Spark plug for spark ignition engine

Abstract

A spark plug for a spark ignition engine spark plug (4) of a spark ignition engine (2), comprising an electrical insulator (41), a base (42) defining a passive ignition pre-chamber (43), the spark plug (4) further comprising: at least one orifice (45) provided in the base (42); at least one passage (46) configured to flow a flow of exhaust air (FV) through at least a portion of the spark plug (4); and at least one regulating device (47) of the exhaust air flow (FV), which is arranged at the level of the at least one orifice (45) and is able to passively control the circulation of the exhaust air flow.

Description

[0001] This invention describes a spark plug for a spark-ignition engine, particularly an engine with a passive pre-combustion chamber, and a cylinder head for a spark-ignition engine equipped with such a spark plug. Furthermore, this invention relates to an engine equipped with the aforementioned spark plug and / or cylinder head. Finally, this invention describes a method of operating such an engine.

[0002] Improving the efficiency of spark-ignition heat engines is one of the challenges facing the automotive industry, and increasing the volumetric efficiency is a key area for improvement. However, increasing the volumetric efficiency of heat engines brings challenges such as fuel auto-ignition (also known as knock), which can potentially damage the engine.

[0003] One solution to these challenges is to use pre-combustion chamber spark plugs, more specifically, spark plugs with a passive pre-combustion chamber, i.e., spark plugs without a fuel injection mechanism that directly injects fuel into the pre-combustion chamber. However, such spark plugs have a drawback: residual combustion gases (or GBR) gradually accumulate in the pre-combustion chamber until they reach a high proportion, which affects the combustion of the carburized mixture and can even lead to low combustion efficiency.

[0004] This invention is proposed against this background, aiming to provide an alternative for pre-combustion chamber spark plugs (especially passive pre-combustion chamber spark plugs), which is designed to exhaust residual combustion exhaust gases that may remain in the pre-combustion chamber after the combustion cycle, thereby ensuring good quality of the combustible mixture in the pre-combustion chamber before spark plug ignition.

[0005] This invention relates to a spark plug for a spark-ignition engine, comprising an electrical insulator and a conductive base, wherein the base defines an ignition pre-combustion chamber having at least one orifice for allowing at least one combustible mixture to pass between a cylinder combustion chamber and the pre-combustion chamber. Furthermore, the spark plug unit includes at least one orifice and a channel, wherein the at least one orifice passes through a wall of the base and is in fluid communication with the pre-combustion chamber via the at least one channel to allow exhaust air to circulate through the at least one pre-combustion chamber. The spark plug also includes at least one exhaust air flow regulating device disposed at the level of the at least one orifice for passively controlling the flow of exhaust air.

[0006] Specifically, at least one channel may be defined by the base and / or the electrical insulator.

[0007] Specifically, the base and / or electrical insulator may extend along a first direction; furthermore, the spark plug has a main electrode and a ground electrode, wherein at least one orifice and at least one adjustment device are arranged such that, along the first direction, the at least one ground electrode is disposed between the at least one orifice located on one side and the at least one orifice of the pre-combustion chamber located on the other side.

[0008] Alternatively, the spark plug may further include at least one intermediate volume disposed between at least one orifice and all or part of the at least one channel, the intermediate volume being defined by the base and / or the electrical insulator and being fluidly connected to the at least one channel and the pre-combustion chamber.

[0009] According to an exemplary embodiment, at least one exhaust airflow regulating device is a non-return valve comprising at least one ball and a spring.

[0010] The present invention also relates to a cylinder head for a spark-ignition engine, the cylinder head including at least one intake valve, at least one exhaust valve, and at least one cavity defining a first volume, wherein a first end of the cavity has an opening configured to lead to a cylinder combustion chamber, the cylinder head further including at least one spark plug according to the present invention, the spark plug being located within the first volume and at the level of the opening such that the at least one orifice extends into the first volume, and the pre-combustion chamber is configured to be in fluid communication with the cylinder combustion chamber.

