Valve assembly

Abstract

Valve assembly for a gaseous fuel supply line, comprises a body 12 defining a fuel passage (A) therethrough for pressurized gaseous fuel, and a purging passage (B) branching from the fuel passage. A v

Description

Technical field The present invention generally relates to a valve assembly for a gaseous fuel supply line, more specifically to a gaseous fuel supply line comprising a hydrogen regulation module. Background Art Hydrogen is increasingly viewed, along with electric vehicles, as one way to slow the environmentally destructive impact of the planet’s 1.2 billion vehicles, most of which burn gasoline and diesel fuel. Manufacturers of large trucks, commercial vehicles as well as passenger vehicles are currently developing hydrogen engines, i.e. where hydrogen is used as fuel instead of the usual liquid fuels. Hydrogen is stored aboard the vehicle in a high-pressure tank, at pressures in the order of 500 to 700 bars and above. The tank is part of a fuel supply system that comprises a variety of components configured to allows discharging predetermined amounts of hydrogen into the respective combustion chambers. On the downstream, low-pressure side of the fuel supply system is a fuel rail to which a number of fuel injectors are connected. Upstream thereof, components with various functionalities are required, such as a shut off valve to stop the flow of hydrogen to the fuel rail when the engine is down, and a pressure regulating valve to expand the high-pressure hydrogen flow discharged from the tank to operational pressure in the range of 20 to 40 bars. Conventionally the fuel supply system further comprises a filter, a pressure relief valve configured to open when the pressure downstream of the pressure regulator increases beyond a predetermined pressure threshold, and a purge valve to empty the fuel supply system when required. Sensors are also required to monitor the hydrogen temperature and pressure upstream of the regulator. Patent applications GB2212554.6 and GB2212553.8, the contents of which are herein incorporated by reference, relate to hydrogen regulation modules. These hydrogen regulation modules are configured to group some or all of the aforementioned components in a single unit easily arrangeable between the fuel tank and the fuel rail. In other words, a single hydrogen regulation module is able to perform the functions of the plurality of components they regroup, thereby simplifying the assembly and maintenance of the fuel supply system. Whilst hydrogen regulation modules already constitute a considerable improvement over standard fuel supply systems, it would be preferable to even further rationalize and reduced diversity of components. Technical problem It is an object of the present invention to provide a valve assembly for a gaseous fuel supply line, of improved design. General Description of the Invention This object is achieved by a valve assembly as claimed in claim 1. Valve assembly for a gaseous fuel supply line, comprising: a body defining a fuel passage therethrough for pressurized gaseous fuel, wherein in use fuel gas flows at a working pressure Pw; a purging passage branching from the fuel passage; a valve module sealingly arranged inside said purging passage to selectively enable or prevent flow of fuel from the fuel passage through the purging passage; wherein the valve module comprises a cavity and an aperture which, when unobstructed, enables flow of fuel from the fuel passage to the valve module cavity and subsequently to the purging passage; wherein the valve module comprises a valve seat surrounding said aperture, which cooperates with a valve member; wherein the valve member is reciprocally movable between a closed position, whereby it rests on the valve seat to obstruct flow of fuel through the aperture, and an open position, whereby it is spaced from said valve seat and the aperture is unobstructed; wherein a spring element is configured to bias the valve member towards its closed position, wherein an actuator module is operatively connected to the valve member via an actuation shaft to selectively move valve member into the open position; wherein the valve seat has a downstream-oriented annular seat surface, and the spring element is configured to exert a predetermined force, designed such that said valve member can spontaneously open when the fuel pressure in the fuel passage exceeds a predetermined pressure Preiief, thereby enabling pressure relief. In embodiments, the valve member is arranged within the valve module cavity. In embodiments, the spring is arranged within the valve module cavity or in a cavity in the actuator module. In embodiments, the actuator module comprises a magnetic armature which is fixedly connected to the actuation shaft; and a solenoid, which when energized, generates a magnetic force that biases the armature away from the valve seat and opens the valve module. In embodiments, the fuel passage is formed by a first through-bore, which defines a gaseous fuel passage therethrough; and the purging passage is formed by a second and a third bore, the second bore intersecting both the first and third bore. In embodiments, the valve module is sealingly arranged in the second bore and the actuator module is sealingly mounted to the body. In embodiments, the annular seat surface comprises knife edge protrusion configured to come in contact with the valve member when the latter is in closed position. In embodiments, the valve module comprises a valve body arranged in the purge passage, the