Patent Application
20200141307
This application claims the benefit of German Patent Application No. 202017103441.0 filed Jun. 8, 2017, the disclosure of which is herein incorporated by reference in its entirety.
The present invention relates to an actuator assembly for a turbocharger, a turbine comprising a corresponding actuator assembly, and a corresponding exhaust gas turbocharger.
Increasingly more vehicles of the more recent generation are equipped with charging devices. In order to achieve the target demands and the legal requirements, it is imperative to promote development in the complete drive train and also to optimize the individual components as well as the system as a whole with respect to their reliability and efficiency.
Exhaust gas turbochargers are known, for example, in which a turbine with a turbine wheel is driven by the exhaust gas flow of the internal combustion engine. A compressor with a compressor wheel, which is arranged with a turbine wheel on a mutual shaft, compresses the fresh air taken in for the engine. By this means, the air or oxygen amount, available to the engine for combustion, is increased, which in turn leads to an increased output of the internal combustion engine.
Known turbines comprise a turbine housing in which a turbine wheel is arranged. A turbine may additionally comprise additional devices, like a variable turbine geometry or a wastegate (turbine bypass valve), which improve the output, efficiency and operating behavior of the turbine. To actuate these types of devices, there are corresponding actuator assemblies, which transfer a movement of an actuator, which is often fixed externally on the turbine housing or on another component of a turbocharger (for example, a compressor housing), to a corresponding control element which is usually arranged within the turbine housing. Correspondingly, these types of actuator assemblies often have a shaft which extends from inside the turbine housing through a wall of the turbine housing to the outside of the turbine housing. To prevent a gas discharge in this area, corresponding means for sealing are provided. For example, one or more piston rings are known in combination with one or more O-rings. However, sealing means of these types require an expensive processing of the shaft to provide corresponding accommodation grooves for the piston rings/O-rings, and do not always provide the desired result.
Accordingly, the object of the present invention is to provide an optimized actuator assembly for a turbocharger which has an improved sealing that is easier to assemble.
The present invention relates to an actuator assembly for a turbocharger according to Claim 1, a turbine according to Claim 11, and an exhaust gas turbocharger according to Claim 15.
The actuator assembly according to the invention comprises a shaft which is designed to be rotatably mounted in a housing of a turbocharger, wherein the shaft is coupled at a first end to an adjusting element and at a second end to a control element. The actuator assembly additionally comprises a cylindrical seal insert which is arranged about a center area of the shaft between the first end and the second end and extends along the shaft in the axial direction. Due to the actuator assembly according to the invention with the cylindrical seal insert, the piston rings and O-rings, previously used in this area for the purpose of sealing, may be omitted. In addition, the machining steps on the shaft for generating the grooves required for the piston rings and O-rings may be omitted, by which means the manufacturing costs for the actuator assembly may be reduced. Another advantage is the simplified assembly of the actuator assembly according to the invention, because only one seal insert has to be mounted instead of up to three piston rings and additional O-rings.
In embodiments, the seal insert may have spring properties in the radial direction. A better sealing effect results due to the spring properties of the cylindrical seal insert, for example, against the leakage of exhaust gases from within the housing. Furthermore, susceptibility with respect to vibrations, which lead to undesired noise and wear, is reduced due to the cylindrical embodiment in combination with the spring properties. In sum, a better damped mounting of the shaft in the housing results, which positively affects the functionality/controllability of the actuator assembly and the life cycle of all components of the actuator assembly and thus ultimately also a turbocharger that comprises an actuator assembly according to the invention.
In embodiments, which are combinable with all previously described embodiments, the seal insert may have a wave-shaped contour in the axial direction. Alternatively, the seal insert may have a stepped contour in the axial direction.
In embodiments, which may be combined with all previously described embodiments, the seal insert may have a circumferentially closed cylindrical shape. Alternatively, the seal insert may have a circumferentially open cylindrical shape. In particular, the seal insert may have a slit extending axially.
In embodiments, which may be combined with all previously described embodiments, a bush may be provided, wherein the seal insert is arranged between the shaft and the bush in the radial direction. The bush may be designed to be arranged rotationally fixed in a housing. The shaft may be rotatably mounted in the bush. A maximum diameter of the seal insert may be larger in the expanded state of the seal insert than the inner diameter of the bush.
