An air intake manifold

Abstract

An air intake manifold defining a primary air conduit and at least two secondary air conduits. The primary air conduit has an inlet end configured to receive air from an air supply and an outlet end in fluid communication with each secondary air conduit. Each secondary air conduit has an inlet end arranged to receive air directly from the outlet end of the primary air conduit and an outlet end configured to supply air to one or more cylinders of an internal combustion engine. Each secondary air conduit defines a fluid pathway that are substantially equal in length to each other.

Description

[0001] AN AIR INTAKE MANIFOLD

[0002] FIELD

[0003] The present teachings relate to an air intake manifold for an internal combustion engine and an air intake manifold for a direct fuel injection internal combustion engine, particularly hydrogen fuelled internal combustion engines. The present teachings also relate to an internal combustion engine comprising either said air intake manifold for an internal combustion engine or said air intake manifold for a direct fuel injection internal combustion engine and a working machine or an electric genset comprising said internal combustion engine.

[0004] BACKGROUND

[0005] There is increasing concern relating to the contribution carbon dioxide emissions make to global warming and, as a way of minimising such emissions, legislation is planned to ban or restrict internal combustion powered vehicles and machines that utilise fossil fuels. As a result, many industries are seeking alternative means for powering vehicles and machines that reduce or eliminate the use of fossil fuels such as gasoline (petrol) or diesel.

[0006] For light vehicles, such as passenger cars, batteries charged using electricity from renewable energy sources appears to be the favoured approach. The duty cycles of light vehicles are less impaired by the reduced energy density of batteries and can accommodate the longer charging time as compared to traditional refuelling time of gasoline and diesel. In addition, the mass of the batteries needed to have a reasonable range does not appreciably restrict the ability of these vehicle to carry the required payload of people and their belongings. However, heavy vehicles may operate for a full working day or over successive shifts with limited downtime and may be required to carry a heavy payload over a significant distance, such as line haul / freight trucks, or carry out a working operation, such as construction or agricultural machinery. For these use cases, the low energy density, cost and recharging time of batteries means they represent a less attractive option because their required mass may restrict the available payload in the case of trucks and in all cases the cost and recharging time may make their use uneconomic and impractical.

[0007] Hydrogen based fuel has been proposed as a solution to these issues as it can be produced in a renewable manner, has a greater energy density than lithium-ion batteries, and refuelling can be carried out as quickly as for gasoline and diesel. Commonly, fuel cells are proposed as a means of "cleanly" converting hydrogen to electricity on a vehicle. The electricity is used in powering electric motors for traction and / or to drive hydraulic pumps that in turn power working arms of working machines such as excavators, materials handlers or the like. However fuel cells are currently expensive and fragile, so their implementation faces practical challenges.

[0008] It is also known to use hydrogen as a fuel in internal combustion engines. This is attractive as supply chains and maintenance expertise already exists for internal combustion engines, even though adaptation is required for them to run on hydrogen.

[0009] Difficulties arise in using hydrogen as a fuel in a traditional diesel combustion engine for heavy machinery. Firstly, hydrogen fuel requires the use of a spark plug for ignition of the hydrogen, which diesel engines do not possess. Further diesel engines are configured to mix diesel fuel with air in a way that is optimised for high efficiency and low emissions with compression ignition. Gasoline internal combustion engines do comprise a spark plug and mix fuel and air in a way that is optimised for spark ignition. However, gasoline engines do not have characteristics required for operation of heavy machines, such as high torque outputs at a low rpm. Beyond this, it is also desirable for existing manufacturers of engines for heavy duty applications to be able carry over their existing engine designs with minimal adaptations for efficient combustion of hydrogen fuel.

[0010] One significant difference between diesel and gasoline fuelled internal combustion engines on the one hand and hydrogen fuelled internal combustion engines on the other is that hydrogen fuelled internal combustion engines require an oversupply of air to the cylinders in order to ensure the complete combustion of the hydrogen fuel on each piston stroke so as to minimise the risk of unburnt hydrogen escaping. In turn, this means that the air supply to the engine has to be large enough to accommodate that requirement. That poses the problem of packaging the larger volume required into the engine compartment, preferably without necessitating the enlargement of the compartment. Also, the higher demand for combustion air on each piston stroke can create unwanted effects on the air supply to other cylinders in the air intake manifold.