[0011] Specifically, at least one spark plug cavity has a second end opposite to its first end that is open, at least partially open, to allow exhaust airflow into the first volume. The second end is designed to restrict or even prevent the inflow of liquids and / or particulate matter.

[0012] The present invention also relates to a spark-ignition engine having a cylinder head according to the invention, at least one cylinder defining a combustion chamber, and a movable piston located within the at least one cylinder, wherein an opening in the cylinder head and a pre-combustion chamber of the at least one spark plug both open into the combustion chamber.

[0013] Alternatively, the engine also has an intake valve control device for regulating the opening of the intake valve, particularly the opening delay.

[0014] Furthermore, the present invention also relates to an operating method of the above-mentioned spark ignition engine, the method comprising:

[0015] - Intake Phase: The intake airflow (FA) is introduced into the cylinder. This phase includes the step of creating negative pressure within the cylinder to allow the exhaust airflow (FV) to flow from the first volume through the spark plug pre-combustion chamber to the combustion chamber. This exhaust airflow (FV) can expel residual combustion gases accumulated in the pre-combustion chamber and / or the spark plug;

[0016] - Compression stage: This stage includes increasing the pressure within the cylinder to allow a portion of the combustible mixture to be introduced into the pre-combustion chamber, and includes igniting the mixture within the pre-combustion chamber; subsequently

[0017] - Expansion Phase: In this phase, the combustible mixture in the cylinder is ignited; subsequently...

[0018] - Exhaust phase: This phase involves raising the piston to an upper position to expel at least the residual combustion gases present in the cylinder combustion chamber to the spark plug's pre-combustion chamber.

[0019] Any further details, features, and advantages will become apparent from the following detailed description, which is exemplary and non-limiting, and is given with reference to various exemplary embodiments shown in the following figures:

[0020] Figure 1 A schematic diagram illustrating the working process of a vehicle equipped with a spark-ignition engine and the spark plug in the pre-combustion chamber.

[0021] Figure 2 This is a schematic diagram of the engine operating during the intake phase.

[0022] Figure 3 This is a schematic diagram of the engine operating during the exhaust phase.

[0023] Figure 1 An example of a motor vehicle 1 designed according to the present invention is illustrated schematically. Specifically, the motor vehicle 1 is equipped with a spark-ignition engine 2 according to the present invention. The spark-ignition engine 2 can be any type of thermal engine. Similarly, the vehicle 1 can be any type, such as a passenger car, commercial vehicle, truck, or bus. In particular, the vehicle 1 under consideration can be a connected vehicle and / or an autonomous vehicle.

[0024] A conventional spark-ignition engine 2 is equipped with at least one cylinder 21, in which a movable piston 22 is provided. The at least one cylinder 21 defines a combustion chamber 23, in which the piston 22 moves and an air-fuel mixture is injected into the combustion chamber 23.

[0025] The engine 2 also includes a cylinder head 3. According to an exemplary embodiment, the cylinder head 3 includes an intake passage 31 with an intake valve 32 and an exhaust passage 33 with an exhaust valve 34, as are known configurations. The cylinder head 3 is mounted on the engine 2 in a manner that ensures fluid communication between the intake passage 31 and exhaust passage 33 on one side and the combustion chamber 23 of at least one cylinder 21 on the other side. The intake valve 32 and exhaust valve 34 are typically mounted in a movable manner, designed to facilitate or block the fluid communication between the passages on which they are mounted and the combustion chamber 23.

[0026] The cylinder head 3 also includes at least one spark plug 4 according to the invention, and a cavity 35 for receiving the spark plug. The cavity 35 defines a first volume 350, which is open on one side and capable of accommodating all or part of the spark plug 4. Specifically, when the cylinder head 3 is mounted on the engine 2, the first end of the cavity 35 includes an opening 36 designed to lead to the combustion chamber 23 of at least one cylinder 21.

