Internal combustion engine with one cylinder head

Abstract

Internal combustion engine with a cylinder head (1) having a combustion chamber-side fire deck (7), with at least one injector sleeve (2) detachably connected to the cylinder head (1) for receiving an injection device, wherein the injector sleeve (2) is screwed to the fire deck (7) at a fire deck-side first end (5) via a first screw connection (4), and wherein the injector sleeve (2) has at least one radially projecting first support area (9) in the region of the first end (5) with a first support surface (10) facing the fire deck (7), which rests on a first counter surface (11) formed by the cylinder head (1), wherein the injector sleeve (2) – preferably in the region of a second end (6) facing away from the first end (5) – has at least one radially projecting second support area (12) with a second support surface (13) facing the fire deck (7), characterized in thatthat the second bearing surface (13) rests on a second counter surface (14) formed by the cylinder head (1), wherein in the relaxed state the distance (a) between the first counter surface (11) and the second counter surface (14) of the cylinder head (1) is greater than the distance (b) between the first bearing surface (10) and the second bearing surface (13) of the injector sleeve (2), so that in the screwed-in state the injector sleeve (2) is under a tensile preload caused by a preload tensile force.

Description

[0001] The invention relates to an internal combustion engine with a cylinder head having a combustion chamber-side fire deck, with at least one injector sleeve detachably connected to the cylinder head for receiving an injection device, wherein the injector sleeve is screwed to the fire deck at a fire deck-side first end via a first screw connection, and wherein the injector sleeve has at least a radially projecting first bearing area in the region of the first end with a first bearing surface facing the fire deck, which rests on a first counter surface formed by the cylinder head, wherein the injector sleeve - preferably in the region of a second end facing away from the first end - has at least a radially projecting second bearing area with a second bearing surface facing the fire deck.

[0002] During operation of the internal combustion engine, the combustion chamber undergoes elastic deformation under ignition pressure, resulting in relative movement between the injector sleeve and the combustion chamber. This can lead to leaks between the combustion chamber and the injector sleeve.

[0003] From JP S54 - 158 920 U, a direct-injection diesel engine with an injector sleeve arranged in the cylinder head is known. The injector sleeve has a first contact surface at one end and a second contact surface at the other. The first contact surface rests on a mating surface formed by the cylinder head. An O-ring is arranged between the second contact surface and the cylinder head, thus preventing the second contact surface from resting on a mating surface formed by the cylinder head.

[0004] US patent 2011 / 0061217A1 relates to a puller for removing an injector sleeve, shown only schematically, from a cylinder head. Here too, O-rings are provided between the second contact surfaces at the second end of the injector sleeve and the cylinder head.

[0005] From GB 363 560 A, an internal combustion engine is known with a cylinder head having an injector sleeve, wherein the injector sleeve, designed to accommodate an injection device, is screwed to an upper deck of the cylinder head via a flange surface. The screw connection presses the injector sleeve against a sealing surface of the fire deck.

[0006] The JP H11-132100A describes a cylinder head structure with a combustion chamber-side fire deck and an upper deck spaced apart from the fire deck, wherein a central injector sleeve is provided for each cylinder to accommodate an injection device. The injector sleeve is screwed to the upper deck via a first screw connection and to the fire deck of the cylinder head via a second screw connection.

[0007] Furthermore, a fastening for an injector sleeve of a cylinder head is known from JP 2002 - 188 547 A, wherein the injector sleeve is screwed into the cylinder head in the area of ​​the fire cover.

[0008] AT 505 049 B1 proposes to attach the injector sleeve to the cylinder head via two screw connections, with the screw connections being located in the area of ​​the opposite ends of the injector sleeve.

[0009] Furthermore, it is known that the injector sleeve is sometimes only secured by a screw in the area of ​​the fire deck in the cylinder head. Under ignition pressure, this causes deformation of the fire deck, which in turn causes the sleeve to move. Here, too, the movement of the injector sleeve can lead to leaks in the long term.

[0010] The object of the invention is to avoid these disadvantages and to increase the rigidity of the cylinder head with minimal material expenditure. This is intended to create a tight connection with a long service life between the injector sleeve and the cylinder head.

[0011] According to the invention, this is achieved by the second bearing surface resting on a second counter surface formed by the cylinder head, wherein in the relaxed or disassembled state the distance between the first counter surface and the second counter surface of the cylinder head is greater than the distance between the first bearing surface and the second bearing surface of the injector sleeve, so that in the screwed-in state the injector sleeve and the first screw connection are under a tensile preload caused by a preload tensile force.

