Internal combustion engine

Abstract

The invention relates to a camshaft (12, 14) for an internal combustion engine, with a recess (20) which is formed in a shell surface (18) on the outer circumference of the camshaft (12, 14) and which is open towards the outside in the radial direction of the camshaft (12, 14) and into which a tool can be plugged and thus brought into positively locking interaction with the camshaft (12, 14), as a result of which the camshaft (12, 14) can be secured against rotation by means of the tool, wherein the recess (20) is arranged offset in the radial direction with respect to the centre (M) of the camshaft (12, 14).

Description

[0001] The invention relates to an internal combustion engine according to the preamble of patent claim 1.

[0002] An internal combustion engine and such a bearing arrangement for camshafts on a cylinder head of the internal combustion engine are already known, for example, from DE 20 2015 008 502 U1. In the bearing arrangement, the respective camshaft is rotatably mounted on the cylinder head. In addition, the respective camshaft has a recess formed in a respective outer circumferential surface of the respective camshaft and open outwards in the radial direction of the respective camshaft, into which recess a tool can be inserted and thereby brought into positive engagement with the respective camshaft. In this way, for example, a torque can be transmitted between the tool and the camshaft, such that the respective camshaft can be secured by means of the tool against rotation, in particular relative to the cylinder head.Furthermore, DE 10 2010 024 721 A1 discloses a cam for a camshaft for an internal combustion engine, wherein the cam has an axial extension with a holding contour suitable for a holding tool. Furthermore, DE 20 2015 105 757 U1 discloses a device for installing and positioning a camshaft of an engine.

[0003] The object of the present invention is to further develop an internal combustion engine of the type mentioned at the outset in such a way that material, weight and costs can be saved.

[0004] This object is achieved by an internal combustion engine having the features of patent claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0005] In order to further develop a camshaft in such a way that particularly simple assembly can be achieved, the recess is arranged radially offset from the center of the camshaft. The center of the camshaft is understood to mean, in particular, its longitudinal axis or longitudinal central axis, which, for example, coincides with a rotational axis about which the camshaft is rotatably mounted on a cylinder head of the internal combustion engine, which is preferably designed as a reciprocating piston engine.

[0006] Advantageously, the wall areas bordering the recess in a section through the recess perpendicular to the camshaft are dimensioned differently in terms of their height and / or wall thickness, thus adapting to the load. This allows the mass of the camshaft to be kept low.

[0007] In order to further develop a bearing arrangement of the type specified in the preamble of claim 1 in such a way that particularly simple assembly of the internal combustion engine can be achieved, it is provided that the respective recess is arranged radially offset from the respective center of the respective camshaft. Advantages and advantageous embodiments of the camshaft according to the invention are to be regarded as advantages and advantageous embodiments of the bearing arrangement according to the invention, and vice versa.

[0008] The invention is based in particular on the following findings: A camshaft for an internal combustion engine can have flat surfaces on both sides of its outer circumference, which form a so-called dihedral. This means that the flat surfaces are arranged, for example, in the radial direction of the camshaft on opposite or opposite sides of the camshaft. A wrench-shaped tool can be applied to the dihedral, i.e. the flat surfaces, whereby the wrench-shaped tool can be brought into positive engagement with the camshaft. This allows a torque to be transmitted between the wrench-shaped tool and the camshaft, whereby the camshaft can be secured against twisting relative to the cylinder head.This is advantageous, for example, when a camshaft adjuster, also known as a phase adjuster, is screwed to the camshaft, particularly at the front. The camshaft is held in place by the tool to prevent the camshaft from twisting when screwing the phase adjuster to the camshaft, or to allow a screw element used to screw the camshaft adjuster to the camshaft to rotate relative to the camshaft and thus screw it to the camshaft.

[0009] A cylinder head cover is usually placed on the cylinder head and camshaft. In order to bring the tool into the previously described, positive engagement with the camshaft without having to dismantle the cylinder head cover, the cylinder head cover usually has a through-opening formed in or on an upper side of the cylinder head cover, which is also simply referred to as the cover. The through-opening is an auxiliary assembly opening through which the tool can reach. Since, for example, at least or exactly two camshafts are rotatably mounted on the cylinder head, with each of the camshafts having a dihedral, the cylinder head cover has an auxiliary assembly opening for each dihedral, so that the cylinder head cover can have two auxiliary assembly openings.If the previously described two-flat tool and the open-end wrench-shaped tool, also known as an open-end wrench, are used to secure the respective camshaft against twisting, the respective assembly aid opening must be relatively large, since the open-end wrench must grip the two-flat tool or the respective camshaft.