[0027] The second end (not shown) of cavity 35 is opposite to the first end and is optionally, but preferably, at least partially sealed to protect cavity 35 from the ingress of liquids and particulate matter that could affect the operation of spark plug 4. Furthermore, cavity 35 is designed to allow an airflow, referred to as exhaust airflow FV, to enter the first volume 350 of cavity 35, which will be described in further detail below. For this purpose, the second end of cavity 35 is at least partially open and optionally has at least one exhaust airflow FV passage designed for the passage of exhaust airflow FV while reducing the risk of liquids and particulate matter passing through.

[0028] It should be understood that the following description refers to the spark plug 4 of the engine 2, which is disposed in the spark plug chamber 35 opposite to the cylinder 21. However, the following description is also extended to a spark-ignition engine 2 having multiple cylinders 21 (each cylinder is equipped with a piston 22), and alternatively, can be extended to a cylinder head 3 having multiple chambers 35, spark plug 4, intake valve 32 and exhaust valve 34.

[0029] In general, the spark plug 4 according to the invention has at least one electrical insulator 41 and a conductive base 42 extending along a first direction 100, wherein the base 42 defines an ignition pre-combustion chamber 43. The ignition pre-combustion chamber 43 has at least one orifice 44 for the passage of at least one air-fuel mixture between the combustion chamber 23 of the cylinder 21 and the pre-combustion chamber 43, and allows exhaust airflow FV to flow toward the combustion chamber 23.

[0030] The spark plug is disposed in cavity 35 of cylinder head 3, extending at least partially into first volume 350. Specifically, the spark plug is disposed at opening 36, such that inside engine 2, pre-combustion chamber 43 can maintain fluid communication with combustion chamber 23 of cylinder 21 through at least one hole 44. Alternatively, but preferably, cylinder head 3 has at least one sealing element 37 disposed at the interface between spark plug 4 and cylinder head 3, for example, surrounding spark plug 4 and / or at opening 36, thereby: preventing combustion gases from flowing from combustion chamber 23 to cavity 35 (i.e., first volume 350) of spark plug 4 during compression, expansion, and exhaust phases (when cylinder pressure is higher than atmospheric pressure); and conversely, preventing fresh air from flowing from cavity 35 (i.e., first volume 350) to combustion chamber 23 during a phase of engine cycle when cylinder 21 may be under negative pressure (e.g., intake phase).

[0031] The insulator 41 is an elongated strip extending along a first direction 100. When the spark plug 4 is disposed in the cylinder head 3 and the engine 2, the insulator 41 includes, for example, an upper end for electrical connection of the spark plug 4, and a lower end opposite the upper end. The insulator 41 is made of an electrically insulating material, such as ceramic, particularly alumina-based ceramic.

[0032] The base 42 is made of a conductive material, particularly a metal. The base 42 has at least one wall, which is generally hollow, for surrounding all or part of the insulator 41. For example, the base 42 may be partially cylindrical or approximately cylindrical. The base 42 and the insulator 41 extend in the same direction (in this case, the first direction), for example, concentrically.

[0033] Specifically, the base 42 defines the internal volume 400 of the spark plug 4, which includes a spark plug pre-combustion chamber 43. Conventionally, the term "pre-combustion chamber" refers to a chamber within the spark plug 4 into which a combustible mixture (also known as an air-fuel mixture) is injected through at least one orifice 44 and then ignited by a spark. A hot jet of combustion gases is subsequently generated, which is discharged to the external environment (in this case, the combustion chamber 23 of the cylinder 21) through at least one orifice 44. In particular, according to the invention, the pre-combustion chamber 43 is a passive chamber, meaning that the pre-combustion chamber 43 has no fuel supply device or injector, and fuel cannot be directly injected into the pre-combustion chamber 43.

