Cylinder head of a hydrogen-fueled spark-ignition internal combustion engine

Description

DESCRIPTION of the industrial invention entitled: “Cylinder head of an internal combustion engine with ignition driven by hydrogen fuel” by: Stellantis Europe SpA, of Italian nationality, Corso Giovanni Agnelli 200, 10135 Turin Designated inventors: OLIVERO Oddone; DI CAPRIO Francesco; D'ANNA Carmelo; GEMELLI Emilio; ROBIGLIO Alberto Filed on: May 15, 2024 **** DESCRIPTION TEXT Field of invention The present invention relates to engines internal combustion with hydrogen fuel. In In particular, the invention was developed with reference to hydrogen-powered internal combustion engines controlled ignition, whose architecture is borrowed from a compression-ignition internal combustion engine diesel powered. Known technique The current trend towards massive reduction of carbon dioxide emissions into the atmosphere invests in various levels the automotive industry supply chain and requires at each of these levels the adoption of solutions - once generally not traveled - in order to fit into the ever more stringent rules both at national and international level community level. The proposed reduction of carbon dioxide emissions carbon dioxide up to total elimination requires, among other things, to resort to self-propulsion systems that do not include combustion (such as those that equip vehicles electric), or to use fuels free of harmful substances carbon, as is the case with hydrogen. Among the salient features of combustion of hydrogen have a very high resistance to detonation high and a much higher flame front velocity with respect to the combustion of fuels containing carbon. These characteristics lead to a high peak of pressure during combustion and therefore require a engine with a structure capable of withstanding the consequent mechanical stresses. The creation of hydrogen engines using architectures derived from diesel cycle engines, or in general compression ignition, it turns out to be particularly advantageous since these engines are generally sized to withstand stresses higher mechanical performance than the equivalent engines controlled ignition, thus allowing to maximize thermodynamic efficiency during combustion of hydrogen. On the other hand, increasingly stringent regulations in emissions issue (e.g. Nox) that must be respected in approval site for vehicles equipped with a petrol engine internal combustion increasingly lead to the effect collateral of an increase in the size of the system of post-treatment of exhaust gases, and in general of the equipment of accessories and sensors on board the engine. The technical problem in question is further aggravated by the upcoming introduction of the Euro 7 standard on the subject of thresholds for emissions of combustion products and acoustics. In this sense, the immediate consequence is the ever decreasing availability of space to allocate and fix the engine components, even the essential ones, inside the engine compartment. Problems of this type are found in relation to to the installation of spark plugs in engines hydrogen based on architectures derived from propulsion systems diesel cycle, where such spark plugs – and in particular the ignition coils individually associated with each spark plug - must be installed where previously diesel injectors were planned. Not only that: in addition to adapt the installation location of the injectors for diesel fuel, on internal combustion engines powered by hydrogen of this type there is a general tendency to relocation of components with respect to the powered engine diesel fuel which often ends up consuming space in areas – such as those intended for the installation of spark plug coils – traditionally free, creating potential situations of interference or impacts with other components and exposure to air flows hot coming from the engine itself. Purpose of the invention The purpose of the present invention is to solve the technical problem described above. In particular, it is intended of the invention is to allow the installation of the spark plugs and their ignition coils in a spark-ignition internal combustion engine hydrogen powered minimizing space consumption, avoiding situations of interference or collisions with others engine components and protecting ignition coils same. Summary of the invention According to the invention, this aim is achieved by a head for an internal combustion engine with ignition driven by a hydrogen-powered combustion engine internal spark ignition powered by hydrogen, and by a cover for a head for a combustion engine internal combustion engine powered by hydrogen having the characteristics forming the subject of the claims that follow, which form part integral to the technical teaching administered here in relation to the invention. Brief description of the drawings The invention will now be described in detail with reference to the attached drawings, provided for information purposes only non-limiting example, in which: - Figure 1 is a schematic perspective view of a part of an internal combustion engine powered by hydrogen equipped with a cylinder head according to the invention; - figure 2 is a sectional view along a trace II-II in figure 1, - figure 3 is a perspective view, in partial transparency (made with different line intensity) and