Internal combustion engine with cooled turbine

Abstract

An internal combustion engine has a cylinder head with at least one cylinder and a cooled turbine. Each cylinder has at least one outlet opening adjoined by an exhaust line for discharging exhaust gases from the cylinder. The exhaust line issues into an inlet region transitioning into an exhaust gas-conducting flow duct of the turbine. The turbine has at least one rotor mounted on a rotatable shaft in a turbine housing. The turbine has at least one coolant duct which is integrated in the housing and which is delimited and formed by at least one wall of the housing to form a cooling arrangement. The at least one wall of the turbine housing that delimits the at least one coolant duct is provided, at least in regions, with a thermal insulation.

Claims

1. An internal combustion engine comprising: at least one cylinder head having at least one cylinder, each cylinder having at least one outlet opening for discharging exhaust gases from the cylinder and each outlet opening being adjoined by an exhaust line; and a turbine having at least one rotor mounted on a rotatable shaft in a turbine housing, the turbine having, to form a cooling arrangement, at least one coolant duct integrated in the turbine housing being delimited and formed by at least one wall; wherein the exhaust line of the at least one cylinder issues into an inlet region, which transitions into an exhaust gas-conducting flow duct, of the turbine; wherein the exhaust gas-conducting flow duct is uninsulated such that introduction of heat into the turbine housing from exhaust gases in the exhaust gas-conducting flow duct is unrestricted; and wherein the at least one wall that delimits the at least one coolant duct is provided, at least in regions, with thermal insulation such that the thermal insulation contacts coolant in the at least one coolant passage such that the introduction of heat from the housing into coolant is impeded.

2. The internal combustion engine as claimed in claim 1, wherein more than 50% of the at least one wall is provided with thermal insulation.

3. The internal combustion engine as claimed in claim 1, wherein more than 70% of the at least one wall is provided with thermal insulation.

4. The internal combustion engine as claimed in claim 1, wherein more than 80% of the at least one wall is provided with thermal insulation.

5. The internal combustion engine as claimed in claim 1, wherein an entirety of the at least one wall is provided with thermal insulation.

6. The internal combustion engine as claimed in claim 1, wherein the thermal insulation comprises enamel.

7. The internal combustion engine as claimed in claim 1, wherein the thermal insulation comprises ceramic.

8. The internal combustion engine as claimed in claim 1, wherein the thermal insulation is formed as a coating by surface treatment.

9. The internal combustion engine as claimed in claim 1, wherein the turbine is a radial turbine.

10. The internal combustion engine as claimed in claim 9, wherein the at least one coolant duct, at least in sections, extends in a spiral form around the shaft in the housing.

11. The internal combustion engine as claimed in claim 9, wherein the at least one coolant duct extends circumferentially around and at a distance from the flow duct over an angle α, where α≦45°.

12. The internal combustion engine as claimed in claim 11, wherein α≦30°.

13. The internal combustion engine as claimed in claim 1, wherein the turbine housing is a cast part into which the thermal insulation is introduced as a coating during post-processing.

14. The internal combustion engine as claimed in claim 1, wherein each cylinder has two outlet openings for discharging the exhaust gases out of the cylinder.

15. The internal combustion engine as claimed in claim 1, wherein the exhaust lines merge to form at least one overall exhaust line, thus forming at least one exhaust manifold, wherein said at least one overall exhaust line issues into the inlet region of the turbine.

16. The internal combustion engine as claimed in claim 1, wherein the exhaust lines of the cylinders merge to form at least one overall exhaust line within the cylinder head, thus forming at least one integrated exhaust manifold, wherein said at least one overall exhaust line issues into the inlet region of the turbine.

17. An engine comprising: a cylinder head defining an outlet opening for discharging exhaust gases to an exhaust line; and a turbine having an inlet region and an uninsulated flow duct receiving exhaust gases from the exhaust line, the turbine having at least one rotor mounted on a rotatable shaft in a turbine housing, the turbine housing defining a cooling duct having a wall to contact coolant, the wall provided with thermal insulation.

