A fuel delivery system

Abstract

A fuel delivery system for supplying pressurized hydrogen fuel to a hydrogen fuelled internal combustion engine, the fuel delivery system comprising: at least one fuel injector for injecting hydrogen fuel into the engine; a fuel supply path leading from a source of hydrogen fuel to the at least one fuel injector, the fuel supply path comprising a downstream portion and an upstream portion; and a fuel shut-off valve in the fuel supply path for selectively fluidically isolating the downstream portion between the fuel shut-off valve and the at least one fuel injector, from the upstream portion, wherein the fuel delivery system comprises a first purge valve in permanent fluid communication with the downstream portion, for selectively venting hydrogen fuel from the downstream portion including the at least one fuel injector.

Description

[0001] P608680PC00

[0002] A FUEL DELIVERY SYSTEM

[0003] FIELD

[0004] The present teachings relate to a fuel delivery system for supplying pressurised hydrogen fuel to a hydrogen fuel internal combustion engine. In addition, the present teachings relate to an engine system including a hydrogen fuel internal combustion engine and a fuel delivery system, a working machine or a genset including a fuel delivery system, and a method of venting pressurised hydrogen fuel from a fuel delivery system.

[0005] BACKGROUND

[0006] In modern internal combustion (IC) engines, fuel is injected directly or indirectly into each combustion chamber by a fuel injector. Upstream of the fuel injector is a common fuel rail which distributes the fuel to each injector under pressure.

[0007] In order to reduce emissions from internal combustion engines, as well as potentially to reduce greenhouse gases, hydrogen is being proposed as an alternative to diesel or gasoline as a fuel for such engines.

[0008] Due to the intrinsic properties of hydrogen as a fuel, including its wide flammability range, ability to burn with a colourless flame and high delivery pressures, particular care has to be taken when performing maintenance on hydrogen fuel delivery systems for internal combustion engines.

[0009] WO2024 / 189325A1 (Bamford Excavators) describes a process for purging hydrogen fuel from a fuel delivery system via the fuel injectors on engine shutdown.

[0010] SUMMARY

[0011] The present teachings seek to overcome or at least mitigate the problems of the prior art. The present teachings provide a working machine, controller and a method according to the appended claims.

[0012] A first aspect of the present teachings provides a fuel delivery system for supplying pressurised hydrogen fuel to a hydrogen fuelled internal combustion engine. The fuel delivery system may comprise at least one fuel injector for injecting hydrogen fuel into the engine; and / or a fuel supply path leading from a source of hydrogen fuel to the at least one fuel injector. The fuel supply path may comprise a downstream portion and an upstream portion. A fuel shut-off valve may be provided in the fuel supply path for selectively flu id ica I ly isolating the downstream portion between the fuel shut-off valve andP608680PC00

[0013] the at least one fuel injector, from the upstream portion. The fuel delivery system may comprise a first purge valve in permanent fluid communication with the downstream portion, for selectively venting hydrogen fuel from the downstream portion including the at least one fuel injector.

[0014] Due to its intrinsic properties, it may be desirable to vent hydrogen from the downstream portion of the fuel supply path in certain circumstances. Advantageously, the first purge valve enables hydrogen fuel in the downstream portion of the fuel supply path to be vented independently of the upstream portion. In situations where fuel is not removed from the downstream portion by a combustion process in the engine prior to engine shutdown, this arrangement enables e.g. service personnel to vent gas from the downstream portion before carrying out maintenance thereon.

[0015] Optionally, the fuel delivery system comprises a control restriction feature for inhibiting unauthorised control of the first purge valve.

[0016] Advantageously, this helps to ensure that only suitably trained authorised personnel, such as service personnel, can readily vent the downstream portion, helping to prevent venting in potentially hazardous circumstances.

[0017] Optionally, the control restriction feature enables control of the first purge valve only via an authorisation token, such as a key, or a passcode.

[0018] Optionally, the first purge valve is manually operable to move from the closed to the open state.

[0019] Advantageously, this enables the downstream portion of the fuel supply path to be vented without requiring electrical power. As such, this is especially beneficial if the fuel delivery system does not have, or has lost, a supply of electrical power.

[0020] Optionally, the first purge valve is electrically operable to move from the closed to the open state.

[0021] Advantageously, this enables the downstream portion of the fuel supply path to be vented from a location remote from the purge valve.

[0022] Optionally, the first purge valve may be biased into the closed state.P608680PC00

[0023] Advantageously this may provide enhanced safety by reducing the risk of unwanted venting of the hydrogen.

[0024] Optionally, the fuel delivery system is further configured to inhibit opening of the purge valve if the engine is in an active state.

[0025] Advantageously this arrangement helps to prevent the venting of hydrogen gas when conditions are not safe.

[0026] Optionally, the fuel delivery system is further configured to inhibit opening of the purge valve if the fuel shut-off valve is open.

[0027] Advantageously this arrangement helps to prevent the venting of hydrogen gas when conditions are not safe.

[0028] Optionally, the fuel delivery system further comprises a controller and optionally wherein the controller is configured to determine if pressurised hydrogen fuel is present in the downstream portion.

[0029] Advantageously, this enables the controller to determine whether a purge operation is required, or has been completed via another process, such as purging via an engine shut down process, which may be a primary purging process.

[0030] Optionally, the fuel delivery system further comprises a sensor in the downstream portion, wherein the controller is configured to determine if the downstream portion contains pressurised hydrogen fuel based on a signal received from the sensor.

[0031] Advantageously, this enables the controller to determine directly if pressurised hydrogen fuel is present in the downstream portion.

[0032] Optionally, the controller is configured to provide a signal to an operator output device to indicate whether pressurised hydrogen fuel is present in the downstream portion.

[0033] Advantageously, this enables service personnel to identify whether they need to vent the downstream portion via the first purge valve before performing any potentially hazardous actions, such as attempting to gain access to the downstream portion.P608680PC00

[0034] Optionally, the controller is configured to selectively signal the first purge valve to move between closed and open states.