[0010] Such an excessively large through-opening in the cylinder head cover can undesirably weaken the cylinder head cover or the cylinder head cover must be designed to be particularly solid in other areas adjacent to the respective auxiliary assembly opening, thus requiring a high weight and installation space.

[0011] Since the invention now provides for the use of the described recess instead of a double flat to secure the camshaft against twisting, the auxiliary assembly opening can be kept particularly small. As a result, the cylinder head cover can be designed to be sufficiently stable in a space-saving, weight-saving, and cost-effective manner. Furthermore, particularly simple, and therefore time- and cost-effective, assembly is possible.

[0012] In an advantageous development of the invention, the respective recesses of the two camshafts of a cylinder head in which two camshafts are rotatably mounted are arranged offset mirror-symmetrically relative to a plane perpendicular to the plane spanned by the longitudinal center axes of the two camshafts, in particular toward the cylinder head center. This makes it possible to offset the two auxiliary assembly openings toward the cylinder head center, or to minimize the overall opening width of a single auxiliary assembly opening common to both camshafts.

[0013] Preferably, at least one of the auxiliary assembly openings is covered by a component of the internal combustion engine, such as an ignition coil, in a fully manufactured state. This eliminates the need for an additional cover for the auxiliary assembly opening separate from the component, thus keeping the cost and weight of the camshaft bearing assembly, or rather the internal combustion engine, low.

[0014] Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing.

[0015] The drawing shows: Fig. 1 shows a partial schematic front view, sectioned through a plane perpendicular to the plane spanned by the longitudinal center axes of the two camshafts, of a bearing arrangement according to the invention for two camshafts according to the invention on a cylinder head of an internal combustion engine, in particular for a motor vehicle; and Fig. 2 shows a partial schematic plan view of the bearing arrangement.

[0016] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0017] Fig. 1 shows, in a schematic and sectional front view, a bearing arrangement 10 of a first camshaft 12 and a second camshaft 14 on a cylinder head 16 of an internal combustion engine of a motor vehicle designed as a reciprocating piston engine. This means that the motor vehicle, which is preferably designed as a motor vehicle, in particular as a passenger car, in its fully manufactured state has the internal combustion engine and thus the camshafts 12 and 14, the cylinder head 16 and the bearing arrangement 10. In the bearing arrangement 10, the camshafts 12 and 14 are rotatably mounted on the cylinder head 16, such that the respective camshaft 12 or 14 can be rotated about a respective axis of rotation relative to the cylinder head 16. The axes of rotation of the camshafts 12 and 14 run parallel to one another and are spaced apart from one another.The respective axis of rotation of the respective camshaft 12 or 14 runs through their respective, in . Fig. 1 center designated M. Thus, the axis of rotation coincides with a respective longitudinal axis or longitudinal center axis of the respective camshaft 12 or 14 passing through the respective center M.

[0018] The respective camshaft 12 or 14 has a respective recess 20 formed in a respective outer circumferential surface 18 of the respective camshaft 12 or 14, which, in the exemplary embodiment shown in the figures, is designed as a blind hole. In particular, the respective recess 20 is a bore, in particular a blind hole.

[0019] During assembly of the cylinder head 16 and thus of the internal combustion engine as a whole, after installation of the camshafts 12 and 14, i.e. after the camshafts 12 and 14 have been rotatably mounted on the cylinder head 16, a phase adjuster, also referred to as a camshaft adjuster, is screwed onto at least one of the camshafts 12 and 14 or onto both camshafts 12 and 14. For this purpose, a central screw is used which is screwed at least substantially centrally, i.e. in the center M of the respective camshaft 12 or 14, into the respective camshaft 12 or 14 and thus screwed to the respective camshaft 12 or 14, in order to screw the respective camshaft adjuster onto the respective camshaft 12 or 14 and thus connect it to the respective camshaft 12 or 14.The camshaft adjuster makes it possible to rotate the respective camshaft 12 or 14 relative to an output shaft of the internal combustion engine, which is designed as a crankshaft, for example, and thus to adjust its phase, while the respective camshaft 12 or 14 is coupled to the output shaft in a torque-transmitting manner and is driven, for example, by the output shaft.

[0020] In order to screw and in particular tighten the central screw to the respective camshaft 12 or 14 using a tightening torque, and so that a desired angular orientation is established between the respective camshaft 12 or 14 and the respective camshaft adjuster, the respective camshaft 12 or 14 is rigidly locked with respect to the cylinder head 16 with regard to its rotational position, i.e., secured against rotation relative to the cylinder head 16. As a result, a tightening torque by means of which the central screw is screwed and in particular tightened to the respective camshaft 12 or 14 can be supported, so that the central screw can be screwed and in particular tightened to the respective camshaft 12 or 14.

