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

Description

DESCRIPTION of the industrial invention entitled: “Cylinder head of a spark-ignition internal combustion engine with hydrogen power supply” by: Stellantis Europe SpA, of Italian nationality, Corso Giovanni Agnelli 200, 10135 Turin. Designated Inventors: GEMELLI Emilio; FERRARA Mario; ROBIGLIO Alberto; D'ANNA Carmelo; DICAPRIO Francesco; OLIVERO Oddone. Filed on: May 15, 2024 **** DESCRIPTION TEXT Field of invention The present invention relates to internal combustion engines with hydrogen fuel. In particular, the invention was developed with reference to hydrogen-fueled internal combustion engines with ignition controlled, whose architecture is borrowed from an internal combustion engine compression ignition diesel powered. Known technique The current trend towards massive reductions in carbon dioxide emissions carbon emissions in the atmosphere affect the automotive industry at various levels and requires at each of these levels the adoption of solutions - once generally not travelled - in order to comply with the increasingly stringent rules both at the both nationally and at community level. The projected reduction of carbon dioxide emissions up to total demolition requires, among other things, the use of self-propelled vehicles which do not involve combustion (such as those fitted to electric vehicles), or to use carbon-free fuels, as is the case with hydrogen. Among the salient features of hydrogen combustion are a very high detonation resistance and a very high flame front velocity higher than the combustion of carbon-containing fuels. These characteristics lead to a high pressure peak during combustion and therefore require an engine with a structure capable of withstanding the consequent mechanical stresses. The realization of hydrogen engines using architectures derived from diesel engines, or in general compression ignition engines, are be particularly advantageous since such engines are generally sized to withstand higher mechanical stresses than the similar spark ignition engines, thus allowing maximize thermodynamic efficiency during hydrogen combustion. On the other hand, increasingly stringent regulations on emissions (for example example Nox) which must be respected during the approval of vehicles equipped with internal combustion engines increasingly carry the side effect of an increase in the size of the exhaust gas after-treatment system, 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 regarding emission thresholds combustion products and acoustics. In this sense, the consequence immediate is the ever decreasing availability of space to allocate and fix the engine components, even essential ones, inside the engine compartment. Problems of this type are for example related to the installation of spark plugs ignition in hydrogen engines based on architectures derived from thrusters diesel cycle, where such spark plugs must be installed where previously Diesel injectors were planned. In addition to adapting the installation location of diesel injectors, on hydrogen-powered internal combustion engines in this type there is a general tendency to relocate components with respect to to the original diesel-powered engine, which often ends up consuming space in traditionally free areas. For example, due to the need for fit a turbocharger to the top of the head of the engine, the space available for the passage of the necessary wiring the electrical power supply of the spark plugs is reduced and the arrangement of the wiring itself problematic. Purpose and summary of the invention The present invention aims mainly to solve the above mentioned drawback. In particular, it is an object of the invention to allow easier and more rational installation of the wiring required for power supply of ignition coils in a spark-ignition internal combustion engine hydrogen-powered, minimizing space consumption and avoiding situations of interference with other engine components. An auxiliary object of the invention is to enable the installation of ignition coils in a spark-ignition internal combustion engine hydrogen-powered vehicle minimizing space consumption and protecting the ignition coils themselves. According to the invention, one or more of such objects are achieved by a cylinder head of a spark-ignition internal combustion engine hydrogen-powered having the characteristics which are the subject of the the following claims, which form an integral part of the teaching technical advice given here in relation to the invention. Brief description of the drawings The invention will now be described in detail with reference to the drawings. annexes, provided purely by way of non-limiting example, in which: - Figure 1 is a schematic perspective view of part of an engine hydrogen-powered engine equipped with a cylinder head according to the invention; And - figure 2 is a partial and schematic perspective view of a lid of the cylinder head of the engine in figure 1, with some components removed. Detailed description of the invention Referring