DE102009005438A1 - Axial bearing for use in exhaust gas turbocharger for supporting rotatable shaft, has connecting edge extended like arc, provided between wedge and locking surfaces and formed in radial direction and/or circumferential direction - Google Patents

Abstract

The bearing (1) has a bearing body (2) firmly connected with a bearing housing, and another bearing body (4) rotating with a shaft. Bearing surfaces (3, 5, 7) comprise three lubricating oil slots (11), and a surface profile comprises a wedge surface (15) formed between the lubricating oil slots. A locking surface (16) is formed at the wedge surface that comprises a pitch in a circumference direction. A connecting edge (19) extended like an arc is provided between the wedge surface and the locking surface and formed in a radial direction and/or a circumferential direction. An independent claim is also included for a method for producing an axial bearing.

Description

The The invention relates to a thrust bearing in the preamble of the claim 1 specified type for storage of a rotatable shaft. Farther the invention relates to an exhaust gas turbocharger in the preamble of the claim 12 specified type and also a method for producing a thrust bearing according to the claim 13th

From the European patent EP 1 644 647 B1 goes out a thrust bearing for supporting a rotatable shaft. The thrust bearing has a first bearing body fixedly connected to a bearing housing and a second bearing body rotating with the shaft. The thrust bearing comprises a substantially planar sliding surface and at least one with this an intermediate lubricating gap forming bearing surface in the form of a circular surface with a surface profile, wherein the bearing surface has at least three extending in the radial direction lubricating oil grooves. The surface profile has between the lubricating oil grooves in each case a wedge surface and adjacent to the wedge surface formed locking surface, wherein between the wedge surface and the adjacent to the wedge surface formed locking surface a connecting edge is formed. The connecting edge is formed extending radially straight. An exhaust gas turbocharger and / or a method for producing the thrust bearing are not specified.

outgoing From the prior art, the invention is based on the object Specify thrust bearing for a rotatable shaft, which In addition to improved running properties a higher load capacity has simultaneously improved wear properties. At the same time, it is an object of the invention to provide an exhaust gas turbocharger which is due to reduced wear at simultaneously improved efficiencies. additionally It is an object of the invention an economical and process-reliable Specify a method for producing a thrust bearing.

The Object is achieved by a thrust bearing for a rotatable shaft with the features of the claim 1 and an exhaust gas turbocharger with the features of claim 12 or a method having the features of claim 13. Advantageous embodiments with appropriate and non-trivial developments of the invention are in the respective Subclaims given, wherein advantageous embodiments the thrust bearing as advantageous embodiments of the exhaust gas turbocharger and vice versa.

According to the invention solved the task of specifying thrust bearing, a thrust bearing for supporting a rotatable shaft, with a fixedly connected to a bearing housing first bearing body and a second bearing body rotating with the shaft, with at least one substantially flat sliding surface and at least one lubrication gap therebetween forming bearing surface in the form of a circular ring surface comprising a surface profile, wherein the bearing surface at least three lubricating oil grooves extending in the radial direction and the surface profile between the lubricating oil grooves, respectively a wedge surface and a to the wedge surface has adjacent formed locking surface, wherein the Wedge surface at least in the circumferential direction at least one Slope, and between the wedge surface and the adjacent to the wedge surface formed locking surface a connecting edge is formed, wherein the connecting edge curved in the radial direction and / or circumferential direction is formed extending.

Of the Advantage of the inventive design of Thrust bearing is one due to moving in the radial direction and / or circumferentially arcuately extending formed Connecting edge hydrodynamically improved transition between the wedge surface and the locking surface is created. This results in a more stable lubricating film, resulting in an improvement the running properties in the operating state of the thrust bearing achievable is because of a sudden breakdown of the lubricating film is reduced. This is both an increase in carrying capacity of the thrust bearing as well as a reduction of the wear-causing Solid body contact between bearing surface and sliding surface can be brought about.

When to an improvement of the running properties particularly advantageous has the arcuate connecting edge, which second according to a mathematical function Order is formed, exposed.

In In another embodiment, the connecting edge is over a tread depth of the surface profile arcuate formed extending, creating additional stabilization of the hydrodynamic lubricating film can be brought about.

In a further embodiment, the connecting line has a first intersection with an outer edge of the bearing surface and a second intersection with an inner edge of the bearing surface, the first intersection and the second intersection being disposed in a region of the bearing surface between two adjacently positioned lubricating oil grooves. In addition to an improvement in the hydrodynamic properties of the thrust bearing, this embodiment can be used to influence the field of use of the thrust bearing. In In a particularly advantageous embodiment, the first intersection point is positioned on a first edge of the wedge surface and the second intersection point on a second edge of the detent surface, wherein the first edge largely corresponds to a first Schmierölnutwandung a Schmierölnut having a Schmierölnut having a second Schmierölnutwandung which the second edge largely corresponds, is positioned adjacent. The advantage of this embodiment is the fact that a locally hydrodynamically optimized transition between the wedge and locking surface can be formed, in particular against the background of the field of application of the thrust bearing. Depending on the field of application of the thrust bearing, the first intersection point and the second intersection point are to be modified accordingly, so that the effective surfaces of the detent and wedge surfaces can be adapted to a requirement profile of a load corresponding to the area of use of the axial bearing. This leads to a further improvement of the running properties and reduced wear of the thrust bearing depending on the application.

