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1. WO2020023372 - TURBOCOMPRESSEUR POUR MOTEUR À COMBUSTION

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

TURBOCHARGER FOR A COMBUSTION ENGINE

Technical Field

[0001] The invention relates to a turbocharger for a combustion engine according to the preamble of claim 1.

Background

[0002] It is known from EP 3 276 140 Al to position the bushing for the shaft of a wastegate valve in a bore of a turbocharger housing. It is further known from experience in the building of turbochargers to permanently fix a bushing of this kind in the bore of the housing by means of mechanical deformation.

[0003] The object of the invention is to specify a turbocharger for a combustion engine in which straightforward and secure installation of a bushing is provided.

Summary of the Invention

[0004] With respect to a turbocharger as referred to hereinabove, this object is achieved according to the invention by means of the characteristic features of claim 1.

[0005] Straightforward installation and a permanently fixed seating of the bushing in the opening of housing is achieved as a result of the bonded connection by means of welding.

[0006] In the context of the invention, "turbocharger actuating arrangement" is understood to mean any movable mechanical components used in particular to influence the operating condition of the turbocharger.

[0007] According to common parlance and in the present context, the term "turbocharger" is understood to be a way of increasing the output of a combustion engine by means of a driven compressor blade. In principle, the drive means in this context can also be in the form of an electric motor or the like. Preferably, however, said drive means is in the form of a driving turbine blade, e.g., an exhaust gas turbine.

[0008] In the context of the invention, a "weld" is understood to mean any bonded connection. In a preferred embodiment, the material of the bushing and the material of the housing are in this case melted. In potential embodiments, however, a high-temperature brazing process can take place in which at least one of the components is not melted or is only slightly melted.

[0009] It may be provided that additional materials are melted or introduced into the weld. The weld is preferably effected in the area of a circumferential interface gap between the bushing and the housing. The weld can preferably be in the form of a circumferential seam around portions of the bushing. Particularly preferably, the weld can be effected at two oppositely situated points. Alternatively, a spot weld or a completely circumferential weld can be provided.

[0010] In a preferential embodiment of the invention, it is provided that the weld is effected by means of a laser beam. The use of a laser welding device is particularly advantageous because of the small welding zone and low overall energy input. Depending upon requirements, an inert gas may be used if necessary.

[0011] In alternative embodiments of the invention, the weld can also be effected by means of electronic beam welding or metal inert gas welding (MIG) or Wolfram inert gas (WIG) welding.

[0012] In a preferential embodiment of the invention, an auxiliary material is provided in the area of the weld, whereby the auxiliary material differs from a material of the bushing and a material of the housing. As a result, the quality of the welding seam can be improved according to the design of the materials for the bushing and the housing.

[0013] Further preferably, the auxiliary material can be in the form of a ring in front of the weld at least partially encompassing, in particular completely encompassing, the bushing. Particularly preferably, the bushing can in this case comprise a retaining sleeve, whereby the auxiliary material is arranged between the retaining sleeve and the housing. In this way, the auxiliary material is positioned in an ideal manner and can simultaneously serve for installation or positioning of the bushing with respect to the housing.

[0014] The auxiliary material can be employed in a particularly effective manner if at least either, or both, the housing (3) or the bushing (9) consists of a steel having a high carbon content of greater than 0.22%, preferably greater than 0.3%. In terms of the brittleness and breaking strength of a weld, steels of this kind having a high carbon content are rather problematic without an auxiliary material.

[0015] In the interest of an effective manufacturing process, at least either, or both, the housing and the bushing are formed as a cast steel component.

[0016] Broadly preferably, the housing and the bushing consist of a high temperature resistant material.

[0017] In an optimized embodiment of the invention, the auxiliary material consists of an alloy with good weldability and a nickel content of greater than 5%, preferably greater than 10%. This is particularly applicable if the materials of the bushing and/or the housing comprise steel with a high carbon content (> 0.22%).

[0018] In a broadly preferable embodiment of the invention, the actuating arrangement comprises a valve, preferably a turbine regulating valve on the exhaust gas side, particularly preferably a wastegate, to reduce the load on the turbine blade in a controllable manner. The high thermal loads on wastegates make an installation according to the invention by means of welding particularly advantageous. However, other embodiments can comprise a different valve or a different turbocharger actuating arrangement, in which case, for example, an electric motor can also be used instead of a turbine blade to drive the compressor blade.

[0019] Further optimization of the manufacturing processes is achieved if a weld for a shaft which comprises a swing arm and is guided into the bushing is effected on the same jig as the weld for the bushing. In particular, the weld for the shaft comprising the swing arm can be effected using the same welding device. Particularly preferably, said device is in this case a laser welding device.

[0020] Broadly preferably, the bushing is mechanically pressed into the opening in the housing before the welding process. As a result, the bushing is seated in a dimensionally accurate and fixed manner. In this context, the weld primarily serves to fix the position of the bushing and prevent it from wandering under varying mechanical and thermal loads.

[0021] Further advantages and features of the invention follow from the embodiment described hereinafter as well as from the dependent claims.

[0022] A preferential embodiment of the invention is described hereinafter and explained in greater detail by way of reference to the attached drawings.

Brief Description of the Drawings

Fig. 1 shows a schematic overall view of a turbocharger for a combustion engine.