[0012] The first screw connection is designed to exert the preload tensile force on the injector sleeve installed in the cylinder head.

[0013] During the installation of the injector sleeve, a tensile preload is applied to the sleeve. During operation, the thermal expansion of the cylinder head results in an additional tensile preload on the injector sleeve, which counteracts and prevents the free thermal expansion of the cylinder head. The cylinder pressure relieves this tensile preload on the injector sleeve. Therefore, the preload force must be sufficient to prevent the injector sleeve from lifting off due to the maximum cylinder pressure.

[0014] An external thread on the injector sleeve can be part of the first screw connection. In a simple design with few components, the external thread of the injector sleeve is screwed into a threaded hole in the fire deck.

[0015] Alternatively, the external thread of the injector sleeve can be screwed to a nut that rests against a bearing surface of the fire deck, which is positioned in a bore in the fire deck from the combustion chamber side. In this variant, it is unnecessary to machine a thread in the injector bore of the cylinder head, thereby reducing stresses in the fire deck caused by the initial screw connection.

[0016] Particularly at high cylinder pressures, it is advantageous to prevent the injector sleeve from loosening if the injector sleeve is screwed to the cylinder head at its second end via a second screw connection, preferably formed by a hollow screw. This second screw connection presses the second bearing surface of the injector sleeve against the second mating surface of the cylinder head. The element can exert pressure on a contact surface of the injector sleeve at its second end with a pressure surface facing the injector sleeve. The second screw connection prevents the injector sleeve from being lifted by the gas forces in the cylinder.

[0017] Alternatively or in addition to the second screw connection, the first bearing surface can be bonded to the first counter surface and / or the second bearing surface to the second counter surface.

[0018] The described invention can reduce the deflection of the fire deck and the resulting stresses caused by the ignition pressure without requiring more material in the cylinder head.

[0019] The invention will be explained in more detail below with reference to the figure. The figure shows: Fig. 1 an injector sleeve for an internal combustion engine according to the invention in a meridian section in a first embodiment; and Fig. 2 an injector sleeve in a partial section in a second design variant.

[0020] The Fig. 1 and Fig. Figures 2 each show an injector sleeve 2 arranged in a cylinder head 1 for receiving an injection device (not shown) which opens into a combustion chamber 3 of an internal combustion engine. Reference numeral 28 denotes the cavity within the injector sleeve 2 for receiving the injection device.

[0021] The injector sleeve 2 is detachably fastened via a first screw connection 4 in a fire deck 7 of the cylinder head 1 adjacent to the combustion chamber 3, and has a first end 5 in the area of ​​the fire deck 7 and a second end 6 facing away from the first end 5. In the area of ​​the first end 5, the injector sleeve 2 has an external thread 16 which interacts with a corresponding internal thread 8 for fastening in the cylinder head 1.

[0022] At the in Fig. In the embodiment shown, the internal thread 8 is formed by a threaded bore 17 of the fire deck 7 of the cylinder head 1. Fig. Figure 2, on the other hand, shows an embodiment in which the internal thread 8 is formed by a nut 19, which is supported on shoulders 20, 21 of the fire deck 7. The nut 19 is arranged in the bore 22 of the fire deck 7 from the side of the combustion chamber 3.

[0023] In the area of ​​the first end 4 of the injector sleeve 2, at least a radially projecting first support area 9 is arranged with a first support surface 10 facing the fire deck 7, which rests on a first counter surface 11 formed by the cylinder head 1.

[0024] In the region of the second end 6, the injector sleeve 2 has at least one radially outwardly projecting second bearing area 12 with a second bearing surface 13 facing the fire deck 7. The second bearing surface 13 rests on a second counter surface 14 formed by the cylinder head 1.

[0025] In the exemplary embodiment, the first bearing surface 10 and the first counter surface 11 are designed as planar annular surfaces perpendicular to the axis 2a of the injector sleeve 2. However, the first bearing surface 10 and the first counter surface 11 can also be designed as corresponding conical surfaces. The same applies to the second bearing surface 13 and the second counter surface 14.

[0026] In the relaxed state, where all contact surfaces 10; 13 and mating surfaces 11; 14 are not in contact, i.e., when, for example, the injector sleeve 2 is not yet screwed into the cylinder head 1, the distance a between the first mating surface 11 and the second mating surface 14 of the cylinder head 1 is greater than the distance b between the first contact surface 10 and the second contact surface 13 of the injector sleeve 2. Therefore, when screwed in, the injector sleeve 2 is subject to a tensile preload caused by a preload force, with the first screw connection 4 being designed to exert this preload force on the injector sleeve 2 installed in the cylinder head 1. The preload force must be chosen to be at least large enough to prevent the injector sleeve 2 from lifting due to the maximum cylinder pressure generated during combustion in the combustion chamber 3.

