Axial bearing arrangement for a shaft of a turbocharger
The invention relates to an axial bearing arrangement for a shaft in a turbocharger, the housing or a section of the housing of the turbocharger preferably being divided in a longitudinal direction into at least two housing halves.
In general, a turbocharger consists of an exhaust gas turbine in an exhaust gas mass flow, which turbine is connected via a shaft to a compressor in the intake duct. In this case the turbine wheel of the turbine is arranged in a turbine housing and the compressor wheel of the compressor in a compressor housing. The shaft is in turn mounted in a bearing housing. In operation, the turbine wheel is driven by the exhaust gas mass flow and in turn drives the compressor wheel. In this case the compressor compresses the aspirated air and conducts it to the internal combustion engine. Normally the shaft is supported in the bearing housing by means of a radial bearing arrangement. As a result of fluid flows impinging on the turbine wheel and the compressor wheel, strong axial forces can arise. In general, such axial forces cannot be appropriately absorbed by the radial bearings. For this reason at least one or two additional axial bearings are provided in order to absorb these axial forces appropriately.
Furthermore, the design of turbochargers up to now has provided individual housings fastened to one another in series and sealed with respect to one another. A new form of turbocharger housing now provides that the turbocharger housing is divided in a longitudinal direction and not, as hitherto, transversely to its longitudinal axis, that is, in a transverse direction. This new turbocharger housing is the subject matter of a further patent application.
Accordingly, it is the object of the present invention to make available an appropriate axial bearing arrangement for a shaft of a turbocharger, in particular of a turbocharger having a turbocharger housing divided in a longitudinal direction.
This object is achieved by a turbocharger having a turbocharger housing with an axial bearing arrangement having the features of claim 1.
According to the invention, therefore, a turbocharger is made available with a turbocharger housing wherein at least one section of the turbocharger housing is configured to be divided or subdivided in a longitudinal direction into at least two housing halves, wherein a shaft is mounted in the turbocharger housing and wherein at least one axial bearing arrangement is provided in order to support the shaft in the axial direction.
In this case the turbocharger has the advantage that the axial bearing arrangement can be fitted to the rotor assembly and the rotor assembly with the axial bearing arrangement can then be placed complete in the housing halves of the turbocharger housing divided in a longitudinal direction.
Advantageous configurations and developments of the invention are apparent from the dependent claims and from the description, with reference to the drawings.
The invention is explained in more detail below with reference to the exemplary embodiments represented in the schematic figures of the drawings, in which:
FIG. 1 is a view of a housing half of a turbocharger which is configured to be divided in a longitudinal direction into two housing halves, the shaft being provided in the turbocharger housing with a radial bearing arrangement and an axial bearing arrangement according to a first embodiment of the invention;
FIG. 2 is a sectional view of the turbocharger according to FIG. 1;
FIG. 3 is a sectional view through a turbocharger housing having an axial bearing arrangement according to a further variant of the first embodiment of the invention;
FIG. 4 is a sectional view through a turbocharger housing having an axial bearing arrangement according to a second embodiment of the invention;
FIG. 5 is a sectional view through a turbocharger housing divided in a longitudinal direction with an axial bearing arrangement according to a third embodiment of the invention;
FIG. 6 is a sectional view through a turbocharger housing divided in a longitudinal direction with an axial bearing arrangement according to a fourth embodiment of the invention, and
FIG. 7 is a sectional view through a turbocharger housing divided in a longitudinal direction with an axial bearing arrangement according to a fifth embodiment of the invention.
In all the figures like or functionally like elements and devices—unless otherwise stated—are denoted by the same reference numerals. Furthermore, the representation of the turbocharger in the following figures is purely schematic, not to scale and highly simplified.