[0021] In order to prevent such rotation of the respective camshaft 12 or 14 relative to the cylinder head 16, the respective camshaft 12 or 14 is locked. For this purpose, it is fundamentally conceivable for the respective camshaft 12 or 14 to have flat surfaces on both sides of its outer circumference, which form a dihedral. This is to be understood in particular that the flat or level surfaces are arranged on opposite sides, in particular in the radial direction of the camshaft 12 or 14. A tool in the shape of an open-end wrench, also referred to as an open-end wrench, can be applied to the dihedral and thus to the flat surfaces and thus brought into positive engagement with the respective camshaft 12 or 14.As a result, a torque can be transmitted between the open-end wrench and the respective camshaft 12 or 14, by means of which torque the camshaft 12 or 14 can be secured against rotation relative to the cylinder head 16 and thus the aforementioned tightening torque can be supported or applied.

[0022] Out of Fig. 1 It can be seen that the internal combustion engine has a cylinder head cover 22 which is formed separately from the cylinder head 16 and is also simply referred to as a cover. This cover is placed on the cylinder head 16 and the camshafts 12 and 14 and is thus arranged above the cylinder head 16 and the camshafts 12 and 14. By means of the cylinder head cover 22, the cylinder head 16 and the camshafts 12 and 14 are each at least partially, in particular at least predominantly, covered and thus concealed in the vertical direction of the internal combustion engine. The cover has, for example, a respective through-opening 24 for each two-flat section and thus for each camshaft 12 or 14.When using the previously described open-end wrench, the respective through-opening 24 must be sufficiently large to allow the open-end wrench to reach through the respective through-opening 24 and subsequently engage the respective two-flat portion, i.e., to engage the respective two-flat portion with a positive fit. When using the open-end wrench, the through-opening 24 must be relatively large, as the open-end wrench must grip the respective camshaft 12 or 14, respectively, and its jaws must be powerfully dimensioned to absorb the torque. If two camshafts 12 and 14 are provided, the two required through-openings 24, located side by side, occupy almost the entire width of the cylinder head cover 22.

[0023] In order to achieve particularly simple assembly on the one hand and to avoid undesired weakening of the cylinder head cover 22 on the other, the aforementioned double flat is not provided, but rather the respective camshaft 12 or 14 has the respective recess 20, into which a tool, in particular different from an open-end wrench, can be inserted and thereby brought into positive engagement with the respective camshaft 12 or 14, whereby the camshaft 12 or 14 can be secured by means of the tool against rotation relative to the cylinder head 16. The respective recess 20, designed for example as a bore, is arranged offset in the radial direction of the respective camshaft 12 or 14 from the respective center M of the respective camshaft 12 or 14.As a result, the through openings 24, which are also simply referred to as openings, can be designed to be particularly small, whereby excessive weakening of the cylinder head cover 22 can be avoided.

[0024] The two recesses 20 are arranged with mirror symmetry offset relative to a plane perpendicular to the plane spanned by the longitudinal center axes of the two camshafts (12, 14). This mirror symmetry arrangement results in the two recesses 20 being spaced closer to each other than the two longitudinal center axes of the camshafts (12, 14). Therefore, the two through-openings 24 are also spaced closer than the two longitudinal center axes of the camshafts (12, 14).

[0025] Out of Fig. 1 It can be seen that the respective through-opening 24, in particular in the fully manufactured state of the internal combustion engine, is closed by means of a respective cover 26. Furthermore, it is provided that a first wall region W1 which at least partially delimits a first of the through-openings 24 and which preferably at least predominantly, in particular completely, surrounds and thus delimits the first through-opening 24, and a second wall region W2 of the cylinder head cover 22 which at least partially, in particular at least predominantly or completely, surrounds and thus delimits the second through-opening 24, are arranged at different heights in the vertical direction of the internal combustion engine. In this case, the wall regions W1 and W2 are formed integrally with one another. The wall regions W1 and W2 are also referred to as flanks.The through-openings 24 are arranged in respective imaginary and spaced-apart planes, which are spaced apart from one another in the vertical direction of the internal combustion engine. As a result, the through-openings 24 are arranged at the aforementioned, different heights.