[0011] Another significant difference is that the fuel injectors used in hydrogen fuelled, direct injection internal combustion engines are considerably larger than equivalent fuel injectors in diesel or gasoline fuelled internal combustion engines. Supporting such injectors whilst limiting the number and complexity of parts and / or without impacting the volume required to accommodate the internal combustion engine poses a problem.

[0012] The present teaching seeks to overcome or at least mitigate the problems which may arise when using hydrogen as a fuel in an internal combustion engine.

[0013] SUMMARY

[0014] The present teachings provide an air intake manifold, an internal combustion engine and / or a working machine or electrical genset according to the appended claims. An aspect of the teachings provides an air intake manifold for an internal combustion engine. The manifold may comprise a body defining a primary air conduit and at least two secondary air conduits. The primary air conduit may have an inlet end configured to receive air from an air supply and an outlet end in fluid communication with each secondary air conduit. Each secondary air conduit may have an inlet end arranged to receive air directly from the outlet end of the primary air conduit and an outlet end configured to supply air to one or more cylinders of an internal combustion engine, wherein each secondary air conduit defines a fluid pathway between the inlet end and the outlet end. The fluid pathways of the secondary air conduits may be substantially equal in length to each other.

[0015] Advantageously, as the lengths of the secondary air pathways are equal to each other, this makes for a more uniform supply of air to each cylinder and reduces the possibility of anomalous effects on that supply.

[0016] The body may further define a mounting arranged to mount one or more fuel injectors so as to allow the or each fuel injector directly to supply fuel to an internal combustion engine.

[0017] A second aspect of the teachings provides an air intake manifold for a direct fuel injection internal combustion engine comprising a body defining an air conduit to allow passage of air from a supply of air to one or more cylinders of an internal combustion engine. The body may further define a mounting arranged to mount one or more fuel injectors so as to allow the or each fuel injector directly to supply fuel to an internal combustion engine.

[0018] Advantageously, by providing a mounting for the injectors in the manifold, the requirement for a separate mounting or the adaptation of other engine parts to mount the injectors is eliminated.

[0019] In the air intake manifold of the second aspect, the body may define a primary air conduit and at least two secondary air conduits, the primary air conduit having an inlet end configured to receive air from an air supply and an outlet end in fluid communication with each secondary air conduit, each secondary air conduit having an inlet end arranged to receive air directly from the outlet end of the primary air conduit and an outlet end configured to supply air to one or more cylinders of an internal combustion engine, wherein each secondary air conduit defines a fluid pathway between the inlet and the outlet end, and wherein the fluid pathways of the secondary air conduits are substantially equal in length to each other.

[0020] Each secondary air conduit may define a longitudinal axis parallel with the longitudinal axis of the or each other secondary air conduit. The primary air conduit may define a longitudinal axis and the longitudinal axis of the primary air conduit may be parallel with the longitudinal axes of the secondary air conduits. Advantageously this creates a flat profile for the manifold, reducing the overall volume required for packaging the manifold in the engine compartment.

[0021] The body may define a port configured to allow inlet of exhaust gas recovery gases from an exhaust gas recovery system of an internal combustion engine.

[0022] Advantageously, this allows an exhaust gas recovery system to be integrated in a simple fashion.

[0023] The outlet end of each secondary air conduit may define a plenum chamber and each plenum chamber may be configured to supply air to two or more cylinders of an internal combustion engine.

[0024] Advantageously, by providing a plenum for plural cylinders, there is sufficient air available when one cylinder is in its inlet stroke to avoid an overdemand and the plenum can be replenished with air in time for the inlet stroke of the other cylinder.

[0025] The air intake manifold may be arranged to supply air to a four-cylinder internal combustion engine, in which two secondary air conduits are provided and the plenum chamber of each secondary air conduit is configured to supply air to two cylinders of an internal combustion engine.

[0026] One plenum chamber may be configured to supply air to one adjacent pair of cylinders in an internal combustion engine and the second plenum chamber may be configured to supply air to a second adjacent pair of cylinders in an internal combustion engine.

[0027] The air intake manifold may be configured to supply air to a six-cylinder internal combustion engine, wherein three secondary air conduits are provided, the plenum chamber of each secondary air conduit being configured to supply air to two cylinders of an internal combustion engine.