valve body defining the cavity and aperture; and a seat member is arranged at an upstream side of the cavity, the seat member defining the aperture and the valve seat. In embodiments, the valve member comprises a hold member mounted at a tip of the actuation shaft, and an obturating member is arranged in a recess of the hold member, the obturating member having a front side resting against the valve seat in closed position. The obturating member is preferably a plastic / resilient member, for example disk-shaped. In embodiments, the body defining the fuel passage and accommodating the control valve is a regulation module body, which further accommodates at least one regulating valve and shut off valve, optionally combined, serially connected in the fuel passage, upstream of the valve assembly. According to another aspect, the invention relates to a regulation module comprising a valve assembly according to the present disclosure, wherein the body defining the fuel passage and accommodating the control valve is a regulation module body, which further accommodates at least one regulating valve and shut off valve, optionally combined, serially connected in the fuel passage, upstream of the valve assembly. According to another aspect, the invention provides a gaseous fuel supply line comprising the purge valve assembly according to present disclosure, a fuel tank, and a fuel rail coupled to a plurality of fuel injectors, wherein the fuel passage of the purge valve assembly is serially connected between the fuel tank and the fuel rail. Embodiments of gaseous fuel supply line are recited in appended claims 13 and 14. 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 schematic view of a gaseous fuel supply line according to the invention; Fig. 2 is a principle cross sectional view of a purge valve assembly according to an embodiment of the invention; Fig.3 is a cross sectional view of a purge valve assembly according to another embodiment of the invention; and Fig. 4 is a view of detail C in Fig.3. Description of Preferred Embodiments Figure 1 shows a schematic view of a gaseous fuel supply line 100 comprising a tank 102 containing pressurized fuel, a regulation module 104, and a fuel gas rail 106 coupled to a plurality of gas injectors 110 (e.g. solenoid actuated injectors). The regulation module 104 is serially connected between the gaseous fuel tank 102 and the fuel rail 106 by means of piping 108. The tank 102 is configured to store pressurized fuel at pressures of up to 350 or 700 bars. The fuel in the tank 102 is typically in gaseous state, and hence herein referred to as gaseous fuel or fuel gas, or even simply fuel. It could however be stored in liquid form in tank 102, and in such case it is however discharged in the piping 108 in gas state. Typically tank 102 is an assembly comprising one ore more tanks connected to a mechanical regulator that discharges gas into piping 108 at a predetermined supply pressure of around 45 to 50 bar. The present system has been designed for hydrogen combustion engines, in which case tank 102 contains pressurized hydrogen at pressures up to 350 or 700 bar. The regulation module 104, which may be also be referred to as hydrogen regulation module or HRM, comprises a plurality of valve assemblies, each valve assembly being configured to perform its associated function. As previously mentioned, hydrogen regulation modules are configured to group a plurality of components in a single unit easily arrangeable between the fuel tank and the fuel rail. In other words, the hydrogen regulation module 104 is able to perform the functions of the valve assemblies it comprises, thereby simplifying the assembly and maintenance of the fuel supply system. As such, the HRM 104 typically comprises a flow regulating valve assembly configured to decreases the flow pressure upstream thereof to a nominal working pressure range, e.g. around 5 to 40 bar. The hydrogen regulation module 104further typically comprises a shut-off valve assembly configured to selectively and sealingly isolate different sections of the gaseous fuel supply line, namely to isolate the section downstream of the HRM 104 from the tank 102. Reference 10 indicates a valve assembly 10 that is integrated in HRM 104 and is configured as a single valve combining the functions of purge valve and PRV. Figure 2 shows a principle cross sectional view of a valve assembly 10 according to an embodiment of the invention. The purge valve assembly 10 comprises a body 12 having a first through-bore 14, which defines a gaseous fuel passage A therethrough for pressurized gaseous fuel, namely H2. Body 12 is the metal body of HRM 104. Hence passage A is the flow passage of the fuel gas downstream of the above-mentioned pressure regulator and shut-off valve. In alternative embodiments (not shown), body 12 can be an independent metal body having fittings at the extremities of bore 14 by which it is serially connected to piping 108 in Fig. 1, for example. A second bore 16 is formed in the body 12 and intersects with the first bore 14. A third bore 18 is formed in the body and intersects with the second bore 16. The second and third bore 16, 18 define a purging passage B branching from the fuel passage A defined by the first bore 14. In preferred embodiments, the second bore 16 is formed perpendicular to the first and third bore 14, 18. A valve module 20 is sealingly fitted within the second bore 16. The valve module 20 is hollow, thereby defining a valve module cavity 20.1. The valve module 20 comprises a cylindrical body 