Abstract:
A compressor housing ( 16 ) of a radial compressor at least two housing portions ( 10, 12, 14 ) at least partially of plastic material and defines compressor impeller installation space ( 48 ) and a spiral duct ( 46 ) that surrounds it radially on the outside with regard to a rotational axis ( 18 ) of an impeller. A securement structure ( 50 ) encloses the compressor impeller installation space ( 48 ) at least partially in an annular manner and is arranged in radial direction between the impeller installation space ( 48 ) and the spiral duct ( 46 ). The securement structure includes a separate burst-protection ring ( 50 ) with a tubular wall section ( 34 ) enclosing the impeller installation space ( 48 ) circumferentially.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 USC 119 to German Patent Application 102011017052.9 filed in Germany on Apr. 14, 2011, the entire contents of which are incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The invention relates to a compressor housing of a radial compressor, in particular of a turbocharger of an internal combustion engine, in particular of a motor vehicle, with at least two housing components consisting at least partially of synthetic material, wherein a compressor impeller installation space and a spiral duct surrounding it radially on the outside with regard to a rotational axis of a compressor impeller are provided, and a securement structure enclosing the compressor impeller installation space at least partially in an annular manner is disposed in radial direction between the compressor impeller installation space and the spiral duct. 
       BACKGROUND OF THE INVENTION 
       [0003]    A radial compressor housing in particular for a turbocharger featuring at least two housing components is known from WO 2009/065881 A1. A compressor impeller installation space and a spiral duct are provided. The housing components are made of synthetic material. The radial compressor housing can be made of synthetic material in an easy and cost-effective way. The wall thicknesses can be optimized depending on the material used and the weight. Radial compressors have to guarantee an adequate operational safety. Due to the high impeller speeds of turbochargers there is a risk that, when the compressor impeller is damaged, metal shards penetrate the housing of the compressor and damage components in the engine compartment of the internal combustion engine. To avoid this, a securement structure encloses the compressor impeller installation space partially in a ring-shaped manner. The securement structure is undetachably connected with one of the housing components. The securement structure consists of a plurality of ribs which are integrally molded to an exterior side of an external wall surrounding the compressor impeller installation space. If parts break away from the compressor impeller, stiffening measures of the ribs shall prevent the housing from being penetrated. 
       SUMMARY OF THE INVENTION 
       [0004]    An objective underlying the invention is to design a compressor housing as mentioned above that can be manufactured easily and which is robust. It should be optimized with regard to the material used and the weight. Furthermore, the operational safety shall be enhanced particularly in the case when parts break away from the compressor impeller. 
         [0005]    This is solved according to the invention by the fact that the securement structure features a separate burst-protection ring with a tubular wall section enclosing the compressor impeller installation space circumferentially and which is disposed in the compressor housing and fixed in its position. 
         [0006]    According to the invention, a burst-protection ring is therefore provided with a tubular wall section that encloses the compressor impeller installation space circumferentially in a closed manner. Thus, the wall section forms circumferentially a preferably complete protection that prevents in particular parts breaking away from the compressor impeller from penetrating radially to the exterior. The separate burst-protection ring can be in particular optimally adapted to the shape and/or size of the compressor housing. The burst-protection ring can also be optimized for different requirements of the radial compressor with regard to its shape, size and/or material. For example, radial compressors can be designed for higher compressor impeller speeds than with known compressor housings made of synthetic material which are subjected to corresponding higher loads. As the burst-protection ring is disposed between the compressor impeller installation space and the spiral duct, it does not expand towards the exterior. In this way, the installation space needed for the compressor housing is smaller. Furthermore, the burst-protection ring cannot be seen from the outside which is optically appealing. The separate burst-protection ring can be made of the same material as the compressor housing, or it can be made of other materials. The tubular shape of the burst-protection ring stabilizes the compressor housing. It furthermore enhances the disruptive strength. A burst-protection ring which is realized separately from the housing components simplifies the manufacture of the housing components unlike the compressor housings known from prior art where the housing components must be equipped with complex shapes that form the safety structure. During installation, the burst-protection ring can simply be connected with one of the housing components before the housing is closed with the second housing component during assembly. When connecting the housing components by ultrasonic welding, the separate burst-protection ring can influence positively the developing inherent vibrations. Advantageously, the burst-protection ring dampens the inherent vibrations. As the burst-protection ring is fixed in the compressor housing in its position, this further enhances the stability of the compressor housing. Furthermore, rattling of the burst-protection ring is prevented during operation of the radial compressor. The burst-protection ring in conjunction with the circumferential wall section ensures an additional stability against a radial expansion of the wall surrounding the compressor impeller installation space. The developing heat during the operation of the radial compressor can cause a stronger expansion of the synthetic material of the compressor housing than of the material of the compressor impeller. If the compressor impeller is in particular made of metal, its thermal expansion is lower than that of the compressor housing made of synthetic material. Due to the different expansion, the radial distance between a radial outer side of the compressor impeller and a radial inner side of the wall, which defines the compressor impeller installation space, can be enlarged. This may result in a reduced efficiency of the radial compressor. The burst-protection ring can prevent the compressor housing from being radially expanded. In this way, the efficiency is less affected when the radial compressor is heated up. Advantageously, the burst-protection ring is made of a material that can absorb the kinetic energy generated by fractions possibly thrown off the compressor impeller. The compressor housing made of synthetic material in conjunction with the burst-protection ring can under severe stress pass a burst-protection test, also known as containment test, than conventional compressor housings made of synthetic material. The burst-protection ring can also be called containment ring. 
