Cylinder head for an internal combustion engine

Abstract

The invention relates to a cylinder head (1) for an internal combustion engine having at least one cylinder, having at least one valve seat ring (3) for a lifting valve, wherein the valve seat ring (3) is surrounded by an annular cooling duct (4) for a coolant that is at least partly molded into the cylinder head (1), wherein the cooling duct (4) at least partly surrounds the valve seat ring and extends between an inlet (5, 15, 25) and at least one outlet (6). In order to reduce the valve wear, provision is made for a plurality of inlets (5, 15, 25) to open into the cooling duct (4), wherein the inlets (5, 15, 25) are preferably arranged asymmetrically in relation to a meridian plane () of the valve seat ring (3) through the outlet (6).

Claims

1. A cylinder head for an internal combustion engine, comprising a cylinder, a valve seat ring for a lifting valve, an annular cooling duct for a coolant at least partly moulded into the cylinder head and at least partly surrounding the valve seat ring, the cooling duct including a plurality of inlets and one outlet, wherein the inlets are arranged asymmetrically in relation to a meridian plane of the valve seat ring which extends through the outlet, wherein a first inlet of said plurality of inlets opens obliquely into the cooling duct, so that an angle between a central line of a first inlet duct extending to the first inlet and a tangent of the cooling duct in a region of the first inlet is greater than 0 and less than 90, and a second inlet opens radially into the cooling duct, so that a central line of a second inlet duct extending to said second inlet extends at a 90 angle to a tangent of the cooling duct in a region of said second inlet.

2. The cylinder head according to claim 1, wherein the angle is <80.

3. The cylinder head according to claim 2, wherein the angle is <75.

4. The cylinder head according to claim 1, wherein one of said plurality of inlets is arranged diametrically opposite the outlet with respect to an axis of the valve seat ring.

5. The cylinder head according to claim 4, wherein the second inlet duct is arranged diametrically opposite the outlet with respect to an axis of the valve seat ring.

6. The cylinder head according to claim 1, wherein one of said plurality of inlets is arranged on a first side of a meridian plane of the valve seat ring through the outlet, said first side facing an exhaust valve bridge.

7. The cylinder head according to claim 1, wherein the cooling duct, when seen in a sectional view normally to the axis of the valve seat ring, comprises at least one substantially sickle-shaped indentation in the region of at least one inlet and/or the outlet.

8. A cylinder head according to claim 7, wherein the indentation substantially has the shape of a circular segment at least in part, and can be produced by a turning tool.

9. The cylinder head according to claim 7, wherein the indentation is arranged asymmetrically with respect to a meridian plane extending through the centre of the first inlet or the outlet.

10. The cylinder head according to claim 7, wherein the following applies to the radius r of the indentation with respect to the radius R of the cooling duct: 0.2.Math.Rr0.8.Math.R.

11. The cylinder head according to claim 7, wherein the central line of the inlet duct of an inlet opening obliquely into the cooling duct is arranged tangentially on a circle of curvature of an indentation of a further inlet which opens radially into the cooling duct.

12. The cylinder head according to claim 1, wherein at least two of said plurality of inlet ducts are arranged in such a way that their central lines extending through the respective inlets intersect in a point on a meridian plane of the valve seat ring through the outlet, and/or in a point in the region of a cooling jacket of a component which opens centrally into the combustion chamber.

13. The cylinder head according to claim 1, wherein the cooling duct of the valve seat ring is separated from a cooling system of the cylinder head.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in greater detail by reference to the drawings, wherein:

(2) FIG. 1 shows a cylinder head in accordance with the invention in a first embodiment in a sectional view along the line I-I in FIG. 3;

(3) FIG. 2 shows a cylinder head in accordance with the invention in a second embodiment in a sectional view analogously to FIG. 1;

(4) FIG. 3 shows the cylinder head in a sectional view along the line III-III in FIG. 1;

(5) FIG. 4 shows the detail IV of FIG. 3;

(6) FIG. 5 shows a cylinder head in accordance with the invention in a third embodiment in a sectional view analogously to FIG. 1;

(7) FIG. 6 shows a cylinder head in accordance with the invention in a fourth embodiment in a sectional view analogously to FIG. 1;

(8) FIG. 7 shows a cylinder head in accordance with the invention in a fifth embodiment in a sectional view analogously to FIG. 1, and

(9) FIG. 8 shows the cylinder head in a sectional view along the line VIII-VIII in FIG. 7.

