Cylinder head for an internal combustion engine

Abstract

Cylinder head (1) for an internal combustion engine, in particular a supercharged internal combustion engine, with at least one tumble-generating inlet port (2) opening into a combustion chamber (3), wherein a port wall (6) of the inlet port (2) has a molded-in flow separation edge (7) immediately upstream of a valve seat ring (4) in the region of a first side (5) further away from the cylinder axis (18), wherein the port wall (6) in the region of a second side (9) closer to the cylinder axis (18) and opposite the flow separation edge (7) is formed - within the manufacturing tolerances - essentially continuously and / or seamlessly between a material-removing reworked and an unmachined cast port region, characterized in that the opening region of the port wall (6) of the inlet port (2) is machined with a material-removing tool (8) having two conical regions (11, 12), wherein opposite surface lines (11a,11b) of the first conical region (11) enclose an angle (α) of approximately 90° ± 10° and opposite surface lines (12a, 12b) of the second conical region (12) enclose an angle (β) <60°.,

Description

The invention relates to a cylinder head for an internal combustion engine, in particular a supercharged internal combustion engine, having at least one tumble-generating inlet duct which opens into a combustion chamber, wherein a duct wall of the inlet duct has a integrally formed flow separation edge directly upstream of a valve seat ring in the region of a first side which is at a distance from the cylinder axis, wherein the duct wall is formed in the region of a second side which is closer to the cylinder axis and is opposite the separation edge--within the manufacturing tolerances--substantially continuously and / or transitionlessly between a material-removingly post-machined and an unprocessed cast duct region.AT 500 926 A2 discloses a supercharged internal combustion engine having tumble-generating inlet ducts which generate a tumble flow in the combustion chamber, the main flow directions of the partial flows which are drawn into the combustion chamber via the inlet valves each enclosing an acute angle with a longitudinal plane determined by the cylinder axes of a cylinder row. Each inlet duct has a flow separation edge formed directly upstream of the valve seat ring, wherein the flow separation edge is formed by a intersection of the essentially continuously running inflow part of the inlet duct with a conical wall section widening in the flow direction in the region of the valve seat ring. The conical wall section is worked in by a control milling cutter which is adjusted coaxially with respect to the valve seat ring axis, wherein the control milling cutter has a cylindrical, conical or curved jacket region. As a result of this material-removing reworking of the opening region of the inlet duct, on the side of the duct wall opposite the flow separation edge, as a result of the intersection of the conical reworking region with the unprocessed duct wall, a discontinuity formed by an edge is produced, which leads to flow turbulences of the inlet flow. It has been found in practice that deposits are produced on the duct wall as a result of these flow turbulences, which deposits could cause engine damage in the event of detachments.EP 1 215 377 A1 discloses a cylinder head for an internal combustion engine having an inlet duct which opens into a combustion chamber and is formed so as to generate a tumble and which has an integrally formed flow separation edge in the region of a first side which is remote from the cylinder axis. In the region of a second side opposite the first side, the channel wall is formed substantially continuously or transitionless between a subsequently machined and an unprocessed cast channel region.WO 2003 / 012 267 A1 discloses a cylinder head with a tumble-generating duct, in which the tear-off edge is part of the valve seat ring.US 2004 / 0 221 830 A1 shows an inlet duct with a tear-off edge, in which the duct wall downstream of the tear-off edge encloses an angle of approximately 90° with an opposite duct wall.It is an object of the invention to avoid these disadvantages and to avoid deposits on the duct wall in an internal combustion engine of the type mentioned at the beginning.According to the invention, this is achieved in that the mouth region of the channel wall of the inlet channel is machined with a material-removing tool having two conical regions, wherein opposite surface lines of the first conical region enclose an angle of approximately 90°±10° and opposite surface lines of the second conical region enclose an angle <60°.Preferably, the inner circumferential surface of the valve seat ring is conically shaped.Furthermore, deposits can be avoided if the inner lateral surface of the valve seat ring merges continuously into the duct wall in the region of the second side of the duct wall, wherein the transition region between the second side of the duct wall and the valve seat ring preferably has a radius of curvature of between approximately 3 mm and 25 mm.Within the scope of the invention, it can furthermore be provided that, viewed in a longitudinal section, a tangent on the first side of the duct wall downstream of the flow separation edge and a tangent on the second side of the duct wall enclose an angle of approximately 90°±10°, and that opposite surface lines of the inner surface area of the valve seat ring or tangents enclose an angle <60° thereon.It is particularly advantageous if the material-removing tool has a transition radius between 3 mm and 25 mm between the first conical region and the second conical region.It is essential that no intersecting edge occurs between the post-machined and the unmachined region of the inlet duct in the region of the second side of the duct wall, which might lead to detachments and turbulences of the inlet flow. The machined surface of the channel wall must thus be formed as tangentially as possible to the unprocessed channel wall, which is ensured by the features mentioned. It is furthermore important that a harmonic transition of the channel wall and / or the lateral surface of the valve seat ring is formed between the inlet channel and the valve seat ring.The invention is explained in more detail below with reference to the figures. The following are shown: FIG. 1 shows an inlet duct of an internal combustion engine according to the invention in longitudinal section; FIG. 2 shows detail II of the inlet duct from FIG. 1 ; FIG. 3 shows detail III of the inlet duct from FIG. 1 ; and FIG. 4 shows detail IV of the inlet duct in FIG. 1.FIG. 1 shows a cylinder head 1 of an internal combustion engine according to the invention with an inlet duct 2 which is designed to generate a tumble and opens into a combustion chamber 3 at a shallow angle. In the opening region of the inlet duct 2 into the combustion chamber 3, a valve seat ring 4 is arranged in the cylinder head 1. In the region of a first side 5 of the duct wall 6 of the inlet duct 2, which is arranged in a region remote from the cylinder axis 18, a flow separation edge 7 is formed in the duct wall 6 directly upstream of the valve seat ring 4. The stall edge 7 is formed by post-machining the cast inlet channel 2 with a tool indicated by reference numeral 8, for example a control milling cutter. The dashed lines 8a indicate a tool known from the prior art. The control cut formed with the known tool 8a has hitherto had the disadvantage that pronounced transition edges have been produced on a second side 9 of the duct wall 6 of the inlet duct 2 lying opposite the first side 5 in the region 10a, 10b, which transition edges have led to the formation of dead spaces 10c and corresponding swirling of the inlet flow. These had the disadvantage that, up to now, severe deposit phenomena have occurred in the region of the second side 9, which could damage parts of the internal combustion engine to a greater or lesser extent when detached from the duct wall 6.In order to avoid this, the control cut is carried out according to a proposal of the invention with a substantially double conical tool 8 which has two differently conical regions 11, 12, the opposite surface lines 11 a, 11 b; 12 a, 12 bthereof spanning different sized angles α, β with one another. The opposite surface lines 11 a, 11 bof the first conical region 11 span an angle α of approximately 90° ±10°. The angle β between the opposite surface lines 12 a, 12 bof the second conical region 12 of the tool 8, on the other hand, is smaller than approximately 60°.Analogously, the angle α of tangents t 1, t 2 is defined on the first side 5 or the second side 9 of the channel wall 6. The angle β can also be defined by the opposite surface lines 4 b, 4 cof the inner surface 4 aof the valve seat ring 4.Alternatively, in the further embodiment variant according to the invention, which is entered with dash-dot lines in FIG. 2, a cylindrical region 19 can adjoin a single conical region 11, wherein a transition radius R of 3 to 25 mm is provided between the conical region 11 and the cylindrical region 19.In both cases, the transition radius produces a harmonic transition between the valve seat ring 4 and the channel wall 6.It is essential that during the post-processing by the material-removing tool 8, no sharp edge occurs between the machined surface and the non-machined surface of the inlet channel 2 in the region of the second side 9 of the channel wall 6-within the scope of the manufacturing tolerances. The casting tolerance is, for example, between 0.5 mm and 0.7 mm in the case of an inlet duct 2. This achieves the effect that the channel wall 6 is continuously curved between the dome 13 of the inlet valve 14 and the valve seat 15 of the valve seat ring 4 in the region of the second side 9, wherein a transition radius R between 3 mm and 25 mm is formed between a first straight section 16 of the channel wall 6 and a second straight section 17 in the region of the valve seat ring 4.A feature of the machining according to the invention is that the inner lateral surface 4 aof the valve seat ring 4 is not cylindrical, but is conical and is formed running with the channel wall 6 in the region of the second side 9 of the channel wall 6, wherein the transition radius R is formed in the transition between the channel wall 6 and the valve seat ring 4.By the described configuration of the inlet duct 2 with the specially shaped tool 8, deposits in the region of the second side 9 of the inlet duct 2 can be reliably prevented.