FIG. 1 shows a sectional view through a turbocharger 10 having a turbocharger housing 12 which is configured to be divided in a longitudinal direction into, for example, at least two housing halves 14. FIG. 1 shows a housing half 14 from the seal side. The housing half 14 has a recess 15 or groove in which a sealing arrangement can be received for fastening the two housing halves in a sealed manner. In this case the recess 15 and the path of the recess 15, in which a sealing arrangement is provided in order to seal the housing halves 14, are purely exemplary and the invention is not limited to this example. Moreover, the sealing of the two housing halves is the subject matter of a separate patent application.
In the example in FIG. 1, the turbocharger housing 12 comprises a bearing housing 18, a turbine housing 20 and a compressor housing 22, all three housings being, for example, combined to form one housing and being configured to be divided along the longitudinal direction into at least two housing halves 14. In principle, the whole turbocharger housing 12, as in FIG. 1, or at least a section of the turbocharger housing 12, may be configured to be divided in a longitudinal direction into at least two housing halves 14.
In the present case the turbocharger housing 12 is configured to be divided in a longitudinal direction, for example in a horizontal plane, the longitudinal axis 24 of the turbocharger housing 12 lying in this case in the horizontal plane. In principle, however, the turbocharger housing 12 may be configured to be divided into at least two housing halves 14 in every plane in the longitudinal direction. Furthermore, the longitudinal axis 24 does not need to lie in this parting plane or, for example, to intersect said parting plane, although it may do so.
In the present example, the turbocharger housing 12 may optionally be configured to be additionally at least partially coolable and/or heatable. More precisely, in the example shown in FIG. 1 the turbocharger housing 12 has in the region of the turbine housing 20 and of the bearing housing 18 an additional fluid jacket 26 or temperature regulating jacket into which a fluid, for example water, can be conducted in order to regulate the temperature of, or to cool and/or heat this region of the turbocharger housing 12, depending on the function and application.
The housing half 14 shown in FIG. 1 is fastened and sealed to the other, corresponding housing half (not shown). For this purpose, at least one or a plurality of bores 28, for example, are provided in order to screw and/or pin the two housing halves 14 to one another. Moreover, any other form of fastening which is suitable for connecting the two housing halves 14 to one another and making possible or itself providing a seal between the two housing halves 14, may be provided. In this case, a bead seal, an O-ring seal and/or an elastomeric seal, for example, may be provided as a sealing device for sealing the two housing halves 14. The bead seal, or one of the other seals, is placed in a suitable recess 15 in one or both of the housing halves 14, while the other housing-half surfaces which are not sealed are, for example, in direct contact with one another.
In FIG. 1, a shaft 30 on which a turbine wheel 32 and a compressor wheel 34 are provided is mounted in the bearing housing section 18 of the turbocharger housing 12. In this case the turbine wheel 32 is arranged in the turbine housing section 20 and the compressor wheel 34 in the compressor housing section 22 of the turbocharger housing 12. In the present example, the shaft 30 has a radial bearing arrangement 36 and an axial bearing arrangement 38, according to the first embodiment of the invention.
For the turbocharger 10, an axial bearing arrangement 38 comprising at least one or a plurality of axial bearings is used in order to absorb, for example, the axial thrust and to position axially the rotor assembly, or the turbine and compressor wheels 32, 34, in such a way as to achieve both relatively high efficiency through narrow flow gaps and to prevent damage. In a turbocharger housing 12 divided in a longitudinal direction, as shown in FIG. 1, an axial bearing can no longer be installed axially since the rotor disk 32, 34 or rotor is inserted radially and axial access no longer exists. Hitherto, with a turbocharger housing divided in a transverse direction, an axial bearing was firmly screw-fastened axially in a closed bearing housing prior to assembly. The rotor assembly was then mounted afterwards with the bearing arrangement.
According to the first embodiment of the invention, as shown in FIG. 1 and the following FIG. 2, the axial bearing arrangement 38 is now also mounted on the rotor assembly, and the bearing surface is provided and machined with the housing half.