[0034] The spark plug 4 also includes at least one orifice 45 and at least one channel 46, which are in fluid communication with each other and with the pre-combustion chamber 43. In other words, at least one orifice 45 penetrates the wall of the base 42 and is in fluid communication with the pre-combustion chamber 43 through at least one channel 46. The at least one orifice 45 and at least one channel 46 are configured to allow exhaust airflow FV to flow through the internal volume 400 of the spark plug, particularly through the pre-combustion chamber 43 and the at least one orifice 44. The “exhaust airflow” refers to the airflow flowing out of the first volume 350 and through the spark plug 4 (particularly through the pre-combustion chamber 43) to vent any residual combustion exhaust gases that may accumulate in the spark plug 4 (particularly in the pre-combustion chamber 43) to the combustion chamber 23. Therefore, the exhaust airflow FV flows from the first volume 350 of the spark plug cavity 35 through the internal volume 400 of the spark plug 4 to the combustion chamber 23, rather than being discharged to the external environment, thereby achieving the cleanliness of the pre-combustion chamber 43. Therefore, the at least one channel 46 allows the exhaust airflow FV to flow from the cavity 35 of the spark plug 4 to the combustion chamber 23, blowing the combustion exhaust gas accumulated in the pre-combustion chamber 43 during the previous combustion process into the combustion chamber 23.

[0035] Specifically, at least one orifice 45 is provided in one wall of the cylinder head 42 such that when the spark plug 4 is installed in the vehicle 1, at least one orifice 45 extends into a first volume 350 of at least one cavity 35 in the cylinder head 3.

[0036] According to a specific exemplary embodiment, at least one channel 46 is defined by a base 42 and / or an electrical insulator 41. For example, at least one channel 46 extends partially along a first direction 100. At least one channel 46 is directly or indirectly connected to at least one orifice 45 and is designed to provide fluid communication between the first volume 350 and the pre-combustion chamber 43 to allow exhaust airflow FV to pass through. Thus, at least one orifice 45 and at least one channel 46 are designed to provide fluid communication between the first volume 350 of the cylinder head 3 and the combustion chamber 23 of at least one cylinder 21.

[0037] As shown in the figure, the spark plug 4 may optionally have a plurality of orifices 45 and a plurality of channels 46, as described above. According to a non-limiting example embodiment, the spark plug 4 includes two orifices 45 and two channels 46. These orifices 45 are distributed along, for example, the outer periphery of the base 42.

[0038] The spark plug 4 according to the invention also includes at least one regulating device 47 for the exhaust airflow FV. This regulating device 47 is disposed within the passage of the exhaust airflow FV inside the spark plug 4, particularly within the internal volume 400 of the spark plug 4, for passively controlling the flow of the airflow. The term "control" as used herein refers to the possibility of blocking the flow of the airflow to interrupt the fluid communication between the first volume 350 and the combustion chamber 23, or the possibility of allowing the airflow to flow from the first volume 350 to the combustion chamber 23. The term "passive" control means that it does not require motor actuation.

[0039] Specifically, the at least one adjusting device 47 is disposed at, for example, opposite and / or adjacent to, the at least one orifice 45. For example, the at least one adjusting device 47 is designed to close the at least one orifice 45 to block the exhaust airflow FV. Therefore, the at least one adjusting device 47 is in contact with the edge of the at least one orifice 45. Furthermore, preferably, the spark plug 4 includes an equal number of adjusting devices 47 as the number of orifices 45, with each adjusting device 47 disposed at one orifice 45.

[0040] According to an exemplary preferred embodiment, as shown in the figure, the at least one regulating device 47 is a one-way valve, which includes at least one ball 47a and a spring 47b. Specifically, the spring 47b is supported on an intermediate surface 47c formed by the walls of the base 42 and / or the insulator 41 to hold the spring 47b in place. On one hand, the ball 47a contacts the edge of the at least one orifice 45. On the other hand, the ball 47a contacts the spring 47b, thereby holding the ball 47a within the internal volume 400 of the spark plug 4. Therefore, the ball 47a is designed to switch between a "closed" state and an "open" state: in the "closed" state, the ball 47a contacts the edge of the at least one orifice 45 to close the orifice, thereby blocking the exhaust airflow FV in the internal volume 400; in the "open" state, the ball 47a applies force to the spring 47b and maintains a non-zero distance extension from the at least one orifice 45, thereby allowing the exhaust airflow FV to pass through the internal volume 400.