         [0007]    In an advantageous embodiment, the burst-protection ring may be disposed in an annular space surrounding the compressor impeller installation space radially outside and which is defined by at least two of the housing components. The annular space may preferably be accessible from the outside prior to the assembly of the housing components. This makes it easy to introduce the burst-protection ring into the annular space during the assembly of the compressor housing. It can also be secured against loss at one of the housing components. When assembling both housing components, the annular space may be closed. This makes it easy to fix the burst-protection ring in the annular space. Additional fasteners are not required. The separate burst-protection ring may be disposed advantageously in an annular space which already exists in the compressor housing. 
         [0008]    Advantageously, the burst-protection ring may be fixed in the compressor housing by means of a form-fit connection, in particular by clamping ribs and/or snap-in hooks and/or beads, and/or by means of a force-fit connection, in particular by pressing on or by pressing in the burst-protection ring, and/or by means of a cohesive connection, in particular by a glued connection, an injection connection or a welded connection. Such connections make it possible to fix the burst-protection ring easily, reliably and in a stable manner in the compressor housing. Before assembly of the housing, the burst-protection ring can be easily fixed by means of the connection at one of the housing components. Thus, it is easy to realize a loss prevention device. Both housing components can then be connected with each other. Form-fit connections can be easily realized in particular by connecting bars and grooves which can cooperate in a form-fit manner when inserting or placing the burst-protection ring on a corresponding housing part. In particular, clamping ribs and/or snap-in hooks and/or beads that already exist in the compressor housing can be used. Form-fit connections can be easily realized in a stable manner. If required, they can be loosened again easily. The advantage of force-fit connections is that they can be realized easily and in a stable manner. Additional connection components such as, in particular, ribs, snap-in hooks or beads at the burst-protection ring and at the corresponding housing component are not required. The manufacturing costs for the burst-protection ring and the housing components can be reduced accordingly. Cohesive connections allow to realize easily an additional sealing function. Cohesive connections enable in particular to seal easily gaps between the burst-protection ring and the corresponding housing component. 
         [0009]    Furthermore, the burst-protection ring can advantageously be made at least in the wall section of a ductile material, in particular metal, synthetic material, carbon fibers, ceramics, aramid fibers or a material mix. Ductile material can feature a high impact strength, a high elongation at break and/or a high vibration damping. Ductile material can give the burst-protection ring, in particular the wall section, optimal characteristics with regard to elasticity, ductility, and deformability. In this way, the burst-protection ring can easily and reliably absorb the energy of thrown-off fractions. It can thus prevent fractions from penetrating. 
         [0010]    In another advantageous embodiment, the burst-protection ring can at least participate in forming a wall section of the spiral duct. In this way, the burst-protection ring can participate in designing one part of the flow contour in the spiral duct. The housing components and the burst-protection ring can be assembled in a modular way to form the spiral duct. The flow contour in the spiral duct can be optimized by the shape and/or size of the burst-protection ring. Furthermore, the burst-protection ring can enhance the stability of the walls of the spiral duct. 
         [0011]    The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying Figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention. 