[0035] Advantageously, this allows venting to be carried out as part of a broader control methodology e.g. only when certain other conditions are met to enhance the safety of operation.

[0036] Optionally, the fuel shut-off valve is electrically operable to move between open and closed states, and wherein the controller is configured to selectively signal the fuel shut-off valve to move between open and closed configurations.

[0037] Advantageously, this allows the controller to ensure that the downstream portion is isolated before enabling venting of the downstream portion of the fuel supply path.

[0038] Optionally, the controller is configured only to signal opening of the purge valve upon receipt of a command from a user input device.

[0039] Advantageously, this enables an operator - e.g. service personnel - to perform checks for example that the surrounding environment is e.g. ventilated and free from ignition sources before venting commences.

[0040] Optionally, the fuel delivery system comprises a plurality of the fuel injectors and a fuel rail arranged to supply fuel to the fuel injectors. A vent line comprising the first purge valve may be arranged to extend from the fuel rail, or the first purge valve may be mounted directly to the fuel rail.

[0041] This arrangement may simplify the connection of the vent line as it may avoid the need for additional T-pieces etc.

[0042] Optionally, a vent line comprising the first purge valve or the first purge valve is directly connected to the downstream portion upstream of the fuel rail or downstream of the fuel rail.

[0043] Optionally, at least one of a first pressure regulator and a proportional valve are provided in the fuel supply path for reducing a pressure of the hydrogen fuel from a transport pressure to an injector pressure, at which the hydrogen fuel is supplied to the at least one fuel injector. The first purge valve may be downstream of the at least one of the first pressure regulator and the proportional valve.P608680PC00

[0044] Advantageously, such a configuration helps ensure hydrogen fuel is supplied to the at least one fuel injector at a suitable pressure, whilst helping to keep the pathway between the at least one fuel injector and first purge valve clear so as to ensure that the at least one fuel injector can be vented quickly.

[0045] Optionally, the first pressure regulator is in the downstream portion.

[0046] Optionally, the first pressure regulator and the fuel shut-off valve are provided within a common valve block.

[0047] Advantageously, such a configuration helps simplify implementation of the fuel delivery system.

[0048] Optionally, the pressure regulator is set to provide a pressure in the downstream portion in the range of 10 to 60 barG; optionally, approximately 40 barG.

[0049] Optionally, the fuel delivery system further comprises a second purge valve in fluid communication with the upstream portion for selectively venting hydrogen fuel in the upstream portion therefrom.

[0050] Advantageously, such a configuration enables the upstream portion to be vented independently of the downstream portion.

[0051] Optionally, the fuel delivery system further comprises a second pressure regulator in the upstream portion for reducing a pressure of hydrogen fuel from a supply pressure, at which hydrogen fuel is supplied to the fuel supply path, to the transport pressure. The second purge valve may be downstream of the second pressure regulator, optionally wherein the transport pressure is set to be in the range of 20 to 65 barG; optionally, approximately 55 barG, in use.

[0052] Advantageously, such a configuration helps ensure hydrogen fuel is transported through the fuel delivery system at an easier to handle pressure, whilst helping to keep the pathway between the upstream portion and the second purge valve clear to ensure quick venting thereof.

[0053] Optionally, the fuel delivery system further comprises a fuel source, such as a storage tank arrangement, for supplying hydrogen fuel to the upstream portion.P608680PC00

[0054] A further aspect of the present teachings comprises an engine system comprising a hydrogen fuel internal combustion engine; and the fuel delivery system of the preceding aspect configured to supply pressurised hydrogen fuel to the engine.

[0055] Optionally, the engine system is further configured to allow hydrogen fuel to be purged from the downstream portion via the engine as a primary purge mechanism. Selective venting via the first purge valve may constitute a secondary purge mechanism.

[0056] It may be preferable to purge the downstream portion via the engine as this may be achieved more rapidly and / or in a more automated way, with the downstream purge valve only being required to be opened if the primary purge mechanism is not successful.

[0057] Optionally, purging via the engine is configured to occur by closing the fuel shut-off valve and causing hydrogen fuel in the downstream portion to enter the engine.

[0058] Optionally, upon receipt of an engine shutdown command purging is configured to occur by operating the engine for a period after the shutdown command.

[0059] This allows the hydrogen fuel held in the downstream portion to be combusted in the engine rather than being vented to atmosphere, minimising the amount of hydrogen which is vented to only those situations where extended running of the engine is not achieved.

[0060] A still further aspect of the teachings comprises a working machine or a genset comprising the fuel delivery system or the engine system according to the preceding aspects.

[0061] Optionally, the working machine comprises a vent outlet in fluid communication with the first purge valve for venting hydrogen fuel from the first purge valve to the environment outside of the working machine, wherein the vent outlet is on an upper portion of the working machine.

[0062] Advantageously, this helps to ensure the hydrogen is vented away from ignition sources on the machine, (e.g. the engine bay of the machine) or surrounding the machine.

[0063] A yet further aspect of the teachings comprises a method of venting pressurised hydrogen fuel from the fuel delivery system comprising the step of enabling opening of the first purge valve if the fuel shut-off valve is closed.P608680PC00

[0064] BRIEF DESCRIPTION OF DRAWINGS

[0065] Embodiments will now be described by way of example only with reference to the accompanying figures, in which:

[0066] Figure 1 is a plan view of an internal combustion engine according to an embodiment;

[0067] Figure 2 is a view along section X-X in Figure 1;

[0068] Figure 3 is a side view of a working machine according to an embodiment, including the engine of Figure 1;

[0069] Figure 4 is a diagram of an engine system including the engine of Figure 1 and a fuel delivery system according to an embodiment; and

[0070] Figure 5 is a flow chart of a method for venting pressurised hydrogen fuel from the fuel delivery system of Figure 4.