DETAILED DESCRIPTION OF THE DEPICTED EMBODIMENTS

(10) Functionally identical parts are provided with the same reference numerals in the embodiments.

(11) The drawings show a cylinder head 1 for at least one cylinder 11 of an internal combustion engine, comprising at least one exhaust valve 2 which is formed by a lifting valve (not shown in greater detail) and of which only the exhaust valve opening is shown, wherein one valve seat ring 3 is arranged in (e.g., pressed into) the cylinder head 1 at least for each exhaust valve 2. The axis of the valve seat ring 3 is designated with reference numeral 3a. The valve seat ring 3, which is pressed or glued into the cylinder head 1, is surrounded by an annular cooling duct 4 for a coolant, which is formed in (e.g., milled into) the cylinder head 1 and which extends between at least one inlet 5 and one outlet 6 over an angular range a of at least 180 around the valve seat ring 3. In the embodiments, the cooling duct 4 is formed circumferentially around the valve seat ring 3. An interrupted configuration can also be considered. The inlet 5 is in connection with an inlet duct 5a, and the outlet 6 with an outlet duct 6a, wherein the inlet duct 5a and the outlet duct 6a can be formed by boreholes. The inlet duct 5a originates from a lateral surface 1a of the cylinder head 1 and is directed radially to the cylinder centre 11a. In the region of the cylinder centre 11a, a component 7 (e.g., a spark plug or an injection device), which opens centrally into the combustion chamber 14 of the cylinder 11, is arranged in the region of the cylinder centre 11a, wherein the component 7 is surrounded at least partly by a cooling chamber 8. The outlet duct 6a enters into the cooling chamber 8.

(12) FIG. 1 shows a first embodiment of a cylinder head 1, wherein the cooling duct 4 comprises a substantially sickle-shaped indentation 10 in the orifice region of the inlet duct 5a into the cooling duct 4, i.e., in the region of the inlet 5. The indentation 10 can substantially have the shape of a circular segment and can be produced by a cutting turning tool such as a milling cutter for example, Non-cutting production can also be considered, e.g., by an electric discharge machining method. The radius r of the indentation is advantageously selected from the range 0.2.Math.Rr0.8.Math.R, wherein preferably the radius r of the indentation 10 lies between preferably 0.4.Math.R and 0.6.Math.R. As a result of an indentation 10 formed in this manner, flow losses in the region of the inlet 5 can be reduced substantially. A similar indentation can also be provided in an analogous manner in the region of the outlet 6 (not shown in greater detail). In FIG. 1, the indentation 10 is symmetrically arranged in relation to a plane E extending through the central line 5.

(13) FIG. 2 shows a second embodiment which differs from FIG. 1 in such a way that the indentation 10 is arranged asymmetrically in relation to a meridian plane extending through the centre 5 of the inlet 5 and/or a meridian plane of the valve seat ring 3 extending through the outlet 6. The flow losses during the incoming flow of the coolant into the cooling duct 4 are reduced on the one hand and an asymmetric division of quantities of the coolant is produced on the other hand into the two annular sections 4a, 4b of the cooling duct 4. Higher heat dissipation can thus be achieved on one side of the meridian plane and than on the other side. In particular, the heat dissipation is increased on the side of the meridian plane , in which the major part of the sickle-shaped indentation 10 is arranged. FIG. 3 and FIG. 4 show the arrangement in a sectional view in the meridian plane , , wherein the inlet 5 is shown in detail in FIG. 4.

(14) FIG. 5 shows the cylinder head 1 in a third embodiment, wherein a tangential inlet 15 with a tangential inlet duct 15a is provided in addition to a radial inlet 5 having a radial inlet duct 5a. The tangential inlet duct 15a opens tangentially into the annular cooling duct 4. This leads to a pronounced highly asymmetrical coolant flow in the cooling duct 4, wherein a higher quantity of coolant flows according to the arrows S.sub.A, S.sub.B through the section 4a of the cooling duct 4 facing the exhaust valve bridge 12 than through the other section 4b that faces away, so that the cylinder head 1 is cooled more strongly on the side A of the Meridian plane and of the valve seat ring 3 than on the side B.