           [0013]    Features of the present invention, which are believed to be novel, are set forth in the drawings and more particularly in the appended claims. The invention, together with the further objects and advantages thereof, may be best understood with reference to the following description, taken in conjunction with the accompanying drawings. The drawings show a form of the invention that is presently preferred; however, the invention is not limited to the precise arrangement shown in the drawings. 
           [0014]      FIG. 1  is a schematic axial cross section of a compressor housing of a radial compressor according to a first example of an embodiment, wherein a burst-protection ring is disposed in an annular space which surrounds a compressor impeller installation space; and 
           [0015]      FIG. 2  is a schematic axial cross section of a compressor housing according to a second example of an embodiment which resembles the compressor housing in  FIG. 1 , wherein the burst-protection ring here forms part of a wall of a spiral duct. 
       
    
    
       [0016]    Identical components in the figures have the same reference numerals. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 
       DETAILED DESCRIPTION 
       [0017]    Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of apparatus components related to a compressor housing of a radial compressor. Accordingly, the apparatus components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
         [0018]    In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. 
         [0019]      FIG. 1  shows a housing  16  made of three housing components, that is an upper section  10 , a bottom section  12 , and a middle section  14 , for a radial compressor of an exhaust gas turbocharger of an internal combustion engine, The exhaust gases of the internal combustion engine drive a turbine impeller which is connected to a compressor impeller not shown in  FIG. 1  for co-rotation. The compressor impeller pivots in the housing  16  around a rotational axis  18  indicated in  FIG. 1 . The rotation of the compressor impeller aspirates combustion air in an intake tract of the internal combustion engine and compresses it to a higher turbo pressure under which the combustion air is supplied to cylinders of the internal combustion engine 
         [0020]    When used herein, terms such as “axial”, “radial”, “circumferentially”, and “in circumferential direction” are to be understood as relative to the rotational axis  18 . 
         [0021]    A middle section  14  is disposed between the upper section  10  and the bottom section  12 . The upper section  10 , the bottom section  12 , and the middle section  14  are made of thermoplastics. Two annular joining areas  20  and  22  are formed at the upper section  10 . A corresponding end face  24  of the middle section  14  abuts on the joining area  20 . An end face  26  of the bottom section  12  abuts on the joining area  22 . The joining area  20  and the end face  24  as well as the joining area  22  and the end face  26  each form weld zones. 
         [0022]    A curvature  28  extending in an annular manner and enlarging in circumferential direction is formed at the upper section  10  in  FIG. 1  and is open at the bottom. At the radially inside placed end of the curvature  28  abuts a curved section  32  on a contact area  30 . The curved section  32  is adapted to the enlarged shape of the curvature  28 . It is integrally molded to the middle section  14 . The middle section  14  comprises furthermore an axial section  34  with a curve  36  towards a radial section  38 . The curved section  32  is integrally molded to the section  38 . 
         [0023]    The bottom section  12  is designed substantially as an annular curvature  40  that enlarges in circumferential direction. A bushing  42  extending axially towards the upper section  10  is attached to the radial exterior side. The end face  26  is located at the free end of the bushing  42 . An axial section  44  of the upper section  10  abuts on the internal wall of the bushing  42 . The housing  16  is in this area double-walled. The bottom section  12  is—at its bottom side facing away from the upper section  10 —designed to receive a housing bottom not shown in the drawing. 
         [0024]    The curvature  28  at the upper section  10 , the curved section  32  at the middle section  14 , and the curvature  40  at the bottom section  12  form a spiral duct  46 . 
         [0025]    A burst-protection ring  50  which forms a compressor impeller installation space  48  is inserted in a force-fit manner to the radial outer wall of the axial section  34 . The burst-protection ring  50  is made of aluminum. The housing  16  is stiffened thanks to the burst-protection ring  50 . If parts break away from the compressor impeller, precautions have been taken by the burst-protection ring  50  which shall prevent the housing  16  from being penetrated. 
         [0026]    The burst-protection ring  50  is located in a circumferential annular space  52 . The annular space  52  is formed between the upper section  10  and the middle section  14 . The annular space  52  encloses the axial section  34  radially outside. It is separated from the axial section  34  via the wall of the middle section  14  with respect to fluid mechanics. The burst-protection ring  50  is disposed between the compressor impeller installation space  48  and the spiral duct  46 . 
