Arrangement comprising cylinder head and spark plug for spark-ignition engine

Abstract

An arrangement (10) comprising a cylinder head (3) equipped with a spark plug (4) comprising at least one hole (46) leading outward to an internal volume (400) of the spark plug and at least one hole (45) providing a fluid connection between the internal volume (400) and a combustion chamber (23), the arrangement (10) comprising: a cooling airflow supply circuit (5) allowing the airflow to circulate to the internal volume (400); a pump (6) configured to propel the gas flow; and at least one regulating device (7) for the circulation of the cooling air flow.

Description

[0001] This invention relates to an arrangement including a cylinder head and spark plugs for a spark-ignition engine. The invention also extends to spark plugs used in the arrangement according to the invention. Finally, the invention relates to operating modes for the arrangement according to the invention.

[0002] In so-called "hydrogen" combustion engines, which use dihydrogen as fuel, combustion is extremely rapid, producing very high gas temperatures in each combustion chamber. This is especially true when the air / fuel mixture is at or near stoichiometric levels. Therefore, in such engines, combustion temperatures must be limited to reduce emissions of nitrogen oxides formed at very high temperatures and to prevent the creation of hot spots, also known as pre-ignition, that could trigger early combustion during subsequent combustion cycles. This pre-ignition occurs when a portion of the air / fuel mixture is ignited by a hot spot before the spark plug ignites it. In fact, hydrogen is highly sensitive to the potentially destructive phenomenon of pre-ignition due to its wide flammability range. In the case of pre-ignition, combustion begins early in the compression phase of the engine cycle, resulting in very rapid combustion that causes a significant rise in temperature and pressure within the cylinder, which in itself creates new hot spots.

[0003] To limit combustion temperature, it is known to increase the air / fuel ratio by using a turbocharger to move away from stoichiometric conditions. However, this principle is tricky to implement, especially during the transition between engine operating modes, when the turbocharger's response time naturally causes a temporary enrichment of the air / fuel mixture, potentially bringing it closer to stoichiometric conditions.

[0004] Spark plugs are naturally one of the potential hot spots in an engine that can serve as the basis for pre-ignition phenomena. On the one hand, spark plugs are naturally hot components because it is at their level that the spark that ignites each combustion is triggered. On the other hand, traditional spark plugs include protruding electrodes that form protrusions from the smooth surface of the combustion chamber, thus easily storing heat through convection during combustion, thereby forming hot spots and damaging the spark plug.

[0005] Therefore, to address these drawbacks, it is known to limit hot spot formation by cooling the cylinder head and / or spark plugs with a liquid coolant, thereby limiting combustion temperature and preventing pre-ignition. This cooling can be achieved by cooling the cylinder head walls away from the spark plugs, but is often insufficient. Other cooling methods implemented at the spark plugs require the integration of complex, large liquid coolant circuits, which are unsuitable for already congested environments.

[0006] This invention falls within this context and aims to provide alternatives to known cylinder heads and spark plugs for hydrogen engines, thereby enabling the limitation or even prevention of hot spot formation within the cylinder head (more specifically, at the level of the spark plug).

[0007] This invention relates to an arrangement for a spark-ignition engine including a cylinder head, the cylinder head including at least one spark plug well configured to open outward to a combustion chamber of a cylinder, the arrangement further comprising:

[0008] - At least one spark plug disposed in the well and including an electrically insulating body and a conductive base, the conductive base defining an internal volume of the spark plug, the base including at least one orifice opening outward to the internal volume and at least one orifice configured to provide a fluid connection between the internal volume and the combustion chamber;

[0009] - A cooling airflow supply circuit, which is arranged to be fluidly connected to the internal volume of the spark plug through the at least one orifice, so as to allow cooling airflow to the internal volume and to contact the spark plug;

[0010] - A pump configured to drive a cooling airflow into the internal volume via at least one supply circuit and orifice;

[0011] - At least one regulating device for cooling airflow is arranged in the channel of cooling airflow in the supply circuit to regulate the flow of the airflow through the internal volume.

[0012] For example, one of the regulating mechanisms for this airflow is a check valve, which includes at least one ball and a spring.

[0013] Specifically, the arrangement further includes: an intake circuit equipped with an intake valve; and an exhaust circuit equipped with an exhaust valve, wherein the at least one supply circuit is fluidly connected to the intake circuit such that cooling airflow is obtained from the intake airflow circulating in the intake circuit.

[0014] For example, the cooling airflow supply circuit includes: a supply manifold arranged upstream of the regulating device in the flow direction of the cooling airflow; and at least one channel arranged downstream of the regulating device.

[0015] According to an exemplary embodiment, the cylinder head includes a plurality of spark plug wells, each spark plug well being equipped with a spark plug, and the power circuit includes:

[0016] - Multiple manifolds, each configured to be fluidly connected to the internal volume of a spark plug arranged in a spark plug well; or

[0017] - A single manifold configured to connect to the internal volumetric fluid characteristic of spark plugs arranged in multiple spark plug wells.

[0018] Specifically, the cooling airflow supply circuit includes at least one intermediate cavity arranged in the cylinder head to receive at least a portion of a spark plug, the intermediate cavity accommodating a portion of the spark plug including at least one orifice.

[0019] According to one exemplary embodiment, the cylinder head includes: an opening configured to open outward to a combustion chamber; a first cavity defining at least a portion of a spark plug well for receiving a spark plug; and a second cavity for receiving an adjustment device, the first cavity and the second cavity being in fluid communication with the opening. Alternatively, the cylinder head includes an opening configured to open outward to a combustion chamber, with the spark plug and adjustment device arranged in a common cavity, different cavities, or multiple cavities.