[0071] DETAILED DESCRIPTION

[0072] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments and the teachings. However, those skilled in the art will understand that: the present teachings may be practiced without these specific details or with known equivalents of these specific details; that the present teachings are not limited to the described embodiments; and, that the present teachings may be practiced in a variety of alternative embodiments. It will also be appreciated that well known methods, procedures, components, and systems may not have been described in detail.

[0073] Referring firstly to Figures 1 and 2, an embodiment includes an internal combustion engine 1. Figure 1 shows a plan view of the engine 1, and Figure 2 shows a view along section X-X in Figure 1.

[0074] The engine 1 is a four-stroke hydrogen fuel IC engine configured to be powered by hydrogen. In this embodiment the engine 1 is fuelled solely by hydrogen. In other embodiments, the engine 1 may be fuelled by hydrogen in combination with other gaseous fuels, such as natural gas.

[0075] The engine 1 may be suitable for use as the prime mover in a working machine 10 - see Figure 3 which depicts a backhoe loader, but may also be a telescopic handler, a forklift truck, a wheeled loading shovel, a dumper, an excavator or a tractor, for example. Such working machines 10 are suitable for use in off-highway applications such as agriculture, forestry and construction. In these industries they are generally configured to performP608680PC00

[0076] tasks such as excavation, load handling, harvesting or planting crops. The engine 1 may also be utilised in a genset - a self-contained unit to provide electrical power at off-grid locations. As such the engine 1 is typically required to have certain characteristics such as a high torque output over a wide engine speed band, with peak torque occurring at a relatively low engine speed, which differ from light passenger vehicles, for example. In off-highway applications, this provides "torque backup" that enables working machines 10 to continue to carry out working operations when encountering increased loads, or resistance to a working operation - e.g. an excavator encountering a particularly solid piece of earth to be excavated.

[0077] In this embodiment, the engine 1 has four-cylinder assemblies indicated generally at 19. As configured the engine has a maximum power output of around 55kW, although it will be appreciated that the present teachings are applicable to engines with a wide range of power outputs. In the present embodiment the engine has a total displacement of 4.8 litres (i.e. 1.2 litres per cylinder). In engines used in off-highway applications each cylinder may typically have a displacement of between 0.75 and 1.5 litres. Such a displacement is relatively high by comparison with passenger vehicle engines but is suited to providing the operating characteristics described above.

[0078] Each cylinder assembly 19 includes a cylinder 5 including a bifurcated inlet port 6 leading to two inlets 6i (one inlet visible in Figure 2) and a bifurcated outlet port 9 leading to two inlets 9o (one outlet visible in Figure 2), a piston 20 translationally movable within the cylinder 5, an intake runner 16 leading from an intake manifold 11 to the inlet port 6, and a fuel injector 22.

[0079] Each cylinder assembly 19 is configured to selectively inject a gaseous hydrogen fuel from the fuel injector 22 into the intake runner 16. The engine 1 includes a common fuel rail 52 for supplying fuel to all of the injectors 22 (i.e. the injector 22 of each cylinder assembly 19).

[0080] Each inlet 6i is selectively opened and closed by intake valves 7i such that there are two intake valves 7i (one visible in Figure 2) per cylinder 5. Each outlet 9o is selectively opened and closed by an exhaust valve 7e such that there are two exhaust valves 7e (one visible in Figure 2) per cylinder 5.

[0081] The engine 1 is configured to supply hydrogen fuel and air from the intake runner 16 to the cylinder 5 via the inlet port 6 during an intake stroke of the piston 20, and exhaust combustion gases from the cylinder 5 via the outlet port 9 during an exhaust stroke of the piston 20.P608680PC00

[0082] In alternative embodiments (not shown), the engine 1 may have more or fewer cylinder assemblies 19, e.g. 2, 3, 6, or 8. In addition, in other embodiments the cylinders 5 may be oriented in a "V" or boxer configuration rather than inline as in the disclosed embodiment.

[0083] The engine 1 includes an engine structure 80 including a cylinder block 2 and a cylinder head 3. The cylinder block 2 includes the cylinders 5. The cylinder head 3 includes at least a part of the intake runner 16 of each cylinder assembly 19.

[0084] The cylinder head 3 is mounted to the cylinder block 2. The intake manifold 11 is mounted to the cylinder head 3. The engine 1 is configured such that the intake runners 16 supply a mixture of air from the intake manifold 11 and fuel from the injectors 22 to the corresponding cylinders 5 of the cylinder block 2 via the inlet port 6. As such, the engine 1 is a port fuel injection engine (i.e. fuel is provided to the cylinders 5 via port fuel injection).

[0085] In other embodiments the engine may additionally or alternatively inject fuel directly into each cylinder via an injector 25 (represented in phantom in Figure 2) located at the roof of each cylinder 5. As such, the engine 1 may be a direct injection engine.

[0086] As the engine 1 utilises hydrogen as fuel, a spark is required to initiate combustion. Thus, each cylinder assembly 19 includes a spark plug 21 (illustrated schematically in Figure 2) mounted intermediate the inlet and outlet ports 6, 9 in the cylinder head 3. The spark plugs 21 are connected to respective coils (not shown) which generate a high tension current to initiate the spark in the spark plug, as required, during the combustion cycle of the engine 1.

[0087] Figure 4 shows a diagram of an engine system 200 of the working machine 10 including the engine 1 and a fuel delivery system 50 for supplying pressurised hydrogen fuel to the engine 1.

[0088] The fuel delivery system 50 includes a storage tank arrangement 53 for supplying pressurised hydrogen fuel to the fuel injectors 22. In the illustrated embodiment, the storage tank arrangement 53 includes first and second storage tanks 53a, 53b for storing pressurised hydrogen, but may include one or more than two storage tanks in other embodiments. The storage tanks 53a, b may be housed in a body of the working machine 10. In alternative embodiments, the fuel delivery system 50 may include an alternative fuel source, such as a hydrolyser for example.P608680PC00

[0089] The fuel delivery system 50 includes a fuel supply path 100 fluidly connecting each storage tank 53a, b to the fuel injectors 22. The fuel supply path 100 includes a plurality of fuel lines as discussed in more detail below.

