Abstract:
A method of manufacturing a turbocharger including a housing with a compressor housing portion, turbine housing portion, and a connecting portion is such that an appropriate attitude setting for various portions is preselected, and the housing is then manufactured using a casting technique. The geometry of the connecting portion is circular and concentric with respect to a common center line passing through all three portions.

Description:
This application is a continuation application filed under 37 CFR § 1.53(b) of patent application Ser. No. 09/305,674, filed May 5, 1999, now abandoned which in turn is a continuation of patent application Ser. No. 08/704,608, filed Sep. 17, 1996, now abandoned, which is a continuation of PCT/GB95/00594, filed Mar. 17, 1995. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to turbochargers, and is particularly concerned with problems associated with what is known as attitude setting of turbochargers. 
     2. Description of the Related Art 
     A turbocharger basically comprises a compressor and a turbine coupled together, generally with a common shaft. Engine exhaust gases are fed into the turbine and rotate the turbine and the common shaft. This drives the compressor, which is used to force air into the engine. 
     The compressor has an inlet and an outlet, as does the turbine. On any given engine, there may be an optimum position for the location of the compressor inlet and/or outlet and an optimum position for the location of the turbine inlet and/or outlet. The compressor position may not necessarily have the same attitude with respect to the turbine position on different engines. 
     It has therefore been necessary to provide means for clamping the compressor housing to the turbine housing in different positions so that the attitude of the compressor housing with respect to the turbine housing can be adjusted to suit any given engine. 
     This not only necessitates the use of complicated clamping rings and associated seals, but a very sophisticated jig is necessary to hold and adjust the housings prior to clamping them together. 
     A further problem associated with known turbochargers is that extensive milling and drilling is required to manufacture the housings. 
     SUMMARY OF THE INVENTION 
     We have now developed a method of turbocharger manufacture, which eliminates or substantially reduces the above-mentioned problems. 
     According to the invention, a method of manufacturing a turbocharger comprises designing a turbocharger housing having a compressor housing portion, a turbine housing portion, and a connecting portion, the geometry of at least the connecting portion being circular and concentric with respect to a common centerline passing through all three positions, and then manufacturing the housing using a casting technique, the attitude of the compressor portion with respect to the turbine portion being preselected prior to casting by appropriate adjustment of the mould utilized in the casting process. 
     There may, for example, be a compressor housing mould portion and a turbine housing mould portion, the two mould portions being rotatable with respect to one another about the said centerline before casting takes place. 
     It is preferred that each inlet and outlet to the housing is circular, with an annular groove, so that connections to other components can be made using annular seals and clamping rings, such as those known as MARMAN fittings. 
     Preferably the dimensions of each inlet and outlet are made substantially identical, so that a single size of clamping fitting can be used for connection to other components. 
     The invention includes a turbocharger having a housing manufactured by the method according to the invention. 
     There may be a series of different turbochargers having different attitude settings. 
     The invention includes casting apparatus for use in carrying out the method according to the invention. 
     The apparatus preferably has a compressor housing mould portion and a turbine housing mould portion, the two mould portions being rotatable with respect to one another. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     By way of example, specific embodiment of the invention will now be described, with reference to the accompanying drawings, in which: 
     FIG. 1 is a view of a first embodiment of turbocharger housing manufactured according to the invention, looking along the centerline of the housing; 
     FIG. 2 is a view looking in the direction of arrow II of FIG. 1; 
     FIG. 3 is a view similar to FIG. 1, but showing a second embodiment of turbocharger housing according to the invention; and 
     FIG. 4 is a view looking in the direction of arrow IV of FIG. 3; 
     FIG. 5 is a side view showing separate turbine and compressor mold portions used in casting a turbocharger housing according to the method of the present invention; 
     FIG. 6 is a side view of the mold portions of FIG. 5 combined to cast a turbocharger housing according to the method of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring firstly to FIGS. 1 and 2, there is shown a turbocharger housing comprising a compressor portion  10  and a turbine portion  11 . A common centerline  13  extends through the housing. 