[0020] Specifically, the spark plug includes threads arranged on at least a portion of the height of a base defined along a first direction of the spark plug, and at least one hole arranged at the level of the threads, or at least one hole arranged in a portion of the base between the threads and an end of the spark plug including the at least one hole.

[0021] Furthermore, the arrangement may include: at least one cylinder defining a combustion chamber; and a movable piston disposed in the at least one cylinder, with a cylinder head associated with the cylinder to form a spark-ignition engine, wherein at least one hole of the spark plug opens outward to the combustion chamber.

[0022] Optionally, the arrangement includes a pump control device and at least one pressure sensor, the control device being configured to regulate the pressure of the cooling airflow in the supply circuit.

[0023] The present invention also relates to a spark plug for use in an arrangement according to the present invention, comprising: an electrically insulating body and a conductive base, the conductive base defining an internal volume of the spark plug, the spark plug comprising:

[0024] - At least one orifice enabling cooling airflow from the internal volume to the combustion chamber of the cylinder, the at least one orifice being disposed on an end wall of the base, the end wall being configured to face the combustion chamber; and

[0025] - At least one hole is disposed on the side wall of the base, the side wall being connected to the end wall, the at least one hole opening outward to the internal volume and being configured to provide a fluid connection between the cooling fluid supply circuit and the internal volume.

[0026] Finally, the present invention relates to an operating mode for an arrangement according to the present invention, comprising:

[0027] - Intake timing, including the injection of intake airflow toward the cylinder and the injection of cooling airflow drawn from the intake airflow, the cooling airflow being propelled by a pump through at least one supply circuit and the internal volume of the spark plug to achieve heat exchange with at least a portion of the spark plug, the cooling airflow being discharged toward the combustion chamber through at least one orifice of the spark plug; then

[0028] - Compression time, including injecting fuel streams toward the cylinder to form an air-fuel mixture, increasing pressure in the cylinder, and then igniting the air-fuel mixture in the combustion chamber; then

[0029] - Expansion time, which includes the ignition of the air-fuel mixture in the cylinder; then

[0030] - Exhaust timing, including the rising piston.

[0031] Referring to the various exemplary embodiments shown in the following figures, any further details, features, and advantages will become apparent from the detailed description given below, which is illustrative and non-limiting:

[0032] Figure 1 This is a schematic diagram of an embodiment of a vehicle equipped with an arrangement according to the invention and a spark-ignition engine including a cylinder head equipped with spark plugs.

[0033] Figure 2 It is a schematic diagram including the arrangement of the cylinder head equipped with spark plugs.

[0034] Figure 3 This is a schematic diagram of the engine operating modes during the intake time.

[0035] Figure 4 This is a schematic diagram of the engine operating mode in the arrangement during the exhaust time.

[0036] Figure 1 An exemplary embodiment of a motor vehicle 1 according to the invention is illustrated schematically. Specifically, the motor vehicle 1 is equipped with a spark-ignition engine 2 according to the invention. The spark-ignition engine 2 is a heat engine, particularly a hydrogen engine, i.e., a combustion engine using dihydrogen as fuel. The vehicle 1 can be of any type, for example, a passenger car, commercial vehicle, truck, or bus. In particular, the vehicle 1 under consideration can be a connected and / or autonomous vehicle.

[0037] A conventional spark-ignition engine 2 is equipped with a cylinder head 3 and at least one cylinder 21, in which a moving piston 22 is positioned. The at least one cylinder 21 defines a combustion chamber 23, in which the piston 22 moves and introduces air and fuel (particularly hydrogen) into the combustion chamber 23, thereby forming an air-fuel mixture, also known as a fuel mixture. In the example shown, in a non-limiting manner, the spark-ignition engine 2 includes four cylinders 21 in series.

[0038] The vehicle specifically includes an arrangement 10 containing a cylinder head 3 of an engine 2, the cylinder head 3 including at least one spark plug well 30. Specifically, the cylinder head 3 includes a plurality of walls, all or part of which define the at least one spark plug well 30. The cylinder head 3 also includes at least one spark plug 4, which is at least partially disposed in the at least one spark plug well 30. The arrangement 10 also includes at least one circuit 5 for supplying a cooling airflow FR, the at least one circuit 5 being configured to allow circulation of the cooling airflow FR capable of capturing calories from the spark plug 4, thereby allowing the spark plug 4 to be cooled. The arrangement 10 also includes: a pump 6 configured to push the cooling airflow FR to the spark plug 4 via the supply circuit 5; and at least one device 7 for regulating the circulation of the airflow.

[0039] Optionally, vehicle 1, particularly arrangement 10, also includes an intake circuit 31 and an exhaust circuit 33, both arranged in fluid connection with cylinder 21 of engine 2. Throughout the following description, the terms "upstream" and "downstream" refer to the circulation direction of the airflow under consideration, as shown by arrows in the figures.

[0040] Optionally but preferably, the intake circuit 31, particularly in the direction of the intake airflow FA, sequentially includes: an air filter 31a; a flow meter 31b capable of measuring the mass flow rate of air entering the engine 2; a turbocharger compressor 31c capable of compressing the intake airflow FA; and an intake manifold 31d, also known as a distributor. Specifically, the intake manifold 31d is equipped with at least one pressure sensor 31e, also known as an intake pressure sensor 31e, configured to measure the pressure of air entering one or more cylinders 21 of the engine 2. This intake pressure sensor 31e is typically housed within the intake manifold 31d. According to an exemplary embodiment, the intake manifold 31d includes a plenum and a plurality of intake ducts, each serving one of the cylinders 21 of the engine 2.