[0090] Each storage tank 53a, b is provided with a tank shut-off valve 54 in the fuel supply path 100 for selectively fluidically isolating the storage tank 53a, b from the rest of the fuel delivery system 50 downstream of the tank shut-off valve 54. The tank valves 54 may be connected in flow communication via a single gas line or manifold 100-1 of the fuel supply path 100 which connects the storage tanks 53a, b together.

[0091] The fuel delivery system 50 includes a fuel shut-off valve 102 (hereinafter referred to as 'the shut-off valve') in the fuel supply path 100 for selectively fluidically isolating a downstream portion 100_D of the fuel supply path 100 extending between the shut-off valve 102 and the fuel injectors 22 (represented by a short dashed double line in Figure 4), from an upstream portion 100_U of the fuel supply path 100 extending between the shut-off valve 102 and the storage tanks 53a, b (represented by an unbroken double line in Figure 4). In other words, the shut-off valve separates or delimits the downstream portion 100_D from the upstream portion 100_U.

[0092] When open, the shut-off valve 102 allows fuel to pass from the storage tanks 53a, b to the injectors 22 via the fuel supply path 100. The shut-off valve 102 is open when the engine 1 is in an active state (i.e. when the engine is running). When closed, the shut-off valve 102 prevents fuel from the storage tanks 53a, b flowing along the fuel supply path 100 to the injectors 22. The shut-off valve 102 is normally closed when the engine 1 has been shut down for safety reasons.

[0093] The storage tanks 53a, b store hydrogen at a supply pressure which is greater than an injector pressure at which the hydrogen fuel is supplied to the injectors 22. The supply pressure may nominally be in the range of 300 to 750 barG, e.g. approximately 350 barG, or in some embodiments approximately 700barG. The supply pressure reduces as the storage tanks 53a, b are progressively depleted, however.

[0094] The fuel delivery system 50 of this embodiment includes an upstream pressure regulator 104 in the upstream portion 100_U of the fuel supply path 100 for reducing a pressure of the hydrogen fuel from the supply pressure to a transport pressure. This helps ensure hydrogen fuel is transported along the fuel supply path 100 at a pressure that may be easier to handle. The transport pressure may be in the range of 20 to 65 barG, e.g. approximately 55 barG. In other embodiments, there may be no upstream regulator, so that the transport pressure is the same as the supply pressure.P608680PC00

[0095] The fuel delivery system 50 includes a downstream pressure regulator 106, downstream of the upstream pressure regulator 104, for reducing a pressure of the hydrogen fuel from the transport pressure to the injector pressure. The pressure regulator 106 may be a mechanical pressure reducing valve. The injector pressure may be in the range of 10 to 50 barG, e.g. approximately 40 barG. In some embodiments the fuel delivery system may comprise a solenoid operated proportional valve (not shown) in addition to or in place of the downstream of the mechanical pressure reducing valve 106 and / or shut-off valve 102 to control the flow of hydrogen fuel to the fuel rail 52. In other words, such a solenoid operated proportional valve may act as both a shut-off valve 102 and a pressure regulator 104.

[0096] In the illustrated embodiment, the downstream pressure regulator 106 is in the downstream portion 100_D of the fuel supply path 100, i.e. downstream of the shut-off valve 102, but may be in the upstream portion 100_U in alternative embodiments. If present, the proportional valve is located downstream of both the shut-off valve 102 and the pressure regulator 106.

[0097] In the illustrated embodiment, the downstream pressure regulator 106 and the shut-off valve 102 are provided within a common valve block 108, which helps simplify implementation of the fuel delivery system 150, but may be in separate valve blocks in alternative embodiments. If present, the proportional valve may also be provided in a common valve block, or separately.

[0098] The engine system 200 includes a controller 110 configured to control the operation of the engine 1 and at least a portion of the fuel delivery system 50 in this embodiment. The controller 110 may be an engine control unit (ECU). Typically, the controller 110 may control the downstream portion 110_D up to the shut-off valve 102 and the engine 1. A separate controller (not shown) may control the upstream portion 102_U, but be in communication with the controller 110. In alternative embodiments, the controller 110 may control the fuel delivery system 50 only.

[0099] The controller 110 may comprise: control circuitry; and / or processor circuitry; and / or at least one application specific integrated circuit (ASIC); and / or at least one field programmable gate array (FPGA); and / or single or multi-processor architectures; and / or sequential / parallel architectures; and / or at least one programmable logic controllers (PLCs); and / or at least one microprocessor; and / or at least one microcontroller; and / or a central processing unit (CPU), to perform the described methods. The controller may include an associated memory 111 or the memory may be located locally to the controller or remotely. The memory may be a non-volatile flash memory.P608680PC00

[0100] The controller 110 receives signals from a user input device 113 and is capable of sending output signals to an audio / visual user output device 115. The user input device 113 may be one or more physical buttons, keys or switches, or may be a. The user output device 115 may be a light, buzzer or raster graphics display. The raster graphics display may be the touchscreen. In some embodiments the user input device 113 and / or user output device 115 may be provided on the working machine 10, e.g. at an operator station. In other embodiments the user input device 113 and / or user output device 115 may be provided on a separate device (not shown) able to communicate with the controller 110 via a wired connection (e.g. via an onboard diagnostics port) a short range wireless connection (e.g. via Bluetooth or other known wireless protocol) or a long range wireless protocol, such as via a cellular data network (e.g. 3G, 4G, 5G etc.).

[0101] As part of its control function, the controller 110 communicates with the fuel injectors 22. The controller 110 may monitor fuel pressure in the common fuel rail 52 via a pressure sensor 112. The controller 110 may also monitor operation of the engine 1, e.g. via monitoring rotation of a crankshaft (not shown) via a crankshaft sensor 117. In this embodiment the controller 110 also signals operation of the shut-off valve 102 and may determine the state (open or closed) of the shut-off valve by open- or closed-loop control.