21 with an aperture 22 surrounded by a valve seat 24 having an annular seat surface 25. The valve seat surface 25 is arranged facing downstream, i.e. away from the gaseous fuel passage A. When unobstructed, the aperture 22 enables flow between the gaseous fuel passage A and the valve module cavity. The valve module 20 comprises a valve member 26 is arranged in the valve module cavity 20.1. The valve member 26 is reciprocally movable between a closed position (as shown on figure 2), in which it engages the valve seat surface 24 and prevents flow through the aperture 22, and an open position in which it is distally spaced and flow through the aperture 22 is enabled. The valve member 26 is biased towards the closed position by a spring 27 also arranged in the valve module cavity 20.1. The valve module further comprises a first through bore 28.1 and a second through bore 28.2 in body 21, which define a fuel passage from the valve module cavity 20.1 to the purging passage B. The first through bore 28.1 is coaxial with the aperture 22, and perpendicular to the second through bore 28.2, which is itself coaxial with the purging passage B. An actuation shaft 29 is fixedly connected to the valve member 26 and movable therewith. The actuation shaft 29 extends from the valve member 26 through the cavity 21.1 the first through bore 28.1 and the second through bore 28.2 to connect an actuator module 30. The spring 27 is arranged around the actuation shaft 29. In this embodiment, the clearance between the first through bore 28.1 and the actuation shaft 29 is large enough to enable gas flow from the valve module cavity 20.1 to the second through bore 28.2 and the purging passage B. The valve module 20 may also comprise additional apertures to promote flow from the valve module cavity 20.1 to the second through bore 28.2 and the purging passage B. In the embodiment of figure 2, the actuator module 30 comprises an actuator body 32 having a cavity 32.1 inside of which a magnetic armature 34 is arranged. The magnetic armature 34 is reciprocally movable between a first and a second position. The actuation shaft 29 is fixedly attached at its second end (opposite valve member 26) to the armature 34 A solenoid 38 is arranged around the actuator module cavity 32.1. When energized, the solenoid 38 generates a magnetic field to actuate the armature 34, and hence the valve member 26. The first and second position of the armature 34 respectively correspond with the closed and open position of the valve member 26, as will be clear below. The actuating shaft 29 passes through an actuator body aperture 32.2, that connects the actuator module cavity 32.1 with the second through bore 28.2 of the valve module 20. The valve assembly 10 is configured to embody purge and pressure relief functions. It may be noted that the armature and valve member are biased in closed position by spring 27. This spring 27 is dimensioned to serve as pressure relief valve. In other words, the seat 24, valve member 26 and particularly the spring 27 are configured such that the valve 10 opens when the pressure in fuel channel A exceeds a predetermined relief pressure Preiief. The actuator 30 is further configured to be able to overcome the force of spring 27 in order to be able to selectively open valve member 26, when a purge is desired. Hence in normal operation, when the pressure in the gas / fuel check language passage A is nominal and the solenoid 38 is not energized, the valve member 26 is maintained closed, under the force of spring 27 which is sufficient to ensure gastight closure up to the pressure Preiief. Conversely, to perform a purge, the solenoid 38 is energized and the valve member 26 is lifted away from the valve seat by way of the magnetic force attracting the armature upward (in the view of fig.2). This enables flow from passage A to the valve body cavity 20.1 and the purging passage B. In summary, the valve module 20 and the actuator module 30 can be operated to selectively prevent or enable flow from the gaseous fuel passage A to the purging passage B. Furthermore, the valve assembly 10 is also configure to provide a pressure relief function. The valve seat surface 24 faces downstream. Hence, when the pressure within the fuel passage A exceeds predetermined pressure Preiief, the valve member 26 is automatically / spontaneously lifted from the valve seat 24 by the gas force, thereby enabling pressure relief. This predetermined pressure may be determined based on characteristics of the gas injectors 110, such as their pop-off pressure. For the sake of exemplification, let us give a few examples. In the case of a direct injection engine, the nominal working pressure Pw, i.e. the pressure in the fuel passage A, is a range between 20 and 40 ± 1.5 bar. In such case the supply pressure Ps, as discharged from the tank / tank regulator, may be between PS=45 and 50 bar. In view of the nominal working pressure Pw range, the spring 27 may be designed to open at a pressure of Preiief = 47 ± 3 bar. In the case port fuel injection (PFI), i.e. where fuel gas is introduced in the intake ports just before the intake valves, the nominal working pressure Pw may be between 0 and 15 ± 1.5 bar. In view of the nominal working pressure Pw range, the spring 27 may be designed to open at a pressure of Preiief = 20 ± 3 bar. As it should be appreciated, the purge valve assembly 10 described above comprises three modular bodies: the main body 12 which defines the fuel passage A and purging passage B, the valve module 20, and the actuator module 