[0041] Alternatively, the intake circuit 31 may include at least one intake valve or throttle valve housing (not shown) arranged downstream of the compressor 31c and enabling regulation of the flow rate of the intake airflow FA entering the engine 2.

[0042] Optionally, the exhaust circuit 33 includes, depending on the circulation direction of the exhaust gas flow leaving the cylinder: an exhaust manifold 33a; a turbine 33b of the turbocharger 31c (e.g., mounted on a shaft shared with the compressor 31c); and at least one pollution control device 33c.

[0043] As shown in the figure, according to an exemplary embodiment, the intake circuit 31 includes an intake pipe 31f disposed in the material of the cylinder head 3, equipped with an intake valve 32, and configured to be connected to either an intake duct or an intake conduit connected to the intake circuit 31. Similarly, the exhaust circuit 33 may include an exhaust pipe 33d disposed in the material of the cylinder head 3, equipped with an exhaust valve 34, and configured to be connected to either an exhaust duct or an exhaust conduit connected to the exhaust circuit 33. The cylinder head 3 is mounted in the engine 2 to participate, on the one hand, in realizing the fluid connection between the intake circuit 31 and the exhaust circuit 33, and on the other hand, in realizing the combustion chamber 23 of one or more cylinders 21. The intake valve 32 and the exhaust valve 34 are conventionally mounted as movable and designed to facilitate or impede the fluid connection between the pipe in which each valve is mounted and the combustion chamber 23.

[0044] It is understood that the following description is made with reference to the cylinder 21 of the engine 2 under consideration and a portion of the cylinder head 3 associated with arrangement 10. However, this description extends to a spark-ignition engine 2 having multiple cylinders 21, each cylinder 21 equipped with a piston 22, or the cylinder head 3 having multiple shafts 30, spark plugs 4 or other intake valves 32 and exhaust valves 34, as further explained below.

[0045] At least one spark plug well 30 is adapted to accommodate all or part of at least one spark plug 4. The first end of the well 30 includes an opening 35, which is designed to lead to the combustion chamber 23 of the associated cylinder 21 when the engine 2 is assembled.

[0046] Spark plug 4 is of the standard type. Here, "standard" means that spark plug 4 does not have a built-in ignition pre-combustion chamber capable of generating a spark; instead, the spark plug 4 of the present invention is capable of directly generating a spark at the level of the combustion chamber 23 of the engine 2, as further explained below. A conventional spark plug 4 has at least one electrically insulating body 41 and a conductive base 42, which together define the internal volume 400 of the spark plug. The electrically insulating body 41 is made of an electrically insulating material (e.g., ceramic, particularly alumina-based ceramic). The base 42 is made of a conductive material (particularly metal). For example, spark plug 4 extends along a first direction 100.

[0047] The spark plug 4 includes at least one wall, particularly the wall of the base 42. For example, the spark plug 4 includes one or more sidewalls 43 connected to the end wall 44 and facing the combustion chamber 23. According to a non-limiting exemplary embodiment, the spark plug 4 includes a cylindrical shape or part of a cylindrical shape. In this case, and in a non-limiting manner, the base 42 includes a single sidewall 43 and an end wall 44, which are inscribed in a cylindrical or substantially cylindrical shape.

[0048] The spark plug 4 includes at least one orifice 45 that provides fluid connection between the internal volume 400 of the spark plug 4 and the combustion chamber 23 of the cylinder 21. Specifically, the at least one orifice 45 allows a cooling airflow FR to pass from the internal volume 400 to the combustion chamber 23 of the cylinder 21, as further described below with reference to the method according to the invention. In this case, the at least one orifice 45 is arranged in the end wall 44.

[0049] The spark plug 4 also includes at least one orifice 46 that opens outward to the internal volume 400 and is configured to provide a fluid connection between the cooling fluid supply circuit 5 and the internal volume 400. The term "opening outwards" means that at least one orifice 46 directly penetrates one wall of the spark plug 4. For example, the at least one orifice 46 is disposed in one or more sidewalls of the spark plug 4, particularly in the sidewall of the base 42. The at least one orifice 46 allows the cooling airflow FR to pass from the supply circuit 5 into the internal volume 400 so that the cooling airflow FR contacts the interior of the spark plug 4 before it is discharged into the combustion chamber 23 via the orifice 45.

[0050] according to Figures 2 to 4 In the specific exemplary embodiment shown, the spark plug 4 includes a thread 47 disposed on at least a portion of the height of the base 42 defined along a first direction 100. The thread 47 is formed at a level on the outer surface of the spark plug 4 (particularly the base 42) (particularly the outer surface of one of the sidewalls 43 or a plurality of sidewalls of the spark plug 4), facing the wall of the cylinder head 3. Figure 2 In the exemplary embodiment shown, the at least one hole 46 is disposed in a portion of a base 42, which is located along a first direction 100 between the thread 47 and the end of the spark plug 4 that includes at least one hole 45 (here, the end wall 44). Alternatively, the at least one hole 46 is disposed at the level of the thread 47.

[0051] As is known, a spark plug 4 includes at least one center electrode 48 and at least one ground electrode 49. The at least one center electrode 48 and the at least one ground electrode 49 are separated from each other by an inter-electrode gap, the gap separating the two non-contacting electrodes intended to serve as a seat for the spark between the electrodes. It is understood that the spark plug 4 may have multiple center electrodes 48 and / or ground electrodes 49. The at least one center electrode 48 extends into the internal volume 400 of the spark plug 4, while the at least one ground electrode 49 is included and arranged in a base 42 to participate in defining the internal volume 400. For example, the at least one ground electrode 49 is included in an end wall 44. Furthermore, the various electrodes are shaped and arranged so as not to form protrusions or projections from the rest of the spark plug 4 (particularly from the wall of the spark plug 4). This principle advantageously allows for limiting or even preventing the formation of hot spots at the electrodes. In particular, the end wall 44 of the spark plug and at least one center electrode 49 are inlaid on a planar or substantially planar surface, which is arranged to be continuous with the inner surface of the cylinder head and facing the combustion chamber 23.