[0102] It will be appreciated that whilst these signal connections are depicted in Figure 4 as being direct links, they may in fact be provided via intermediate controllers controlling other parts of an overall machine. In addition, the communication may in some instances be via a network connection, such as a CAN bus.

[0103] In an embodiment, the controller 110 is configured to instruct a shutdown purge process engine on engine shutdown for purging hydrogen fuel from the downstream portion 100_D. The shutdown purge process may fully or partially empty the downstream portion 100_D of pressurised hydrogen fuel prior to a complete stop of the engine 1. This minimises the risk of the hydrogen leaking past the fuel injector nozzles whilst the engine 1 is off, dwelling in the cylinders 5, intake manifold 11 and intake runners 16, and then being ignited in an uncontrolled way when the engine restarts, which may cause damage to the engine 1. In addition, the purge process allows for the safe maintenance of the downstream portion 110_D of the system, in particular of the fuel injectors 22, fuel rail 52 etc. and / or for safe transportation of the engine 1.

[0104] As part of the shutdown purge process, once a key-off signal has been detected, the controller 110 is configured to signal closing of the shut-off valve 102, blocking the flow of fuel from the storage tanks 53a, 53b to the fuel injectors 22. The controller 110 then runs the engine 1 for a predetermined duration sufficient for the hydrogen fuel containedP608680PC00

[0105] in the downstream portion 100_D to have been injected into the engine 1 and burned. Typically, this may equate to a time of approximately 1-3 seconds.

[0106] Once, the shutdown purge process has completed, the controller 110 stores a completed shutdown purge flag in a memory 111. If the engine stops abnormally without the shutdown purge process completing, e.g. due to a stall or an emergency shutdown, this flag will not be set, or a different flag set.

[0107] An emergency shutdown may occur when an operator shuts off the engine 1 via an isolator switch (not shown), rather than using the engine start device. Such isolator switches are a legislative requirement on working machines to isolate the machine electrics for safety during maintenance, but are sometimes used by operators as a "shortcut" means of stopping an engine from outside the cab. An emergency shutdown may also occur if an engine or aftertreatment fault detected by the controller 110 necessitates an immediate shutdown. In such scenarios, the controller 110 may not have been able to purge the downstream portion 100_D of hydrogen via extended operation of the engine 1 prior to the engine 1 shutting down.

[0108] In some embodiments, the controller 110 is configured to crank the engine 1 without sparking of the spark plugs 21 upon a subsequent engine start to purge hydrogen before resuming normal engine operation. However, in some circumstances such a restart may not be desirable, since it may risk causing damage to the engine 1 or an associated aftertreatment system, or may not be possible, e.g. due to a seized component, starter motor failure, depleted battery etc.. A maintenance operation on the downstream portion 100_D may be required in this scenario.

[0109] In an embodiment, the aforesaid engine shutdown process and / or engine start purge process may be regarded as a primary purge process. In other embodiments the engine 1 may not be configured to operate a purge process at shut down and / or start up.

[0110] As such, the present inventors have identified a need to vent the pressurised hydrogen in the downstream portion 100_D for maintenance or transport scenarios, in the absence of hydrogen having been purged by normal engine 1 operation.

[0111] To address this need, the fuel delivery system 50 includes a downstream (first) purge valve 114 in fluid communication with the downstream portion 100_D, for selectively venting hydrogen fuel from the downstream portion 100_D. By 'permanent fluid communication' it is intended to mean that the fuel delivery system 50 does not include any means (e.g. a valve) capable of preventing fluid communication between theP608680PC00

[0112] downstream purge valve 114 and the downstream portion 100_D during normal operation of the fuel delivery system.

[0113] Advantageously, the downstream purge valve 114 enables hydrogen fuel in the downstream portion 100_D to be vented independently of the upstream portion 100_U. In situations where fuel is not removed from the downstream portion 100_D by operation of the engine 1, as described above, this arrangement enables service personnel to vent gas from the downstream portion 100_D before carrying out maintenance thereon, or maintenance on the engine involving the injectors 22, fuel rail 52 etc . In addition, the purge valve 114 may also enable gas to be vented prior to a possible leakage of the gas from the fuel injectors 22 into the engine 1, which may cause damage to the engine 1 if combusted on engine start, without requiring more complex operations.

[0114] The downstream purge valve 114 may be any suitable valve for selectively enabling and preventing fluid to pass through it, such as a ball valve, for example.

[0115] In the illustrated embodiment, the downstream purge valve 114 and the shut-off valve 102 are mounted to the engine structure 80. In alternative embodiments, one or both of the downstream purge valve 114 and the shut-off valve 102 may be mounted elsewhere on the working machine 10.

[0116] In the illustrated embodiment, the downstream purge valve 114 is in a first part 116_1 of a vent line 116 (represented by long dashed double lines in Figure 4). The vent line is fluidly connected to the downstream portion 100_D at a point upstream of the fuel rail 52 in this embodiment. In alternative embodiments, the vent line 116 may be fluidly connected to the fuel rail 52, or fluidly connected downstream of the fuel rail 52. In some embodiments, the downstream purge valve 114 may be directly mounted to the fuel rail 52 or pipework of the downstream portion 100_D upstream or downstream of the fuel rail 52.