partially exploded cover for a cylinder head according to the invention. Detailed description of the invention With reference to figure 1, the reference number 1 refers overall to an internal combustion engine with hydrogen power, borrowed from a combustion engine internal compression ignition diesel powered. Engine 1 comprises - in a manner known per se - a base, a part of which is indicated by 2, which includes an aligned arrangement of cylinders and a crankshaft, not illustrated, at one end of which is keyed a drive pulley or gear wheel P. the CY reference in Figure 1 denotes both the alignment direction of the aligned arrangement of cylinders, both the direction of a axis of rotation of the crankshaft and one or more shafts engine camshaft 1. Even in a way known in itself the engine 1 is provided top of a 4 cylinder head which includes a arrangement of at least one intake valve, at least one corresponding intake duct, at least one valve exhaust and at least one corresponding exhaust duct associated with each cylinder. with reference to figure 2, the head 4 in question has a layered construction including a directly arranged flow module coupled to the base 2 and including the arrangement of at least one intake valve, at least one corresponding intake duct, at least one exhaust valve and at least one corresponding exhaust duct associated with each cylinder, and a cam module arranged in overcome the flow module (which is thus located in position between the base and the cam module) and including – rotatably supported – at least one shaft camshafts for actuating the intake valves and / or of exhaust. In the preferred embodiment here illustrated head 4 is of the double camshaft type with cam-to-cam drive, and includes a camshaft ICS intake configured for valve actuation intake and an ECS camshaft configured for the operation of the exhaust valves. They are naturally possible alternative constructions – all known in themselves – in which the flow module 5 and the cam module 6 are made in one piece and / or in which in place cam-to-cam drive features a timing wheel for each camshaft. Regardless of the construction of the head 4, a cover 8 is fixed to the head 4 delimiting with it a space for housing one or more camshafts, in this case ICS camshafts, ECS. The cover 8 is then fixed to the head 4 – in particular to the cam holder module 6 – in a position such as to overcome the cam holder module 6 by isolating the environment in where one or more ICS, ECS camshafts are located outside (the cover 8 is generally fitted tightly of fluid). The cover 8 is preferably made of plastic material, even more preferably material plastic loaded – therefore reinforced – with a dispersion granular or in fibres (e.g. glass fibres). On one side of the head 4 (or “suction side”) oriented along the aligned arrangement of cylinders is arranged an intake manifold 10 with inlet 11 in corresponding to which a butterfly valve is placed TV, and outputs corresponding to the positions of the ducts IC suction. Preferably, on the same side there is also present a BS casing of a blow-by separator. In the preferred embodiment illustrated here, the manifold of suction 10 is made in one piece with the head 4 (with flow module 5 in the case of construction layered head 4), and in particular it is fused entirely with head 4 (or with module 5 in this case case). On an opposite side (or “exhaust side”) of head 4, always oriented along the aligned arrangement of cylinders, a 12 exhaust manifold with inlets is arranged at the EC exhaust ducts and an outlet in correspondence of a turbine inlet mouth centripetal of a supercharging group (turbine centripetal-centrifugal compressor) TC. In the form of preferred execution illustrated here is the exhaust manifold 12 is a separate element from head 4, and is mechanically coupled to it. With reference to figures 1 to 3, according to the invention the cover 8 includes a housing 14 in correspondence of each cylinder of engine 1, in which each housing 14 is recessed with respect to a outer surface of the cover 8. The housings 14 they are placed side by side along the CY direction, and in the form of preferred execution illustrated here the cover 8 comprises four slots 14 arranged aligned along the CY direction, one per cylinder. Referring to figure 2, each housing 14 is configured to receive a respective coil of ignition 15 and includes a bottom 16 at the which has a through hole 17 through which a tubular element 18 is routed which connects electrically the coil 15 and a terminal end of a corresponding spark plug 19 screwed or in general housed in head 4 (here a 19 cm spark plug for cylinder), especially in flow module 5. The end spark plug terminal 19 where the end spark plug terminal 19 is opposite to one end of the spark plug itself facing the ignition inside the corresponding cylinder. Referring in particular to Figure 2 and Figure 3, the housings 14 have the shape of cavities or recesses with an approximately quadrangular perimeter, and in substantially rectangular detail with longer sides transversal to the CY direction. In other words, each housing 14 comprises the bottom 16 surrounded by walls for the entire perimeter of it, in which the walls have height substantially equal to the depth of the recess bottom 16 itself. An exception is at least partially a gap 20 