[0052] Alternatively, vehicle 1 is equipped with a spark ignition system (not shown), including a spark control unit and a high-voltage circuit designed to supply electrical energy to one or more center electrodes 48 of spark plug 4.

[0053] Advantageously, arrangement 10 includes at least one sealing device 36 arranged at the interface between spark plug 4 and cylinder head 3, for example positioned around spark plug 4. This sealing device 36 advantageously enables the restriction of the circulation of cooling airflow FR in spark plug well 30.

[0054] As shown above, the cooling airflow FR supply circuit 5 is configured to supply cooling airflow FR to the spark plug 4 to cool it. Therefore, "cooling airflow FR" is understood to refer to an airflow capable of capturing at least a portion of the calories accumulated by the spark plug 4 during previous combustion. The circuit is at least partially included in the cylinder head 3 (e.g., in at least one wall of the cylinder head 3). The supply circuit 5 is arranged to be fluidly connected to the internal volume 400 of the spark plug 4 via at least one orifice 46 to allow the cooling airflow FR to flow into and enter the internal volume 400. The cooling airflow FR then circulates in contact with at least a portion of the base 42 of the spark plug 4, allowing the latter to be cooled. Furthermore, the cooling airflow circulates within the internal volume 400 and flows towards the combustion chamber 23 to capture calories from at least one center electrode 48 and at least one ground electrode 49. Thus, the cooling airflow prevents the formation of hot spots at the base 42 and various electrodes by lowering their temperature, particularly before combustion.

[0055] according to Figure 1In the preferred exemplary embodiment shown, the supply circuit 5 of the cooling airflow FR is connected via a fluid connection to the intake circuit 31 at the bifurcation point 51, thereby removing the cooling airflow FR from the intake airflow FA circulating in the intake circuit 31. Therefore, at the bifurcation point 51, a portion of the intake airflow FA is removed and separated so that, on the one hand, the cooling airflow FR is guided to the supply circuit 5 and to the internal volume 400 of the spark plug 4 before returning to the combustion chamber 23; and on the other hand, the remaining intake airflow FAr is sent to the combustion chamber 23 of the cylinder 21 for combustion without passing through the internal volume 400 of the spark plug 4.

[0056] Preferably, the supply circuit 5 is connected to the intake duct 31 downstream of the filter 31a and flow meter 31b according to the flow direction of the intake airflow FA. In other words, the bifurcation point 51 is arranged downstream of the filter 31a and flow meter 31b. In this way, the air extracted to form the cooling airflow FR is free of particles (i.e., clean) and is taken into account when calculating the flow rate of fresh air reaching the combustion chamber 23, which is typically determined by the engine control software 2. The total amount of air drawn into the cylinder 21 thus corresponds to the airflow rate measured by the flow meter, which corresponds to the sum of the flow rate of the cooling airflow FR and the flow rate of the remaining intake airflow FAr.

[0057] According to the exemplary embodiment shown (which is more easily implemented), the supply circuit 5 is connected to the intake circuit 31 at a bifurcation point 51, which is arranged upstream of the compressor 31c according to the flow direction of the intake airflow. Alternatively, the supply circuit 5 is connected to the intake circuit 31 at a bifurcation point 51, which is arranged downstream of the compressor 31c according to the flow direction of the intake airflow. This principle is more complex to implement due to the presence of a large amount of gas downstream of the compressor 31c, but it advantageously allows for the sampling of the compressed cooling airflow FR, thereby reducing the force required by the pump 6.

[0058] Figures 1 to 4An exemplary embodiment is shown, in which a power supply circuit 5 typically includes at least one power supply manifold 52 and at least one channel 53. A regulating device 7 is arranged over the channel of the cooling airflow FR in the supply circuit 5, corresponding to the trajectory of the cooling airflow FR. Specifically, the at least one manifold 52 is arranged upstream of the regulating device 7 in the circulation direction of the cooling airflow FR, while the at least one channel 53 is arranged downstream of the regulating device 7, particularly extending between the at least one regulating device 7 and at least one orifice 46. The at least one manifold 52 and the at least one channel 53 are configured to be fluidly connected to each other, thus opening at their different ends. Therefore, a first portion 5a of the supply circuit 5 arranged upstream of the regulating device 7 (particularly between the bifurcation point 51 and the regulating device 7) and a second portion 5b of the supply circuit 5 arranged downstream of the regulating device 7 (e.g., between the regulating device 7 and at least one orifice 46 of the spark plug 4) can be distinguished.

[0059] The at least one manifold 52 is machined at least partially at the level of at least one wall of the cylinder head 3 in the material of the cylinder head 3. Furthermore, for example, a portion of the manifold 52 may be formed by at least one pipe connecting the bifurcation point 51 to one wall of the cylinder head 3. Similarly, the at least one channel 53 is machined in the material of the cylinder head 3. The arrangement 10 preferably includes at least as many channels 53 as the number of spark plugs 4 and / or cylinders 21, each of which is configured to be in fluid communication with an internal volume 400 specific to one of the spark plugs 4 of the cylinder head 3, and indirectly in fluid communication with a combustion chamber 23 of one of the cylinders 21 of the engine 2.

