Housing for a radical compressor

Abstract

A housing for a radial compressor is comprised of at least two housing parts manufactured of plastic material for receiving a compressor wheel and for forming a spiral-shaped compressor passage, wherein into the housing between compressor wheel receptacle and compressor passage an annular space is introduced that annularly surrounds the compressor wheel and into which a stabilization element is introduced.

Description

This is a cip application of pending international patent application PCT/EP2008/063146 filed Oct. 1, 2008 and claiming the priority of German patent application 10 2007 055 615.4 filed Nov. 20, 2007.

TECHNICAL FIELD

The invention concerns a housing for a radial compressor comprising two housing parts consisting of plastic and having a spiral-shaped compressor passage and a compressor wheel disposed in the housing.

PRIOR ART

In DE 103 14 209 B3 a radial compressor as a component of an exhaust gas turbocharger is described that is comprised of two shell-shaped housing parts that are injection-molded from thermoset material. This material has a high density so that, in comparison to other conventional charger housings of metal, no weight-related advantage results. DE 103 14 209 B3 attempts to counteract this in that into one of the housing parts chamber-like recesses are introduced that are separated from one another by partitions and that essentially extend concentrically to an air intake axis.

The housing parts are glued together which however requires a relatively high manufacturing expenditure. Thermoset resin as a material is furthermore characterized by a relatively high brittleness and high water absorption as well as a relatively minimal dimensional stability at high temperatures. Moreover, there is great acoustic radiation and the manufacturing costs are also relatively expensive.

In case of radial compressors moreover a satisfactory operating safety must be taken into consideration. Because of the high wheel speeds of turbochargers there is the risk that upon damage of the compressor wheel metal fragments of the wheel will penetrate the housing of the compressor and will damage components in the engine compartment of the internal combustion engine.

SUMMARY OF THE INVENTION

The invention has the object to produce a lightweight dimensionally precise housing for a radial compressor with satisfactory seal-tightness and high heat resistance from plastic material wherein, in case of damage of the compressor wheel, the risk of metal fragments flying about is to be reduced.

This object is solved according to the invention in that an annular hollow space is provided in the housing which extends around the compressor wheel and at least one stabilizing element is disposed in the annular space.

The housing according to the invention for a radial compressor is comprised of at least two housing parts manufactured of plastic material which, on the one hand, are designed for receiving a compressor wheel and between which, on the other hand, a spiral-shaped compressor passage is formed. Into the housing between a compressor receptacle that serves for receiving and supporting the compressor wheel and the spiral-shaped compressor passage a circumferentially extending annular space is formed that annularly surrounds the compressor wheel. In this annular space at least one stabilization element is introduced.

The housing parts manufactured of plastic material, comprised in particular of thermoplastic material and produced by the injection-molding process, for example, of polyphenylene sulfide (PPS), fulfill together with the annular space in which at least one stabilization element is introduced also high safety requirements, in particular in case of fracture of the compressor wheel. The annular space is located at the radial outer side of the compressor wheel so that broken-off wheel fragments that are thrown off tangentially outwardly as a result of the high rotary speed of the compressor wheel will impact on the annular space and the stabilizing element arranged therein. The walls of the annular space ensure already an effective reduction of the broken-off tangentially thrown wheel parts; in addition, there is the stabilizing element that is received in the annular space that, on the one hand, counteracts deformation of the walls of the annular space and improves as a whole the stability of the housing and, on the other hand, upon impact of a broken-off wheel fragment, provides effective damping. The stabilization element therefore has a double function: on the one hand, the annular space and thus the entire housing is supported or reinforced; on the other hand, in case of an accident, the protection from thrown-off wheel fragments is improved.

In axial direction the annular space advantageously extends at least about the axis length of the compressor wheel wherein optionally also an extension substantially about the length of one of the housing parts that delimits the annular space may be considered.