In this case the axial bearing arrangement 38 according to the invention comprises at least one axial bearing 40, for example in the form of an axial bearing disk. As shown in FIG. 1, this axial bearing 40 is fastened to the shaft 30 of the rotor assembly. In order to be fastened to the shaft 30, the axial bearing arrangement 38 may be cramped, screwed, pressed and/or shrunk thereon, to mention only a few examples of fastening possibilities. This applies to all embodiments of the invention. In this case the axial bearing 40 may be bounded on one side by a step of the shaft, and optionally on the other side additionally by a bush element 42 or a sleeve. In this case the bush element 42 additionally has on its outer side at least one sealing device 44 for sealing the bearing housing section 18 with respect to the compressor housing section 22. As the sealing device 44 in this case, two piston ring seals in corresponding grooves on the outside of the bush element 42 may, for example, be provided.
In addition, in the example shown in FIG. 1, the shaft 30 is mounted by means of a radial bearing arrangement 36. In this case, the radial bearing arrangement 36 has on its outer side a sleeve element 46 consisting, for example, of metal, e.g. steel, or including same, and has a collar section 48 at each end. In this case at least one or both collar sections 48 of the sleeve element 46 are, for example, configured to be resilient, in order to be tensioned between two stops or receptacles 50, or in this case projections of the turbocharger housing 12, and to tension the bearing arrangement provided in the sleeve element 46 in the axial direction. Equally, one or both collar sections 48 may be configured to be non-resilient or stiff, and may be placed between the two stops 50. In this case one or both collar sections 48 may optionally be additionally fastened, for example by means of screws, to the associated receptacle 50. Optionally, at least one resiliently-acting or stiff collar section may also be additionally screw-fastened and/or pinned to the respective associated receptacle 50. In this case one or both collar sections 48 are, for example, connected integrally or as separate parts to the sleeve element 46. In this case the separate collar section 48 may optionally be additionally fastened to the sleeve element 46, for example locked and/or screwed thereto, after the sleeve element 46 has been inserted in the bore.
In this case, one or both collar sections 48 of the sleeve element 46 may also optionally project additionally from the oil chamber, both on the turbine side, as shown in FIG. 1, and on the compressor side (not shown), and take over further functions, for example that of a heat shield. One or both collar sections 48 may, however, remain within the oil chamber, like the collar section 48 on the compressor side in FIG. 1. The sleeve element 46 may now itself be configured, for example, as a radial sliding bearing arrangement (not shown) and form two sliding bearing sections. Alternatively, the sleeve element 46, as shown in the embodiment in FIG. 1, may also receive a sleeve 54 which includes the two sliding bearing sections 52. Instead of the sleeve 54, however, two radial bearings may, for example, be also provided as sliding bearings, which radial bearings optionally are additionally arranged in the sleeve element 46 and spaced from one another by means of a spacer sleeve (not shown). Alternatively, the sleeve element 46 may also be configured on its inner side as a spacer sleeve with a stop for each sliding bearing (not shown). Furthermore, a layer 56 consisting of at least one or a plurality of plies of an elastic, heat-resistant or temperature-resistant material may optionally be provided additionally on the inner and/or outer side of the sleeve element 46, as shown in FIG. 1. In this case the material consists, for example, of a polymer, an elastomer and/or a hard rubber. However, the invention is not limited to these materials. In principle, any other suitable, heat-resistant or temperature-resistant, elastic material may be used.
As is shown in FIG. 1, the sleeve 54 is fitted to the shaft 30, the shaft 30 having, for example, a step with a stop for the sleeve 54. The axial bearing arrangement 38, which forms a stop for the sleeve 54 or the radial bearing arrangement 36 in the axial direction, is provided at the other end of the sleeve 54. Optionally, a sheet metal oil barrier 58, for example, may additionally be arranged on the axial bearing arrangement 38 or the axial bearing disk 40, the axial bearing disk 40 optionally having additionally a receptacle 60 for the sheet metal oil barrier 58. The shaft 30 can easily be placed, together with the sleeve 54, the layer 56 made of an elastic material or material combinations, and the sleeve element 46 with the two collar sections 48, in the housing halves 14 of the longitudinally divided turbocharger housing 12.