In embodiments, which may be combined with all previously described embodiments, the shaft may have a reduced diameter along the center area, about which the seal insert is arranged, in comparison to the areas adjacent to the center area. During the assembly of the actuator assembly, the seal insert may be positioned in the center area and then inserted together with the shaft into the bush. Due to the spring effect, the seal insert is compressed during the insertion into the bush, by which means the sealing effect is generated.
In embodiments, which may be combined with all previously described embodiments, the actuator assembly may be a wastegate assembly. Alternatively, the actuator assembly may be designed for adjusting a variable turbine geometry.
The invention additionally comprises a turbine for an exhaust gas turbocharger with a turbine housing and an actuator assembly according to any one of the previously described embodiments.
In embodiments, the turbine housing may have a hole through an outer wall of the turbine housing, wherein the shaft extends through the hole so that the first and second ends of the shaft are arranged on opposite sides of the outer wall. The seal insert may be arranged radially between a wall of the hole and the shaft. Alternatively, a bush may be provided which is arranged rotationally fixed in the hole. The seal insert is the arranged between the shaft and the bush, and the bush is arranged radially between the seal insert and the wall of the hole.
The invention additionally comprises an exhaust gas turbocharger with a turbine according to any one of the previously described embodiments.
Additional details and features of the invention are subsequently described by way of the figures.
Embodiments of the actuator assembly 100 according to the invention will subsequently be described based on the figures. All details and advantages subsequently described apply both for actuator assembly 100 and also for a corresponding turbine comprising such an actuator assembly 100. Within the context of this application, the term “axial” refers to directions/orientations that extend substantially parallel to the axis of rotation 300. The term “radial” refers to directions/orientations that extend substantially perpendicular to axis of rotation 300.
Actuator assembly 100 according to the invention likewise comprises a shaft 110 which is rotatably mounted in a turbine housing 200. Shaft 110 is again coupled at its first end 112 to an adjusting element 120 and at its second end 114 to a control element 150. The actuator assembly according to the invention additionally comprises a cylindrical seal insert 130 which is arranged about a center area 116 of shaft 110 between first end 112 and second end 114 and extends along shaft 110 in the axial direction (see
During actuation of the actuator assembly, shaft 110 rotates about axis of rotation 300, driven by an actuator that transmits a movement to shaft 110 via adjusting element 120. Shaft 110 then transmits the movement to control element 150 (for example, as part of a wastegate valve, for opening or closing the wastegate valve).
Sealing insert 130 has spring properties in the radial direction. An improved sealing effect results due to the spring properties of cylindrical seal insert 130, for example, against the leakage of exhaust gases from within turbine housing 200 into the environment. Furthermore, susceptibility with respect to vibrations, which lead to undesired noise and wear, is reduced by the cylindrical embodiment of seal insert 130 in combination with the spring properties. In sum, a better damped mounting of shaft 110 in turbine housing 200 results, which positively affects the functionality and controllability of actuator assembly 100 and the life cycle of all components of actuator assembly 100 and thus ultimately also a turbocharger that comprises an actuator assembly 100 according to the invention.
As is clear in
Seal insert 130 may have a circumferentially closed cylinder shape. Alternatively, seal insert 130 may have a circumferentially open cylinder shape. In this case, seal insert 130 may have a slit extending axially. Seal insert 130 may be manufactured, for example, in a stamping method, in which a cylindrical stamped blank is provided with a corresponding structure to provide the spring effect. Alternatively, seal insert 130 may be manufactured from a metal sheet, wherein the metal sheet has a corresponding structure, and after a cutting process is shaped into the final cylindrical shape. The axially extending slit is thereby created, which increases the elasticity of seal insert 130 and may be completely closed in the installed state of seal insert 130. In both cases, the material used (in particular heat resistant metals of all types) may be heat treated.
As is clear in
A maximum diameter of seal insert 130 may be larger in the expanded state of seal insert 130 than the inner diameter d4 of bush 140 (see
As already mentioned, the invention comprises both an actuator assembly 100 and also a turbine for an exhaust gas turbocharger comprising one of the previously described embodiments of actuator assembly 100. In addition, the invention comprises an exhaust gas turbocharger comprising a turbine of this type.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202017103441.0 | Jun 2017 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2018/036456 | 6/7/2018 | WO | 00 |
