal bore of the armature, the second sealing means being configured to prevent flow between the armature cavity and the hollow length of the pintle shaft when the pintle is in the closed position.

The invention thus provides a gas injector in which sealing of gaseous fuel therein occurs both at its distal end with the pintle-valve seat sealing interface, and within the injector cavity with the first and second sealing means. The load required to ensure proper sealing of gaseous fuel may thus be distributed between the pintlevalve seat sealing interface and the first and second sealing means, thereby improving the durability of the pintle-valve seat sealing interface.

When the pintle is in its closed position, the armature is exposed to a non-uniform distribution of pressure as gaseous fuel within the armature cavity is isolated from gaseous fuel within the rest of the injector channel. The balance of pressure (i.e. the net force from the pressure) applied by the gaseous fuel onto the armature is dependent on the sealing diameters of the first and second sealing means. In other words, the sealing diameters of the first and second sealing means may be selected to either bias the armature proximally or distally, or to perfectly balance it (i.e. the armature is not biased towards any direction).

Furthermore, the invention proposes an injector design for gaseous fuel which uses a hollow pintle shaft extending along the injector axis to convey fluid from the armature cavity to the outlet portion. The gas exits the pintle, respectively pintle shaft, at or near its distal end, typically via a lateral aperture upstream of the valve seat. Gas can thus be sent through the injector in a straight channel (provided by the hollow shaft and the armature cavity), avoiding flow around components such as pole pieces or springs, hence avoiding pressure drops due to meandering flow paths.

In embodiments, a sealing diameter of the first sealing means is equal to or greater than a sealing diameter of the second sealing means. In this configuration, the armature is biased distally.

In embodiments, a ratio between a sealing diameter of the first sealing means and a sealing diameter of the second sealing means is comprised between 0.8 and 1.2. Restricting the ratio between the sealing diameters ensures the armature is not overly biased towards a direction.

In embodiments, the elongate shaft is hollow and comprises at least one orifice, thereby defining a gas passage into the armature cavity. Preferably, the orifice is formed on a lateral surface of the elongate shaft. The elongate shaft thus defines an inlet shaft which feeds gaseous fuel from a gas rail straight to the inside of the armature cavity.

Preferably, the elongate shaft is integral with and extends from an inlet member, the inlet member being arranged proximally from the armature within the injector channel. In alternative embodiments, an orifice may be formed elsewhere in the inlet member or the injector body (i.e. the elongate shaft may be solid) to put the armature cavity in fluid communication with the gas rail.

In embodiments, the gas injector further comprises an armature spring configured to bias the armature in the closed direction. The armature spring may be arranged within the armature cavity, resting at one end against a proximal inner surface of the armature and at the other end against a shoulder of the elongate shaft. By arranging the armature spring within the armature cavity, the volume of the injector channel downstream of the armature may be reduced (when compared to a configuration whereby the armature spring is arranged downstream of the armature). Reducing the volume of the injector channel downstream of the armature decreases potential leaks through the pintle-valve seat interface.

In embodiments, the first sealing means is arranged on a proximal outer surface of the armature and/or wherein the second sealing means is arranged on a distal inner surface of the armature.

In embodiments, the armature or the injector body comprise a third sealing means facing the first sealing means, the third sealing means being configured cooperate with the first sealing means to prevent flow between the armature cavity and the outlet portion around the armature when the pintle is in the closed position.

In embodiments, the armature or the elongate shaft comprise a fourth sealing means facing the second sealing means, the fourth sealing means being configured cooperate with the second sealing means to prevent flow between the armature cavity and the outlet portion through the armature when the pintle is in the closed position.

In embodiments, each sealing means comprise a knife-edge protrusion or a seal ring, preferably wherein said seal ring is made of elastomer.

Preferably one of the first and third sealing means comprises an annual knife-edge protrusion whilst the other comprises a seal ring of corresponding diameter. Likewise, one of the second and fourth sealing means comprises an annual knife-edge protrusion whilst the other comprises a seal ring of corresponding diameter. More preferably, the two knife-edge protrusions extend from and are integral with the armature, whilst the seal rings are arranged on the inlet member/injector body and the head of the elongate shaft opposite of said knife-edge protrusions. In this configuration, the sealing diameter of the first and second sealing means is effectively defined by the diameter of the knife-edge protrusions.