FIG. 2 shows in addition a sectional view through the turbocharger housing 12, both housing halves 14, 16 being represented. In this case the seal between the two housing halves 14, 16 is also indicated in highly simplified form.
FIG. 3 further shows a sectional side view through a turbocharger housing 12 with an axial bearing arrangement 38 according to a further variant of the first embodiment of the invention. In this case a portion of the bearing housing section 18 of both housing halves 14, 16 is shown in a sectional view. The shaft 30 is mounted in the housing 18 by means of a radial bearing arrangement 36 consisting, for example, of two sliding bearings 62 between which, for example, a spacer sleeve 64 is additionally arranged. An axial bearing arrangement 38 comprising at least one axial bearing 40, for example in the form of an axial bearing disk, is further provided. The axial bearing disk 40 is in this case fastened to the shaft 30 of the rotor assembly, being, for example, cramped, pressed or shrunk thereon, to mention only a few examples of possibilities of fastening the axial bearing arrangement 38 to the rotor or to the shaft 30. As shown in FIG. 3, the axial bearing 40 may be arranged in a hollow or recess of the turbocharger housing 12, the recess having on one or both sides a boundary portion 66 for the axial bearing arrangement 38. The boundary portion 66 or projection may be formed integrally or may be fastened to the turbocharger housing 12 as a separate part. In this case the boundary portion 66 additionally opposes unwanted axial movement of the axial bearing 40, and serves here as an axial boundary portion.
Furthermore, a bush element 42, which may additionally have sealing elements on its outer side, may optionally be additionally provided for sealing the bearing housing section with respect to the rotor housing section (not shown). A disk element 79, which serves, for example, to spin off lubricant from the shaft 30, may, for example, be additionally provided adjacent to the bush element 42.
The first embodiment according to the invention, in which the rotor assembly includes an axial bearing arrangement 38 mounted on the shaft 30, has the advantage that it is no longer necessary to fasten an axial bearing arrangement 38 separately in the housing 12. The assembled rotor assembly can be placed directly therein. In addition, the recess or boundary portion 66 on one or both sides of the axial bearing 40 opposes unwanted axial movement of the axial bearing 40. However, the axial bearing 40 does not need to be placed in a recess or to have one or two lateral boundary portions 66, since the axial bearing 40 is itself fastened firmly to the shaft 30.
FIG. 4 shows in addition a sectional view through both housing halves 14, 16 of a longitudinally divided turbocharger housing 12 having an axial bearing arrangement 38 according to a second embodiment of the invention. In this case the housing halves 14, 16 are shown from the front. The axial bearing arrangement 38 also comprises at least one axial bearing 40, for example in the form of an axial bearing disk. The axial bearing 40 has at least one or two bracket elements 68 or projections with which the axial bearing 40 is screwed firmly to a housing half 16. In this case it is not necessary additionally to fasten the axial bearing arrangement 38 firmly to the shaft 30, for example by cramping or shrinking, etc., as shown in FIGS. 1, 2 and 3. The axial bearing arrangement 38 may have play between its opening 70 and the external circumference of the shaft 30.
The advantage of the second embodiment according to the invention, in which the axial bearing arrangement 38 is fixed radially with bracket elements 68, is that the axial bearing arrangement 38 can already be fitted to the rotor assembly and then fastened, for example screwed and/or pinned, in the housing half 16 perpendicularly to the main or longitudinal axis 24. In this case one has very easy, unobstructed access with a screwdriver to the screwing location.
