Cylinder head with pre-combustion chamber

Abstract

Cylinder head (1) with pre-combustion chamber (2) and a two-sided stepped bore (3) with a central bore section (3a), a first bore step (3b) with an inner diameter on one side of the central bore section (3a) that is larger than the inner diameter of the central bore section (3a), and a second bore step (3c) with an inner diameter on the other side of the central bore section (3a) that is larger than the inner diameter of the central bore section (3a), wherein a cap (4) with at least one transfer port is arranged in the first bore step (3b) and a sleeve (5) is arranged in the second bore step (3c), and the cap (4) and the sleeve (5) are connected to each other by means of a common threaded connection (6) in the sense of a through-bolt connection.

Description

Technical field

[0001] The present invention relates to a cylinder head with a pre-combustion chamber, within which an ignition device is arranged. The pre-combustion chamber is formed from several parts which are received in the cylinder head. State of the art

[0002] Various approaches exist for improving the efficiency and reducing emissions of spark-ignition internal combustion engines. In particular, pre-chamber ignition is considered a viable option for reducing fuel consumption and emissions. With pre-chamber ignition, a pre-combustion chamber with transfer ports is provided to the main combustion chamber of one cylinder of the internal combustion engine. Within this chamber, an ignition device ignites and combusts a combustible gas mixture. The combustion gases are then directed from the pre-combustion chamber into the main combustion chamber via the transfer ports in the form of torch jets, thus igniting the gas mixture there.

[0003] This gas mixture in the pre-combustion chamber can have a significantly different composition than the gas mixture in the main combustion chamber. This makes it possible to ignite a lean gas mixture in the main combustion chamber, which would otherwise be non-ignitable, using pre-chamber ignition, since pre-chamber ignition can provide a significantly higher ignition energy than conventional hook spark plugs.

[0004] Pre-chamber ignition is already used in stationary gas engines as well as in special high-performance racing engines. However, pre-chamber ignition also represents a particularly promising approach for mass-produced internal combustion engines for personal transportation.

[0005] Solutions are known from the prior art for constructing such a pre-combustion chamber and integrating it into the cylinder head of an internal combustion engine. In particular, solutions are known in which the pre-combustion chamber is at least partially formed by a cap with transfer ports, which is inserted into a bore in the cylinder head on the main combustion chamber side.

[0006] Utility model JP S53-12 904 U discloses a pre-combustion chamber arrangement for spark-ignition internal combustion engines. The pre-combustion chamber of a cylinder is formed by a cap inserted into the cylinder head of the internal combustion engine, which is fitted into a bore in the cylinder head on the main combustion chamber side. The cap is secured against rotation and dislodgement by a positive locking connection, which is formed by at least one lug on a combustion chamber roof of the cylinder and a corresponding recess in the cap. The lug is created by plastic deformation when the cap is positioned in the bore. This results in a permanent connection between the cap and the cylinder head.

[0007] German patent application DE 12 12 350 B discloses a pre-combustion chamber designed as a swirl chamber, which is formed in a cylinder head and has a base plate with a transfer port. The base plate is inserted in the cylinder head and extends partially into a sealing surface of the cylinder head. Only when the cylinder head is connected to a cylinder block is the base plate additionally held in place by a cylinder head gasket and the cylinder block with a cylinder liner.

[0008] German patent application DE 31 45 119 A1 discloses a spark plug for an internal combustion engine. When installed in the engine, the spark plug's combustion chamber end is connected to a terminal cap, which is mounted in the cylinder head and extends through a bore into the combustion chamber. The terminal cap, which has several transfer ports, also features a flange that secures it in the cylinder head and prevents it from falling into the combustion chamber. When the spark plug is mounted in the cylinder head, an annular end face of the spark plug presses against the flange via a seal, thus securing the terminal cap in a seat within the cylinder head. The terminal cap also serves as the spark plug's ground electrode, with the electrode gap being partially determined by the seal.

[0009] Patent DE 689 072 A discloses a pre-chamber which is formed from a sleeve and a cap, wherein the sleeve and the cap are screwed together by means of a threaded connection and the pre-chamber is fastened in the cylinder head by means of a further threaded connection as a push-in screw connection.