In embodiments, the gas injector further comprises a pintle spring configured to bias the pintle in the closed direction. The pintle spring is arranged in the channel, resting at one end against a pintle perch fixedly connected to the pintle shaft and at the other end against a shoulder of the injector body.

In embodiments, the gas injector further comprises a pole piece arranged distally from the armature and an armature spring. The pole piece and/or the armature has a recess, and the armature spring is at least partially arranged is said recess/recesses distally from the armature, resting at one end against a shoulder of the armature and at the other end against a shoulder of the pole piece or the injector body.

Preferably, at least the pole piece and/or the springs are arranged within the injector channel so as to surround the pintle at points along the injector axis located strictly between the proximal aperture and the distal aperture. By isolating these components from the gas flow path, the total pressure drop is further reduced.

In embodiments, the pintle is outwardly opening.

In embodiments, a sealing diameter of the first sealing means and a sealing diameter of the second sealing means are at least twice as large as a sealing diameter of the pintle head on the valve seat.

In embodiments, the pintle shaft is partially inserted in the distal bore of the armature, such that the armature and the pintle cooperate to define a continuous axial gas passage extending from the proximal side to the distal side of the injector when the pintle is in its open position.

In embodiments, the valve seat is part of an external piece fixedly mounted at the distal end of the injector body. Preferably, an optional injector cap is mounted on this external piece to control the spray of hydrogen during an injection event.

It may be noted that the present injector has been developed in the context of hydrogen combustion engines and is thus adapted for injection of hydrogen (gas). However, it is also compatible with other gaseous fuels, such as e.g. CNG and other gaseous, biogas, synthetic gas, etc. The Invention further provides a fuel delivery system comprising a gaseous fuel tank configured to store pressurized gaseous fuel (in gas or liquefied state), and a fuel rail fluidly coupled to at least one fuel injector as described above.

In embodiments, the fuel delivery system further comprises pressure regulating means configured to decrease the pressure of fuel flow therethrough, wherein the pressure regulating means is serially connected between the fuel tank and the fuel rail.

Brief Description of the Drawings

A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig. 1 is a cross sectional view of the gas injector according an embodiment of the invention; Fig. 2 is a schematic view of a gaseous fuel delivery system comprising the inventive gas injector; Figs. 3a-d are principle views of alternative configurations of the pintle; Fig. 4 is an enlarged view of the armature of the gas injector of figure 1.

Description of Preferred Embodiments

Figure 1 shows a first embodiment of the gas injector 10 according to the present invention. The gas injector 10 is adapted to inject a gaseous fuel, in particular hydrogen (H2) or natural gas (CH4), into a combustion chamber of an internal combustion engine (not shown). The term "gaseous fuel" generally includes combustible fluids which are in their gaseous state when exposed to nominal operating conditions of the injector and the engine, e.g. pressure and temperature. Regarding more specifically hydrogen as gaseous fuel for an ICE, it typically consists of a gas with at least 90% hydrogen (H2), preferably pure hydrogen with no more than 2% impurities.

Figure 4 shows an enlarged view of the armature of the gas injector 10 of figure 1. Figure 1 shows the gas injector in its closed position, whilst figure 4 shows the gas injector in its open position, with dashed arrows representing flow of gaseous fuel.

The gas injector 10 is mostly symmetrical about an injector axis A and comprises an injector body 12, which may be made of one or several pieces. The injector body 12 comprises a main body 12a and a distal body 12b, which are here made of separate parts fixed together but could alternatively be integral.

The injector 10 includes an inlet portion 14 on a proximal side P and an outlet portion 18 on a distal side D, where an outlet opening 22 is surrounded by a valve seat 24. The inlet portion 14 is typically fluidly coupled to a fuel rail 106 at the proximal side P for supply of pressurized gaseous fuel to the gas injector 10. When installed on the engine, the injector body portion with the outlet portion 18, i.e. the distal body 12b, is arranged in a bore in the cylinder head, which opens into a combustion chamber (not shown) of the engine.