[0028] Advantageously, by providing a plenum for each pair of cylinders there is sufficient air available when one cylinder is in its inlet stroke to avoid an overdemand and the plenum can be replenished with air from the air supply in time for the inlet stroke of the other cylinder, without that affecting the air supply to the other plenum, by virtue of the spacing between plenums.

[0029] The air intake manifold may be arranged to supply air to a six-cylinder internal combustion engine, in which two secondary air conduits are provided and each plenum chamber is configured to supply air to three cylinders of an internal combustion engine.

[0030] Advantageously this arrangement simplifies the construction of a manifold for a six- cylinder engine. A baffle may be formed in each plenum chamber and arranged so as to separate the fluid pathway in each secondary air conduit into two fluid sub-pathways, substantially equal in length to each other and the baffle being arranged within the plenum so as to separate the plenum into two volumes of approximately equal size.

[0031] Where each plenum supplies three cylinders, two baffles may be formed in each plenum chamber and arranged so as to separate the fluid pathway in each secondary air conduit into three fluid sub-pathways, substantially equal in length to each other, the baffles being arranged within the plenum so as to separate the plenum into three volumes of approximately equal size.

[0032] Advantageously, this facilitates the substantially equal division of the air flow in the plenum and reduces any deleterious air flow effects which may be caused by the air demand of one cylinder supplied by the plenum on the other cylinder.

[0033] The body may define a plurality of passageways, each configured to allow a securing member to pass through the body so as to facilitate securing of the air intake manifold to an internal combustion engine. Each securing member may comprise a bolt.

[0034] Advantageously this allows the straightforward assembly of the manifold onto the engine.

[0035] The mounting arranged to mount one or more fuel injectors may comprise an elongate injector passageways formed in the body of the manifold and arranged to receive a substantial portion of the body of the mounted fuel injector. The body may define a plurality of mounting passageways, each arranged to receive a respective fuel injector.

[0036] Advantageously, this provides a more secure mounting for the fuel injector(s).

[0037] The or each mounting passageway may further define a wider part, arranged at least partially to surround an injector received in the passageway, the wider part being arranged in fluid connection with a source of cooling fluid to effect cooling of a fuel injector received within the or each mounting passageway.

[0038] Advantageously, this provides cooling for the fuel injector, replacing or supplementing other cooling arrangements.

[0039] One or more clamps may be mounted to the body, the or each clamp being configured to mount one or more fuel injectors to the body of the air intake manifold. The or each clamp may be releasably fastened or releasably mated to the body of the air intake manifold, for example via bolting to the body of the air intake manifold.

[0040] Advantageously a releasable mounting / mating allows the or each injector to be removed for inspection or replacement if this required. A third aspect of the teachings provides an internal combustion engine having an air intake manifold of the first or second aspect.

[0041] Such an internal combustion engine may be hydrogen fuelled. The internal combustion engine may be configured to run exclusively on hydrogen.

[0042] Advantageously, equipping a hydrogen fuelled engine with an intake according to the first aspect facilitates the desired oversupply of combustion air whilst mitigating the effect on the airflow in the intake caused by the higher demand for air on each piston stroke. Also advantageously, equipping a hydrogen fuelled, direct injection engine with an intake according to the second aspect provides mounting support for hydrogen fuel injectors which tend to have a greater length than liquid fuel injectors.

[0043] A fourth aspect of the teachings provides a working machine or an electric genset comprising an internal combustion engine of the third aspect.

[0044] BRIEF DESCRIPTION OF DRAWINGS

[0045] Embodiments will now be described by way of example only with reference to the accompanying figures, in which:

[0046] Figure 1 is a perspective view of an air intake manifold in accordance with the present disclosure shown mounted to a cylinder head of an internal combustion engine in accordance with the present disclosure (shown schematically);

[0047] Figure 2 is an end view of the air intake manifold and internal combustion engine of Figure 1 looking in the direction of arrow A in Figure 1;

[0048] Figure 3 an end view of the air intake manifold and internal combustion engine of Figure 1 looking in the direction of arrow B in Figure 1;

[0049] Figure 4 is a cross-sectional view of the air manifold of Figures 1-3 taken on the line C in Figure 2 and looking in the direction of arrows X-X;

[0050] Figure 5 is a cross-sectional view of air intake manifold of Figures 1-3 taken on the line C in Figure 2 and looking in the direction of arrows Y-Y;

[0051] Figure 6 is a view similar to Figure 4 with a schematic representation of airflow pathways in the air intake manifold;

[0052] Figure 7 is a view similar to Figure 6 of a variation of the air intake manifold of Figures 1- 6.