(15) FIG. 6 shows a fourth embodiment of the cylinder head 1, wherein similar to FIG. 5 a further inlet 25 with a further inlet duct 25a is provided in addition to the radial inlet 5. The further (oblique) inlet duct 25a opens on a side A of the plane and under an acute angle into the annular cooling duct 4, wherein the angle is formed between a tangent t on the annular cooling duct 4 in the region of the further (oblique) inlet 25 and the central line 25 of the second inlet duct 25. The angle is selected between 0 and 90. In the embodiment, the central line 25 of the oblique inlet duct 25a is arranged tangentially to a circle of curvature k with the radius of curvature r of an indentation 10 of the first inlet 5. This leads to a pronounced asymmetrical cooling flow according to the arrows S.sub.A, S.sub.B in the cooling duct 4, wherein a higher quantity of coolant flows through the section 4a of the cooling duct 4 facing the exhaust valve bridge 12 than through the other section 4b that faces away. The cylinder head 1 is also cooled more strongly here on the side A of the plane and than on the side B.

(16) FIG. 7 shows a fifth embodiment of the cylinder head 1 with a combination of the measures shown in FIG. 5 and FIG. 6. In addition to the radial inlet 5, two further inlets (i.e. a tangential inlet 15 and an oblique inlet 25) are provided, wherein the one tangential inlet 15 comprises a tangential inlet duct 15a which opens tangentially into the cooling duct 4 and the oblique inlet 25 comprises an oblique inlet duct 25a which enters at an acute angle into the cooling duct 4. The oblique cooling duct 25a enters into the annular cooling duct 4 on a side A of the plane and under an acute angle , wherein the angle is formed between a tangent t on the annular cooling duct 4 in the region of the oblique inlet 25 and the central line 25 of the oblique inlet duct 25. The angle is selected between 0 and 90. Both second inlet ducts 15a, 25a open into the annular cooling duct 4 on a side A of the plane and , which faces the exhaust valve bridge 12. This leads to an especially strongly pronounced asymmetrical coolant flow according to the arrows S.sub.A, S.sub.B in the cooling duct 4, wherein a substantially higher quantity of coolant flows through the section 4a of the cooling duct 4 facing the exhaust valve bridge 12 than through the other section 4b that faces away. The cylinder head 1 is thus cooled to a substantially higher extent on the side A of the plane than on the side B.

(17) As is shown in FIG. 5, FIG. 6 and FIG. 7, the inlet ducts 5, 15, 25 can be formed in such a way that their central lines 5, 15, 25 extending through the respective inlets 5, 15, 25 intersect in a point P on a meridian plane of the valve seat ring 3 through the outlet 6. The point P is advantageously located in the region of the cooling jacket 8 of the component 7 opening centrally into the combustion chamber 14. This allows simple production in combination with simultaneously highly effective heat dissipation from the region of the exhaust valve bridge 12.

(18) Boreholes for the first and second inlet ducts 5a, 15a, 25a are subsequently sealed in the region of the side surface is of the cylinder head 1 by plugs 9, 19, 29.

(19) The embodiments are shown by way of example with one single outlet 6 each. It is understood that configurations with several outlets lie within the scope of the invention.

(20) The inlet ducts 5a, 15a, 25a of the inlets 5, 15, 25 can be connected to a pressure source in the cylinder block 13 (indicated in FIG. 3 and FIG. 8), which is flanged onto the cylinder head 1, via vertical boreholes 5b, 15b, 25b, so that the coolant flow occurs from the inlets 5, 15, 25 to the outlets 6. The outlet duct 6a of the outlet 6 can be flow-connected via the cooling jacket 8 of the central component 7 to the cooling jacket 8 of the cylinder head 1. Alternatively thereto, embodiments with reversed coolant flow from the outlets 6 to the inlets 5, 15, 25 can be considered, in which therefore the outlets 6 are connected to a pressure source and the inlets 5, 15, 25 are connected to a pressure sink. The scope of protection of the present application covers all possible directions of coolant flow.

(21) Variants can also be considered within the scope of the present application in which the coolant circuit for the coolant ducts 4 are formed for cooling the valve seat rings 3 separate from the cooling circuit of the cylinder head 1. As a result, various cooling media such as cooling water on the one hand and lubricating oil on the other hand can thus be used for cooling the cylinder head 1 and for cooling the valve seat rings 3.