[0010] Patent AT 137 602 B discloses a pre-chamber housing consisting of three parts that are screwed together and inserted as a unit into the cylinder head. An injection nozzle is mounted in the pre-chamber housing, which then holds the housing in the cylinder head.

[0011] Patent DE 10 2019 111 091 B3 describes a pre-chamber spark plug with a three-part design. The pre-chamber spark plug consists of a spark plug body, a sleeve, and a cap. The spark plug body is screwed to the internal combustion engine via an external thread. The sleeve is mounted in a bore in the cylinder head with a clearance fit, and the cap with an interference fit. When the spark plug body is screwed in, the sleeve is pressed against the fixed cap, thus holding it in the cylinder head to form the pre-chamber spark plug. Object of the invention

[0012] The object of the invention is to provide a cylinder head with a pre-combustion chamber in which the pre-combustion chamber is improved. Solution to the task

[0013] The problem is solved by a cylinder head with a pre-combustion chamber according to the features of claim 1. Advantageous further developments are described in the dependent claims and the exemplary embodiment. Description of the invention

[0014] The invention provides an advantageous cylinder head with a pre-combustion chamber for an internal combustion engine, in which reproducible positioning of the pre-combustion chamber in the cylinder head is enabled with simple assembly. Furthermore, the use of conventional hook spark plugs is permitted.

[0015] Advantageously, according to the invention, the cylinder head has a pre-combustion chamber separated from the main combustion chamber of the internal combustion engine, which is at least partially formed by a cap and a sleeve. An underside of the cylinder head forms the fire deck, closing off the main combustion chamber of a cylinder in the internal combustion engine. The cap and the sleeve are received in a bore in the cylinder head with at least two recesses and, when installed, are connected to each other by means of a through-bolt connection and thus held in the bore in the cylinder head. This forms a pre-combustion chamber that is easy to assemble and disassemble. Furthermore, an ignition device is positioned in the bore in the cylinder head, with ignition elements of the ignition device projecting into the pre-combustion chamber, in particular into the sleeve. If the ignition device is designed as a hook spark plug, the ignition electrodes project into the sleeve.Preferably, the ignition device is not in contact with the sleeve.

[0016] The bore in the cylinder head is designed as a through bore with at least two, and in particular two-sided, stepped sections, wherein a first step is provided at the main combustion chamber end of the bore, a central bore section adjacent to the first step, and a second step adjacent to the central bore section. A step is understood to be a bore section adjacent to the central bore section whose inner diameter is larger than that of the central bore section. Thus, a bore is formed in which, starting from the main combustion chamber end, the first step, the central bore section, and the second step are arranged successively. A receptacle for the ignition device follows the second step.The bore opens primarily into the center of the main combustion chamber and is therefore located in the cylinder head between an intake side, determined by the position of the intake ports, and an exhaust side, determined by the position of the exhaust ports. The bore runs from the top of the cylinder head, between the intake and exhaust sides, to the underside of the cylinder head and opens into the main combustion chamber.

[0017] The cap is positioned at least in the first bore section at a main combustion chamber-side end of the bore and forms a main combustion chamber-side closure of the pre-combustion chamber of the internal combustion engine. The cap incorporates at least one transfer port to create a fluid connection between the pre-combustion chamber and the main combustion chamber. The sleeve is positioned at least in the second bore section. The sleeve is connected to the cap via a common threaded connection. The ignition device forms the closure of the pre-combustion chamber opposite the cap.

[0018] The cap has a cap section by means of which the cap is received in the first bore section. The outer diameter of the cap section essentially corresponds to the inner diameter of the first bore section. The cap section has an outer contour corresponding to the first bore section. The cap preferably extends beyond the underside of the cylinder head into the main combustion chamber. Furthermore, the cap is preferably designed as a dome-shaped cap, with the dome arch projecting into the main combustion chamber.

[0019] The sleeve has a sleeve section by means of which the sleeve is received in the second bore section. The outer diameter of the sleeve section essentially corresponds to the inner diameter of the second bore section. The sleeve section has an outer contour corresponding to the second bore section.

[0020] Accordingly, the cap can only be installed in the bore from the underside of the cylinder head, and the sleeve can only be installed from the top of the cylinder head.