[0053] Figure 8 is an enlarged cross-sectional view of the lower part of another variation of the air intake manifold of Figures 1 to 6.

[0054] Figure 9 is a view similar to Figure 6 of the air intake manifold of Figure 8. Figure 10 is an enlarged cross-sectional view of the lower part of a further variation of the air intake manifold of Figures 1 to 6.

[0055] Figure 11 is a view similar to Figure 6 of the air intake manifold of Figure 10.

[0056] Figure 12 is a side elevation of a working machine in accordance with the present disclosure.

[0057] DETAILED DESCRIPTION

[0058] 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.

[0059] References to vertical and horizontal in the present disclosure should be understood to be in relation to the machine when stood on horizontal ground in a non-working condition.

[0060] Referring to figures 1 to 6 initially, an embodiment includes an internal combustion engine 1. The engine 1, shown schematically in the figures, comprises a cylinder block 2, a cylinder head 3 and an air intake assembly 10. The cylinder block 2 and cylinder head 3 are shown partially and schematically in figure 1.

[0061] The cylinder head 3 is mounted to the cylinder block 2. The intake assembly 10 is mounted to the cylinder 3. As shown in Figures 2-5, the cylinder block 2 and cylinder head 3 together define four cylinders, 4, 5, 6, 7 (see Figures 4 and 5, in broken lines). The cylinder head 3 further defines airflow passageways 8 between the air intake 10 and the cylinders 4, 5, 6, 7. The airflow passageways 8 are shown schematically in Figures 2 and 3.

[0062] In this embodiment, the engine is configured to be powered by a gaseous fuel such as hydrogen, compressed natural gas (CNG), biogas (e.g. methane) or the like. In an alternative embodiment, the engine 1 may be configured to be powered by liquid fuels such as petroleum (gasoline) or diesel for example, or by a combination of liquid and gaseous fuels. The engine in this embodiment has four cylinders but in other embodiments may have more or fewer cylinders. In addition, in other embodiments, the cylinders may be oriented in a "V" or "boxer" configuration rather than in line as in the disclosed embodiment. The engine 1 may be suitable for use as the prime mover in a working machine (not shown) such as a telescopic handler, a fork lift truck, a backhoe loader, a wheeled loading shovel, a dumper, an excavator or a tractor, for example. Such working machines are suitable for use in off-highway industries such as agriculture and construction. In these industries they are generally configured to perform tasks such as excavation, load handling, harvesting or planting crops. As such, the engine is typically required to have certain characteristics such as a high torque output over a wide engine speed band, which differ from light passenger vehicles, for example. In addition, the engine 1 may be suitable for use in a genset - i.e. to be connected to an electrical generator as a self-contained unit to provide electrical power where a mains supply is not available. The figures show the typical orientation of the engine 1 when implemented in a vehicle, such as working machine or a genset, in use, with the axis of the cylinders arranged substantially vertically. However, in some embodiments, the cylinders may be oriented at an inclined angle with respect to the vertical.

[0063] Four hydrogen fuel injectors 9, one for each cylinder 4-7 are provided and, as shown in figures 3 and 4, supply fuel directly to each of the cylinders 4-7. "Directly" in this context means that the fuel injectors supply fuel to the cylinders and not to the air manifold.

[0064] The air inlet assembly 10 comprises an air supply 12 and an air manifold 14.

[0065] The air supply 12 (see fig.5) comprises an air supply control valve 16 and a source of air 18. The source of air may be an impeller powered electrically or by a turbo charger or super charger.

[0066] The air manifold 14 comprises a body 20 formed by casting and / or machining. The body 20 defines a primary air conduit 22 and two secondary air conduits 24, 26. The body further defines a plurality of mounting bolt pathways 28 and four fuel injector mounting pathways 30.

[0067] The primary air conduit 22 comprises an inlet end 32, an elongate primary air duct 34, an elbow 36 and an outlet end 38, which together define a primary air pathway 22A (see fig.6) and an exhaust gas recovery inlet port 40.