[0117] The vent line 116 leads to a vent outlet 118 in fluid communication with the downstream purge valve 114 for venting hydrogen fuel to the ambient environment outside of the working machine 10 when the downstream purge valve 114 is open. The vent outlet 118 may be on an upper portion (e.g. on or adjacent a roof) of the working machine 10 as shown in Figure 3. This helps to ensure the hydrogen is vented away from ignition sources on the working machine 10 (e.g. an engine bay of the machine) or surrounding the machine. In other embodiments the vented gas may alternatively be captured in a separate reservoir.P608680PC00

[0118] In the present embodiment, the downstream purge valve 114 is downstream of the downstream pressure regulator 106 (and proportional valve if provided). This helps to keep the pathway between the fuel injectors 22 and downstream purge valve 114 clear so as to ensure that the critical parts of the downstream portion 100_D can be vented quickly. It will however be appreciated that a section of the downstream portion 100_D which is upstream of the downstream pressure regulator 106 / proportional valve and downstream of the shut-off valve 102 may not be vented via the downstream purge valve 114, but may be vented via opening the shut-off valve 102 and an upstream purge valve 120 (see below), if required.

[0119] In the illustrated embodiment, the downstream purge valve 114 is electrically operable to move between open and closed configurations. The downstream purge valve 114 includes an electric actuator, such as a motor or solenoid, configured to move the valve 114 between open and closed configurations.

[0120] In the illustrated embodiment, the downstream purge valve 114 is also manually operable to move the downstream purge valve 114 between open and closed configurations. This enables the downstream portion 100_D to be vented without requiring electrical power, and so is beneficial if the machine's battery has depleted, and an external power source is not available. In embodiments where it is manually actuable, the purge valve 114 may be accessibly located - e.g. under a machine bonnet (hood) or service hatch. In some more compact machines such as backhoe loaders or telescopic handlers, the purge valve 114 may be located within 1.8m of the ground surface, optionally 1.5m, optionally 1.2m so it can be actuated by service personnel standing at ground level. For other machines, such as large slew excavators, this may not be practical, however.

[0121] In alternative embodiments, the downstream purge valve 114 may only be manually operable or only electrically operable.

[0122] The fuel delivery system 50 includes a control restriction feature for inhibiting unauthorised control of the downstream purge valve 114 in this embodiment. Advantageously, this helps to ensure that only trained and authorised personnel can vent the downstream portion 100_D, e.g. to prevent venting in unsuitable circumstances (e.g. when the working machine 10 is near an ignition source or in an enclosed environment). The control restriction feature may enable control of the downstream purge valve 114 only via an authorisation token or device.

[0123] In embodiments where the purge valve 114 is manually actuable, the security device is a service tool having a non-standard interface to connect to and actuate the valve. For example, this may be a handle (not shown) with an interface that is not a standard hex,P608680PC00

[0124] Torx or other form. In other embodiments, access to the purge valve 114 may require a key or number combination in possession of suitably trained and authorised personnel.

[0125] In embodiments where the valve is electrically / electronically controlled, the token may be a smartcard, a passcode or biometric identifier (e.g. received by the controller 110).

[0126] In other embodiments, the downstream purge valve 114 may include a handle for moving the valve between open and closed configurations or may be operable by a standard tool, such as a screwdriver or Allen key if this is considered to meet safety requirements.

[0127] With reference to Figure 4, the fuel delivery system 50 may include an upstream purge valve 120 in fluid communication with the upstream portion 100_U for selectively venting hydrogen fuel in the upstream portion 100_U therefrom. Advantageously, such a configuration enables the upstream portion 100_U to be vented independently of the downstream portion 100_D. The upstream purge valve 120 may share any of the features described in relation to the downstream purge valve 114.

[0128] In the illustrated embodiment, the upstream purge valve 120 is in a second part 116_2 of the vent line 116 in fluid communication with the vent outlet 118. The second part 116_2 is fluidly connected to the upstream portion 100_U at a point downstream of the upstream pressure regulator 104. In alternative embodiments, the upstream purge valve 120 may be upstream of the upstream pressure regulator 104.

[0129] In the illustrated embodiment, the controller 110 is configured to control operation of the downstream purge valve 114. Specifically, the controller 110 may selectively inhibit or permit a service personnel request to open the downstream purge valve 114 as described below.

[0130] A method of venting pressurised hydrogen fuel from the fuel delivery system according to an embodiment of the present teachings is now described with reference to Figure 5.

[0131] The method may be a background process run periodically by the controller 110 to determine whether service personnel are permitted to perform maintenance on the downstream portion and need to ensure that hydrogen fuel is vented, e.g. in response to a suitable input from the user input device 113. Alternatively, the process may be instigated by service personnel causing the controller 110 to enter a service mode or specific purge mode.

[0132] In this embodiment, the process commences at step SI by the controller 110 confirming whether the engine 1 has been shut down. If the engine 1 is running e.g. as determined from the crankshaft sensor 117, the process does not proceed further, since ventingP608680PC00

[0133] cannot commence with the engine running. If the engine is shut down the process proceeds to step S2.

[0134] In step S2 of the method, the controller 110 determines if the downstream portion 100_D contains pressurised hydrogen fuel. To make such a determination, the controller 110 may interrogate the memory 111 to check for the completed shutdown purge flag indicating that the previous shutdown purge process had completed, as described above. Presence of this flag indicates that the shut-off valve 102 is closed and that the pressurised hydrogen in the downstream portion 100_D was injected into the engine 1 and burned off before the engine 1 had shut down.

[0135] Additionally or alternatively, the controller 110 may determine if the downstream portion 100_D contains pressurised hydrogen fuel based on the pressure in the fuel rail 52 determined via the pressure sensor 112. For example, if the pressure in the fuel rail 52 is greater than a pressure threshold (e.g. atmospheric pressure), the controller 110 may determine that the downstream portion 100_D includes pressurised hydrogen fuel. Additionally or alternatively, the controller 110 may make such a determination based on a measurement from any suitable sensor in the downstream portion 100_D.

[0136] If the controller 110 determines that the downstream portion 100_D does not contain pressurised hydrogen, the method proceeds to step S3. Otherwise, the method proceeds to step S4.