Claims

Cylinder head (1) for an internal combustion engine, in particular a supercharged internal combustion engine, having at least one tumble-generating inlet duct (2) which opens into a combustion chamber (3), wherein a duct wall (6) of the inlet duct (2) has a moulded-in flow separation edge (7) directly upstream of a valve seat ring (4) in the region of a first side (5) which is at a distance from the cylinder axis (18), wherein the duct wall (6) is formed - within the manufacturing tolerances - substantially continuously and / or transitionless between a material-removingly post-machined and an unprocessed cast duct region in the region of a second side (9) which is closer to the cylinder axis (18) and lies opposite the flow separation edge (7), characterized in that the opening region of the duct wall (6) of the inlet duct (2) is machined with a material-removing tool (8) having two conical regions (11, 12), wherein opposite surface lines (11a, 11b) of the first conical region (11) form an angle (α) of approximately 90°±10° and opposite surface lines (12a, 12b) of the second conical region (12) form an angle (β)<60°.Cylinder head (1) according to Claim 1, characterized in that the inner lateral surface (4a) of the valve seat ring (4) is of conical shape.Cylinder head (1) according to Claim 1 or 2, characterized in that the duct wall (6) merges continuously into the inner lateral surface (4a) of the valve seat ring (4) in the region of the second side (9) of the duct wall (6).Cylinder head (1) according to one of Claims 1 to 3, characterized in that the transition region between the second side (9) of the duct wall (6) and the valve seat ring (4) has a radius of curvature (R) of between approximately 3 mm and 25 mm.Cylinder head (1) according to one of Claims 1 to 4, characterized in that - as viewed in a longitudinal section - a tangent (t 1) on the first side (5) of the duct wall (6) downstream of the stall edge (7) and a tangent (t 2) on the second side (9) of the duct wall (6) enclose an angle (α) of approximately 90° ±10°.Cylinder head (1) according to one of Claims 1 to 5, characterized in that opposite surface lines (4b, 4c) of the inner surface (4a) of the valve seat ring (4) or tangents thereon enclose an angle (β) < 600°.Cylinder head (1) according to one of Claims 1 to 6, characterized in that a harmonic transition of the duct wall (6) and / or of the lateral surface (4a) of the valve seat ring (4) is formed between the inlet duct (2) and the valve seat ring (4).Cylinder head (1) according to one of Claims 1 to 7, characterized in that the material-removing tool (8) has a transition radius (R) between the first conical region (11) and the second conical region (12) of between 3 mm and 25 mm.

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