[0068] Each secondary air conduit 24, 26 comprises, respectively, an inlet end 42, 54, an elongate secondary air duct 44, 56, an elbow 46, 58, a plenum 48, 60 and a pair of outlets 50 & 52, 62 & 64, which respectively together define respective secondary air pathways 24A, 26A (see fig. 6).

[0069] Eight mounting bolt pathways 28 are defined in the body 20, comprising four upper mounting bolt pathways 28a and four lower mounting bolt pathways 28b.

[0070] Four clamps 66 are mounted to the body 20 of the manifold 14. Each clamp 66 comprises a clamp head 68 having a depending stem 70 extending at right angles from the clamp head. Each clamp 66 further comprises a clamp bolt 72 extending through part of the clamp head 68 to releasably mount the clamps 66 to the body 20.

[0071] The air intake assembly 10 is mounted to the cylinder head 3 along one side thereof so that it extends parallel to a line connecting the longitudinal axes of the cylinders 4-7. The mounting of the intake assembly 10 to the cylinder head 3 is effected by mounting bolts 74 passing through the mounting bolt pathways 28 in the intake manifold body 20 and into the cylinder head 3. The body 20 of the intake manifold 16 thus has a face 20a which is adjacent to the cylinder head and an opposite face 20b spaced from the cylinder head.

[0072] The air supply 12 is mounted to the body 20 of the manifold 16 in fluid communication with the primary air conduit 22.

[0073] The primary air duct 34 of the primary air conduit 22 extends substantially horizontally from the inlet end 32 to the elbow 36. The elbow 36 forms a right-angle bend in the primary air conduit 22 so that the outlet end 38 of the primary air conduit is at approximately 90 degrees to the inlet end of the primary air conduit (and faces downwardly). The inlet port 40 for exhaust gas recovery (EGR) gases is formed in a wall of the primary air duct 34 on the opposite face 20b of the body and at a position upstream relative to the outlet end 38 of the primary air conduit 22.

[0074] The outlet end 38 of the primary air conduit 22 terminates and splits into the inlet ends 42, 54 of respective secondary air conduits 24, 26. The secondary air duct 44 of the secondary air conduit 24 extends away from the inlet end 42 thereof in a first direction which is substantially parallel to the primary air duct 34. The secondary air conduit 24 has an elbow 46 by which the secondary air pathway 24A turns through substantially 90 degrees into the plenum 48. The plenum 48 terminates in two secondary air outlets 50, 52. The other secondary air conduit 26 is a mirror image of the secondary air conduit 24 so that the secondary air duct 56 of the secondary air conduit 26 extends away from the inlet end 54 thereof in the opposite direction to the secondary air duct 44 of the secondary air conduit 24.

[0075] The secondary air duct 56 of the secondary air conduit 26 also extends substantially parallel to the primary air duct 34 of the primary air conduit 22. The secondary air conduit 26 also has an elbow 58 by which the secondary air pathway 26A turns through substantially 90 degrees into the plenum 60. The plenum 60 terminates in two secondary air outlets 62, 64.

[0076] The manifold 16 and cylinder head 3 are arranged such that, when the manifold 16 is mounted to the cylinder head, the secondary air outlets 50, 52, 62, 64 line up with respective airflow passageways 8 in the cylinder head 3 so as to allow passage of air from the manifold 16 to the cylinders 4-7.

[0077] In use, air from air supply 12 is provided under pressure, via the air supply control valve (throttle) 16, to the primary inlet end 32 of the primary air conduit 22. The air passes along the primary air duct 34 and turns downwardly through 90 degrees at the elbow 36, whereupon it is, optionally mixed with EGR gas (recycled exhaust gas), entering the primary air duct via EGR port 40. The air, with the optionally mixed EGR gas, passes to the primary outlet end 38 where it splits into two separate secondary air flows.

[0078] The air in each secondary air flow passes from the respective secondary air inlet 42, 54, along the respective secondary air duct 44, 56 and turns downwardly through 90 degrees at the respective secondary elbow 46, 58 and passes into the respective plenum 48, 60. Air in each plenum is then supplied to the cylinders 4, 5, 6, 7 of the engine 1 via the outlets 50, 52, 62, 64 and the airflow passageways 8 in the cylinder head 3.