[0041] As will be further explained below in conjunction with the method of the present invention, the regulating device 47 is passively actuated, in this case by the movement of the ball 47a—based on the pressure difference between the measured pressure in the first volume 350 and the measured pressure in the combustion chamber 23. For example, the spring 47b is preloaded so that when a negative pressure is generated in the combustion chamber 23 (and consequently in the internal volume 400 of the spark plug 4 and the pre-combustion chamber 43) during the intake phase of engine cycle 2, the regulating device 47 is actuated. The term "negative pressure" as used herein refers to a pressure reduced to a value significantly below atmospheric pressure. Therefore, the spring 47b is lightly loaded to hold the ball 47a in the proper position within the spark plug 4. The ball 47a is subjected to atmospheric pressure on the side of cavity 35 (i.e., the first volume 350) and to the pressure of cylinder 21 on the side of pre-combustion chamber 43. Thus, when the pressure in cylinder 21 is below atmospheric pressure, the ball 47a is drawn towards cylinder 21, thereby opening the passage for the exhaust airflow FV. Specifically, when a negative pressure is generated in the combustion chamber 23, the ball 47a is drawn into the combustion chamber 23 through the channels (i.e., at least one channel 46 and the pre-combustion chamber 43) present in the internal volume 400 of the spark plug 4. Subsequently, the ball 47a moves against the spring 47b and compresses the spring 47b so that it abuts against the intermediate surface 47c.

[0042] It should be noted that when using the turbocharged engine 2, the intake pressure may be higher than atmospheric pressure depending on the operating conditions. As described below, the opening of the intake valve 32 needs to be delayed in order to generate appropriate pressure in the cylinder 21, which is lower than atmospheric pressure due to the downward movement of the piston 22.

[0043] Typically, the spark plug 4 also includes at least one main electrode 5 and at least one ground electrode 51. For example, the main electrode 5 passes through the insulator 41. The at least one ground electrode 51 is contained in the base 42 and forms a primary inter-electrode gap relative to the at least one main electrode 5, i.e., a gap between two non-contact electrodes, for supporting ignition between the respective electrodes. For example, the at least one ground electrode 51 extends from the inner surface of the base 42 into the inner volume 400 and extends into the interior of the volume. It is understood that the spark plug 4 may have multiple main electrodes 5 and / or multiple ground electrodes 51.

[0044] Alternatively, vehicle 1 is equipped with a spark ignition system consisting of an ignition control unit and a high-voltage circuit, which provides electrical energy to the at least one main electrode 5 of the spark plug 4.

[0045] According to the preferred embodiment shown, the at least one orifice 45 and the at least one adjusting device 47 are configured such that, along a first direction 100, the at least one ground electrode 51 is disposed between the at least one orifice 45 located on one side and the at least one hole 44 located in the pre-combustion chamber 43 on the other side. Specifically, the at least one orifice 45 and the at least one adjusting device 47 extend at a non-zero distance from the pre-combustion chamber 43 of the spark plug 4. For example, the at least one orifice 45 is located in the upper part (e.g., the upper half) of the spark plug 4, which is designed to be located within at least one cavity 35 of the cylinder head 3.

[0046] Alternatively, the spark plug 4 may also include at least one intermediate volume 48 disposed between the at least one orifice 45 and all or part of the at least one channel 46. This intermediate volume 48 forms part of the internal volume 400 of the spark plug 4 and is distinct from the volume of the pre-combustion chamber 43. The intermediate volume 48 is also in fluid communication with the at least one orifice 45, the at least one channel 46, and the pre-combustion chamber 43. The intermediate volume 48 is defined by an electrically insulating base 42 and / or an insulator 41. For example, the intermediate volume may be annular, at least partially surrounding the insulator 41. The intermediate volume 48 ensures fluid communication between the at least one orifice and the at least one channel 46, or between different channels 46. It should be understood that the shapes of the illustrated intermediate volume 48 and the at least one channel 46 are not limiting, and other variations are contemplated.