Fig. 2 shows a partial sectional view through a housing for the turbocharger in Fig. 1 in the area of a bushing designed according to the invention.

Detailed Description

[0023] The turbocharger 1 for a combustion engine shown in Fig. 1 is designed as an exhaust gas turbocharger comprising an actuating arrangement 2 for controlling turbine output. The turbocharger 1 comprises a housing 3, a driven compressor blade 4, and a driving turbine blade 5.

[0024] The actuating arrangement 2 for regulating the turbocharger 1 is designed as a valve, more precisely a turbine regulating valve on the exhaust gas side, in the present case a wastegate, for reducing the load on the turbine blade 5 in a controllable manner.

[0025] The actuating arrangement, i.e. the wastegate 2, comprises a flap plate 6, by means of which a shaft 7 and an externally situated swing arm 8 can be actuated.

[0026] In this case, the shaft 7 is guided into a bushing 9. The bushing 9 is received in an opening 10 of the housing 3. The opening 10 is in the form of a cylindrical bore and is processed to precise dimensions.

[0027] The bushing 9 comprises a cylindrical bore 9a used for guiding the shaft 7. An exterior surface 9b of the bushing 9 is likewise cylindrical, and its upper area comprises a radially projecting retaining sleeve 9c. Underneath the retaining sleeve 9c, the bushing 9 has an undercut 9d. In addition to the undercut 9d, an upper edge of the opening 10 has a chamfer.

[0028] The bushing 9 is connected to the housing 3 in a bonded connection by means of a weld 11. For the sake of clarity, the weld 11 in the sectional view in Fig. 2 is only indicated symbolically and on one side.

[0029] An auxiliary material 12 is provided in the area of the weld 11, whereby the auxiliary material differs from a material of the bushing and a material of the housing. As a result, the quality of the welding seam can be improved according to the design of the materials for the bushing and the housing.

[0030] In the present context, the auxiliary material can be in the form of a ring 12 in front of the weld at least partially encompassing the bushing 9. The ring 12, or rather the auxiliary material, is arranged in an axial direction between the retaining sleeve 9c and the housing 3. In this way, the auxiliary material 12 is positioned in an ideal manner and can simultaneously serve for installation or positioning of the bushing 9 with respect to the housing 3. The specified thickness of the ring 12 determines, by way of its retaining function, the exact position of the bushing 9 in an axial direction.

[0031] The bushing 9 is mechanically pressed into the opening 10 in the housing 3 before the welding process. As a result, the bushing 9 is seated in a dimensionally accurate and fixed manner. In this context, the weld 11 primarily serves to fix the position of the bushing 9 and prevent it from wandering under varying mechanical and thermal loads.

[0032] In the context of the present invention, the weld 11 is a bonded connection in which the material of the bushing 9, the material of the housing 3, and the material of the auxiliary material 12 are melted and mixed. By means of the auxiliary material 12, an additional material is introduced into the weld 11 between the bushing 9 and the housing 3.

[0033] In the present context, it is provided that the weld is effected by means of a laser beam. The use of a laser welding device (not shown) is particularly advantageous because of the small welding zone and low overall energy input.

[0034] The weld 11 is effected in the area of a circumferential interface gap 13 between the bushing 9 and the housing 3. The weld 11 can be in the form of a circumferential seam around portions of the bushing 9. The weld is effected at two oppositely situated points or areas. Alternatively, a spot weld or a completely circumferential weld can be provided. The purpose of the laser beam is to fabricate the weld 11 in a suitable manner on the interface gap 13 and/or the auxiliary material 12 and/or the bushing 9.

[0035] In the present context, both the housing 3 and the bushing 9 are in the form of cast steel components. The housing 3 and the bushing 9 consist in this case of a high temperature resistant material, with the result that hot exhaust gases in the area of the wastegate 2 will not be harmful to the components. One possible material for the bushing 9 is steel number 1.4091 (= DIN/EN GXl50CrNiMoN35-l5-3), an austenitic, castable steel with a high carbon context of at least 1%. One possible steel for the housing 3 is steel number 1.4837 (= DIN/EN GX40CrNiSi25-l2), which has a carbon content from 0.3% to 0.5%.

[0036] In terms of the brittleness and breaking strength of a weld, steels of this kind having a high carbon content can be problematic without an auxiliary material. In the present context, the ring 12 is therefore implemented as an auxiliary material. The ring 12 consists of an alloy with good weldability and a nickel content of greater than 10%. One example of a possible material for the auxiliary material, i.e. the ring 12, is steel number 1.4828 (= DIN/EN Xl5CrNiSi20-l2).

[0037] In order to optimize the manufacturing processes, it is provided that a weld 14 for a shaft 7 which comprises the swing arm 8 and is guided into the bushing is effected on the same jig as the weld 11 for the bushing 9. In particular, the weld 14 for the shaft 7 comprising the swing arm 8 can be effected using the same welding device.

List of reference signs

1 Turbocharger

2 Actuating arrangement, wastegate

3 Housing

4 Compressor blade

5 Turbine blade

6 Flap plate

7 Shaft

8 Swivel arm

9 Bushing

9a Cylindrical bore of the bushing

9b Exterior surface of the bushing

9c Retaining sleeve

9d Undercut

10 Opening of the housing

11 Weld for the bushing

12 Auxiliary material, ring

13 Interface gap between the bushing and the housing 14 Weld for the shaft