The injector body 12 defines a channel 20, which extends along injector axis A from the inlet portion 14 to the outlet portion 18. The channel 20 forms an internal, elongate passageway (or cavity) that extends throughout the injector body 12, from an inlet opening 21 to the outlet opening 22. Depending on the design, the channel 20 may comprise sections of different shapes or cross-sections along its length. Where the body is made of several pieces, they are assembled together in a gastight manner, such that the channel 20 defines a gas-tight passage.

In the shown embodiment, an inlet member 15 is engaged in the channel 20 through inlet opening 21, and fixed in gas-tight manner (e.g. by welding). This inlet member 15 defines a gas feed passage for supplying hydrogen to the injector. The proximal part of the inlet member 15 is shown in Fig. 1 and can be shaped in any appropriate manner for the purpose of coupling to the fuel rail (e.g. via a pipe), and possibly to cooperate with an adapter. The inlet member hence closes the inlet opening 21 of the body 12, but defines the gas passage for feeding gas into the channel.

The valve seat 24 defines an annular surface that faces outwardly, i.e. away from the channel 20, and which may typically be a conical surface. A pintle 26 is axially movable between closed and open positions to control flow of gas through the outlet opening 22. The pintle 26 comprises a pintle shaft 28, which extends along the injector axis A and is moveably received inside channel 20, and a pintle head 30, which radially protrudes from the pintle shaft 28 at the distal end thereof. The pintle head 30 forms a valve member (or plug) that is adapted to cooperate with the valve seat 24. When the injector 10 is in its closed position (as shown in Fig.1), the pintle head 30 engages the valve seat 24, thereby preventing gas flow through the outlet opening 22. Conversely, when the injector 10 is in its open position (as shown on Fig, 4), the pintle head 30 is distally spaced from the valve seat 24, thereby enabling gas flow through the outlet opening 22. It may be noted that the pintle head 30 is located downstream (in gas flow direction) of the valve seat 24 and the pintle 26 opens in flow direction; hence the gas injector 10 is said to open outwardly. The pintle 26 further comprises a pintle perch 29 radially protruding from the pintle shaft 28. In this embodiment, the pintle perch 29 is a separate annular piece fixedly attached to the pintle shaft 28. A first spring 31 is arranged in the injector channel 20, loaded between the pintle perch 29 and a shoulder formed in the injector body 12 to bias the pintle 26 proximally, i.e. towards its closed position.

Reference sign 36 designates a solenoid coil that cooperates with a magnetic armature 32 to actuate the pintle 26. The armature 32 is fitted in the injector channel 20 with a small clearance. The armature 32 is movable along the injector axis A. When the solenoid 36 is energized, the armature 32 moves distally, thereby displacing the pintle shaft 28 into its open position. The armature movement is limited axially by body portions, e.g. proximally by inlet member 15 and distally by a body portion 54 that is formed by a pole piece. The pintle shaft 28 may be press fitted in a distal bore 42 of the armature 32 such that the latter guides its motion along injector axis A. Alternatively, the pintle shaft 28 may be clearance fitted in the distal bore 42. The distal bore 42 advantageously comprises a shoulder, which serves as abutment and engages the pintle shaft 28 when the armature 32 moves distally, thereby moving the pintle 26 to its open position. A guide ring 34 is further arranged in the injector cavity 20 so as to closely surround the pintle shaft 28 and guide its motion.

Remarkably, the armature 32 is a generally cylindrical body that comprises a hollow portion defining an armature cavity 38, a proximal bore 40 and the distal bore 42. The proximal bore 40, armature cavity 38 and distal bore 42 are in fluid communication and arranged successively along the injector axis, thereby enabling flow of gaseous fuel through the armature 32. In this embodiment, the cylindrical body comprises a disk-like base portion 32.2 with the distal bore 42 therethrough, and an annular wall 32.3 extending proximally from the base portion 32.2 and comprising an inwardly protruding rim which defines the proximal bore 40. Guiding elements 39 are arranged around the annular wall 32.3 to guide the motion of the armature 32.

