Patent Application
20080031728
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
A partial assembly 10 of a turbocharger in accordance with an embodiment of the invention is shown in perspective view in
The opposite wall of the nozzle is formed in part by a generally annular cover or plate 22 that is affixed to a center housing 24 of the partial assembly 10. The cover 22 has a generally cylindrical flange at its outer diameter that engages the radially outer surface of a generally cylindrical flange on the center housing. The center housing houses a bearing 25 for the shaft 14 passing through the center housing. The end of the shaft 14 opposite from the turbine wheel 12 is connected to a compressor wheel (not shown) driven by the turbine wheel 12.
With reference to
The nozzle ring 26 supports a plurality of adjustable vanes 32 that are disposed in the nozzle between the wall formed by the nozzle ring 26 and plate 22 and the opposite wall formed by the annular portion 20 of the insert 16. The vanes 32 are circumferentially spaced apart about the circumference of the nozzle ring. With reference to
Each vane 32 further includes an arm 42 immovably connected with the airfoil/axle assembly. The arm 42 is connected at a location intermediate the distal end of the airfoil portion 34 and the distal end of the axle 36, contrary to prior-art vanes in which the arm is connected to the distal end of the axle. The arm advantageously is connected proximate the proximal end of the airfoil portion 34. The arm 42 extends perpendicular to the axis of the axle 36 and terminates in a distal end 44. The distal end includes a projection 46 that extends axially away from the proximal end of the airfoil portion 34, in the same direction as the axle 36. The vane 32 with its associated axle 36 and arm 42 is a one-piece integral structure. The structure can be formed by manufacturing the airfoil portion 34 and axle 36 together as a single part (e.g., by casting or machining), manufacturing the arm 42 as a separate part, and then joining the two parts together by welding or the like. Alternatively, however, the entire vane structure can be formed as a single part by casting, by machining, by metal injection molding (MIM), or by any other suitable technique.
With reference to
More specifically, the distal end of each vane arm 42 defines a connecting element that connects with a cooperative connecting element defined by the actuator ring 48. In the illustrated embodiment, the connecting elements of the actuator ring 48 comprise receptacles 50 defined in the actuator ring, and the connecting elements of the vane arms comprise the projections 46 that are received in the receptacles 50. Alternatively, the actuator ring could define projections received in receptacles defined in the vane arms, or the connection between the vane arms and actuator ring could be accomplished in another way.
In preferred embodiments, such as the illustrated embodiment, the variable vane assembly is configured to ease the assembly of the parts. In particular, during assembly the actuator ring 48 is assembled to the nozzle ring 26 and is rotatably positioned with respect to the nozzle ring so that a receptacle 50 is generally aligned with each aperture 38 in the nozzle ring. The axles 36 of the vanes are inserted into the apertures 38 in the nozzle ring in such an orientation that the projections 46 on the vane arms 42 are received in the receptacles 50. Each aperture 38 in the nozzle ring has a relatively small-diameter portion that receives one of the axles 36 and forms a bearing surface therefor, and a relatively larger-diameter countersunk portion surrounding the small-diameter portion at the annular surface 40 of the nozzle ring. A lengthwise portion of the arm 42 of each vane adjacent the proximal end of the arm is accommodated in the countersunk portion of the respective aperture. The motion of inserting the axle 36 into an aperture 38 substantially concurrently connects the vane arm projection 46 with the cooperating connecting element (i.e., the receptacle 50) of the actuator ring, or at least places the projection 46 in a position to be connected with the actuator ring. Thus, the one-piece vanes and the arrangement for connecting the vane arms with the actuator ring in accordance with the invention avoid the need for welding of vane parts during assembly. This is in contrast to some prior variable vane assemblies in which each vane is formed in two separate parts that must be welded together during the assembly process.
With primary reference to
In the illustrative embodiment shown and described herein, the actuator ring 48 has receptacles 50 for the vane arms 42 that are formed by recesses in the radially inner surface of the actuator ring. Alternatively, however, it is possible for the receptacles to be formed by recesses in the radially outer surface of the actuator ring. In the illustrative embodiment, the cover 22 also defines recesses 23 (
The apertures 38 in the nozzle ring that form bearing surfaces for the vane axles 36 can be either blind holes or can extend entirely through the nozzle ring to its back side. Blind holes offer the advantage that exhaust gas cannot leak through the holes to the back side of the nozzle ring, but the length of the bearing surfaces cannot be as great with blind holes as it can be with through holes unless the axial thickness of the nozzle ring is increased.
In the illustrative embodiment, the vane arms 42 are connected to the axles 36 adjacent the proximal ends of the airfoil portions 34, and hence the arms 42 do not project into the stream of exhaust gas flowing through the nozzle or at least the extent of their projection into the stream is minimal. Alternatively, however, the arms 42 could attach to the airfoil portions 34, although this is not preferred because the arms would be in the exhaust gas stream and thus would cause aerodynamic losses that would impair the efficiency of the turbine.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