to figure 1, 1 generally indicates the upper part of an internal combustion engine powered by hydrogen according to the invention, borrowed from an internal combustion engine with ignition for diesel-powered compression. The engine 1 comprises in a manner known per se a cylinder head 2 which includes an arrangement of at least one intake valve, at least one corresponding intake duct, at least one exhaust valve and at least a corresponding exhaust duct associated with each cylinder. On one side of the head 2 is equipped with an intake manifold 2a, with relative inlet 2a', and a blow-by separator casing 2b. Referring to figure 1, the head 2 has a head body of construction layered, including a flow module 3 configured to be directly coupled to the crankcase (not shown) of engine 1, and including the arrangement of at least one intake valve, at least one corresponding one intake duct, at least one exhaust valve and at least one corresponding exhaust duct associated with each cylinder. Head 2 It also includes a cam holder module (not visible in the figure, as covered by the lid indicated with 10) arranged to surmount the flow module 3 and which includes – rotatably supported – at least one camshaft for the actuation of the intake and / or exhaust valves. In various forms of preferred implementation head 2 is of the double camshaft type with cam-to-cam actuation, and therefore includes a first configured camshaft for actuating the intake valves and a second camshaft configured to operate the exhaust valves. They are naturally possible alternative constructions – all known in themselves – in which the module of flow 3 and the cam holder module are made in one piece and / or in which in place In the cam-to-cam drive there is a timing wheel for each shaft cam. Whatever the construction of the head 2, a cover 10 is fixed to the head itself, delimiting with it a space for housing one or more shafts cam. The cover 10 is preferably fixed to the head 2 in such a position as to overcome the aforementioned cam holder module, isolating the environment in which they are located the one or more camshafts with respect to the outside (the cover 10 is generally (assembled in a fluid-tight manner). The cover 10 is preferably made of plastic material, even more preferably filled plastic material – that is reinforced – with a granular or fibre dispersion (e.g. glass fibres). A plurality of ignition coils C are mounted on the cover 10, each in a position corresponding to a relative cylinder of the engine. coils C extend in length in a Z direction that is transverse to the longitudinal extension direction X of the head 2 and are arranged substantially parallel to each other. In preferred embodiments, the cover 10 defines a series of housings, indicated by 11, for the C coils. The housings are placed side by side between them in a longitudinal extension direction X of the head 2. Each housing 11 is therefore in correspondence with each cylinder of engine 1, and is recessed with respect to the top face of the cover 10. In the example the motor 1 is a four-cylinder engine and therefore four housings 11 and four C coils. On a portion of the cover 10, on the side where the casing 2b is located, it is obtained a casing 13 for a PRV pressure reducing valve. The casing 13 is preferably formed integrally with the lid 10 by molding, which not only reduces the overall dimensions but also simplifies the manufacturing of the head 2 as a whole. Each housing 11 is configured to receive a respective coil. of ignition C. Referring to figure 2 (in which the representation of the coils (C has been omitted for clarity), each slot 11 It includes a bottom 11a in correspondence with which a through hole is made 12, through which a tubular element is routed that connects electrically the coil C to one terminal end of a corresponding spark plug, which is screwed or generally housed in head 2 (here one spark plug per cylinder), especially in flow module 3. The housings 11 are in the form of cavities having a peripheral profile approximately quadrangular, particularly substantially rectangular with longer sides transverse to the longitudinal direction X. In in other words, each housing 11 has its own bottom 11a surrounded by walls for its entire perimeter, where these walls have a height substantially equal to the depth of the relevant bottom 11a. The cover 10 is preferably shaped so that each housing 11 has a lateral passage or gap 11' (in figure 1, it is indicated only the passage corresponding to the first housing starting from the left). The passage 11' interrupts the wall of the housing 11 which is located in correspondence with the exhaust side of engine 1 (i.e. the side opposite the intake manifold 2a). As can be clearly seen in figure 2, the 11' gates are therefore located in correspondence of a smaller side of the rectangular perimeter of the housings 11. The ignition coils C have, each corresponding to its own longitudinal end facing one of the suction side and the discharge side head 2 exhaust (here the exhaust side), a respective first electrical