[0137] In step S3, the controller 110 stores a flag in the memory 111 indicating that the downstream portion 100_D does not contain pressurised hydrogen. Whereas, in step S4, the controller 110 stores a flag in the memory 111 indicating that the downstream portion 100_D does contain pressurised hydrogen. Advantageously, this enables service personnel interrogating the memory 111 to identify whether they need to take action to vent the downstream portion 100_D. This helps to prevent the service personnel performing potentially hazardous actions (e.g. attempting to gain access to the downstream portion 100_D) whilst the downstream portion 100_D contains pressurised hydrogen. In some embodiments, in steps S3 and S4, the controller 110 may provide an output to the user output device 115 to inform service personnel that the downstream portion 100_D does not or does contain pressurised hydrogen.

[0138] In subsequent steps S5-S12, the controller 110 is configured to take further steps to allow safe venting to occur.

[0139] In step S5, the controller 110 determines whether the shut-off valve 102 is closed. If the shut-off valve 102 is closed, the method proceeds to step S7. Otherwise, in step S6, theP608680PC00

[0140] controller 110 signals the shut-off valve 102 to move from its open state to its closed state, so as to flu idically isolate the downstream portion 100_D from the upstream portion 100_U. The controller 110 may additionally monitor the shut-off valve 102 to confirm the desired closed state is achieved, given the safety implications of this being achieved.

[0141] In step S7, the controller 110 enables the downstream purge valve 114 to be moved to the open position. The controller may issue a signal to the user output device 115 to indicate that the downstream purge valve 114 may be opened.

[0142] At step S8, the controller then monitors for vent request from the user input device 113 to vent the pressurised hydrogen from the downstream portion 100_D and if a request is detected, signals the opening of the downstream purge valve 114 at step S9.

[0143] It will be appreciated that this may provide a process comprising two distinct inputs for venting to occur; first, the input command of the service personnel causing the controller 110 to enter a service or purge mode, and second the input command to open the purge valve 114. This may reduce the risk of accidental venting occurring, or venting occurring when conditions are not safe to do so.

[0144] In step S10, the controller 110 determines if one or more predetermined vent conditions have been met. The predetermined vent conditions, when met, indicate that the required amount of hydrogen fuel (e.g. substantially all) has been vented from the downstream portion 100_D. Such vent conditions may include, for example, whether a predetermined amount of time has elapsed from the downstream purge valve 114 being opened in step S9, or a pressure in the fuel rail 52 (e.g. as measured by pressure sensor 112) is at or below a predetermined threshold (e.g. at atmospheric pressure).

[0145] Once the one or more predetermined vent conditions have been met in step S10, the method proceeds to step Sil, in which the controller 110 indicates to service personnel that the venting is complete via the user output device 115 and they may now close the downstream purge valve 114 to cease fluid communication between the downstream portion 100_D and the vent outlet 118. In other embodiments, the controller 110 may close the purge valve without user intervention.

[0146] In step S12, the controller 110 stores a flag in memory 111 indicating that the downstream portion 100_D does not contain pressurised hydrogen, which may be queried in other processes run by the controller 110, e.g. upon a demand to re-start the engine 1.

[0147] In some embodiments, the closed state of the downstream purge valve 114 may be confirmed prior to the controller 110 permitting the engine 1 to be started (and the shutoff valve 102 to be opened for an extended period). This may provide an additionalP608680PC00

[0148] safeguard against the uncontrolled venting of hydrogen via the downstream purge valve 114. This may be achieved by the purge valve having a suitable switch or sensor (not shown) to provide direct feedback to the controller 110 of its status. In other embodiments the controller 110 may instruct opening of the shut-off valve 102 for a predetermined period (e.g. 1-3 seconds) and then read the pressure at the sensor 112, with a pressure rise to a certain level being indicative the purge valve is closed. If such a rise is not detected, then the controller 110 may infer that the downstream purge valve is at least partially open, instruct the closing of the shut-off valve 102, and output an indication to the user output device 115 that the downstream purge valve is not closed.

[0149] In alternative embodiments, control of the venting process via the downstream purge valve 114 may be a solely manual process carried out by physical actuation of the purge valve or may have greater service personnel intervention compared to the embodiment described above.

[0150] In manual operation, no intervention of a controller is required and maintenance personnel may be required to manually check that the engine 1 is not running and the shut-off valve 102 is closed via inspection thereof, before opening the downstream purge valve 114 for a suitable period known to allow pressurised hydrogen to escape. Once the period has elapsed, the service personnel may close the downstream purge valve 114 and carry out the required maintenance on the downstream portion 100_D and / or engine 1. In some embodiments the timed closing may be automated e.g. by utilising a downstream purge valve 114 that manually actuated to open and is self-closing with or without a delay once not externally actuated (e.g. comprises a manually actuatable button or lever that is resiliently biased into a closed position).

[0151] As described above, the controller 110 may directly or indirectly confirm that the downstream purge valve 114 is closed prior to permitting the engine 1 to be restarted (and the shut-off valve 102 to be opened whilst the engine is running).

[0152] In other embodiments the controller 111 may carry out steps SI to S5 of the process above and then instruct service personnel (e.g. via the user output device 115) to manually open the downstream purge valve 114 where it is not electrically actuable. The controller may monitor the pressure via the pressure sensor 112 and indicate to the operator when the vent process is complete and the purge valve 114 may be closed.

[0153] In other embodiments, the downstream purge valve 114 may comprise a suitable mechanical or electrical interlock that prevents the purge valve from being opened if the shut-off valve 102 is also open and / or an interlock which prevents the downstream purge valve from being opened if the engine 1 is operating. In addition, a further suitableP608680PC00

[0154] interlock may prevent the shut-off valve 102 from opening if the downstream purge valve 114 is open. A further suitable interlock may prevent the engine 1 from running if the downstream purge valve 114 is open.

[0155] In some embodiments, the controller 111 may autonomously signal opening and / or closing of the purge valve 114 as part of the method, rather than requiring an input from service personnel to do so.

[0156] The aforementioned purge / vent processes utilising the downstream purge valve 114 may in some embodiments be regarded as a secondary or back-up purging process if the primary process described above, involving purging via the engine 1 operation has not been undertaken, or cannot be undertaken.