     The compressor portion has an inlet  14  and an outlet  15 . The turbine has an inlet  16  and an outlet  17 . 
     The housing is manufactured from ductile iron using a casting process. It can be seen from FIG. 1 that the axis  18  of the compressor outlet  15  is at 90° with respect to the axis  19  of the turbine inlet. 
     Different engines may require different attitudes of the axis  18  with respect to the axis  19 . The invention makes it possible to pre-select attitude setting before manufacture. Because the geometry of the connecting portion  12  of the housing is circular and concentric with respect to the axis  13 , portions of the mould used in the casting process can be adjusted with respect to each other about the axis  13  to bring about any desired attitude setting. 
     In FIGS. 3 and 4, for example, a second embodiment of housing is shown, which is substantially identical to that shown in FIGS. 1 and 2, similar reference numerals being used throughout. However, it will be seen that the compressor outlet axis  18  now extends in the same direction as the turbine inlet attitude  19 , instead of being at 90° to one another. Any attitude setting whatsoever can be selected. 
     Because attitude setting is pre-selected during manufacture, no complicated attitude setting is necessary after manufacture, and no special components are needed to clamp housing parts together. Customers received exactly the attitude setting that they have requested, and the desired attitude cannot subsequently get out of alignment. 
     Referring to FIG. 5, representative turbine, connector, and compressor mold portions  50  and  70 , respectively, are depicted. The mold portions are shown aligned with common centerline  13 ′ in preparation for assembly. 
     The interior of turbine mold portion  50  is formed as is known in the art to create a turbine portion  11 ′ shown in ghost outline. 
     Compressor mold portion  70  includes an interior formed, again as is known in the art, to create a compressor portion  10 ′ also shown in ghost outline. 
     In FIG. 6, mold portions  50  and  70  are shown combined in preparation for casting the turbocharger housing. Mold portions  50  and  70  are shown in a stacked arrangement along common centerline  13 ′. The mold portions are connected, and the housing is cast using techniques well known in the art. In FIG. 6, inlet  16 ′ of turbine portion  50  and outlet  15 ′ of compressor portion  70  are oriented 180 degrees apart to produce the housing of FIGS. 3 and 4 wherein turbine inlet air flow and compressor outlet air flow are in the same directions. The invention contemplates rotation of the turbine mold portion  50 , relative to the compressor mold portion  70  to achieve whatever attitude is prescribed in the design of the particular turbocharger housing being cast. This feature is made possible by the cylindrical geometry of the connecting body portion of the turbocharger housing. 
     Manufacture of the housing takes place in a single process, and no milling or drilling is required. 
     Turbocharger assembly time is substantially reduced. 
     Because the housing is a single component, there is a risk of undesirable heat conduction from the turbine to the compressor, but this can be minimized by casting into the housing webs or fins such as those shown at  20  in FIGS. 2 and 4. Alternatively, air or water jackets may be provided, for example, cast as an integral part of the turbine section, or the center section, or both. 
     A further advantage of the embodiments of housing shown in the drawings is that we have eliminated not only milling and drilling, but also the need for tapping. Conventional housings are generally connected at inlets and outlets by flanges, which are bolted together. This necessitates drilling and tapping of bolt holes. 
     In the embodiments shown, each inlet or outlet is circular, and has an annular groove  21 . This makes it possible to make a connection to a similar-shaped component by using a clamping ring, and appropriate seals, the clamping ring, for example, having a U-shaped or V-shaped groove in its inner periphery, so that one wall of the clamping ring will seat in one of the grooves  21 , and the other wall of the clamping ring will seat in a similar groove of the component to which the housing is connected. Fittings known as MARMAN fittings may, for example, be used. 
     Yet another advantage is that each of the inlets and outlets, and associated annular grooves  21 , are of the same size, so that only one size of clamping ring needs to be stocked to make all the necessary connections to the housing. 
     The reader&#39;s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. 
     All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. 
     Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
     This invention is not restricted to the details of the foregoing embodiment (s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 
     Now that the invention has been described.