connector 15, for example a female connector. Connector 15 is preferably integrated in the body of the respective coil C, or in a fixed position with respect to it. As can be seen in figure 1, each gate 11' has the function of allowing the passage of a second electrical connector 16, for example a connector male, intended for mating with the first connector 15 belonging to a corresponding coil C. In preferred embodiments, cover 10 defines fully, in correspondence with each housing 11, elements of hook and / or positioning elements for a respective ignition coil C. The aforementioned attachment elements and / or the aforementioned positioning elements are located at least partly inside the relevant housing 11. In preferred embodiments, a said coupling element and a said positioning element are both defined by the same portion of the body of the cover 10, particularly a body portion relatively thin and / or at least partly elastically deformable. In preferred embodiments, such as the one shown in figure 2, from bottom 11a of each housing 11 at least two fins 20 rise, opposite each other, the through hole 12 being in an intermediate position to the two fins 20. The fins 20 have respective wall portions substantially parallel to each other, which extend transversely with respect to the direction X. The parallel wall portions of the fins 20 define each, in corresponding to their upper edge, a respective coupling tooth 20a which, as seen in figure 1, it is intended to cooperate with a respective coil of ignition C, especially with its upper face. Preferably, on the opposite side to the 11' gap of a housing 11, each fin 20 is shaped so as to define a profile of positioning or feedback for the relevant ignition coil C. For this purpose, as can be seen in figure 2, the fins 20 each have a respective portion of wall 20b generally bent inwards, that is towards one side central, of the housing 11. Preferably, the wall portions 20b are portions of the wall are generally arched, although this does not constitute essential feature: in general, it is preferable that the profile of each portion of wall 20b is congruent to a corresponding portion of the profile outside of the coil. The wall portions 20b face each other, a define a feedback for the correct positioning of a relative coil of ignition C. As can be seen in figure 1, in the assembled condition, the coupling teeth 20a of the pairs of fins 20 are engaged relative to the upper surface of the coil C, so as to avoid its movements in the axial direction. Obviously, for this purpose, the height engagement position of the teeth 20a is choice based on the height dimension of the coil C with respect to the bottom 11a of the housing 11. The coupling between the teeth 20a and the coil C is substantially a snap-fit, allowing for a certain elasticity of the fins 20. Again from figure 1 we can see how the lateral passage 11' of each housing 11 allows the passage and positioning of the connector 16, and preferably at least part of connector 15, without increasing the overall dimensions. Coil C is also completely or mostly housed inside of the relative housing 11. The wall portions 20b of the fins 20 define a reference of position for a longitudinal end zone of the coil C, to ensure its correct positioning. Preferably, therefore, the fins 20 of each pair are shaped to copy at least part of the external side profile of the relative coil C, in correspondence with the aforementioned end zone longitudinal. For assembly purposes, each coil C is inserted from above into the relative housing 11 between the two fins 20, causing a slight elastic spreading of the same. When the top surface of the coil C overrides the relevant coupling teeth 20a, the fins 20 return elastically to the original position, with a substantially snap-fit ​​connection, with the teeth themselves which axially hold the coil C in position. The wall portions 20b they provide, as mentioned, a position reference for the end of the coil C opposite the lateral passage 11a of the housing 11. In accordance with the invention, the head 2 is equipped with a device electrical connection, indicated as a whole with 30 in figure 1, for the simplified connection of the C coils. The device 30 includes a tubular guide body 31, which extends substantially in the longitudinal direction X and along which they are constrained mechanically, or in any case arranged in a fixed position, the second connectors electrical 16, spaced apart from each other. Each connector 16 is constrained or fixed to the tubular body 31 in a position corresponding to a respective connector 15. Connectors 15 and 16 are of complementary type, and preferably provided with elements for mutual engagement in position; such mutual engagement elements they can be snap-on, and include for example at least one wing or tooth hook on one connector, and a corresponding hook seat on the other connector – see for example reference 17 on the right in figure 1. The tubular guide body 31 partially extends inside the conductors or electrical cables for powering the coils