Internal combustion engine having at least one cylinder

Abstract

The present invention relates to a cylinder head (1) for an internal combustion engine having at least one cylinder (16) with a top-down cooling system, comprising a first sub-cooling chamber (2) adjacent to an intermediate deck (4) and spaced apart from the combustion chamber, and a second sub-cooling chamber (3) adjacent to a fire deck (5) and arranged near the combustion chamber, wherein the intermediate deck (4) is arranged between the first sub-cooling chamber (2) and the second sub-cooling chamber (3), and wherein at least one preferably annular first transition opening (11) is arranged between the first sub-cooling chamber (2) and the second sub-cooling chamber (3) in the region of a central receptacle (10) for an injection or ignition device, the central receptacle (10) preferably being formed concentrically with respect to the cylinder axis (16a) of the cylinder. According to the invention, in order to improve the cooling of thermally highly stressed parts of the cylinder head (1), at least one second transfer opening (12a, 12b, 12c, 12d) between the first sub-cooling chamber (2) and the second sub-cooling chamber (3) is arranged in the region of at least one valve bridge (8a, 8b, 8c, 8d) between two adjacent gas exchange valves (7a, 7b, 7c, 7d).

Description

[Technical field]

[0001] The present invention relates to a cylinder head for an internal combustion engine having at least one cylinder with a top-down cooling system, comprising a first sub-cooling chamber adjacent to an intermediate deck and spaced apart from a combustion chamber, and a second sub-cooling chamber adjacent to a fire deck and arranged near said combustion chamber, wherein said intermediate deck is arranged between said first and second sub-cooling chambers, and wherein at least one preferably annular first transition opening is arranged between said first and second sub-cooling chambers in the region of a central receptacle for an injection or ignition device, preferably formed concentrically with respect to the cylinder axis of said cylinder.Furthermore, the present invention also relates to a method for cooling said cylinder head. [Background technology]

[0002] In a cylinder head with two cooling chambers arranged one above the other, top-down cooling is a cooling concept in which the coolant flows from the upper cooling chamber through a transition opening into the lower cooling chamber, the coolant inlet being located in the area of ​​the upper cooling chamber and the coolant outlet being located in the area of ​​the lower cooling chamber.

[0003] Cylinder heads operating on the basis of the top-down cooling concept are known, for example, from patent documents 1 to 3 (US 10047660, WO 2012 / 004340 or WO 2018 / 037368).

[0004] Nos. 6,681,727 and 6,899,063 describe cylinder heads with upper and lower cooling chambers separated from each other by an intermediate deck. In the region of the central receptacle for the fuel injector in each case, transition openings are arranged in the intermediate deck in order to connect the two cooling chambers to each other in flow. Furthermore, one vent opening is provided in the intermediate deck for each cylinder in order to prevent the accumulation of gas bubbles in the lower cooling chambers. Each vent opening is located in the region of a transverse plane passing through the cylinder axis radially outside the valve bridge and is further away from the cylinder axis than the axis of the gas exchange valve. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 10047660 [Patent Document 2] International Publication No. 2012 / 004340 [Patent Document 3] International Publication No. 2018 / 037368 [Patent Document 4] U.S. Patent No. 6,681,727 [Patent Document 5] U.S. Patent No. 6,899,063 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the invention is to improve the cooling of thermally highly stressed parts of a cylinder head. [Means for solving the problem]

[0007] Based on a cylinder head of the type described at the beginning, this problem is solved according to the invention in that at least one second transition opening is arranged between the first and the second sub-cooling chamber in the region of at least one valve bridge between two adjacent gas exchange valves.

[0008] It is advantageous if the first sub-cooling chamber is arranged above the second sub-cooling chamber, such that the cooling liquid flows from the first sub-cooling chamber through the first transition opening and at least one second transition opening into the second sub-cooling chamber in the region between two adjacent gas exchange valves. This provides top-down cooling. The cooling liquid flows from the upper (first) sub-cooling chamber into the lower (second) sub-cooling chamber.