[0021] The pre-combustion chamber is formed by a common threaded connection, a through-bolt fitting between the cap and sleeve. This connection extends over the first bore section, the central bore section, and the second bore section. Alignment of the cap, and thus the at least one transfer port, with the cylinder head is achieved using a suitable assembly tool or by a positive-locking connection between the cap and cylinder head. This also allows for disassembly of the pre-combustion chamber. The threads of the common threaded connection are designed as lock-fit threads, specifically as sealing lock-fit threads.

[0022] In an advantageous embodiment of the cylinder head with pre-combustion chamber according to the invention, the cap has a cap contact surface at an end facing away from the main combustion chamber. This contact surface rests directly or indirectly, via an intermediate seal, against a first contact surface of the first bore shoulder of the bore. The cap contact surface is oriented away from the main combustion chamber, and the first contact surface of the first bore shoulder is oriented towards the main combustion chamber. The cap contact surface and the first contact surface of the first bore shoulder are designed to correspond to each other, with the surfaces preferably being formed as flat or conical annular surfaces. Accordingly, the cap can only be installed into the bore of the cylinder head from below, from the direction of the main combustion chamber, with the installation depth of the cap in the bore being determined by the first bore shoulder.

[0023] The sleeve is designed as a stepped sleeve with at least a single step and extends at least partially over the second bore step, over the central bore section, and at least partially over the first bore step, projecting into the cap. The sleeve has a shoulder on its outer surface, which defines a sleeve contact surface. This contact surface rests directly or indirectly, via an intermediate seal, against a second contact surface of the second bore step. The sleeve contact surface faces the main combustion chamber, and the second contact surface of the second bore step faces away from the main combustion chamber. The sleeve contact surface and the second contact surface of the second bore step are designed to correspond to each other, with the surfaces preferably being formed as flat or conical annular surfaces.Accordingly, the sleeve can only be installed into the bore of the cylinder head from the top, in the opposite direction to the main combustion chamber, with the installation depth of the sleeve in the bore being determined by the second bore shoulder.

[0024] An internal thread is provided on the inside of the cap, located at the end of the cap furthest from the main combustion chamber. An external thread is provided on the outside of the sleeve, located at the end of the sleeve closest to the main combustion chamber. The internal and external threads engage to form a threaded connection, creating the pre-combustion chamber and securely holding the components within the bore. This threaded connection is primarily located in the area of ​​the first bore shoulder.

[0025] In an advantageous alternative embodiment of the cylinder head with pre-combustion chamber according to the invention, the sleeve has a sleeve contact surface at an end facing the main combustion chamber, which rests directly or indirectly via an intermediate seal against the second contact surface of the second bore section of the bore. The sleeve contact surface is oriented towards the main combustion chamber, and the second contact surface of the second bore section is oriented away from the main combustion chamber. The sleeve contact surface and the second contact surface of the second bore section are designed to correspond to each other, with the surfaces preferably being formed as flat or conical annular surfaces. Accordingly, the sleeve can only be installed into the bore of the cylinder head from the top, opposite to the direction of the main combustion chamber, with the installation depth of the sleeve in the bore being determined by the second bore section.

[0026] The cap is designed as a stepped cap with at least a single step and extends at least partially over the first bore shoulder, the central bore section, and at least partially over the second bore shoulder, projecting into the sleeve. The cap has a shoulder on its outer surface, which defines a cap contact surface. The cap contact surface rests directly or indirectly, via an intermediate seal, against a first contact surface of the first bore shoulder. The cap contact surface faces away from the main combustion chamber, while the first contact surface of the first bore shoulder faces the main combustion chamber. The cap contact surface and the first contact surface of the first bore shoulder are designed to correspond to each other, with the surfaces preferably being formed as flat or conical annular surfaces.Accordingly, the cap can be mounted into the bore of the cylinder head from the direction of the main combustion chamber from below, with the installation depth of the cap in the bore being determined by the first bore shoulder.

[0027] An external thread is provided on the outer side of the cap, located at the end furthest from the main combustion chamber. An internal thread is provided on the inner side of the sleeve, located at the end closest to the main combustion chamber. The internal and external threads engage to form a threaded connection, creating the pre-combustion chamber and securely holding the components within the bore. This threaded connection is primarily located in the area of ​​the second bore shoulder. Example of implementation

[0028] An advantageous embodiment of a cylinder head 1 according to the invention, comprising a pre-combustion chamber 2, is shown here by way of example. The accompanying figure illustrates: Fig. 1 a schematic representation of the cylinder head 1 with pre-combustion chamber 2.