[0047] The present invention also relates to a method of operating the spark-ignition engine 2 of the present invention. This method is carried out during a cycle in the engine 2, which typically includes intake, compression, expansion, and exhaust phases.

[0048] During the intake phase, such as Figure 2 As shown, intake airflow FA is supplied to at least one cylinder 21, a process that includes a phase in which negative pressure is generated within cylinder 21 (particularly within combustion chamber 23). As previously stated, negative pressure here refers to a pressure drop within the cylinder (and therefore within the spark plug 4 internal volume 400 and pre-combustion chamber 43) to a value significantly below atmospheric pressure. The generated negative pressure activates at least one regulating device 47 (e.g., by moving the ball to the "on" position), thereby enabling exhaust airflow FV to flow from the first volume 350 through the spark plug internal volume 400 to combustion chamber 23.

[0049] Depending on the operating time and conditions of engine 2, negative pressure can be achieved in different ways. When the engine is running under low load, an initial strategy of obtaining negative pressure in at least one cylinder 21 can be implemented. At this time, the pressure in the intake manifold 31 (more broadly, the intake port) of engine 2 drops below atmospheric pressure. When engine 2 is operating in the atmospheric zone, negative pressure will naturally be generated in at least one cylinder 21 and the intake manifold 31. The operating conditions observed in engine 2 at this time are conducive to the actuation of the regulating device 47 without mechanical intervention. The regulating device 47 is preloaded to ensure that passive actuation of the regulating device 47 (e.g., the spring 47b of the one-way valve) can be achieved when such negative pressure is naturally generated.

[0050] On the other hand, engine 2 can operate under high load (i.e., overload or turbocharging). At this time, in the early stages of the intake phase, the pressure within the intake manifold 31 of engine 2 is significantly higher than atmospheric pressure. Since at least one cylinder 21 and the pressure within the intake manifold 31 are higher than atmospheric pressure, a negative pressure must be generated mechanically. In this case, the negative pressure is achieved by implementing intake delay opening (ROA), i.e., keeping the intake valve 32 closed as the piston 22 begins to descend. For example, intake delay opening is executed by a control device (not shown) of the intake valve 32, which can trigger a change in its valve opening action during the engine cycle. As described above, this delay generates a negative pressure in cylinder 21 (particularly combustion chamber 23) and the spark plug internal volume 400 (particularly pre-combustion chamber 43), sufficient to passively open at least one regulating device 47 36. When the regulating device 47 includes a one-way valve, the valve spring 47b is advantageously preloaded to open the valve opening 36 due to the negative pressure present in cylinder 21.

[0051] Advantageously, the method of the present invention provides different strategies for generating negative pressure in at least one cylinder 21, which are applicable to different operating points of the engine 2. It should be noted that, preferably, the method of the present invention can be implemented only when the engine is operating under low load, thereby allowing venting of the spark plug 4 without interfering with the normal operation of the engine cycle. When the engine 2 is operating under overload, the method of the present invention may not be implemented, and venting may not be performed.

[0052] With the help of the natural or generated negative pressure within cylinder 21 and pre-combustion chamber 43, fresh air contained in the first volume 350 of spark plug chamber 35 is drawn into the internal volume 400 and flows to the combustion chamber 23 of cylinder 21. Exhaust air flow FV then flows through the pre-combustion chamber 43 and then through at least one orifice 44. For example, exhaust air flow FV sequentially passes through at least one orifice 45, intermediate volume 48, at least one passage 46, and then through pre-combustion chamber 43, thereby removing all residual combustion gases accumulated during the combustion process of the previous engine cycle 2. The exhaust air flow FV flowing through the internal volume 400 of spark plug 4 enables passive purging to expel residual combustion gases remaining in the internal volume 400 of spark plug 4 after the previous engine cycle. For example, exhaust air flow FV can expel residual combustion gases remaining in the pre-combustion chamber 43, at least one passage 46, and / or intermediate volume 48.