[0009] It is further advantageous if the first transition opening is formed with a particular continuous taper in the direction of the second sub-cooling chamber. In particular, this taper is configured to extend into the central part, i.e., so that material is removed from the central part. In principle, the taper can also be formed non-uniformly, in which case it consists of a number of adjacent partial elements with different angles of inclination. In particular, the taper is created by conical machining of the cylinder head.

[0010] The at least one second transition opening is advantageously configured and arranged parallel to the cylinder axis or inclined with respect to the flow direction of the coolant (specifically in the range of 0 degrees to 45 degrees from the cylinder axis).

[0011] However, it is particularly preferred to configure the second transition openings in the direction of flow of the coolant in the valve bridge at an inclination of about 0° to about 45°, in particular about 15° and about 30°, from the cylinder axis. This inclination of the transition openings allows a particularly efficient flow of the coolant, which results in a particularly efficient cooling of the valve bridge and the cylinder head as a whole. The distance of the second transition openings is preferably about 15% to about 40% of the diameter of the cylinder bore. Furthermore, the at least one second transition opening can be arranged centrally or off-centrally with respect to the valve bridge. If more than one second transition opening is provided for each valve bridge, it can be advantageous to configure these to have an offset with respect to the longitudinal direction of the valve bridge.

[0012] At least one second transition opening is advantageously arranged above, preferably towards, a local hot spot of the fire deck, thereby ensuring efficient heat diffusion. A local hot spot is defined as a thermally stressed area of ​​the fire deck with a local temperature peak, for example a valve bridge of the fire deck between two outlet valves or between an outlet valve and an inlet valve of a gas exchange valve.

[0013] The separate secondary transition openings allow for targeted inflow, thereby allowing for improved cooling in desired areas, and can also be used for venting when the engine is not running.

[0014] The second transition opening can be manufactured by a casting method or by a material removal manufacturing process. For ease of manufacturing, it is advantageous to arrange the second transition opening substantially parallel to the cylinder axis.

[0015] In the context of the present invention, a top-down cooling system as mentioned above is understood to mean a cooling system in which, in the case of a cylinder head with two cooling chambers arranged one above the other, the coolant flows from the upper cooling chamber through a transition opening into the lower cooling chamber, the coolant inlet being arranged in the area of ​​the upper cooling chamber and the coolant outlet being arranged in the area of ​​the lower cooling chamber.

[0016] The second sub-cooling chamber thus adjoins both the fire deck and the intermediate deck, whereby the intermediate deck separates the first and second sub-cooling chambers, which are flow connected by the first transition opening and the at least one second transition opening. The first transition opening is in particular annular in shape and is preferably arranged concentrically around the central receptacle. In other words, the first transition opening allows a flow transition between the first and second sub-cooling chambers in the entire area radially around the central receptacle.

[0017] Preferably, the distance between the at least one second transition opening and the cylinder axis is 15%-40%, preferably 20%-25%, particularly preferably about 20% of the diameter of the cylinder. This distance allows, on the one hand, a particularly efficient cooling and, on the other hand, a relatively simple manufacture of the cylinder head. In the context of the present invention, the diameter of the cylinder means, in particular, the cylinder bore diameter. The transition openings are shaped and arranged for the transition of the cooling water. Particularly preferably, the distance of the transition of the cooling water around the sleeve is about 10%-20% of the cylinder bore diameter.

[0018] In another embodiment of the invention, at least one second transition opening is arranged in the region of the first valve bridge and at least one further second transition opening is arranged in the region of the second valve bridge. In one embodiment of the invention, at least one second transition opening is arranged in the region of the first valve bridge, in the region of the second valve bridge and in the region of the third valve bridge, preferably also in the region of the fourth valve bridge. This allows a uniform flow of the coolant and thus a uniform and efficient cooling of the areas subjected to high thermal loads.

[0019] In one embodiment variant of the invention, at least two second transition openings are arranged equidistantly from the cylinder axis. In particular, the centers of at least three second transition openings are arranged on a center line around the cylinder axis, the diameter of this center line being 30% to 80%, preferably 35% to 50%, particularly preferably about 40% of the cylinder diameter. Simulations within the scope of the invention have shown that with such an arrangement a particularly effective flow and cooling can be achieved.