[0029] In the embodiment advantageous according to the invention, the cylinder head 1 has a pre-combustion chamber 2, as shown in Fig.Figure 1 shows a two-sided, stepped bore 3 with a central bore section 3a, a first bore step 3b on one side of the central bore section 3a, and a second bore step 3c on the other side of the central bore section 3a. To represent the pre-combustion chamber 2, a cap 4 with at least one transfer port (not shown) is arranged in the first bore step 3b, and a sleeve 5 is arranged in the second bore step 3c, the cap 4 and the sleeve 5 being connected to each other by means of a common threaded connection 6. The cap 4 and the sleeve 5 are thus connected to each other in the sense of a through-bolt connection and are thereby firmly received in the bore 3 in the cylinder head 1.

[0030] The cap 4 has a cylindrical cap section 4a by means of which the cap 4 is received in the first bore section 3b. Furthermore, the cap 4 has an annular, flat cap contact surface 4b, which bears against an annular, flat first contact surface 3ba of the first bore section 3b.

[0031] The sleeve 5 is designed as a simply stepped sleeve 5 and extends at least partially over the second bore shoulder 3c, over the central bore section 3a, and at least partially over the first bore shoulder 3b, projecting into the cap 4. The sleeve 5 has a cylindrical sleeve section 5a by means of which the sleeve 5 is received in the second bore shoulder 3c. The sleeve 5 further has a sleeve shoulder 5b on an outer surface, which defines a conical sleeve contact surface 5ba. The sleeve contact surface 5ba abuts a conical second contact surface 3ca of the second bore shoulder 3c.

[0032] An internal thread 6a is provided on the inside of the cap 4. An external thread 6b is provided on the outside of the sleeve 5. The internal thread 6a and the external thread 6b engage with each other in the area of ​​the first bore shoulder 3b to form the common threaded connection 6.

[0033] Furthermore, an ignition device 7 is positioned in the bore 3 in the cylinder head 1, wherein ignition electrodes 7a, 7b of the ignition device 7 protrude into the sleeve 5 and the ignition device 7 forms the end of the pre-combustion chamber 2 opposite the cap 4. List of reference symbols used 1 cylinder head 2 Pre-combustion chamber 3 holes 3a central borehole section 3b first drilling step 3ba first planting area 3c second drilling step 3ca second planting area 4 caps 4a Cap section 4b Cap mounting surface 5 Sleeve 5a Sleeve section 5b Sleeve heel 5ba sleeve mounting surface 6 threaded connection 6a Internal thread 6b External thread 7 Ignition device 7a Ignition electrode 7b Ignition electrode

Claims

[1] Cylinder head (1) with pre-combustion chamber (2) and a two-sided stepped bore (3) with a central bore section (3a), a first bore step (3b) with an inner diameter on one side of the central bore section (3a) that is larger than the inner diameter of the central bore section (3a) and a second bore step (3c) with an inner diameter on the other side of the central bore section (3a) that is larger than the inner diameter of the central bore section (3a), wherein a cap (4) with at least one transfer port is arranged in the first bore step (3b) and a sleeve (5) is arranged in the second bore step (3c), and the cap (4) and the sleeve (5) are connected to each other by means of a common threaded connection (6) in the sense of a through-bolt connection. [2] Cylinder head (1) with pre-combustion chamber (2) according to claim 1, characterized by, that an ignition device (7) is positioned in the bore (3) in the cylinder head (1), wherein ignition electrodes (7a, 7b) of the ignition device (7) protrude into the sleeve (5) and the ignition device (7) forms the end of the pre-combustion chamber (2) opposite the cap (4). [3] Cylinder head (1) with pre-combustion chamber (2) according to one of the preceding claims, characterized by , that the threaded connection (6) is designed as a fixed-fit thread. [4] Cylinder head (1) with pre-combustion chamber (2) according to one of the preceding claims, characterized by , that the cap (4) is aligned with respect to the cylinder head (1) by means of a positive locking connection between the cap (4) and the cylinder head (1).

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