[0079] The internal combustion engine 1 operates a conventional four-stroke scheme of air / fuel intake, compression, ignition and exhaust for each cylinder 4, 5, 6, 7. In the embodiment, the intake stroke of the cylinders is in the order 4, 6, 5, 7. In that way, the demand from the engine for air from each plenum 48, 60 alternates so that neither plenum is subject to an overdemand.

[0080] By arranging the primary air conduit 22 and secondary air conduits 24, 26 substantially parallel with each other and with the primary air conduit 22 extending over one of the two secondary air conduits, the overall volume taken up by the air manifold is minimised.

[0081] This is particularly the case as depicted, where the primary air conduit 22 is above the secondary air conduits (i.e. the respective axes are aligned in a vertical plane, meaning that the transverse footprint of the manifold 16, and the engine 1 are minimised).

[0082] As the lengths of the secondary air pathways are equal to each other, this makes for a more uniform supply of air to each cylinder and reduces the possibility of anomalous effects on that supply.

[0083] By providing a plenum for a pair of cylinders, supplied by air from an elongate secondary air pathway, there is sufficient air available when one cylinder is in its inlet stroke to avoid an overdemand and the plenum can be replenished with air from the air supply in time for the inlet stroke of the other cylinder, without that affecting the air supply to the other plenum, by virtue of the spacing between plenums. This is particularly beneficial for hydrogen fuelled engines, in which it is desirable for emissions and / or safety reasons to run the engine lean (with more air than is required to fully combust / oxidise the hydrogen). This effect is improved further by arranging an engine timing such that the inlet stroke of a cylinder supplied by one plenum alternates with the inlet stroke of a cylinder supplied by the other plenum.

[0084] In figure 7, another embodiment is shown. The embodiment of figure 7 is identical in all respects to the embodiment of figs. 1 to 6 except for the addition of baffles. Parts of the air intake assembly of fig.7 corresponding to parts of the air intake assembly of figs. 1-6 bear the same reference numerals but prefixed with a "1". The engine parts and fuel injectors bear the same reference numerals. For clarity, many of the detailed parts of the air intake assembly of figure 7 do not bear reference numerals at all, where those parts are identical to the embodiment of figs. 1-6.

[0085] The embodiment in fig.7 is supplemented by the addition of a baffle, 176, 178 in each plenum 148, 160. Each baffle extends upwardly from the floor of the respective plenum at the horizontal mid-point thereof to a position just short of the vertical mid-point. The function of the baffle is to facilitate the splitting of the secondary airflow coming into the plenum into two streams, one for each outlet 150, 152, 162, 164. The baffle also serves to reduce any deleterious effects that the demand of air from one cylinder 4, 6 supplied by the plenum has on the other cylinder 5, 7.

[0086] Figures 8 and 9 show an enlarged section of part of the air intake assembly of a further embodiment. The embodiment of figures 8 and 9 is identical in all respects to the embodiment of figs. 1 to 6 except for the provision of a cooling arrangement for the fuel injectors 9. Parts of the air intake assembly of figs. 8 and 9 corresponding to parts of the air intake assembly of figs. 1-6 bear the same reference numerals but prefixed with a "2". The fuel injectors bear the same reference numerals. For clarity, many of the detailed parts of the air intake assembly of figures 8 and 9 do not bear reference numerals at all, where those parts are identical to the embodiment of figs. 1-6.

[0087] In the embodiment of figures 8 and 9, the injector mount passageways 230 define a wider annular space 280 for part of their length. Each passageway 230 also includes an annular channel 282 at each end thereof to receive an O-ring seal 284.

[0088] An inlet air passage 286 is formed in the body 220 from the lower wall of each plenum which connects the wider annular space 280 with the plenum in fluid connection. An outlet air passage 288 is formed in the body 220 from the wider annular space 280 to the exterior of the body 220, so that the wider annular space is in fluid communication with the exterior of the intake manifold. Either or both passages may include a one-way valve (not shown).

[0089] The O-rings 284 provide an air-tight seal between the bodies of the injectors 9 and the wall or walls of the injector mount passageway.