As a stabilization element a separate component is to be considered that is inserted into the annular space. For example, the stabilization element is embodied as a fill hose, for example, comprised of aramide fiber or the like, that is inserted into the annular space upon assembly of the housing. For the purpose of facilitating assembly of the housing, an annular groove can be introduced into one of components delimiting the annular space and forms part of the annular space and provides a receptacle for the stabilization element already before assembly of the two housing parts.

In the radial direction, the annular space has an extension that enables insertion of the stabilization element. Relative to the wall thickness of the delimiting wall the radial extension is preferably a multiple of the wall thickness, for example, three times to five times the wall thickness. Moreover, it may be expedient to match the radial extension of the annular space, viewed about the circumference, to the shape of the spiral-shaped compressor passage. Since the compressor passage in the circumferential direction has a variable diameter, a greater radial extension for the annular space is available in sections of smaller diameter of the compressor passage than in sections with greater diameter.

The manufacture of the compressor housing of thermoplastic material, in particular PPS, has the advantage of easy manufacture as well as good recyclability. In the manufacture by injection molding, a lost core technology is not required; manufacture is realized by injection molding by means of molds of a simple configuration that can be opened and closed. A further advantage resides in the manufacture of complex geometries of the housing, for example, a spiral passage with several undercuts. Finally, thermoplastic materials can be produced with high dimensional precision so that post-processing can be dispensed with or the need for it is limited. Moreover, the thermoplastic material is heat-resistant, pressure-tight and has excellent sound-insulating properties at minimal weight.

A further advantage resides in the possibility of configuring housing parts with constant wall thickness so that material accumulations are avoided and the risk of cavity formation is reduced.

The housing parts can be welded together in particular by way of ultrasonic welding. In order to be able to position the ultrasonic probe (sonotrode) in a simple way at the required welding seam, advantageously the contact area between the housing parts to be welded is adjacent to the axial end face of the housing, in particular adjacent to the intake side. Moreover, the contact areas between the housing parts are preferably located at a spacing to the spiral-shaped compressor passage; they are thus removed from the critical spiral area so that the air guiding action on the inner side of the spiral is not impaired by an undesirable burr caused by welding in the wall.

According to a further advantageous embodiment, the housing as a whole is comprised of three housing parts including a compressor front part, a compressor rear wall, and an inwardly positioned bearing shell. The compressor front part and compressor rear wall form the outer housing parts between which the bearing shell is positioned that serves for receiving the compressor wheel. The annular space is provided preferably between the bearing shell and the compressor front part.

Further advantages and expedient embodiments are disclosed in the further claims, the figure descriptions, and the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The only FIGURE shows a section of a housing for a radial compressor comprised of three individual housing parts of thermoplastic material that are welded together by ultrasonic welding wherein between an inwardly positioned bearing shell and a compressor front part an annular space is formed that surrounds the compressor wheel receptacle.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The illustrated housing 1 for a radial compressor is a component of an exhaust gas turbocharger of an internal combustion engine in which the exhaust gases of an internal combustion engine drive a turbine wheel that is fixedly connected to compressor wheel that is rotatably supported in the housing 1. By rotation of the compressor wheel combustion air is sucked into the intake manifold and compressed to an increased charge pressure at which the combustion air is supplied to the cylinders of the internal combustion engine.

The housing 1 is of a three-part configuration and comprises a compressor rear wall 2, a compressor front part 3, and an inwardly positioned bearing shell 4 that delimits a compressor wheel receptacle 5 for receiving and supporting the compressor wheel that in the embodiment is referenced by reference numeral 7 and is illustrated only schematically by a dotted line. The combustion air is axially supplied to the compressor wheel 7 by an intake socket 6 that is formed in the compressor front part 3. The compressed combustion air is guided radially through diffuser 9 into a spiral-shaped compressor passage 8 that is delimited by the compressor front part 3 and compressor rear wall 2 and that opens into an outlet socket by means of which the compressed combustion air is supplied finally to the cylinders of the internal combustion engine.