which interrupts the wall surrounding the bottom 16 in corresponding to the exhaust side of engine 1 (therefore in correspondence of a minor side of the perimeter rectangular), in which the gap 20 has the function of allow the passage of electrical wiring that feeds each individual coil. According to the invention, each coil 15 is fixed inside the housing 14 by means of a connection threaded. The threaded connection includes a seat threaded provided inside the housing 14, a through seat provided on the coil 15, in particular in position coinciding with the threaded seat inside of the housing 14, and a coupling element threaded that passes through the through seat on the coil 15 and engages the threaded seat in housing 14. In the preferred embodiment illustrated herein the threaded connection includes in particular: - as a threaded seat, a first protruding bushing 21 from the bottom 16 and provided with a threaded hole 22; of preference, the bushing 21 is made in a loop 23 which creates an extension of the perimeter of housing 14 protruding externally from it in the form of a bulge, - which through seat on the coil 15, a second bushing 24 obtained on a body of the coil 15, in particular protruding externally in the shape of an ear with respect to the coil body 15 itself, and including a through hole 25 (preferably smooth, not threaded), - as a threaded coupling element, a screw 26 which passes through hole 25, and whose threaded stem goes to finally engage in hole 22 of bushing 21 as illustrated in figure 2, also comparing with a head 27 on the second bushing 24 itself. An interaxis between hole 22 and hole 17 is identical to an interaxis between hole 25 and hole 17, so that at the moment of the installation of the coil 15 on the cover 8 – which occurs with spark plug 19 already fixed in head 4 and the tubular element 18 already coupled to the coil 15 and routed through hole 17 itself in one direction (and (towards) M visible in figure 3 – holes 22 and 25 are located coaxial with respect to each other and ready to welcome the screw 26. Operationally, the 15-element coil complex tubular 18 is routed through hole 17 to the point where where a coupling is created between the terminal end of the spark plug 19 and the tubular element 18 and until it is made a match between coil 15 and housing 14, in especially between the second bushing 24 and the bushing 21. Then screw 26 is inserted into the sequence of holes (in this order) 25 and 22 and screwed into the latter until that the head 27 of it matches the bushing 24. The coil is therefore electrically connected to spark plug 19 and secured to the lid 8, then to the head 4. Note that the depth of each housing 14 is such as to to house the coil 15 entirely or almost entirely, eliminating or limiting its protrusion with respect to the external surface of the lid 8 itself. In this way the area above the lid 8 remains substantially clear from obstacles and allows the installation of additional engine components 1, solving problems of placement or relocation described at the beginning of the description. An example of a component that can be installed on above the lid 8 and benefiting from such a installation of the coils 15 is represented by one air-water heat exchanger (cd WCAC) for air compressed air coming from a compressor outlet TC supercharging group, or even from an element of combustion air filtration. Furthermore, the arrangement of the coils 15 in substantially correct position recessed provides an effective shielding action coils themselves from hot flows coming from the engine, so such as accidental impacts with surrounding components, such as example as a result of oscillations or vibrations of the same. The solution according to the invention then presents two additional technical advantages: - the presence of a 20-gap for each housing 14 allows for more rational routing and arrangement of electrical wires connecting each coil to the unit power electronics that manages the ignition, avoiding – for example – solutions in which the housing is made up of from a common channel and all cables must pass within the channel with the result that the closest coil at the entrance to the canal it remains surrounded by cables of all the other coils, generating a situation of notable crowding. Furthermore, as visible in figure 1 for the coil 15 rightmost in the drawing, you can place gate 20 where it is most convenient from a routing perspective of the electrical connection cable relating to the coil same, especially considering the proximity to other components (here, in particular, the BS separator casing); - fixing the coil 15 to the cover 8 by means of threaded connection in an eccentric position with respect to the hole 17 is a unique assembly reference and error-proof, thus facilitating the operations of assembly in the factory. The coupling by means of threaded connection is then substantially insensitive wear, unlike other types of coupling – as a snap fit (especially with the lid 8 made of plastic material) - maintaining its characteristics even as time passes and the accumulation of kilometers traveled by the vehicle. Naturally the construction details and the shapes of realization may be widely varied with respect to as described and illustrated, without however going beyond from the scope of the present invention.