18. An engine turbine comprising: a housing forming an inlet region and an uninsulated flow duct configured to receive engine exhaust gases and introduce heat into the housing; and a rotor mounted on a rotatable shaft within the flow duct; wherein the housing defines a cooling duct therein, a thermal insulation provided on the cooling duct to contact coolant and to limit cooling of the turbine, the insulation having a lower thermal conductivity than the housing.

19. The engine turbine of claim 18 wherein the cooling duct extends in a spiral form around the shaft.

20. The engine of claim 17 wherein the cooling duct extends in a spiral form around the shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the turbine of a first embodiment in a section perpendicular to the shaft of the turbine rotor on the basis of an exemplary embodiment,

(2) FIG. 2 shows the section A-A indicated in FIG. 1, and

(3) FIG. 3 shows a schematic of an internal combustion engine and the turbine of FIG. 1.

DETAILED DESCRIPTION

(4) As required, detailed embodiments of the present disclosure are provided herein; however, it is to be understood that the disclosed embodiments are merely examples of the invention that may be embodied in various and alternative forms. The Figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

(5) FIG. 1 shows the turbine 1 of a first embodiment in a section perpendicular to the shaft 7 of the turbine rotor 6.

(6) The turbine 1 is a radial turbine 1a which comprises a rotor 6 which is arranged in a turbine housing 3 and which is mounted on a rotatable shaft 7. In order that the rotor blades can be approached by flow radially, the flow duct 5 leading from the inlet region 4 is of spiral form, and the housing 3 for the supply of the exhaust gas is in the form of an encircling spiral housing.

(7) To form a cooling arrangement, the housing 3 has an integrated coolant duct 8 which extends in spiral form around the shaft 7 in the housing 3 and which thus follows the flow duct 5 as far as the inlet for the exhaust gas into the rotor 6. It can be seen that the coolant duct 8 runs at a distance from the flow duct 5, specifically on that side of the flow duct 5 which faces away from the rotor 6. Adjacent to the inlet region 4 of the turbine housing 3 there are provided duct openings 9 for allowing coolant to be introduced into and discharged again from the coolant duct 8. For the fastening of the turbine 1 to the cylinder head, the housing 3 is equipped with a flange 10.

(8) The walls 2 that delimit the coolant duct 8 are equipped, that is to say coated, with thermal insulation 2a. By the introduction of said insulation 2a, the introduction of heat from the housing 3 into the coolant is impeded, whereby it is achieved both that less heat is extracted from the housing 3 and also less heat is introduced into the coolant. The cooling power is targetedly reduced by the insulation 2a in that the thermal permeability of the heat-transmitting wall 2 is reduced.

(9) FIG. 2 shows the section A-A indicated in FIG. 1. It is sought merely to explain the additional features in relation to FIG. 1, for which reason reference is made otherwise to FIG. 1. The same reference symbols have been used for the same components.

(10) In the embodiment illustrated in FIG. 2, the coolant duct 8 extends circumferentially around the flow duct 5 over an angle α≈90° measured from the central line of the flow duct 5. Consequently, in the present case, the coolant duct 8 does not lie—similarly to a coolant jacket—around the flow duct 5 over as large an area as possible. In this way, the amount of heat absorbed by the coolant is likewise limited, specifically by way of a reduction in size of the heat transfer surfaces.

(11) FIG. 3 illustrates a schematic of an internal combustion engine 12 and the turbine 1. The engine 12 has at least one cylinder head 14 with at least one cylinder 16, and each cylinder has at least one outlet 18 opening for discharging the exhaust gases from the cylinder and each outlet opening is adjoined by an exhaust line 20. The at least one exhaust line 20 of at least one cylinder issues into an inlet region, which transitions into an exhaust gas-conducting flow duct, of the turbine 1.

(12) While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.