         [0027]    The burst-protection ring  50  features a tubular wall section  54  that is coaxial to the compressor impeller installation space  48 . The wall section  54  encloses the compressor impeller installation space  48  circumferentially in a closed manner. The burst-protection ring  50  is fixed in its position by means of a force-fit connector assembly on the axial section  34  of the middle section  14  in the housing  16 . 
         [0028]    For manufacturing the housing  16 , the upper section  10 , the bottom section  12 , and the middle section  14  are made of synthetic material in separate processes. The burst-protection ring  50  is made of aluminum as a separate component. 
         [0029]    The burst-protection ring  50  is placed in a force-fit manner in axial direction on the axial section  34  of the middle section  14 . In this way, it is secured against loss at the middle section  14 . The middle section  14  together with the burst-protection ring  50  is inserted in axial direction into the upper section  10  so that the joining area  20  of the upper section  10  and the joining area  22  of the middle section  14  abut each other and the contact area  30  of the curved section  32  abuts against the end of the curvature  28 . 
         [0030]    The bottom section  12  is then placed in axial direction on the upper section  10  so that the end face  26  of the bottom section  12  abuts against the end face  22  of the upper section  10 . The joining area  20  and the end face  24  as well as the joining area  24  and the end face  26  are then welded with each other by means of ultrasonic welding. During the welding process, the burst-protection ring  50  acts as vibration damping. 
         [0031]    The compressor impeller is now disposed in the compressor impeller installation space  48  in a manner that is of no interest here. 
         [0032]      FIG. 2  shows a second example of an embodiment of a housing  116 . Those elements that are similar to those in the first example of an embodiment in  FIG. 1  have the same reference numerals with the difference that the value  100  is added. The second example of an embodiment differs from the first example of an embodiment in that the curved section  132  that defines also the spiral duct  146 , and the radial section  138  are parts of the burst-protection ring  150  instead of being integrally molded to the middle section  114 , as is the case in the first example of an embodiment. The curved section  132  and the radial section  138  are integrally molded to the side of the coaxial wall section  154  of the burst-protection ring  150  that faces the bottom section  112 . Thus, the burst-protection ring  150  also forms the radial wall section  138  of the spiral duct  146 . 
         [0033]    The curve  136  of the middle section  114  ends in radial direction approximately at the height of the radial outer interior side of the annular space  152 . That end of the curve  136  supports the radial section  138  of the burst-protection ring  150  at its backside in radial direction that faces away from the spiral duct  146 . The burst-protection ring  150  features between the coaxial wall section  154  and the radial section  138  a curve  158  that fits closely to the radial outer surface of the curve  136  of the middle section  114 . 
         [0034]    Furthermore, a plurality of ribs  156  is integrally molded to the radial outer circumferential side of the coaxial wall section  154  and the curve  158  of the burst-protection ring  150 . The ribs  156  achieve a further stiffening of the burst-protection ring  150  and therefore of the housing  116 . 
         [0035]    In all the above described examples of an embodiment of a housing  16 ;  116  of a radial compressor of a turbocharger, the following modifications are among others possible: 
         [0036]    The invention is not limited to housing  16 ;  116  of a radial compressor of a turbocharger of a motor vehicle. Rather, it can also be used with different radial compressors, for example with industrial engines. 
         [0037]    The terms upper section  10 ;  110  and bottom section  12 ;  112  refer only to the exemplary orientation of the housing  16 ;  116  in  FIGS. 1 and 2 . The housings  16 ;  116  can also be oriented differently in the space, for example such that the upper section  10 ;  110  is located spatially at the bottom and the bottom section  12 ;  112  spatially at the top. 
         [0038]    Instead of aluminum, the burst-protection rings  50 ;  150  can also be made of a different, preferably ductile material, in particular of a metal, synthetic material, carbon fiber, ceramics, aramid fibers or a material mix. 
         [0039]    The burst-protection rings  50 ;  150  may also be fixed in the housing  16 ;  116  in a different way instead of pressing them on the axial section  34 ;  134 . For example, the burst-protection rings  50 ;  150  may be fixed in the housing  16 ;  116  by means of another force-fit connection, a form-fit connection, for example by means of clamping ribs and/or snap-in hooks and/or beads and/or by means of a cohesive connection, for example by means of a glued connection, an injection connection or a welded connection. 
         [0040]    In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.