30. These modular bodies, in combination with one another, enable the purge valve assembly 10 to perform the functions of both a purge valve and a pressure relief valve. These modules are easily arranged with one another and may be easily replaced during maintenance operations. In practice, the valve module 20 may be pre-mounted to the actuator module, and the resulting pre-assembly is put in place by inserting the valve module into the bore 16. The valve module 20 is preferably partially received in the actuator module that has a gas-tight housing. The actuator module 30 is fixed to the body 12 via a flange and screws, and has one or more annular sealing elements (not shown). An alternative embodiment of the present valve assembly with valve module is shown in Figs. 3 and 4. Similar elements are indicated by same reference signs. One will recognize the body 12 with fuel passage A and purge passage B. A valve module 20 is arranged in bore 16 which is part of the purge passage B. Actuator module 30 is arranged on top of the valve module 20 and closes the bore 16. Actuator module 30 comprises a housing 30.1 sealing assembled to the HRM body 12. The armature 34 is axially mobile and fixedly connected to actuating shaft 29. The armature is biased toward the interior of body 12 by spring 27’, to bias the valve module 20 in closed position. The armature 34 can be selectively actuated, i.e. moved in opposite direction (upward in the figure) to lift the actuation shaft 29 and open the valve, by energizing the solenoid 38. The valve module 20 comprises a generally cylindrical body 21 that has an axial bore 18.1 which defines a cavity or internal passage 21.1 and a perpendicular bore 18.2. The body 21 is sealingly mounted in bore 16, in which it may be press-fittingly inserted. An O-ring 50 is arranged in an outer peripheral groove 51 of body 21, which comes into contact with the inner surface of bore 18.1. On the opposite side, the end of cylindrical body 21 is received in a mounting sleeve 54 of actuator module body 30. The mounting sleeve 54 comprises an outer peripheral groove 56 with an O-ring 58, which comes into contact with the inner surface of bore 18.1, at an enlarged inlet section. An aperture 22 is arranged on the upstream side of first bore 18.1, forming the only access from passage A to the cavity 21.1. The perpendicular bore 18.2 forms two outlets 18.3, allowing gas to flow from the cavity 21.1 into the purge passage B. In bore 18.1 the actuation shaft 29 is partially guided by a bushing 17. The aperture 22 is surrounded by a valve seat 24, which is oriented downstream and has an annular sealing surface 25. The aperture 22 and sealing surface 25 are borne by a seat member 23 that is inserted at the upstream end of bore 18.1. The seat member 23 is preferably provided with a continuous annular weld 40 for fixing and gas sealing purposes. The seat member 23 has an annular wall 23.1 with an end shoulder 23.2 (at it upstream end) that defines the aperture 22. The shoulder 23.2 forms the valve seat 24, facing downstream, with its annular seat surface 25 provided with an annular knife edge 25.1. Reference sign 26 designates an obturating member that is formed as an annular disk of elastic material. Obturating member 26 is made of plastic material, e.g. an elastomer, in order to be resilient, durable and compressible against the valve seat. The obturating member 26 may be made of EPDM or PTFE or similar. The elastomer preferably has a hardness of 70 to 90 shore D. The obturating member 26 is arranged in a hold member 42 attached to the actuating shaft 29. The hold member 42 comprises a front recess 44 which receives the obturating member 26. The obturating member is tightly fitted in, or over-molded, in recess 44.. In this embodiment, the hold member 42 has a H-shaped profile, with a cylindrical wall 42.1 and an inner transversal partition 42.2, which defines recess 44 on one side and another recess on the opposite side, by which it is engaged onto actuating shaft 29. Fixation of the hold member 42 to the actuating shaft may be done via press-fit or welding / brazing. Cylindrical Wall 42.2 of the hold member preferably has an outer barrel-shape (outer surface), for ease of guiding I alignment within seat member 23. The hold member 42 comprises a through bore 46 that opens in the recess 44 and communicates with an axial through bore 29.1 in the front end of actuating shaft 29. This through bore 29.1 further comprises a perpendicular bore 29.2 that opens into the cavity 21.1 of valve module 20. These bores define a passage allowing escape of air when mounting the obturating member 26. In the configuration of Fig.5 the valve module 20 is closed. The obturating member 26 rests against the valve seat 24 (seat surface 25 with knife edge 25.1) and is biased thereon by spring 27’. The pressure in passage A is nominal and no gas can flow through the valve module. If a purge is desired, the actuator module 30 is energized and the actuating shaft 29 is lifted from the valve seat 24. The pressurized gas will flow around the hold member 42, through circumferential gap between hold member 42 and wall 23.1, and then escape through bores 18.3. The gas flow path in open position of the obturating member 26 is shown dashed arrow F in Fig.4. In embodiments, axial grooves (not shown) may be arranged in the internal surface of wall 23.1 to facilitate gas flow from the seat region downstream. 5 The same flow path will open in case the working pressure in passage A exceeds the relief pressure Preiief.