An elongate shaft 44 extends through the proximal bore 40 such that a head 45 of the elongate shaft lies within the armature cavity 38. The clearance gap between the elongate shaft and the proximal bore may be selected according to desired configurations (e.g. narrow or wide gap). As will be described in detail below, the head 45 is configured to obturate the distal bore 42 in closed position. In this embodiment, the elongate shaft 44 is hollow and comprises a plurality of apertures 46 through which gaseous fuel is delivered from the inlet of the injector 10 to the armature cavity 38. The elongate shaft 44 thus defines a fuel passage (gas feed passage) from the inlet of the injector to the armature cavity 38.

In this embodiment, the shaft 44 is combined (integral) with the inlet member 15 and extends therefrom proximally along axis A. The shaft forms an axial continuation of the feed passage into the armature cavity 38.

The head 45 is formed as a cone-like element that extends radially from axis A and closes the end of shaft 44. The outer diameter of head 45 is selected to circumscribe the distal bore 42, which is thus covered by head 45 in closed position. The diameter of the head 45 is here smaller than that of the proximal bore 40 to facilitate insertion of the elongate shaft 44 in the armature cavity.

A second spring 48 is arranged to bias the armature 32 towards the proximal side P. The second spring 48 is arranged outside of the armature and distally therefrom, partially surrounded by the pole piece 54 portion of the body.

In use, to perform an injection event where gas is discharged through the outlet opening 22, the solenoid 36 is energized to create a magnetic field that attracts the armature 32 in the distal direction and causes the pintle 26 to move distally in an open position, when the force of the magnetic field overcomes the spring forces of the first and second spring 31, 48. Conventionally, to guide the magnetic field, a non-magnetic ring 50 is incorporated in the injector body; alternatively, the wall thickness of the main body 12a can be locally reduced to form a so-called magnetic shunt.

The pintle shaft 28 comprises a hollow length 28.1 extending from the distal bore 42 to the distal side D. The pintle 26 further comprises a proximal aperture 26.1 and a distal aperture 26.2. As will be understood, the pintle shaft 28 defines an axial gas passage that enables to convey gas from the armature cavity 38 to the outlet portion 18.

In this embodiment, the pintle shaft 28 is realized as a straight tube having a proximal axial open end which forms the proximal aperture 26.1, whereas the opposite tube end is closed by the pintle head 30, which is partially inserted in the pintle shaft 28, see fig. 1. Therefore, the distal aperture 26.2 is laterally or radially arranged, here about the distal end of the pintle shaft 28. In the embodiment of Fig.1, the distal aperture 26.2 is formed by one hole, or typically a number of holes, in the peripheral wall of the pintle shaft 28 proximal to the pintle head 30. The size and number of the holes depend on the desired flow rate.

The pintle shaft 28 is partially inserted in the distal bore 42 of the armature 32, such that the armature 32 and the pintle 26 cooperate to define a continuous axial gas passage extending from the proximal side P to the distal side D of the injector 10 when the pintle 26 is in its open position. The present injector 10 thus provides a design with a straight gas passage extending throughout the injector length. Gas entering the gas passage at the inlet portion 14 flows through the armature cavity 38 and the hollow pintle shaft 28, then exits through the distal aperture 26.2 near the outlet opening 22 and upstream of the valve seat 24. A straight gas passage is thus provided, thereby avoiding significant pressure drops as undergone in conventional designs with solid pintle shafts, where the fuel has to flow around the pintle and through the pole piece and springs.

Sealing means are configured to prevent flow from the armature cavity towards outlet portion in the closed position. In the embodiment of Fig.1 and 4, the armature 32 comprises a first sealing means 52.1 surrounding the proximal bore 40. The first sealing means 52.1 cooperate with a third sealing means 52.3 arranged on an opposite surface of the injector body 12. More specifically, the third sealing means 52.3 is arranged on an annular sealing surface, transversal to axis A, around shaft 44. The first and third sealing means 52.1 and 52.3 cooperate to prevent flow of gaseous fuel through the proximal bore 40 and around the armature 32, i.e. towards the distal side D, when the armature 32 is in its proximal position.