[0053] Typically, intake valve 32 then opens, and intake air FA from intake manifold 33 fills cylinder 21, initiating fuel injection. Atomized fuel mixes with the intake air stream FA, thereby forming a combustible mixture (also known as an air-fuel mixture) within combustion chamber 23.

[0054] Similarly, engine cycle 2 continues into the compression phase. Fuel injection continues, and the combustible mixture is homogenized through turbulence in combustion chamber 23 of cylinder 21. Piston 22 retracts into cylinder 21, and intake valve 32 closes, causing the pressure in combustion chamber 23 and the internal volume 400 of spark plug (especially pre-combustion chamber 43) to increase. At this point, the pressure in combustion chamber 23 (and consequently the pressure in internal volume 400 of spark plug) is greater than or equal to the pressure in the first volume 350, and all regulating devices 47 are closed, thereby hindering the exhaust airflow FV. Subsequently, a portion of this combustible mixture is sent to pre-combustion chamber 43, where, at the end of the compression phase, the spark ignition system generates a spark at spark plug 4, causing the compressed combustible mixture to burn in pre-combustion chamber 43.

[0055] Subsequently, engine cycle 2 enters the expansion phase. The flame front spreads into the pre-combustion chamber 43. As the pressure inside the pre-combustion chamber 43 increases, the combusted gas enters the combustion chamber 23 in the form of a flame jet, forming multiple ignition points, thereby optimizing the calibration of the heat release mechanism and combustion efficiency. At this time, the intake valve 32, exhaust valve 34, and all regulating devices 47 are closed, ensuring a seal between the combustion chamber 23 and the first volume 350 of the spark plug 4's cavity 35.

[0056] Finally, in the exhaust stage (such as...) Figure 3As shown), exhaust valve 34 opens. As piston 22 retracts, it simultaneously discharges the residual combustion gases remaining in combustion chamber 23 of cylinder 21 to exhaust passage 33 and the internal volume 400 of spark plug 4, particularly to at least the pre-combustion chamber 43. For example, some residual combustion gases are sent to at least one passage 46 and the entire ignition pre-combustion chamber 43, particularly into the intermediate volume 48. At the same time, some residual gases are discharged from engine 2 through exhaust passage 33. As mentioned above, during the intake phase of subsequent engine cycle 2, the residual combustion gases accumulated in internal volume 400 can be discharged from spark plug 4.

[0057] Therefore, the spark plug 4 and method according to the present invention can achieve passive venting of the spark plug 4, thereby limiting the accumulation of residual combustion exhaust gas in the pre-combustion chamber 43 to an excessively high concentration that may hinder the initiation of combustion of the combustible mixture. Therefore, venting the residual combustion exhaust gas generated in the previous combustion process to the cylinder 21 during the intake phase can clean the pre-combustion chamber 43 before it is refilled with the combustible mixture.

[0058] Therefore, this invention provides an alternative to the pre-combustion chamber spark plug, which prevents the accumulation of residual gases after combustion within the spark plug. Advantageously, the proposed solution is simple to implement and inexpensive, and because it is directly integrated into the spark plug, it can be widely used in various cylinder heads and internal combustion engines. Furthermore, this invention does not affect the structure or operation of the pre-combustion chamber.

[0059] However, the present invention is not limited to the methods and configurations described and illustrated herein, but extends to any other equivalent methods or configurations, and any technically effective combinations of such methods, provided that they ultimately achieve the functionality described and illustrated herein.

Claims

1. A spark plug (4) for a spark-ignition engine (2), comprising an electrical insulator (41) and a conductive base (42), the base (42) defining an ignition pre-combustion chamber (43), the ignition pre-combustion chamber including at least one orifice (44) capable of allowing at least one combustible mixture to pass between a combustion chamber (23) of a cylinder (21) and the pre-combustion chamber (43), the spark plug (4) further comprising: - At least one orifice (45) and at least one channel (46), the at least one orifice (45) passing through the wall of the base (42) and being in fluid communication with the pre-combustion chamber (43) through the at least one channel (46) so as to allow exhaust air flow (FV) to flow through at least the pre-combustion chamber (43). - At least one regulating device (47) for the flow of exhaust air (FV) is disposed at the level of the at least one orifice (45) and is capable of passively controlling the flow of exhaust air.