[0026] Compared to conventional solutions, the through-openings 24 can be designed to be significantly smaller, i.e., as significantly smaller assembly openings. If the heights of the wall areas W1 and W2, also referred to as flank heights, and thus of the through-openings 24, are different depending on the load, so that the openings are arranged at different heights, and / or if the wall areas W1 and W2 (flanks) are designed with different thicknesses or strengths, material and thus weight and costs can be saved. In internal combustion engines, also simply referred to as motors or internal combustion engines, whose camshafts 12 and 14 rotate in opposite directions or have an opposite direction of rotation, the central screws are rotated in different directions and thus using a right-hand thread and a left-hand thread, and are thus screwed and tightened or tightened.Therefore, the effective directions of the tightening torques to be supported are opposite to each other. A mirror-symmetrical design of the recesses 20, also referred to as locking openings, enables a load-adapted design for both camshafts 12 and 14. The wall areas bordering the recess (20) are dimensioned differently in terms of their height and wall thickness. Furthermore, in the embodiment shown in the figures, the recesses 20 are arranged at different heights. Furthermore, the centers M are arranged at different heights.

[0027] If the recesses 20 are offset towards the cylinder or cylinder head center, as shown in Fig. 1 As shown, for example, the respective ignition coils can be arranged toward the center and further away from an exhaust gas turbocharger. This keeps their thermal load low. If the recesses 20, also referred to as support openings, are arranged mirror-symmetrically to the cylinder center or cylinder head center, both through-openings 24, also referred to as auxiliary assembly openings, together require a particularly small width in or on the cylinder head cover 22. If another component covers the respective auxiliary assembly opening, the respective cover 26, also referred to as a closure cover, can be avoided.

[0028] The previously mentioned cylinder head center is in Fig. 1 and labeled M2. The aforementioned turbocharger is also visible, which is located in Fig. 1 designated 28 and has a compressor wheel 30, a shaft 32, also referred to as a turbocharger shaft, and a turbine wheel 34 driven by exhaust gas from the internal combustion engine. The compressor wheel 30 and the turbine wheel 34 are impellers, each of which is connected in a rotationally fixed manner to the shaft 32. As a result, the compressor wheel 30 can be driven by the turbine wheel 34 via the shaft 32, by means of which air, which is supplied to at least one combustion chamber of the internal combustion engine, is compressed. In addition, Fig. 1 an oil return 36 with a pipe elbow can be seen.

[0029] Fig. 2 shows the bearing arrangement 10 in a schematic plan view. Fig. 2 One of the previously mentioned ignition coils is identified by 38. A double arrow 40 in Fig. 2 1 illustrates a distance between the ignition coil 38 and an exhaust system of the internal combustion engine through which exhaust gas from the combustion chamber flows. Furthermore, it is provided, for example, that the camshaft 12 is an intake camshaft and the camshaft 14 is an exhaust camshaft. Furthermore, according to Fig. 2 the respective recess 20 is formed as a groove, the respective center of which is in Fig. 2 marked M3. Particularly good Fig. 2It can be seen that the respective recess 20, in particular its respective center M3, of the respective camshaft 12 or 14 is arranged in the radial direction of the respective camshaft 12 or 14, mirror-symmetrically offset from the other camshaft 14 or 12, and thus from the cylinder head center M2. The same applies to the respective through-opening 24, in particular its respective center, in particular relative to the respective center M of the respective camshaft 12 or 14.

Claims

1. An internal combustion engine having a bearing arrangement (10) of a first camshaft (12) and a second camshaft (14) on a cylinder head (16) of the internal combustion engine, in which the particular camshaft (12, 14) is rotatably mounted on the cylinder head (16) and has a recess that is formed in a particular outer circumferential jacket surface (18) of the particular camshaft (12, 14) and is open to the outside in the radial direction of the particular camshaft (12, 14), into which recess a tool can be inserted and thereby brought into positive engagement with the particular camshaft (12, 14), whereby the particular camshaft (12, 14) can be secured against rotation by means of the tool, wherein the particular recess (20) is arranged offset in the radial direction with respect to the particular center (M) of the particular camshaft (12, 14), and wherein a cylinder head cover (22) is placed on the cylinder head (16) and the camshafts (12, 14), which cylinder head cover (22) has, for each recess (20), a through opening (24) associated with the particular recess (20) through which the tool can be inserted, characterized in that a first wall region (W1) of the cylinder head cover (22) at least partially delimiting a first of the through openings (24) and a second wall region (W2) of the cylinder head cover (22) at least partially delimiting a second of the through openings (24) and the recesses (20) are arranged at different heights.

2. The internal combustion engine having the bearing arrangement (10) according to claim 1, characterized in that the through opening (24) is covered by a component of the internal combustion engine, such as an ignition coil, in a fully manufactured state of the internal combustion engine.

3. The internal combustion engine having the bearing arrangement (10) according to any of the preceding claims, characterized in that the wall regions (W1, W2) are formed integrally with one another.

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