Likewise, the armature 32 comprises a second sealing means 52.2 surrounding the distal bore 42. The second sealing means 52.2 cooperate with a fourth sealing means 52.4 arranged on an opposite surface of the head 45 of the elongate shaft 44 to prevent flow of gaseous fuel through the distal bore 42 when the armature 32 is in its proximal position. In other words, in the proximal position of the armature 32, the head 45 of the elongate shaft 44 engages the armature 32 to prevent flow through the distal bore 42 towards the pintle shaft 28. More specifically, the second sealing means 52.2 are annular shaped to surround the distal bore 42. The fourth sealing means 52.4 are provided on a distal annular sealing surface of the head 45. Hence, when the armature 32 is in proximal position, the head 45 engages the base portion 32.2 and the second 52.2 and fourth 52.4 sealing means cooperate to provide a circumferential seal that prevents gas flow from the cavity towards the distal bore 42.

In the embodiment of fig. 1 and 4, the first and second sealing means 52.1, 52.2 each comprise an annual knife edge protrusion formed in the body of the armature 32, whilst the third and fourth sealing means 52.3, 52.4 each comprise an elastomeric seal ring of corresponding diameter. Flow of gaseous fuel through the proximal and distal bores 40, 42 is thus prevented when the armature 32 is in proximal position by contact between the knife edge protrusions and the seal rings. When the armature 32 is in its distal position, the knife edge protrusions are spaced from the seal rings, thereby enabling flow of gaseous fuel through the proximal and distal bores 40, 42.

The injector 10 according to the invention thus comprises two means for selectively enabling or preventing flow of gaseous fuel through the injector 10. On the distal side D, the pintle head 30 cooperates with the valve seat 24 to prevent flow of fuel through the outlet opening 22 and to protect the interior of the injector 10 against the hot and high-pressure combustion gasses of the engine. On the proximal side P, the first and second sealing means 52.1, 52.2 of the armature cooperate with corresponding third and fourth sealing means 52.3, 52.4 to prevent flow of fuel through and around the armature 32. By providing an additional means for selectively enabling or preventing flow of gaseous fuel, a smaller preload for the first spring 31 can be selected, thereby reducing the closing speed of the pintle head 30 against the valve seat 24 and improving the durability of the metal-metal contact interface therebetween. Furthermore, the seal ring of the third and fourth sealing means soften the impact of the pintle head 30 against the valve seat 24, further improving their durability.

The inventors have found that, when the injector is in its closed position, the pressure applied onto the armature 32 by the gaseous fuel is non-uniform. This nonuniform pressure onto the armature 32 may bias it towards the proximal side P or the distal side D, depending on a sealing diameter of the first and third sealing means 0D1 and a sealing diameter of the second and fourth sealing means 0D2. By design, the biasing force obtained by adjustment of the diameters 0D1 and 0D2 is configured to be insufficient to open by itself the injector, i.e. injector opening can only be obtained by means of the actuator.

Typically, in the present configuration, the sealing diameters are assumed to be the diameter of their respective knife edge protrusions 52.1, 52.2. When 0D1 > 0D2, the armature 32 is biased towards the distal side D by the pressure of the gaseous fuel in the inlet portion 14. Conversely, when OD1 < 0D2, the armature 32 is biased towards the proximal side P. Finally, when 0D1 = 0D2, the pressure is balanced such that it does not bias the armature 32 towards any particular direction. Advantageously, for the most stable injector opening and closing behavior, the sealing diameters are selected such that 0.8 OD1/0D2 1.2. By selecting of a smaller preload for the second spring 48, the electrical energy required by the solenoid 36 to displace the armature 32 is decreased. As the present design allows to adjusted the gas pressure bias acting on the armature 32, it is referred to as pressure balanced armature.

The inventors have also found that, when the injector 10 is in its open position, the gap between each pair of sealing means 52.1-52.3, 52.2-52.4, defines a rather narrow flow cross sectional area and may overly restrict gas flow. Indeed the seal rings need to be compressed to obtain good sealing, but the compression depth takes up a portion of the armature stroke, causing a loss of effective area available for the gas to flow through. To solve this issue, the sealing diameters OD1, 0D2 are advantageously at least twice as large as a sealing diameter OS of the pintle head 30 on the valve-seat 24.