[0020] In one embodiment variant of the invention, the distance between at least one second transition opening and the cylinder axis is smaller than the distance between a valve axis of an adjacent gas exchange valve and the cylinder axis.

[0021] The ratio of the sum of the cross sections of the first flow transfers to the sum of the cross sections of the second flow transfers essentially depends on the number of the separate transfers and / or the number of undesired heat inputs into the cylinder head.

[0022] The cylinder head is cooled by the cooling liquid flowing into the first sub-cooling chamber of the cylinder head, at least a part of the cooling liquid flowing from the first sub-cooling chamber in the region of a central receptacle for an injection or ignition device through at least one first transition opening into the second sub-cooling chamber, and the cooling liquid leaving the cylinder head after leaving the second sub-cooling chamber. According to the invention, at least another part of the cooling liquid flows from the first sub-cooling chamber into the second sub-cooling chamber through at least one second transition opening in the region of at least one valve bridge between two adjacent gas exchange valves.

[0023] The second transition opening is less subject to tolerances between the first and second sub-cooling chambers than the first cast transition opening.

[0024] The exact location of the second transition openings can be adapted to the respective cooling requirements in each case, and in doing so it is possible to generate very high turbulence in the desired areas to improve heat dissipation.

[0025] The invention will now be explained in more detail with reference to the non-limiting drawings. [Brief description of the drawings]

[0026] [Figure 1] 4 is a cross-sectional view of the cylinder head according to the present invention taken along line II in FIG. 3. [Diagram 2] FIG. 2 shows detail II from FIG. 1. [Diagram 3] 3 is a cross-sectional view of the cylinder head taken along line III-III in FIG. 1. [Figure 4] FIG. 11 is a diagram showing details of a cylinder head according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] 1-3 illustrate a cylinder head 1 configured for one or more cylinders 16. Each of the figures 1-3 illustrates a cylinder head 1 with one cylinder 16.

[0028] The cylinder head 1 configured with a top-down cooling system has a first sub-cooling chamber 2 above, i.e. remote from the combustion chamber, and a second sub-cooling chamber 3 below, i.e. close to the combustion chamber, the first sub-cooling chamber 2 being separated from the second sub-cooling chamber 3 by an intermediate deck 4. The second sub-cooling chamber 3 is adjacent to a fire deck 5 which forms the roof of the combustion chamber. The combustion chamber adjacent to the fire deck 5 is indicated by reference number 17.

[0029] A number of valve openings 6a, 6b, 6c, 6d for gas exchange valves 7a, 7b, 7c, 7d opening into the combustion chamber 17 are arranged on the fire deck 5 for each cylinder 16. The gas exchange valves 7a, 7b, 7c, 7d form inlet valves for supplying air or an air-fuel mixture to the combustion chamber and outlet valves for discharging exhaust gases from the combustion chamber 17. Valve bridges 8a, 8b, 8c, 8d are arranged between the valve openings 6a, 6b; 6b, 6c; 6c, 6d; 6d, 6a of adjacent gas exchange valves 7a, 7b, 7c, 7d.

[0030] In the region of the cylinder axis 16a, the cylinder head 1 has a central receptacle 10, for example formed by an insert sleeve, for a central element, for example a spark plug or an injector, which is formed, for example, concentrically relative to the cylinder axis 16a. In the region of the central receptacle 10, at least one first transition opening 11 is arranged between the first sub-cooling chamber 2 and the second sub-cooling chamber 3, which in this embodiment is formed by an annular gap between the intermediate deck 4 and the receptacle 10.