Claims

1. Head (4) for a hydrogen-fueled spark-ignition internal combustion engine (1) including an aligned arrangement (CY) of cylinders, the head comprising: - an arrangement of at least one intake valve, at least one corresponding intake duct (IC), at least one exhaust valve and at least one corresponding exhaust duct (EC) for each cylinder of the engine, - at least one camshaft (ICS, ECS) configured to operate the intake valves and / or the exhaust valves, - a cover (8) fixed to the head (4) delimiting therewith a housing compartment for the at least one camshaft (ICS, ECS), wherein the cover (8) comprises a housing (14) in association with each cylinder of the engine (1), each housing (14) being recessed with respect to an external surface of the cover (8) and being configured to receive a corresponding ignition coil (15),wherein each housing (14) comprises a threaded seat (21, 22) configured to receive a threaded mating member (26) configured to secure the corresponding ignition coil (15) within the housing (14)., 2. Head (4) according to claim 1, wherein each housing comprises a bottom (16) in correspondence with which a through hole (17) is obtained configured to receive a tubular element (18) for the electrical connection of the corresponding ignition coil (15) to a spark plug (19).

3. Head (4) according to claim 2, wherein said threaded seat (21, 22) is arranged in an eccentric position with respect to the through hole obtained at the bottom (16) of the housing (14).

4. Head (4) according to any of claims 2, 3, wherein the bottom (16) of each housing is surrounded by walls interrupted by a passage (20) configured for the routing of an electrical wiring relating to the corresponding coil (15).

5. Head (4) according to any of claims 2 to 4, wherein said threaded seat (21, 22) comprises a first bushing (21) protruding from the bottom (16) of the housing (14) and provided with a threaded hole (22).

6. Hydrogen-fuelled spark-ignition internal combustion engine (1), the internal combustion engine (1) comprising a crankcase including an aligned arrangement (CY) of cylinders, and a head (4) according to any of the preceding claims arranged to fill said crankcase (2), the internal combustion engine (1) comprising a spark plug (19) for each cylinder and an ignition coil (15) electrically connected to the spark plug (19), wherein the coil is arranged within a corresponding housing (14) of the cover (8) of said head (4) and is fixed thereto by means of a threaded connection comprising said threaded seat provided inside the housing (14), a through seat (25) provided on the ignition coil (15), in particular in a position coinciding with the threaded seat inside the housing (14),and said threaded coupling element (26) which passes through the through seat (25) on the - 13 ignition coil (15) and engages the threaded seat in the housing (14)., 7. Internal combustion engine (1) according to claim 6, wherein: - said threaded seat comprises a first bushing (21) protruding from the bottom (16) of the housing (14) and provided with a threaded hole (22), - said through-seat comprises a second bushing (24) formed on a body of the ignition coil (15), including a through-hole (25), - said threaded coupling element comprises a screw (26) passing through the through-hole (25) of the second bushing (24), the screw (26) having a threaded stem engaging said threaded hole (22) of the first bushing (21), the screw (26) also abutting the second bushing (24) by means of a head (27) of the screw itself.

8. Internal combustion engine (1) according to any of claims 6, 7, wherein each ignition coil (15) is electrically connected to a terminal end of a spark plug housed in said head (4) by means of a tubular element inserted into the through hole (17) obtained at the bottom (16) of the housing (14) on said cover (8), the terminal end being opposite an ignition end facing the inside of the corresponding cylinder.

9. Internal combustion engine (1) according to any of claims 6 to 8, wherein each coil is connected to a corresponding electrical wiring routed through the gap (20) in the wall of the respective housing (14).

10. A cover (8) for a head (4) of an internal combustion engine (1), the cover (8) being attachable - 14 to said head (4) to delimit a housing compartment for one or more camshafts (ICS, ECS) of the head (4), wherein the cover (8) comprises a housing (14) in association with each cylinder of an internal combustion engine (1), each housing (14) being recessed with respect to an external surface of the cover (8) and being configured to receive a respective ignition coil (15), wherein each housing (14) comprises a threaded seat (21, 22) configured to receive a threaded coupling member (26) configured for securing the corresponding ignition coil (15) within the housing (14).