[0027] For additional securing, an element can be screwed to the cylinder head 1 by a second screw connection 15 in the area of ​​the second end 6 of the injector sleeve 2, which – in addition to the preload tensile force – presses the second bearing surface 13 against the second counter surface 14. The in Fig. In the embodiment shown in Figure 1, the element formed by a hollow screw 24 acts with a pressure surface 23 facing the injector sleeve 3 on an opposing contact surface 24 of the injector sleeve 2 in the region of the second end 6. The second screw connection 15 has in the Fig.In the embodiment shown in Figure 1, an external thread 26 is provided on the hollow screw 25, which is screwed into an internal thread 27 of the cylinder head 1. The second screw connection 15 reliably prevents the injector sleeve 2 from lifting off – in particular, the first bearing surface 10, which forms a sealing surface 18, from the first counter surface 11 – due to the gas forces in the combustion chamber 3.

[0028] Alternatively or in addition to the second screw connection 15, it can also be provided that the first bearing surface 10 is bonded to the first counter surface 11 and / or the second bearing surface 13 is bonded to the second counter surface 14 by means of an adhesive.

[0029] Each of the described designs reduces the deflection of the fire deck 7 and the resulting stresses caused by the ignition pressure without requiring more material in the cylinder head 1. This allows for a very rigid cylinder head 1 design and low weight.

Claims

[1] Internal combustion engine with a cylinder head (1) having a combustion chamber-side fire deck (7), with at least one injector sleeve (2) detachably connected to the cylinder head (1) for receiving an injection device, wherein the injector sleeve (2) is screwed to the fire deck (7) at a fire deck-side first end (5) via a first screw connection (4), and wherein the injector sleeve (2) has at least one radially projecting first support area (9) in the region of the first end (5) with a first support surface (10) facing the fire deck (7), which rests on a first counter surface (11) formed by the cylinder head (1), wherein the injector sleeve (2) - preferably in the region of a second end (6) facing away from the first end (5) - has at least one radially projecting second support area (12) with a second support surface (13) facing the fire deck (7), characterized by, that the second bearing surface (13) rests on a second counter surface (14) formed by the cylinder head (1), wherein in the relaxed state the distance (a) between the first counter surface (11) and the second counter surface (14) of the cylinder head (1) is greater than the distance (b) between the first bearing surface (10) and the second bearing surface (13) of the injector sleeve (2), so that in the screwed-in state the injector sleeve (2) is under a tensile preload caused by a preload tensile force. [2] Internal combustion engine according to claim 1, characterized by , that the first screw connection (4) is designed to exert the preload tensile force on the injector sleeve (2) installed in the cylinder head (1). [3] Internal combustion engine according to one of claims 1 or 2, characterized by , that the preload tensile force is designed to be at least large enough to prevent the injector sleeve (2) from lifting off due to the maximum cylinder pressure. [4] Internal combustion engine according to any one of claims 1 to 3, characterized by , that an external thread (16) of the injector sleeve (2) in the area of ​​the fire cover (7) is part of the first screw connection (4). [5] Internal combustion engine according to claim 4, characterized by , that the external thread (16) of the injector sleeve (2) is screwed into a threaded bore (17) of the fire deck (7). [6] Internal combustion engine according to claim 4, characterized by , that the external thread (16) of the injector sleeve (2) is screwed to a nut (19) which is supported on at least one shoulder (20, 21) of the fire deck (7) and which is arranged from the side of the combustion chamber (3) in a bore (22) of the fire deck (7). [7] Internal combustion engine according to any one of claims 1 to 6, characterized by, that an element, preferably a hollow screw (25), is screwed to the cylinder head (1) in the region of the second end (6) by a second screw connection (15), wherein the second screw connection (15) presses the second bearing surface (13) of the injector sleeve (2) against the second counter surface (14) of the cylinder head (1). [8] Internal combustion engine according to claim 7, characterized by , that the element with a pressure surface (23) facing the injector sleeve (2) acts on an attack surface (24) of the injector sleeve (2) in the area of ​​its second end (6). [9] Internal combustion engine according to any one of claims 1 to 8, characterized by , that the first support surface (10) is bonded to the first counter surface (11) and / or the second support surface (13) is bonded to the second counter surface (14).

Images