FIG. 5 shows a sectional side view through a turbocharger housing 12 with an axial bearing arrangement 38 according to a third embodiment of the invention. In this case a shaft 30 supported radially by means of two radial sliding bearings 62 is represented, it being possible for the radial sliding bearings optionally to be arranged additionally in an insert sleeve 54, as shown in FIG. 5. In the example in FIG. 5 a shaft step is, for example, provided on one or both sides of the radial bearing arrangement 36, on which shaft step an additional bearing collar 72 serving to provide the bearing surfaces for the axial bearing is arranged. In this case the bearing collar 72 is configured, for example, as a rotary part or a rotationally symmetrical part. The bearing collar 72 has in turn on its outer side a receptacle 74, for example in the form of a step or a recess (not shown), for the axial bearing arrangement 38. In this case the axial bearing arrangement 38 comprises at least one axial bearing 40, for example in the form of an axial bearing disk. Play is provided between the axial bearing 40 and the bearing collar 72, since the bearing collar 72 rotates with the shaft 30 while the axial bearing 40 is fixed. For this purpose the axial bearing 40 may be fastened, for example by means of one or more screws 76 and/or pins (not shown), to the insert sleeve 54 and/or to the housing 12. The bearing collar 72, by contrast, is fastened in such a way that it rotates with the shaft 30. For this purpose the bearing collar 72 is, for example, clamped to the shaft 30 by means of a shaft nut, in which case a clearance fit or transition fit may be provided between the shaft 30 and the bearing collar 72. However, the bearing collar 72 may also be fastened to the shaft 30 in any other way.
The axial bearing arrangement 38 may be fastened, for example, to a separately installed insert sleeve 54, as shown in FIG. 5, for example by means of the fastening methods and fastening means described previously. Optionally, a further disk element 79, which can be used to spin off lubricant such as oil from the shaft 30, may be additionally provided adjacent to the bearing collar 72. Because the axial bearing arrangement can be fastened to the housing 12 and/or to the insert sleeve 54, an additional step or boundary portion which additionally opposes axial movement of the axial bearing arrangement, as in FIG. 3, can be dispensed with in this case. In principle, however, such a boundary portion may be provided on one or both sides of the axial bearing 40, depending on function and application.
The third embodiment according to the invention, in which the axial bearing arrangement 38 is arranged on a bearing collar 72 or bearing core or is screwed to an insert sleeve 54, has the advantage that the axial bearing arrangement 38 can be assembled outside the housing halves of the turbocharger housing 12 and then placed therein together with the rotor.
FIG. 6 further shows a sectional side view through a turbocharger housing 12 and its two housing halves 14, 16, with an axial bearing arrangement 38 according to a fourth embodiment of the invention. In this embodiment the axial bearing arrangement 38 may be arranged, for example, directly on the rotor or the shaft 30 (not shown) or, as shown in FIG. 6, on a bearing collar 72. In this case the axial bearing arrangement 38 likewise comprises at least one axial bearing 40, for example in the form of an axial bearing disk. The axial bearing 40 may in this case be provided on the bearing block 72 as described earlier, for example in FIG. 5, the bearing collar 72 serving to provide the bearing surfaces for the axial bearing. In this case the axial bearing 40 is fixed rigidly or via at least one spring element 78, while the bearing collar 72 rotates with the shaft 30. Depending on the function and application, the bearing collar 72 may also be omitted. In that case the shaft 30 provides the bearing surface for the axial bearing 40 (not shown).
In order to fix the axial bearing arrangement 38, at least one spring element 78, with which the axial bearing arrangement 38 is braced axially in the turbocharger housing 12, is used according to the fourth embodiment according to the invention. In this case the axial bearing arrangement 38 is fitted in a receptacle 60 in the form, for example, of a recess or hollow in the bearing housing section 18 and braced in the receptacle 60 by means of the spring element 78, so that unwanted movement of the axial bearing 40 in the axial direction is opposed. In this case the axial bearing arrangement 38 is pressed against an axial surface of the receptacle 60 by the at least one spring element 78. Optionally, at least one oil barrier ring 79 which is also tensioned on the shaft 30 may additionally be provided, as shown in FIG. 6, the oil barrier ring 79 spinning off the oil or lubricant. Likewise, a spring element (not shown), which is arranged, for example, on the shaft 30 in the receptacle 60, may optionally be provided additionally in order to fix the axial bearing 40 additionally in the axial direction.