In this embodiment, the valve seat is part of an external piece 55 fixedly mounted at the end of the injector nozzle. An optional injector cap 56 is mounted on this external piece 55 to control the spray of hydrogen during an injection event.

Figure 2 shows a schematic view of a gaseous fuel delivery system 100 comprising a gas tank 102, a (electronic) pressure regulator 104, and a fuel rail 106 coupled to a plurality of inventive gas injectors 10 as described above. The gas tank contains pressurized combustible gas, in gaseous state, but could be liquefied. The pressure regulator 104 is serially connected between the gaseous fuel tank 102 and the fuel rail 106 by means of piping 108. The pressure regulator is configured to decreases 104 the flow pressure upstream thereof to a controllable, nominal working pressure range, e.g. around 5 to 40 bar. The gaseous fuel tank 102 is configured to store pressurized gaseous fuel at pressures of up to 700 bars. Typically, a mechanical pressure reducer is associated with the tank 102 to discharge a gas stream at reduced pressure, e.g. around 50 bar, into piping 108 (i.e. upstream of regulator 104).

Turning to Figs 3a-3d, possible alternative embodiments of the pintle design are shown, with different configurations for the distal aperture 26.2. Specifically, the pintle shaft 28 may be inserted in a blind bore formed in the pintle head 30, as shown on figure 3a-c. The distal aperture 26.2 may be formed through both the pintle shaft 28 and the pintle head 30, as shown on figure 3b, the recess may be formed exclusively through the pintle head 30, as shown on figure 3c, and the pintle head 30 may comprise a through-hole surrounding a filled portion of the pintle shaft 28, the filled portion being distal to the distal opening 26.2 and preventing flow through the pintle head 30.