[0090] In use, air in the plenum is allowed to pass through the inlet air passage 286, into the wider annular space 280, over the body of the fuel injector 9 so as to cool the injector, and then through the outlet air passage 286 to atmosphere. The air passages and wider annular space 280 are sized so as not to disrupt the principal function of the manifold, the supply of air to the cylinders.

[0091] This arrangement provides cooling of the body of the fuel injectors, which may supplement or replace other cooling systems for the fuel injectors.

[0092] Figures 10 and 11 show an enlarged section of part of the air intake assembly of a still further embodiment. The embodiment of figures 10 and 11 is identical in all respects to the embodiment of figs. 1 to 6 except for the provision of a cooling arrangement for the fuel injectors 9. Parts of the air intake assembly of figs. 10 and 11 corresponding to parts of the air intake assembly of figs. 1-6 bear the same reference numerals but prefixed with a "3". The fuel injectors bear the same reference numerals. For clarity, many of the detailed parts of the air intake assembly of figures 10 and 11 do not bear reference numerals at all, where those parts are identical to the embodiment of figs. 1-6.

[0093] In the embodiment of figures 10 and 11, the injector mount passageways 330 define a wider annular space 380 for part of their length. Each passageway 330 also includes an annular channel 382 at each end thereof to receive an O-ring seal 384.

[0094] The O-rings 384 provide a substantially fluid-tight seal between the bodies of the injectors 9 and the wall or walls of the injector mount passageway.

[0095] A coolant inlet passage 386 is formed in the body 320, extending from the face of the body which, in use, is mounted against the cylinder head 3, to the wider annular space 380. A coolant outlet passage 388 is formed in the body 320 from the wider annular space 380 to the exterior of the body 320 on the same face as the coolant inlet passage, so that the wider annular space is in fluid communication with the exterior of the intake manifold. Either or both passages may include a one-way valve (not shown).

[0096] In use, liquid coolant from a coolant system (not shown) is supplied to the inlet air passage 286 and passes into the wider annular space 380, over the body of the fuel injector 9 so as to cool the injector, and then through the coolant outlet passage 386 back to the coolant system. The coolant system may be a dedicated injector coolant system or it may use coolant from an existing coolant system used for cooling other engine parts. The coolant may be supplied from the cylinder head 3.

[0097] This arrangement provides cooling of the body of the fuel injectors, which may supplement or replace other cooling systems for the fuel injectors.

[0098] In figure 12, a working machine WM, in this case a backhoe loader, has a hydrogen fuelled engine 1 to which an air intake assembly 10 in accordance with the disclosure is fitted. The engine 1 is supplied with hydrogen from a hydrogen fuel tank HFT. The embodiments are described above by way of example only and it will be appreciated that variations are possible without departing from the scope of protection afforded by the appended claims. For example the EGR port 40 may be provided on the upper face of the primary air conduit 22 or side face of the primary air conduit opposing the air supply control valve 16.

Claims

Claims1. An air intake manifold for an internal combustion engine comprising a body defining a primary air conduit and at least two secondary air conduits, the primary air conduit having an inlet end configured to receive air from an air supply and an outlet end in fluid communication with each secondary air conduit, each secondary air conduit having an inlet end arranged to receive air directly from the outlet end of the primary air conduit and an outlet end configured to supply air to one or more cylinders of an internal combustion engine, wherein each secondary air conduit defines a fluid pathway between the inlet end and the outlet end, and wherein the fluid pathways of the secondary air conduits are substantially equal in length to each other.

2. An air intake manifold according to claim 1 for use in a direct fluid injection internal combustion engine, in which the body further defines a mounting arranged to mount one or more fuel injectors so as to allow the or each fuel injector directly to supply fuel to an internal combustion engine.

3. An air intake manifold for a direct fuel injection internal combustion engine comprising a body defining an air conduit to allow passage of air from a supply of air to one or more cylinders of an internal combustion engine, the body further defining a mounting arranged to mount one or more fuel injectors so as to allow the or each fuel injector directly to supply fuel to an internal combustion engine.

4. The air intake manifold of claim 3 in which the body defines a primary air conduit and at least two secondary air conduits, the primary air conduit having an inlet end configured to receive air from an air supply and an outlet end in fluid communication with each secondary air conduit, each secondary air conduit having an inlet end arranged to receive air directly from the outlet end of the primary air conduit and an outlet end configured to supply air to one or more cylinders of an internal combustion engine, wherein each secondary air conduit defines a fluid pathway between the inlet and the outlet end, and wherein the fluid pathways of the secondary air conduits are substantially equal in length to each other.