The fourth embodiment according to the invention has the advantage that the spring element 78 and the receptacle or groove allow the axial bearing arrangement 38 to be fitted onto the rotor. In this case screw-fixing processes are omitted.
FIG. 7 shows a sectional side view through a turbocharger housing 12 with an axial bearing arrangement 38 according to a fifth embodiment of the invention. The axial bearing arrangement 38 also comprises at least one axial bearing 40, for example in the form of an axial bearing disk. In this case the axial bearing 40, as described previously, may be arranged, for example, directly on the shaft 30 (not shown) or, for example, on a bearing collar 72, as shown in FIG. 7, and may form, for example, a clearance fit with the shaft 30 or with the bearing collar 72. In other words, the axial bearing 40 is fixed while the bearing collar 72 rotates with the shaft 30. In this case the axial bearing 40 may be simply fitted into an associated receptacle 60 or, optionally, may additionally be clamped or fastened therein. In order to fasten the axial bearing 40, it may optionally be fixed, for example in the housing 12, on its outer circumference with at least one sealing device 44, for example an O-ring or a piston ring seal, etc.
In the fifth embodiment of the invention, the receptacle 60 for receiving an axial bearing 40 in the turbocharger housing 12 is configured in the form of a recess or a groove, the receptacle 60 having a first receptacle section 80 in which the axial bearing disk 40 is received, and the first receptacle section 80 being configured in such a way that, or having a boundary portion such that, it opposes unwanted axial movement of the axial bearing 40. In this case the first receptacle section 80 forms with the axial bearing 40 a clearance fit or a transition fit, for example. This has the advantage that the axial bearing 40 can be fitted very easily into the first receptacle section 80 of the receptacle 60 and at the same time unwanted axial movement of the axial bearing 40 can be prevented, since the boundary portion 66 of the receptacle section 80 prevents unwanted axial movement of the axial bearing 40.
A second receptacle section 82 of the receptacle 60 is configured in such a way that at least one disk element 79, for example an oil barrier ring and/or a spring element, can be arranged in the receptacle 60, for example on the shaft 30, in order to oppose unwanted axial movement of the bearing collar 72 or of the axial bearing 40. In this case the receptacle 60 is configured, for example, with a step, as shown in FIG. 7, in order to form the first and second receptacle sections 80, 82. In this case the second receptacle section 82 forms, for example, an oil chamber or lubricant chamber in which an oil barrier ring 79, by means of which oil or lubricant can be spun off, may be arranged. In this case the oil barrier ring 79 forms an axial bearing surface for the axial bearing 40.
The fifth embodiment according to the invention has the advantage that the groove or the first receptacle section 80 allows the axial bearing arrangement 38 to be fitted to the rotor. In this case additional fastening processes, such as screw fixing processes, are likewise omitted.
The invention is not restricted to the aforedescribed embodiments. In particular, the aforedescribed embodiments, especially individual features of the different embodiments, may be combined with one another.
The invention is also not restricted to the radial bearing arrangements 36 as described hereinbefore with reference to the figures. In principle, any other radial bearing arrangement may be used to support the shaft 30 of the turbocharger. The core of this invention is the axial bearing arrangement 38. In this case, in addition to the axial bearing disk 40 shown in the figures, any other axial bearing 40 can be used, for example an axial contactless bearing such as an axial magnetic bearing, an axial rolling bearing and/or an axial sliding bearing, etc., to mention only a few further examples of axial bearings 40.
Patent Application
20120269624