Between the compressor front part 3 and the bearing shell 4 a circumferentially extending annular space 10 is formed that radially surrounds the compressor wheel receptacle 5 and is separated fluid-tightly from the compressor wheel receptacle 5 by means of the wall of the bearing shell 4. The annular space 10 has substantially the same axial extension as the bearing shell 4 and thus also the compressor wheel receptacle 5. A separate component in the form of a fill hose 11 is inserted into the annular space 10 that has the function of a stabilization element and, in addition to providing reinforcement of the housing 1, also takes on a safety function in case of an accident in that broken-off wheel fragments of the compressor wheel 7 that are tangentially thrown outwardly are caught by the stabilization element 11.

The housing parts 2, 3, 4 are comprised of thermoplastic material and are joined by way of ultrasonic welding. This is done such that a sonotrode is placed onto the contact areas 14, between the compressor rear wall 2, and the compressor front part 3, or 15, between the bearing shell 4 and the compressor front part 3, in order to perform the process of ultrasonic welding. The first contact area 14 between compressor rear wall 2 and compressor front part 3 is located in the radial outer area, neighboring the end face that forms the intake side of the housing. The contact area 15, on the other hand, is positioned radially inwardly displaced between the bearing shell 4 and the compressor front part 3 immediately neighboring the compressor wheel receptacle 5 but also on the side of the housing that is facing the intake side.

The bearing shell 4 is formed in such a way that in the area of the annular space 10 in the bearing shell 4 an annular groove 16 is formed that is supplemented to the annular space 10 by the compressor front part 3 to be positioned thereon. The annular groove 16 has the advantage that already before positioning the compressor front part 3 a receptacle for insertion of the stabilization element is provided; this is in particular advantageous in the variant embodied as a separate component in accordance with FIG. 1 because in this case the stabilization element embodied as a separate component is received safely in the annular groove 16 before positioning the compressor front part.

Claims

1. A housing for a radial compressor, comprised of at least two housing parts (2, 3, 4) manufactured of plastic material for receiving a compressor wheel (7) and for forming a spiral-shaped compressor passage (8), wherein in the housing (1) between a compressor wheel receptacle (5) and the spiral-shaped compressor passage (8) a hollow space is introduced, the hollow space being an annular space (10) that surrounds the compressor wheel (7) with at least one stabilization element disposed in the annular space (10).

2. The housing according to claim 1, wherein the annular space (10) is delimited by two housing parts (3, 4).

3. The housing according to claim 2, wherein the housing parts that delimit the annular space (10) are embodied as inwardly positioned bearing shell (4) forming the compressor wheel receptacle (5) and as compressor front part (3).

4. The housing according to claim 3, wherein the bearing shell (4), on the side facing away from the compressor wheel receptacle (5), forms an annular groove (16) that forms a part of the annular space (10).

5. The housing according to claim 1, wherein the housing is of a three-part configuration and comprises the compressor front part (3), a compressor rear wall (2), and the inwardly positioned bearing shell (4).

6. The housing according to claim 5, wherein the compressor front part (3) has a contact area (15) with the bearing shell (4) and a further contact area (14) with the compressor rear wall (2).

7. The housing according to claim 1, wherein the contact areas (14, 15) between the housing parts (2, 3, 4) are arranged at a spacing to the spiral-shaped compressor passage (8).

8. The housing according to claim 7, wherein the contact areas (14, 15) are positioned adjacent to the intake opening (6) of the housing (1).

9. The housing according to claim 1, wherein the housing parts (2, 3, 4) are welded to one another, in particular by ultrasonic welding.

10. The housing according to claim 1, wherein a stabilization element in the annular space (10) is embodied as fill material.

11. The housing according to claim 10, wherein the fill material is comprised of plastic material.

12. The housing according to claim 1, wherein the stabilization element in the annular space (10) is embodied as a separate component, for example, as a fill hose (11).

13. The housing according to claim 1, wherein the housing parts (2, 3, 4) are manufactured of thermoplastic material and in particular producible by injection molding.

14. The housing according to claim 13, wherein the housing parts are comprised of polyphenylene sulfide (PPS).