Claims

Claims 1. A gas injector (10) for injection of gaseous fuel in an internal combustion engine, extending along an injector axis (A) from a proximal side (P) to a distal side (D) and comprising: an injector body (12) defining an injector channel (20) extending from a proximal inlet portion (14) to a distal outlet portion (18) having an outlet opening (22) surrounded by a valve seat (24); a pintle (26) having a pintle shaft (28) and pintle head (30); wherein the pintle (26) is movable along the injector axis (A) between a closed position, in which the pintle head (30) engages said outlet valve seat (24) to prevent gas flow through the outlet opening (22), and an open position, in which the pintle head (30) is distally spaced from the valve seat (24) to enable flow of gas through the outlet opening (22); a magnetic armature (32) mechanically coupled to the pintle shaft (28) to be axially moveable therewith, and a solenoid (36) configured to selectively generate a magnetic field, thereby displacing the magnetic armature (32) and forcing the pintle (26) into its open position; wherein the armature (32) comprises an armature cavity (38) in fluid communication with the inlet portion (14); wherein an elongate shaft (44) is partially inserted in the armature (32) via a proximal bore (40), such that an end of the shaft (44) lies within the armature cavity (38); wherein the armature (32) or the injector body (12) comprises first sealing means (52.1) surrounding the at least one proximal bore (40) of the armature (32), the first sealing means (52.1) being configured to prevent flow between the armature cavity (38) and the outlet portion (18) around the armature (32) when the pintle (26) is in the closed position; wherein the armature (32) comprises at least one distal bore (42) which enables flow through the armature (32) when the pintle (26) is in the open position; wherein the pintle shaft (28) comprises a hollow length (28.1) extending from the armature (32) to the distal side (D) of the injector body, a proximal end with a proximal aperture (26.1) being inserted in the distal bore (42), and a distal aperture (26.2), thereby defining an axial gas passage between the armature cavity (38) and the outlet portion (18); wherein the armature (32) or the elongate shaft (44) comprises second sealing means (52.2) surrounding the at least one distal bore (42) of the armature (32), the second sealing means (52.2) being configured to prevent flow from the armature cavity (38) to the distal bore (42) and the hollow length (28.1) of the pintle shaft (28) when the pintle (26) is in the closed position.
2. Gas injector according to claim one, wherein a sealing diameter of the first sealing means (52.1) is smaller, equal to or greater than a sealing diameter of the second sealing means (52.2).
3. Gas injector according to any of the preceding claims, wherein a ratio between a sealing diameter of the first sealing means (52.1) and a sealing diameter of the second sealing means (52.2) is comprised between 0.8 and 1.2.
4. Gas injector according to any of the preceding claims, wherein a sealing diameter of the first sealing means (52.1) and a sealing diameter of the second sealing means (52.2) are at least twice as large as a sealing diameter of the pintle head (30) on the valve seat (24).
5. Gas injector according to any of the preceding claims, wherein the elongate shaft (44) is hollow and comprises at least one aperture (46), thereby defining a gas passage into the armature cavity (38), preferably wherein the aperture (46) is formed on a lateral surface of the elongate shaft (44).
6. Gas injector according to any of the preceding claims, wherein the elongate shaft (44) is integral with and extends from an inlet member (14), said inlet member (14) being arranged proximally from the armature (32) within the injector channel (20).
7. Gas injector according to any of the preceding claims, wherein the first sealing means (52.1) is arranged on a proximal outer surface of the armature (32) and/or wherein the second sealing means (52.2) is arranged on a distal inner surface of the armature (32).
8. Gas injector according to any of the preceding claims, wherein the armature (32) or the injector body (12) comprise a third sealing means (52.3) facing the first sealing means (52.1), the third sealing means (52.3) being configured cooperate with the first sealing means (52.1) to prevent flow between the armature cavity (38) and the outlet portion (18) around the armature (32) when the pintle (26) is in the closed position.
9. Gas injector according to any of the preceding claims, wherein the armature (32) or the elongate shaft (44) comprise a fourth sealing means (52.4) facing the second sealing means (52.2), the fourth sealing means (52.4) being configured cooperate with the second sealing means (52.2) to prevent flow between the armature cavity (38) and the outlet portion (18) through the armature (32) when the pintle (26) is in the closed position.
10. Gas injector according to any of the preceding claims, wherein each sealing means (52.1, 52.2, 52.3, 52.4) comprise a knife-edge protrusion or a seal ring, preferably wherein said seal ring is made of elastomer.
11. Gas injector according to any of the preceding claims, further comprising a pintle spring (31) configured to bias the pintle (26) in the closed direction; wherein the pintle spring (31) is arranged in the injector channel (20), resting at one end against a pintle perch (29) fixedly connected to the pintle shaft (28) and at the other end against a shoulder of the injector body.
12. Gas injector according to any of the preceding claims, further comprising a pole piece (54) arranged distally from the armature (32) and an armature spring (48), wherein the pole piece (54) and/or the armature (32) has a recess, and wherein the armature spring (48) is at least partially arranged is said recess/recesses distally from the armature (32), resting at one end against a shoulder of the armature (32) and at the other end against a shoulder of the pole piece (54) or the injector body (12).
13. Gas injector according to the preceding claims, wherein at least the pole piece (54) and/or a spring (31, 48) is arranged within the injector channel (20) so as to surround the pintle (26) at points along the injector axis (A) located strictly between its proximal aperture (26.1) and its distal aperture (26.2)
14. Gas injector according to any of the preceding claims, wherein the pintle (26) is outwardly opening.
15. Gas injector according to any of the preceding claims, wherein the pintle shaft (28) is partially inserted in the distal bore (42) of the armature (32), such that the armature (32) and the pintle (26) cooperate to define a continuous axial gas passage extending from the proximal side (P) to the distal side (D) of the injector (10) when the pintle (26) is in its open position.
16. Gas injector according to any of the preceding claims, wherein the valve seat (24) is part of an external piece (55) fixedly mounted at the distal end of the injector body (12), preferably wherein an optional injector cap (56) is mounted on this external piece (55) to control the spray of hydrogen during an injection event.
17. Fuel delivery system (100) comprising a gaseous fuel tank (102) configured to store pressurized gaseous fuel, and a fuel rail (106) fluidly coupled to at least one fuel injector (10) according to any of the preceding claims.Fuel delivery system (100) according to the preceding claim, further comprising pressure regulating means (104) configured to decrease the pressure of fuel flow therethrough, wherein the pressure regulating means (104) is serially connected between the fuel tank (102) and the fuel rail (106).