[0031] In addition to the first transition opening 11, at least one, preferably each, second transition opening 12a, 12b, 12c, 12d is arranged in the region of the valve bridge 8a, 8b, 8c, 8d at a certain distance from the cylinder axis 16a of the cylinder 16. The second transition openings 12a, 12b, 12c, 12d are formed parallel to the cylinder axis 16a. The centers 13a, 13b, 13c, 13d of these second transition openings 12a, 12b, 12c, 12d are arranged on a circular line 14 around the cylinder axis 16a, the diameter d of which is 30%-80%, for example 50%, of the diameter D of the cylinder 16. The distance between the center 13a, 13b, 13c, 13d of at least one second transition opening 12a, 12b, 12c, 12d and the cylinder axis 16a is smaller in this embodiment than the distance between the valve axis 9a, 9b, 9c, 9d of the adjacent gas exchange valve 7a, 7b, 7c, 7d and the cylinder axis 16a. In other words, the center 13a, 13b, 13c, 13d of the second transition opening 12a, 12b, 12c, 12d is arranged in this embodiment closer to the cylinder axis 16a than the valve axis 9a, 9b, 9c, 9d of the nearest gas exchange valve 7a, 7b, 7c, 7d.

[0032] 2, at least one secondary transition opening 12a, 12b, 12c, 12d is directed toward a hot spot 15 of the nearest valve bridge 8a, 8b, 8c, 8d of the fire deck 5. Thus, the separate secondary transition openings 12a, 12b, 12c, 12d allow for targeted flow and improved cooling in desired areas.

[0033] As shown by arrows S in Figures 1 and 2, coolant flows from the first sub-cooling chamber 2 through the first transition opening 11 and the second transition openings 12a, 12b, 12c, 12d into the second sub-cooling chamber 3 and then flows radially outward along the valve bridges 8a, 8b, 8c, 8d of the fire deck 5, absorbing and dissipating heat from hot spots 15 in areas subject to high thermal stress.

[0034] The arrangement of the second transition openings 12a, 12b, 12c, 12d, each of which can be individually configured for a particular case, allows for very high turbulence to be generated in the desired areas, thereby improving cooling.

[0035] A further advantage is that the flow S through the second transition openings 12a, 12b, 12c, 12d is less sensitive to manufacturing tolerances than the flow S through the first transition opening 11.

[0036] 4 shows a detail of another cylinder head 1 according to the invention, where the transfer opening 11 is tapered towards the second sub-cooling chamber 3, thereby allowing the coolant to flow towards the member. In a cross-sectional view, the tapered transfer opening 11 therefore represents a conical annular gap.

Claims

1. A cylinder head (1) for an internal combustion engine having at least one cylinder (16) with a top-down cooling system, the cylinder head (1) having a first sub-cooling chamber (2) adjacent to an intermediate deck (4) and remote from a combustion chamber, and a second sub-cooling chamber (3) adjacent to a fire deck (5) and close to said combustion chamber, the intermediate deck (4) being arranged between said first sub-cooling chamber (2) and said second sub-cooling chamber (3), at least one first transfer opening (11) being arranged between said first sub-cooling chamber (2) and said second sub-cooling chamber (3) in the region of a central receptacle (10) for an injection or ignition device, 1. A cylinder head comprising: at least one second transfer opening (12a, 12b, 12c, 12d) between the first sub-cooling chamber (2) and the second sub-cooling chamber (3) arranged in the region of at least one valve bridge (8a, 8b, 8c, 8d) between two adjacent gas exchange valves (7a, 7b, 7c, 7d); the cylinder head (1) comprises at least two valve bridges (8a, 8b, 8c, 8d); and a distance (a) between the at least one second transfer opening (12a, 12b, 12c, 12d) and a cylinder axis (16a) is smaller than a distance (A) between a valve axis (9a, 9b, 9c, 9d) of at least one adjacent gas exchange valve (7a, 7b, 7c, 7d) and the cylinder axis (16a).

2. 2. A cylinder head (1) according to claim 1, wherein the first transfer opening (11) is tubular.

3. 3. A cylinder head (1) according to claim 1 or 2, wherein the central receptacle (10) is arranged concentrically with respect to a cylinder axis (16a) of the cylinder.

4. 4. A cylinder head (1) according to claim 1, wherein the first sub-cooling chamber (2) is arranged above the second sub-cooling chamber (3) such that the coolant flows from the first sub-cooling chamber (2) into the second sub-cooling chamber (3) through the first transfer opening (11) and the at least one second transfer opening (12a, 12b, 12c, 12d) in the area between two adjacent gas exchange valves (7a, 7b, 7c, 7d).