[0060] Figure 1 A preferred exemplary embodiment of a cylinder head 3 is schematically illustrated. The cylinder head 3 is equipped with a plurality of spark plugs 4 and a regulating device 47 associated with a supply circuit 5 including a single manifold 52 configured to deliver a cooling airflow FR to the different spark plugs 4. The single manifold 52 is associated with a plurality of channels, each channel directing a portion of the cooling airflow FR to one of the spark plugs 4. The supply circuit 5 is then advantageously connected via a single branch point 51. Each regulating device may be arranged within or upstream of one of the channels 53, for example, arranged in or between the manifold 52 and the channel 53 as described above.

[0061] According to an alternative embodiment not shown, the supply circuit 5 includes a plurality of manifolds 52 and channels 53, each manifold 52 being configured to supply cooling airflow FR to at least one in the channel 53 and one of the spark plugs 4. The arrangement 10 then includes a plurality of branch points 51, which are connected in particular to the intake circuit 31.

[0062] Optionally, the supply circuit 5 for the cooling airflow FR includes at least one intermediate cavity 50 disposed in at least one wall of the cylinder head 3 to surround and / or receive at least a portion of the spark plug 4. Specifically, the intermediate cavity 50 is formed in the cylinder head 3 as a recess around the spark plug 4 along its entire circumference of the outer surface of the spark plug 4. The intermediate cavity 50 is machined in the cylinder head 3 and defines a cylindrical shape that allows the circulation of the cooling airflow FR to contact a portion of the base of the spark plug 4. This principle advantageously allows cooling of a portion of the outer surface of the spark plug 4. The intermediate cavity 50 receives a portion of the spark plug 4 (particularly the base 42), which includes the at least one hole 46 to ensure fluid connection between the remainder of the supply circuit 5 and the at least one hole 46. Optionally, the spark plug 4 (particularly the base 42) includes a plurality of holes 46 distributed around the circumference of the spark plug, and the intermediate cavity 50 is shaped and sized to receive the portion of the spark plug 4 that receives the holes. In this way, the cooling airflow FR enters the internal volume 400 through the various holes 46, and the intermediate cavity 50 allows the cooling airflow FR to be distributed in the various holes 46.

[0063] As shown above, pump 6 is configured to acquire a portion of the intake airflow FA to form a cooling airflow FR. Pump 6 also allows the cooling airflow FR to be pushed toward the internal volume 400 of spark plug 4 via supply circuit 5 and at least one orifice 46. In particular, pump 6 is an electric pump 6. Pump 6 advantageously allows the cooling airflow FR to circulate at a desired, defined pressure, particularly at a pressure higher than the prevailing pressure in combustion chamber 23 of engine 2, specifically corresponding to the prevailing pressure in exhaust manifold 33a during the intake time when intake valve 32 of engine 2 is open, and particularly the pressure measured by intake pressure sensor 31e.

[0064] It should also be noted that during the intake time, when the intake valve 32 (or multiple intake valves 32) of engine 2 is open, the pressure in cylinder 21 (more precisely, the pressure in combustion chamber 23) can be considered to be substantially equal to the boost pressure measured by the supply pressure sensor 31e, and the load loss between the pressure measurement point and combustion chamber 23 can be ignored.

[0065] Optionally, but preferably, vehicle 1 and / or arrangement 10 include a control device 61 for pump 6 and at least one pressure sensor 54 for cooling airflow FR. The control device 61 is configured to control the operation of pump 6 to adjust the pressure of cooling airflow FR as needed based on pressure measured at at least one point in cylinder head 3 and / or intake circuit 31. For example, as... Figure 1As shown, vehicle 1 includes: an intake pressure sensor 31e, which is capable of measuring the pressure of the remaining intake airflow FAr in the intake duct, for example, the intake pressure sensor 31e is arranged at the intake manifold 31d; and / or a pressure sensor 54, which is arranged at the level of the supply circuit 5 and is configured to measure the pressure of the cooling airflow FR.

[0066] The regulating device 7 is configured to regulate the circulation of the cooling airflow FR through the supply circuit 5 and toward the internal volume 400 of the spark plug 4. The term "regulation" is understood to mean the possibility of allowing or interrupting the circulation of the cooling airflow in at least a portion of the supply circuit 5 and through the spark plug 4. Therefore, this regulation also involves allowing or interrupting the fluid connection between at least a portion of the supply circuit 5 and the internal volume 400 of the spark plug 4. In particular, the regulating device 7 is passive. "Passive" control means that the regulating device 7 itself is not directly actuated in a motorized manner, or that it does not require an energy supply (e.g., an electrical supply).

[0067] According to an exemplary preferred embodiment, one or more adjusting mechanisms 7 are check valves comprising at least one ball 71 and a spring 72. The spring 72 is particularly arranged to rest on an intermediate surface, enabling retention of the spring 72. Optionally, the adjusting device 7 further includes a device 74 for retaining the ball 71. The retaining device 74 includes a tubing continuously arranged with respect to a channel or trajectory in the cooling airflow FR to allow circulation of the airflow. The retaining device 74 also includes a recess arranged relative to the tubing and configured to receive the ball 71.

[0068] When the pressure in the supply circuit 5, particularly the pressure in the first portion 5a of the supply circuit 5, is greater than the general pressure in the combustion chamber 23 of the engine 2 (i.e., the general intake pressure in the intake manifold 31d as described above), the regulating device 7 allows the cooling airflow FR to flow to the internal volume 400 of the spark plug 4. Furthermore, when the pressure in the internal volume 400 and / or the combustion chamber 23 is greater than the pressure in the supply circuit 5 (particularly the first portion 5a of the supply circuit 5 located upstream of the regulating device 7), the regulating device 7 prevents the air-fuel mixture from circulating backwards from the internal volume 400 to the entire supply circuit 5.