C, which are connected to the respective connectors 16. In the example in figure 1, W indicates a bundle of cables, or a multi-core cable, to power all the C coils. In preferred embodiments, the tubular guide body 31 is a body made of rigid or semi-rigid plastic material, such as a plastic material loaded, for example with glass fibres. The connectors 16 can be mechanically constrained in various ways to the tubular body 31. For example, body 31 may be an overmolded body to the plurality of connectors 16 and to part of the related conductors or cables power supply. It is also possible to provide a snap-on fastening or hook-up. between the rear end of the connectors 16 and the respective through-hook seats defined by the tubular body 31. Alternatively, the mechanical constraint can be obtained by forming in a single piece the tubular body 31 and part of the connectors 16. For example, each electrical connector 16 may have a respective casing body, within which is housed a relative electrical connection insert (i.e. an internal part, more properly electrical, which includes, for example, the connection pins, in the case of a male connector). In embodiments of this type the body of connector casing 16 can be formed integrally with the tubular body 31, for example by molding. In this type of construction, in the productive, after the molding of the body 31 integrating the aforementioned casings of connector, electrical conductors can be electrically connected to the the aforementioned connecting inserts, with which they are then inserted through the connector casings and the tubular body 31, until they come out from the end open of the latter (the right end, in figure 1). The aforementioned inserts of connection are then coupled – for example by snapping – each inside the relevant connector casing, according to methods known per se. The ends of the conductors opposite the connectors 16 can then be connected – for example with the mediation of a multi-pole connector – to the unit power electronics that manages engine ignition. Regardless of the specific embodiment of the device 30, as is you understand, the electrical connection of the C coils can be done in a way simplified, through a single operation with which all the 16 connectors are simultaneously coupled to the connectors 15 of the C coils. In addition to the simplicity of connection, the advantages are evident also in relation to the most rational routing of the wiring and the associated connectors, and their smaller footprint for the benefit of installing additional engine components 1, solving the placement or relocation problems described at the beginning of the description. It is also worth highlighting the additional advantages deriving from the preferred configuration described for the cover 10, characterized by the presence of the individual housings 11 and / or the presence of the means of coupling and / or positioning of the C coils. In particular: - the depth of each housing 11 is such as to accommodate entirely or almost entirely the coil C, eliminating or limiting its protrusion compared to the external surface of the lid itself: in this way, and also thanks to to the connecting device 30, the area above the cover 10 remains It essentially clears obstacles and allows for the installation of additional engine components 1; - the presence of a passage 11' for each slot 11 is helpful in this regard of the most rational arrangement of the wiring and the associated connectors 15, 16; - the presence of the 20a coupling elements of the C coils allows for avoid the use of separate fastening elements (such as screws) for to secure the coils themselves in place, and to have to correspondingly provide 2 specific seats on the cylinder head cover for these elements separate fixings; - the presence of positioning elements, here represented by the arched wall portions 20b, constitutes a unique assembly reference and error-proof, thus facilitating assembly operations in the factory; - the fastening elements and positioning elements described can be advantageously integrated into a single piece, in view of the possibility of obtaining the cylinder head cover 10 by stamping plastic material. Even the assembly of the coils in position is therefore overall faster and more intuitive for operators. Naturally the construction details and the forms of implementation may vary widely from those described and illustrated, without thereby departing from the scope of the present invention. Fixing the C coils in place inside their housings 11 could be achieved without the aid of fins of the type previously indicated by 20. For example, each housing 11 could include a single threaded seat configured to receive a corresponding element of threaded coupling, such as a screw, for fixing the corresponding coil C within the housing. The aforementioned single threaded seat can be advantageously arranged in an eccentric position with respect to the hole pass-through 12 obtained at the bottom 11a of the housing 11, in so as to provide a unique and foolproof assembly reference.