5. An air intake manifold according to any of claims 1, 2 or 4, in which each secondary air conduit defines a longitudinal axis and the longitudinal axis of each secondary air conduit is parallel with the longitudinal axis of the or each other secondary air conduit.

6. An air intake manifold according to claim 5 in which the primary air conduit defines a longitudinal axis and the longitudinal axis of the primary air conduit is parallel with the longitudinal axes of the secondary air conduits.

7. An air intake manifold according to any preceding claim in which the body defines a port configured to allow inlet of exhaust gas recovery gases from an exhaust gas recovery system of an internal combustion engine.

8. An air intake manifold according to any of claims 1, 2, 4, 5 or 6, in which the outlet end of each secondary air conduit defines a plenum chamber and each plenum chamber is configured to supply air to two or more cylinders of an internal combustion engine.

9. An air intake manifold according to claim 8 in which the air intake manifold is arranged to supply air to a four-cylinder internal combustion engine, in which two secondary air conduits are provided and plenum chamber of each secondary air conduit is configured to supply air to two cylinders of an internal combustion engine.

10. An air intake manifold according to claim 9 in which one plenum chamber is configured to supply air to one adjacent pair of cylinders in an internal combustion engine and the second plenum chamber is configured to supply air to a second adjacent pair of cylinders in an internal combustion engine.

11. An air intake manifold according to claim 8 in which the air intake manifold is configured to supply air to a six-cylinder internal combustion engine, wherein three secondary air conduits are provided, the plenum chamber of each secondary air conduit being configured to supply air to two cylinders of an internal combustion engine.

12. An air intake manifold according to claim 8 arranged to supply air to a six-cylinder internal combustion engine, in which two secondary air conduits are provided and each plenum chamber is configured to supply air to three cylinders of an internal combustion engine.

13. An air intake manifold according to claim 8, in which a baffle is formed in each plenum chamber and arranged so as to separate the fluid pathway in each secondary air conduit into two fluid sub-pathways, substantially equal in length to each other and a baffle being arranged within the plenum so as to separate the plenum into two volumes of approximately equal size.

14. An air intake manifold according to claim 12, in which two baffles are formed in each plenum chamber and arranged so as to separate the fluid pathway in each secondary air conduit into three fluid sub-pathways, substantially equal in length to each other, the baffles being arranged within the plenum so as to separate the plenum into three volumes of approximately equal size.

15. An air intake manifold according to any preceding claim, in which the body defines a plurality of passageways, each configured to allow a securing member to pass through the body so as to facilitate securing of the air intake manifold to an internal combustion engine.16 An air intake manifold according to claim 15 in which each securing member comprises a bolt.

17. An air intake manifold according to claim 2, 3 or any of claims 4 to 16 when dependent on claim 2 or claim 3, in which the mounting is arranged to mount one or more fuel injectors comprises an elongate injector passageway formed in the body of the manifold and arranged to receive a substantial portion of the body of the mounted fuel injector.18 An air intake manifold according to claim 17 in which the body defines a plurality of mounting passageways, each arranged to receive a respective fuel injector.

19. An air intake manifold according to claim 17 or 18 in which the or each mounting passageway further defines a wider part, arranged at least partially to surround an injector received in the passageway, the wider part being arranged in fluid connection with a source of cooling fluid to effect cooling of a fuel injector received within the or each mounting passageway.

20. An air intake manifold according to any preceding claim in which one or more clamps are mounted to the body, the or each clamp being configured to mount one or more fuel injectors to the body of the air intake manifold.

21. An air intake manifold according to claim 20 in which the or each clamp is releasably fastened or releasably mated to the body of the air intake manifold.

22. An air intake manifold according to claim 20 in which the or each clamp is bolted to the body of the air intake manifold.

23. An internal combustion engine comprising an air intake manifold according to any preceding claim.

24. An internal combustion engine according to claim 23, in which the engine is hydrogen fuelled, preferably exclusively hydrogen fuelled.

25. A working machine or an electric genset comprising an internal combustion engine according to claim 23 or 24.

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