[0069] More specifically, the ball 71 is configured to move between a "closed" configuration and an "open" configuration. In the "closed" configuration, the spring 72 is in its nominal position, and the ball 71 is arranged to support the spring 72, specifically extending into the recess of the retaining device 74. As a result, the ball 71 here blocks the cooling airflow FR from flowing through the tube of the retaining device 74 and through the latter, thus preventing the cooling airflow FR from flowing into the internal volume 400 of the spark plug 4. In the "open" configuration, the cooling airflow FR is forced into the supply circuit 5 with sufficient pressure to move the ball 71, thereby removing it from the recess of the retaining device 74. The ball 71 then exerts a force on the spring 72 and compresses the spring 72. The movement of the ball 71 then allows the cooling airflow FR to pass through the retaining device 74 toward the internal volume 400, in which the cooling airflow FR captures heat from a portion of the base 42 and the different electrodes, thus allowing them to cool. The airflow is then discharged into the combustion chamber 23 through at least one orifice 45.

[0070] Additionally, ball bearing 71 prevents the air-fuel mixture from entering the entire supply circuit 5, particularly from rising to the first section 5a of the supply circuit 5. This configuration can be observed when no cooling airflow FR is projected into the supply circuit 5 or when the pressure of the cooling airflow FR is insufficient to allow the activation of the regulating device 7 (in this case, the displacement of ball bearing 71).

[0071] For example, spring 72 is pre-calibrated to activate regulator 7 from a predetermined pressure threshold of cooling airflow FR during the intake time of engine cycle 2, and / or from a predetermined pressure difference threshold between the pressure of cooling airflow FR and the pressure in the second part of combustion chamber 23 and / or intake circuit 5b.

[0072] For example, at least one regulating device 7 is arranged in a support 75 that defines an intermediate channel within the supply circuit 5. Specifically, the support 75 is a component arranged in the cylinder head 3 via a ring, which is made of a metal material such as steel and is capable of withstanding temperatures exceeding 600°C. Therefore, the support 75 carries the regulating device 7 and includes slits to ensure the circulation of the cooling airflow FR (particularly its inlet and outlet within the support 75). Specifically and in a non-limiting manner, a first slit is arranged upstream of the regulating device 7 and configured to ensure fluid connection with a first portion 5a of the supply circuit 5, here formed particularly by a manifold 52, while a second slit is arranged downstream of the regulating device 7 and configured to ensure fluid connection with a second portion 5b of the supply circuit 5, here formed by a channel or one of a plurality of channels 53.

[0073] Optionally, but preferably, the cylinder head 3 includes a first cavity 301 and a second cavity 302, both fluidly connected to an opening 35 configured to open outward to the combustion chamber 23. The first cavity 301 forms a spark plug well 30 for receiving a spark plug 4, while the second cavity 302 receives an adjustment device 7, specifically an assembly formed by a support member 75 and the adjustment device 7. For example, the first cavity 301 and the second cavity extend along a first direction 100, parallel or substantially parallel to each other. In particular, the first cavity 301 and the second cavity 302 are adjacent to each other and separated by at least one intermediate wall of the cylinder head 3.

[0074] The present invention also relates to an operating mode including an arrangement 10 of an engine 2 with spark ignition according to the present invention. This process is carried out during engine cycle 2, which typically includes intake time, compression time, expansion time, and exhaust time.

[0075] like Figure 3 As shown, during the intake time, in a conventional manner, the intake valve 32 opens, the piston descends to the bottom dead center, and the intake airflow FA circulates in the intake circuit 31 along the direction of the combustion chamber 23.

[0076] The method then includes the circulation of a cooling airflow FR parallel to the intake airflow FA in the supply circuit 5. The cooling airflow FR is propelled by pump 6 through the supply circuit 5 to the internal volume 400 of the spark plug 4. Contacting the spark plug 4 (particularly the base 42 and various electrodes), the cooling airflow FR captures heat from the heated spark plug 4 and allows the spark plug 4 to cool before initiating new combustion. The heated cooling airflow FR is then discharged into the combustion chamber through at least one orifice 51.

[0077] As shown above, according to a preferred embodiment, the cooling airflow FR is drawn from the intake airflow FA, particularly from the intake circuit 31 upstream or downstream of the compressor 31c. The cooling airflow FR is then a portion of the intake airflow FA drawn by the pump 6 and diverted from its normal trajectory (i.e., from the intake circuit 31), redirected via the supply circuit 5 to the internal volume 400 of the spark plug 4, while the remaining intake airflow FAr continues in the intake circuit 31 to the combustion chamber 23. Advantageously, drawing a portion of the intake airflow FA allows the spark plug to be cooled without requiring a built-in air reservoir in the cylinder head 3.

[0078] The cooling airflow FR is propelled under pressure by an electric pump 6 controlled by a control device 71. The pressure of the cooling airflow FR is specifically regulated to allow actuation of at least one regulating device 6. Specifically, the pressure of the cooling airflow FR, measured in the supply circuit 5, is strictly higher than the pressure measured in the combustion chamber 23, which is measured during the intake time by an intake pressure sensor 31e housed in the intake manifold 31d, to allow at least one regulating device 7 to be activated. As previously described, due to this pressure difference, the ball 71 is moved and applies force to the spring 72. The ball 71 frees the passage of the cooling airflow FR by moving out of the recess and releasing the tube of the retaining device 74, thereby allowing the cooling airflow to circulate toward the internal volume 400 of the spark plug 4. Furthermore, at least one regulating device 7 advantageously prevents the backflow of the cooling airflow.