Claims

1. Valve assembly for a gaseous fuel supply line, comprising:a body (12) defining a fuel passage (A) therethrough for pressurized gaseous fuel, wherein in use fuel gas flows at a working pressure Pw;a purging passage (B) branching from the fuel passage;a valve module (20) sealingly arranged inside said purging passage to selectively enable or prevent flow of fuel from the fuel passage through the purging passage;wherein the valve module (20) comprises a cavity (20.1) and an aperture (22) which, when unobstructed, enables flow of fuel from the fuel passage to the valve module cavity and subsequently to the purging passage;wherein the valve module comprises a valve seat (24) surrounding said aperture, which cooperates with a valve member (26);wherein the valve member is reciprocally movable between a closed position, whereby it rests on the valve seat to obstruct flow of fuel through the aperture, and an open position, whereby it is spaced from said valve seat and the aperture is unobstructed;wherein a spring element (27) is configured to bias the valve member towards its closed position,wherein an actuator module (30) is operatively connected to the valve member via an actuation shaft (29) to selectively move valve member (26) into the open position;wherein the valve seat has a downstream-oriented annular seat surface (25), and the spring element is configured to exert a predetermined force, designed such that said valve member (26) can spontaneously open when the fuel pressure in the fuel passage exceeds a predetermined pressure P relief, thereby enabling pressure relief.

2. Valve assembly according to any of the preceding claims, wherein the valve member (26) is arranged within the valve module cavity (20.1).

3. Valve assembly according to any of the preceding claims, wherein the spring is arranged within the valve module cavity or in a cavity in the actuator module.

4. Valve assembly according to any of the preceding claims, wherein the actuator module comprisesa magnetic armature (34) which is fixedly connected to the actuation shaft (29); anda solenoid (38), which when energized, generates a magnetic force that biases the armature away from the valve seat and opens the valve module.

5. Valve assembly according to any of the preceding claims, wherein the fuel passage is formed by a first through-bore (14), which defines a gaseous fuel passage therethrough; andwherein the purging passage is formed by a second (16) and a third bore (18), the second bore intersecting both the first and third bore.

6. Valve assembly according to any of the preceding claims, wherein the valve module is sealingly arranged in the second bore (16) and the actuator module (30) is sealingly mounted to the body.

7. Valve assembly according to any of the preceding claims, wherein the annular seat surface (25) comprises knife edge protrusion (25.1) configured to come in contact with the valve member when the latter is in closed position.

8. Valve assembly according to any of the preceding claims, wherein the valve module comprises a valve body (21) arranged in the purge passage, the valve body defining the cavity (20.1) and aperture (22); and a seat member (23) is arranged at an upstream side of the cavity, the seat member defining the aperture and the valve seat.

9. Valve assembly according to any of the preceding claims, whereinthe valve member comprises a hold member (42) mounted at a tip of the actuation shaft (29),and an obturating member (26) is arranged in a recess (44) of the hold member, the obturating member having a front side resting against the valve seat (24) in closed position.

10. Valve assembly according to claim 9, wherein the obturating member (26) is a plastic member, in particular disk-shaped.

11. Regulation module comprising a valve assembly according to any of the preceding claims, wherein the body defining the fuel passage and accommodating the control valve is a regulation module body, which further accommodates at least one regulating valve and shut off valve, optionally combined, serially connected in the fuel passage, upstream of the valve assembly.

12. Gaseous fuel supply line comprising the purge valve assembly according to any of the preceding claims, a fuel tank, and a fuel rail coupled to a plurality of fuel injectors, wherein the fuel passage of the purge valve assembly is serially connected between the fuel tank and the fuel rail.

13. Gaseous fuel supply linec according to claim 12, further comprising a shut-off valve assembly and / or a flow regulating valve assembly.

14. Gaseous fuel supply line according to the preceding claim, wherein the shut-off valve and / or flow regulating valve is arranged downstream of the fuel tank and upstream of the purge valve assembly.

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