2. The spark plug (4) according to the preceding claim, wherein, The at least one channel (46) is defined by the base (42) and / or the electrical insulator (41).

3. The spark plug (4) according to any one of the preceding claims, wherein, The base (42) and / or the electrical insulator (41) extend along a first direction (100), and the spark plug (4) further includes at least one main electrode (5) and at least one ground electrode (51). The at least one orifice (45) and the at least one adjusting device (47) are arranged such that, along the first direction (100), the at least one ground electrode (51) is disposed between the at least one orifice (45) located on one side and the at least one hole (44) of the pre-combustion chamber (43) located on the other side.

4. The spark plug (4) according to any one of the preceding claims further includes at least one intermediate volume (48) disposed between the at least one orifice (45) and all or part of the at least one channel (46), the intermediate volume (48) being defined by the base (42) and / or the electrical insulator (41), and the intermediate volume (48) being fluidly connected to the at least one channel (46) and the pre-combustion chamber (43).

5. The spark plug (4) according to any one of the preceding claims, wherein, The at least one regulating device (47) for the flow of the exhaust airflow (FV) is a one-way valve, which includes at least one ball (47a) and a spring (47b).

6. A cylinder head (3) for a spark-ignition engine (2) comprising at least one intake valve (32), an exhaust valve (34), and at least one cavity (35) defining a first volume (350), the first end of the cavity (35) comprising an opening (36) configured to lead into a combustion chamber (23) of a cylinder (21), the cylinder head (3) further comprising at least one spark plug (4) according to any one of the preceding claims, the spark plug being disposed in the first volume (350) and at the level of the opening (36) such that at least one orifice (45) extends into the first volume (350), and such that a pre-combustion chamber (43) is configured to be in fluid communication with the combustion chamber (23) of the cylinder (21).

7. The cylinder head (3) according to the preceding claim, wherein, The second end of the at least one cavity (35) of the spark plug, opposite the first end, is at least partially open to allow exhaust airflow (FV) to enter the first volume (350), and the second end is configured to restrict or even eliminate the entry of liquids and / or particulate matter.

8. A spark-ignition engine (2) comprising a cylinder head (3) according to claim 6 or 7, at least one cylinder (21) defining a combustion chamber (23), and a movable piston (22) disposed in the at least one cylinder (21), wherein an opening (36) in the cylinder head (3) and a pre-combustion chamber (43) of the at least one spark plug (4) both open into the combustion chamber (23).

9. The spark-ignition engine (2) according to the preceding claims further includes means for controlling the opening of the intake valve (32), which is capable of controlling the opening of the intake valve, particularly delaying the opening.

10. A method of operating a spark-ignition engine (2) according to claim 8 or 9, comprising: - During the intake phase, an intake airflow (FA) is introduced into the cylinder (21). This phase includes a step of generating a negative pressure in the cylinder (21) to allow an exhaust airflow (FV) to flow from the first volume (350) through the pre-combustion chamber (43) of the spark plug (4) to the combustion chamber (23). The exhaust airflow (FV) is able to expel residual combustion exhaust gases accumulated in the pre-combustion chamber (43) and / or the spark plug (4). - The compression phase includes increasing the pressure within the cylinder, causing a portion of the combustible mixture to be introduced into the pre-combustion chamber (43); and includes igniting the mixture within the pre-combustion chamber (43); subsequently - During the expansion phase, the combustible mixture contained within the cylinder (21) is ignited; subsequently - The exhaust phase includes raising the piston (22) to an upper position to exhaust residual combustion exhaust gases present in the combustion chamber (23) of the cylinder (21) to at least the pre-combustion chamber (43) of the spark plug (4).

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