[0079] Optionally, but preferably, the pressure of the cooling airflow FR can be regulated by the control device 71 of pump 6 based on the measured pressure of the remaining intake airflow FAr, particularly based on the mainstream pressure in the intake manifold 31d measured by the intake pressure sensor 31e. It should be noted that when the intake valve 32 opens and the piston 22 descends, the pressure in cylinder 21 and combustion chamber 23 tends to approach the pressure measured in the intake circuit 31. The pressure of the intake airflow FA varies depending on the engine's operating mode. This also applies to the pressure of the remaining intake airflow.

[0080] Specifically, at low loads, the residual intake airflow pressure FAr (e.g., measured at the level of intake manifold 31d) is significantly lower than atmospheric pressure. The pressure of the cooling airflow FR circulating in the supply circuit can then be lower, as long as it remains strictly higher than the pressure of the residual intake airflow or the pressure of combustion chamber 23. Because fuel combustion temperatures are lower at low loads, spark plug 4 will be less heated and less likely to generate hot spots. The flow rate of cooling airflow FR can therefore be lower than under boost conditions, while ensuring proper cooling of spark plug 4.

[0081] Conversely, when engine 2 is boosted, i.e., operating under high load, the pressure of the intake airflow FA, especially the residual intake airflow FAr, is much higher than atmospheric pressure. Therefore, it is necessary to push the cooling airflow FR to a higher pressure than that implemented under low load conditions. Furthermore, since combustion temperatures are often higher than under low load conditions, the flow rate of the cooling airflow FR must be higher to prevent hot spots from forming at spark plug 4.

[0082] As is well known, engine cycle 2 continues with compression time. Intake valve 32 and exhaust valve 34 are closed. Fuel injection (especially dihydrogen in this case) begins. Atomized fuel mixes with the moving intake airflow FA to form a fuel-air mixture in combustion chamber 23.

[0083] It will be noted that in the case of hydrogen, fuel is injected during the compression time, with valves 32 and 34 closed, instead of being injected during the intake time as is the case with conventional fuels such as gasoline, to prevent the fuel mixture from flowing back into the intake manifold 31d. In fact, hydrogen has a very wide flammability limit, and its hot spots are sufficient to ignite the mixture in the intake circuit 31. An explosion resulting from this could damage the circuit.

[0084] The fuel mixture is homogenized by turbulence in the combustion chamber 23 of cylinder 21. Piston 22 rises towards top dead center in cylinder 21, thereby increasing the pressure in combustion chamber 23. The regulating device 7 is in a "closed" configuration, and the circulation of the cooling airflow FR is interrupted in the internal volume 400. The fluid connection between the internal volume 400 and the entire supply circuit is thus interrupted. Specifically, the fluid connection between the first portion 5a of the supply circuit 5 and the internal volume 400 is interrupted.

[0085] It should be noted that the cooling airflow FR can be maintained during the compression time and by extending it for the remainder of engine cycle 2; in other words, the cooling airflow FR is uninterrupted and permanent. On the other hand, the pressure of the airflow is modified by pump 6 as a function of the intake pressure, keeping the regulating device 7 closed. Pump 6 is then active for the entire duration of engine cycle 2. Specifically, the intake pressure, and by extending the pressure in cylinder 21, is then strictly greater than the pressure of the cooling airflow FR. Once the mainstream pressure in cylinder 21 is strictly greater than the pressure measured in the first part 5a of the supply circuit 5, particularly the pressure measured in manifold 52, the regulating device 7 (e.g., a check valve) immediately closes.

[0086] Near the end of the compression time, the spark ignition system triggers a spark at spark plug 4, which causes the compressed fuel mixture to burn in combustion chamber 23. It should be noted that, due to the structure of the spark plug 4 according to the invention, there is no pre-combustion chamber; therefore, ignition at the level of combustion chamber 23 occurs essentially outside of spark plug 4 and internal volume 400.

[0087] Then, during the expansion time of engine cycle 2, the front of the flame propagates into combustion chamber 23. Intake valve 32 and exhaust valve 34 subsequently close. The piston moves to down dead center, and, due to the prevailing high pressure in combustion chamber 23, regulating device 7 closes, preventing any circulation between the combustion chamber and the entire supply circuit, and vice versa.

[0088] Finally, Figure 4During the exhaust time shown, exhaust valve 34 opens. Piston 22 moves upward, expelling residual combustion gases remaining in combustion chamber 23 into exhaust circuit 33. The pressure in combustion chamber 23 decreases, but remains significantly higher than the pressure in supply circuit 5, particularly the pressure in the first section 5a of supply circuit 5, causing regulating device 7 to remain in the "closed" configuration as shown above, and the fluid connection between the internal volume 400 of spark plug 4 and the entire supply circuit 5 remains interrupted.

[0089] Therefore, the arrangement and method according to the invention enable the solution of one of the problems faced by internal combustion engines supplied with dihydrogen, namely, the high temperature that the spark plug may experience due to the high combustion temperature, which can generate hot spots at the spark plug.

[0090] This invention advantageously enables the cooling of spark plugs, particularly before each combustion, thereby ensuring their reliability and durability over time and preventing them from becoming hot spots that could lead to pre-ignition of the air-fuel mixture. The circulation of cooling airflow in direct contact with the spark plugs allows for optimized cooling, and the integration of this cooling in the cylinder head and engine overcomes the need to integrate specific cooling fluids and any associated reservoirs, thus limiting the required space and associated costs.