Claims

1. Cylinder head (2) of a hydrogen-fuelled spark-ignition internal combustion engine (1) including an aligned arrangement of cylinders, the cylinder head (2) having a head body (3) with an intake side and an exhaust side, and a cover (10) fixed above the head body (3), wherein on the cover (10) are mounted a plurality of ignition coils (C), each in a position corresponding to a relevant cylinder of the engine (1), the ignition coils (C) extending in a direction (Z) substantially transverse to a longitudinal direction (X) of the cylinder head (2), and being arranged substantially parallel to each other, wherein the ignition coils (C) have, each at its longitudinal end facing one of the intake side and the exhaust side of the cylinder head (2), a first electrical connector (15),wherein the cylinder head (2) is equipped with an electrical connection device (30), including a tubular guide body (31) extending substantially in said longitudinal direction (X) and along which a plurality of second electrical connectors (16) are arranged in a fixed position, each second electrical connector (16) being in a position corresponding to a respective first electrical connector (15) and configured for coupling thereto, wherein inside the tubular guide body (31) partially extend electrical conductors (W) for powering the ignition coils (C), which are connected to the second electrical connectors (16).

2. Cylinder head (2) according to claim 1, wherein the first electrical connectors (15) and the second electrical connectors (16) are provided with elements for mutual interlocking in position (17), in particular snap-lock elements.

3. Cylinder head (2) according to claim 1 or claim 2, wherein the tubular guide body (31) is a body formed from rigid or semi-rigid plastic material, such as a filled plastic material.

4. Cylinder head (2) according to any of claims 1-3, wherein the second electrical connectors (16) each have a respective connector housing which is formed in one piece with the tubular guide body (31), or at least part of the second electrical connectors (16) has the tubular guide body (31) overmoulded, or the second electrical connectors (16) each have a rear end which is fixed or hooked into a respective through-seat defined in the tubular guide body (31).

5. Cylinder head (2) according to any of claims 1-4, wherein the cover (10) has a body defining a plurality of housings (11) placed side by side in said longitudinal direction (X), each housing (11) being associated with each cylinder of the engine (1), being recessed with respect to a top face of the cover (10) and being configured to receive a corresponding ignition coil (C), wherein, at a bottom (11a) of each housing (11), the body of the cover (10) defines a corresponding through hole (12).

6. Cylinder head (2) according to claim 5, wherein each housing (11) defines a lateral passage (11'), in a position corresponding to a said first electrical connector (15), the lateral passage (11') being configured for the passage of at least one respective second electrical connector (16).

7. Cylinder head (2) according to claim 4 or claim 5, wherein the cover body (10) integrally defines, at each housing (11), attachment elements (20a), in particular snap-fit ​​attachment elements, and / or positioning elements (20b) for a respective ignition coil (C).

8. Cylinder head (2) according to claim 7, wherein said hooking element (20a) and said positioning element (20b) are both defined by the same fin-shaped portion (20) of the cover body (10) which is at least partly elastically deformable, and wherein from the bottom (11a) of each housing (11) two said fin-shaped portions (20) rise, opposite each other, said through hole (12) being in an intermediate position between the two fin-shaped portions (20).

9. Cylinder head (2) according to claim 8, wherein - the two fin-shaped portions (20) each have a first wall portion extending transversely to said longitudinal direction (X), the first wall portions of the two fin-shaped portions (20) being preferably substantially parallel, and - each first wall portion defines, at an upper edge thereof, at least one engagement tooth (20a) susceptible to engagement with a respective ignition coil (C).

10. Cylinder head (2) according to claim 9, wherein each fin-shaped portion (20) is shaped so as to define a positioning or abutment profile for an end zone of a respective ignition coil (C), wherein in particular each fin-shaped portion (20) has a second wall portion (20b) generally bent inwardly of its housing (11), the second wall portions (20b) of the two fin-shaped portions (20) defining said positioning or abutment profile, each second wall portion (20b) being preferably substantially curved.