5. A cylinder head according to any one of the preceding claims, wherein the first transfer opening (11) is formed with a particular continuous taper in the direction towards the second sub-cooling chamber (3).

6. 6. The cylinder head according to claim 1, wherein the second transfer opening (12a, 12b, 12c, 12d) is inclined in the flow direction of the coolant of the valve bridge (8a, 8b, 8c, 8d), and the inclination is greater than 0 degrees and is not more than 45 degrees from the cylinder axis.

7. 7. The cylinder head according to claim 6, wherein the inclination is from 15 degrees to 30 degrees from the cylinder axis.

8. 8. The cylinder head (1) according to any one of the preceding claims, wherein at least one second transfer opening (12a, 12b, 12c, 12d) is located above a hot spot (15) of the fire deck (5).

9. 9. The cylinder head (1) according to claim 8, wherein the second transfer openings (12a, 12b, 12c, 12d) are directed towards the hot spot (15).

10. 10. Cylinder head (1) according to any one of the preceding claims, wherein at least one second transfer opening (12a, 12b, 12c, 12d) is arranged parallel to the cylinder axis (16a).

11. A cylinder head (1) according to any one of claims 1 to 10, wherein a distance (a) between at least one second transfer opening (12a, 12b, 12c, 12d) and the cylinder axis (16a) is between 15% and 40% of a diameter (D) of the cylinder (16).

12. 12. The cylinder head (1) according to claim 11, wherein a distance (a) between at least one second transfer opening (12a, 12b, 12c, 12d) and the cylinder axis (16a) is between 20% and 25% of a diameter (D) of the cylinder (16).

13. 12. The cylinder head (1) according to claim 11, wherein the distance (a) between the at least one second transfer opening (12a, 12b, 12c, 12d) and the cylinder axis (16a) is 20% of the diameter (D) of the cylinder (16).

14. 14. A cylinder head (1) according to any one of the preceding claims, comprising at least two valve bridges (8a, 8b), wherein at least one second transfer opening (12a) is arranged in the region of a first valve bridge (8a) and at least another second transfer opening (12b) is arranged in the region of a second valve bridge (8b).

15. 15. A cylinder head (1) according to claim 14, characterized in that at least one second transfer opening (12a, 12b, 12c) is arranged respectively in the region of the first valve bridge (8a), in the region of the second valve bridge (8b) and in the region of the third valve bridge (8c).

16. 16. Cylinder head (1) according to claim 15, characterized in that a further second transfer opening (12d) is arranged in the region of the fourth valve bridge (8d).

17. 17. The cylinder head (1) according to any one of claims 14 to 16, wherein at least two second transfer openings (12a, 12b, 12c, 12d) are equidistant from the cylinder axis (16a).

18. 18. The cylinder head (1) according to claim 17, wherein the centres (13a, 13b, 13c, 13d) of the at least three second transfer openings (12a, 12b, 12c, 12d) are located on a circular line (14) around the cylinder axis (16a), the diameter (d) of this circular line being 30% to 80% of the diameter (D) of the cylinder (16).

19. The cylinder head (1) according to claim 18, wherein the diameter (d) of the circular line is between 35% and 50% of the diameter (D) of the cylinder (16).

20. 19. Cylinder head (1) according to claim 18, wherein the diameter (d) of the circular line is 40% of the diameter (D) of the cylinder (16).

21. A method for cooling a cylinder head (1) according to any one of claims 1 to 20, comprising the steps of: A method in which a coolant flows into the first sub-cooling chamber (2) of the cylinder head (1), at least a part of the coolant flows from the first sub-cooling chamber (2) through at least one first transfer opening (11) into the second sub-cooling chamber (3) in the region of the central receptacle (10) for an injection or ignition device, and the coolant leaves the cylinder head (1) after having flowed through the second sub-cooling chamber (3), wherein at least a part of the cooling liquid flows from the first sub-cooling chamber (2) into the second sub-cooling chamber (12a, 12b, 12c, 12d) via at least one second transfer opening (12a, 12b, 12c, 12d) in the region of at least one valve bridge (8a, 8b, 8c, 8d) between two adjacent gas exchange valves (7a, 7b, 7c, 7d).

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