[0091] However, the present invention is not limited to the methods and configurations described and illustrated herein, and it extends to any equivalent methods or configurations, and any technically effective combinations of such methods, provided that they ultimately achieve the functions described and illustrated herein.

Claims

1. An arrangement (10) for a spark-ignition engine (2) including a cylinder head (3), the cylinder head (3) including at least one spark plug well (30) configured to open outward to a combustion chamber (23) of a cylinder (21), the arrangement (10) further comprising: - At least one spark plug (4) disposed in the well (30) and including an electrically insulating body (41) and a conductive base (42) defining an internal volume (400) of the spark plug, the base (42) including at least one hole (46) opening outward to the internal volume (400) and at least one hole (45) configured to provide a fluid connection between the internal volume (400) and the combustion chamber (23); - Cooling airflow (FR) supply circuit (5), which is arranged to be fluidly connected to the internal volume (400) of the spark plug (4) through the at least one hole (46) so as to allow the cooling airflow (FR) to flow into the internal volume (400) and contact the spark plug (4); - Pump (6), configured to push the cooling airflow (FR) into the internal volume (400) via at least one supply circuit (5) and at least one orifice (46). - At least one device (7) for regulating the circulation of the cooling airflow (FR), which is arranged in the channel of the cooling airflow (FR) in the supply circuit (5) to regulate the circulation of the airflow through the internal volume (400).

2. The arrangement (10) according to the preceding claim further includes: An intake circuit (31) equipped with an intake valve (32); and an exhaust circuit (33) equipped with an exhaust valve (34), wherein at least one supply circuit (5) is connected to the intake circuit (31) by a fluid connection so that a cooling airflow (FR) is obtained from the intake airflow (FA) circulating in the intake circuit (31).

3. The arrangement (10) according to any one of the preceding claims, wherein, The cylinder head (3) includes a plurality of spark plug wells (30), each spark plug well (30) being equipped with a spark plug (4), and the power circuit (5) includes: - Multiple manifolds (52), each manifold (52) configured to be fluidly connected to the internal volume (400) of one of the spark plugs (4) arranged in one of the spark plug wells (30); or - A single manifold (52) configured to be fluidly connected to the internal volume (400) of the spark plug (4) arranged in the plurality of spark plug wells (30).

4. The arrangement (10) according to any one of the preceding claims, wherein, The cooling airflow (FR) supply circuit (5) includes at least one intermediate cavity (50) disposed in the cylinder head (3) to receive at least a portion of the spark plug (4), the intermediate cavity (50) including a portion of the spark plug (4) including the at least one hole (46).

5. The arrangement (10) according to any one of the preceding claims, wherein, The cylinder head (3) includes: an opening (35) configured to lead to the combustion chamber (23); a first cavity (301) defining at least a portion of the spark plug well (30) that accommodates the spark plug (4); and a second cavity (302) that accommodates an adjustment device (7), the first cavity (301) and the second cavity (302) being in fluid connection with the opening (35).

6. The arrangement (10) according to any one of the preceding claims, wherein, The spark plug (4) includes a thread (47) arranged on at least a portion of the height of the base (42) defined along a first direction (100) of the spark plug (4), and the at least one hole (46) is arranged at the level of the thread (47), or the at least one hole (46) is arranged in a portion of the base (42), the portion of the base (42) being located between the thread (47) and an end of the spark plug (4) including the at least one hole (45).

7. The arrangement (10) according to any one of the preceding claims comprises: At least one cylinder (21) that defines a combustion chamber (23); And a movable piston (22) arranged in the at least one cylinder (21), the cylinder head (3) associated with the cylinder to form a spark-ignition engine (2), the at least one hole (45) of the spark plug (4) opening outward to the combustion chamber (23).

8. The arrangement (10) according to the preceding claim includes a control device (61) for the pump (6) and at least one pressure sensor (31e), the control device (61) being configured to regulate the pressure of the cooling airflow (FR) in the supply circuit (5).

9. A spark plug (4) for an arrangement (10) according to any one of the preceding claims, comprising an electrically insulating body (41) and a conductive base (42), the conductive base (42) defining an internal volume (400) of the spark plug, the spark plug (4) comprising: - At least one hole (45) that allows cooling airflow (FR) to flow from the internal volume (400) to the combustion chamber (23) of the cylinder (21), the at least one hole (45) being disposed on the end wall (44) of the base (42), the end wall (44) being configured to face the combustion chamber (23). as well as - At least one hole (46) is arranged on the side wall (43) of the base (42), the side wall (43) being connected to the end wall (44), the at least one hole (46) opening outward to the internal volume (400) and being configured to provide a fluid connection between the cooling fluid supply circuit (5) and the internal volume (400).

10. A method of operation for the arrangement according to claim 7 or 8, comprising: -Intake timing, which includes injecting intake airflow (FA) and cooling airflow (FR) toward the cylinder (21), the cooling airflow (FR) being drawn from the intake airflow (FA) and pushed by the pump (6) through the at least one supply circuit (5) and the internal volume (400) of the spark plug (4) to exchange heat with at least a portion of the spark plug, the cooling airflow (FR) being discharged toward the combustion chamber (23) through at least one hole (45) of the spark plug (4); Then - Compression time, which includes injecting a fuel stream toward the cylinder (21) to form an air-fuel mixture, increasing the pressure in the cylinder (21), and then igniting the air-fuel mixture in the combustion chamber (23); then - Expansion time, which includes the ignition of the air-fuel mixture in the cylinder (21); then - Exhaust time, which includes the rise of the piston (22).

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