[0157] The one or more embodiments are described above by way of example only and it will be appreciated that the variations are possible without departing from the scope of protection afforded by the appended claims.

Claims

P608680PC00Claims1. A fuel delivery system for supplying pressurised hydrogen fuel to a hydrogen fuelled internal combustion engine, the fuel delivery system comprising:at least one fuel injector for injecting hydrogen fuel into the engine;a fuel supply path leading from a source of hydrogen fuel to the at least one fuel injector, the fuel supply path comprising a downstream portion and an upstream portion; anda fuel shut-off valve in the fuel supply path for selectively flu id ically isolating the downstream portion between the fuel shut-off valve and the at least one fuel injector, from the upstream portion,wherein the fuel delivery system comprises a first purge valve in permanent fluid communication with the downstream portion, for selectively venting hydrogen fuel from the downstream portion including the at least one fuel injector.

2. The fuel delivery system of claim 1, comprising a control restriction feature for inhibiting unauthorised control of the first purge valve.

3. The fuel delivery system of claim 2, wherein the control restriction feature enables control of the first purge valve only via an authorisation token, such as a key, or a passcode.

4. The fuel delivery system of any preceding claim, wherein the first purge valve is manually operable to move the from the closed to the open state.

5. The fuel delivery system of any preceding claim, wherein the first purge valve is electrically operable to move from the closed to the open state.

6. The fuel delivery system of any preceding claim, further configured to inhibit opening of the purge valve if the engine is in an active state.

7. The fuel delivery system of any preceding claim, further configured to inhibit opening of the purge valve if the fuel shut-off valve is open.

8. The fuel delivery system of any preceding claim, further comprising a controller and optionally wherein the controller is configured to determine if pressurised hydrogen fuel is present in the downstream portion.P608680PC009. The fuel delivery system of claim 8 further comprising a sensor in the downstream portion, wherein the controller is configured to determine if the downstream portion contains pressurised hydrogen fuel based on a signal received from the sensor.

10. The fuel delivery system of claims 8 or claim 9, wherein the controller is configured to provide a signal to an operator output device to indicate whether pressurised hydrogen fuel is present in the downstream portion.

11. The fuel delivery system of any one of claims 8 to 10, wherein the controller is configured to selectively signal the first purge valve to move between closed and open states.

12. The fuel delivery system of any one of claims 8 to 11, wherein the fuel shut-off valve is electrically operable to move between open and closed states, and wherein the controller is configured to selectively signal the fuel shut-off valve to move between open and closed configurations.

13. The fuel delivery system of claim 11 or claim 12, wherein the controller is configured only to signal opening of the purge valve upon receipt of a command from a user input device.

14. The fuel delivery system of any preceding claim, comprising a plurality of the fuel injectors and a fuel rail arranged to supply fuel to the fuel injectors, wherein a vent line comprising the first purge valve is arranged to extend from the fuel rail, or the first purge valve is mounted directly to the fuel rail.

15. The fuel delivery system of any preceding claim, wherein a vent line comprising the first purge valve or the first purge valve is directly connected to the downstream portion upstream of the fuel rail or downstream of the fuel rail.

16. The fuel delivery system of any preceding claim, further comprising at least one of a first pressure regulator and a proportional valve in the fuel supply path for reducing a pressure of the hydrogen fuel from a transport pressure to an injector pressure, at which the hydrogen fuel is supplied to the at least one fuel injector, wherein the first purge valve is downstream of the at least one of the first pressure regulator and the proportional valve.

17. The fuel delivery system of claim 16, wherein the first pressure regulator is in the downstream portion.P608680PC0018. The fuel delivery system of claims 16 or claim 17, wherein the first pressure regulator and the fuel shut-off valve are provided within a common valve block.

19. The fuel delivery system of any one of claims 16 to 18, wherein the pressure regulator is set to provide a pressure in the downstream portion in the range of 10 to 60 barG; optionally, approximately 40 barG.

20. The fuel delivery system of any preceding claim, further comprising a second purge valve in fluid communication with the upstream portion for selectively venting hydrogen fuel in the upstream portion therefrom.

21. The fuel delivery system of any preceding claim, further comprising a second pressure regulator in the upstream portion for reducing a pressure of hydrogen fuel from a supply pressure, at which hydrogen fuel is supplied to the fuel supply path, to the transport pressure, wherein the second purge valve is downstream of the second pressure regulator, optionally wherein the transport pressure is set to be in the range of 20 to 65 barG; optionally, approximately 55 barG, in use.

22. The fuel delivery system of any preceding claim, further comprising a fuel source, such as a storage tank arrangement, for supplying hydrogen fuel to the upstream portion.

23. An engine system comprising:a hydrogen fuel internal combustion engine; andthe fuel delivery system of any preceding claim configured to supply pressurised hydrogen fuel to the engine.

24. The engine system of claim 23 further configured to allow hydrogen fuel to be purged from the downstream portion via the engine as a primary purge mechanism, and wherein selective venting via the first purge valve constitutes a secondary purge mechanism.

25. The engine system of claim 24, wherein purging via the engine is configured to occur by closing the fuel shut-off valve and causing the hydrogen fuel to enter the engine.

26. The engine system of claim 25, wherein upon receipt of an engine shutdown command purging is configured to occur by running the engine for a period after the shutdown command.P608680PC0027. working machine or a genset comprising the fuel delivery system of any one of claims 1 to 22, or the engine system of any one of claim 23 to 26.

28. The working machine of claim 27, comprising a vent outlet in fluid communication with the first purge valve for venting hydrogen fuel from the first purge valve to the environment outside of the working machine, wherein the vent outlet is on an upper portion of the working machine.

29. A method of venting pressurised hydrogen fuel from the fuel delivery system of any one of claims 1 to 22, comprising the step of:enabling opening of the first purge valve if the fuel shut-off valve is closed.

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