In a further embodiment of the invention Thrust bearing is in a direction provided for the shaft rotation the second intersection positioned following the first intersection, whereby an effective lubricating film distribution in both radial Direction as well as in the circumferential direction is feasible.

In Another embodiment is the slope of the wedge surface variable in the radial direction and / or circumferential direction. The advantage this configuration is that variable by the in the radial direction Trained slope of the wedge surface a hydrodynamic improved contour of the wedge surface is created, from which a more homogeneous pressure distribution of the lubricating film and accordingly a more stable lubricating film during operation.

In a further embodiment, the slope of the wedge surface a transition from a positive to a negative slope on, in particular advantageous embodiment of the wedge surface in of the type is that starting from a first edge of the wedge surface, where the slope of the wedge surface is a positive Value, the value of the slope steadily decreases until the slope assumes the value zero, and then up to a second edge of the wedge surface the value of the slope steadily has increasingly negative values. The point in the radial direction at which the slope is the value Zero, lies in a region of the wedge surface, which is arranged near the second edge. This will improve the Running properties of the thrust bearing, as the pressure distribution of the lubricating film substantially is more homogeneous and a sudden collapse of the hydrodynamic Compressive forces during operation of the thrust bearing is avoidable.

In In another embodiment, the thrust bearing has at least one oil supply hole, which opens into the storage area and a non-round, unbalanced and / or free-formed outlet opening in the bearing surface, wherein the surface transition from the outlet opening to the bearing surface elastohydrodynamisch improved trained. The advantage of this embodiment is that the oil supply holes directly in the storage area are introduced by their special design of their outlet opening towards the storage area towards a defined supply of lubricating oil in the lubricating gap, without the hydrodynamic lubrication state during operation of the thrust bearing, d. H. with predominantly fast rotating relative movements of sliding and bearing surface to each other, in terms of turbulence essential to influence.

Preferably while the lubricant is supplied under pressure. The design of the outlet opening of the oil supply hole is here to the respective specific embodiment of the thrust bearing and the lubricant. For example, the outlet opening be configured star-shaped, or in the form of an ellipse. Basically essential for an elastohydrodynamic optimized design is that a transition of a wall of the oil supply hole to the storage area is designed so that in the operation of Thrust bearings as little turbulence or breaks as possible of the lubricating film occur, for example, by rounding off the transition.

In a further advantageous embodiment, the storage area and / or sliding at least partially a microstructuring in particular in the region of at least one wedge surface and / or latching surface on which a flow-directing and micro-dynamic Has an effect on a lubricant. Through the microstructuring results in a flow-directed and micro-dynamic Effect on the lubricant, creating a more stable lubricating film can be brought and thus the load capacity of the thrust bearing can be increased, eventually increasing the running characteristics the thrust bearing further improved significantly and the wear of the thrust bearing be further reduced.

alternative or additive points in a further embodiment of the thrust bearing the sliding and / or bearing surface at least partially one friction and / or wear-reducing surface coating which, for example, based on a carbon coating is designed. This results in further improved running characteristics and a further reduction of the wear of the thrust bearing.

Another aspect of the invention relates to an exhaust gas turbocharger with a housing and egg nem running gear, in particular comprising a compressor wheel and a shaft rotatably connected by means of a turbine wheel, wherein according to the invention for supporting a shaft of the running tool, the housing has a thrust bearing, which is designed according to one of the embodiments described above. This results in an improvement of its efficiency for the exhaust gas turbocharger, since according to the embodiments of the thrust bearing the running properties are improved, which have a significant influence on the efficiency of the exhaust gas turbocharger during operation of the exhaust gas turbocharger. Furthermore, as a result of the improved wear properties, the service life of the exhaust gas turbocharger is to be increased.

The Task with regard to the process to be specified for the production a thrust bearing is inventively characterized solved that the storage area in a first step by means of a material-removing process and in a second Step is processed by means of an electrochemical process. Compared to conventional methods where the storage area can be produced solely by machining in this process complex surfaces and contours will be realized. Furthermore, with the help of electrochemical Machining the storage areas one editing on easy Way possible, which in contrast to the usual milling method requires only a small effort. Thus, the economy the production of elastohydrodynamic optimized thrust bearings be significantly improved.

In an embodiment of the method according to the invention the electrochemical process is a pulsed electrochemical Method, a so-called PECM method (Pulsed ElectroChemical Machining), with no direct contact between a tool and the workpiece. In contrast to the electrochemical Procedure, a machining current is not permanent, but is pulsed supplied. Between the tool and the workpiece an electrical voltage is applied, the tool as Cathode and the workpiece is connected as an anode. to Machining becomes an existing between the cathode and the anode Rinsed gap with an electrolyte solution. A Material removal takes place electrochemically and that of the workpiece (Anode) abraded material is called metal hydroxide from the electrolyte solution flushed out. In contrast to the electrochemical process The pulsed electrochemical process has a much smaller gap width and thus has a much higher machining accuracy. The process is characterized overall by a high process stability out.

advantageously, becomes the effective manufacturing methodology of processing the storage area, alternatively or cumulatively the structuring of the storage area, the Production of lubricating oil grooves, production of wedge and locking surfaces and the production of the outlet openings the oil supply holes, combined in one processing step done.

Further Advantages, features and details of the invention will be apparent from the following description of several embodiments and Based on the drawings, in which the same or functionally identical Elements are provided with identical reference numerals.

there demonstrate:

1 In a plan view of a bearing surface of a thrust bearing according to the invention,

2 in an enlarged view a section of a bearing surface of the thrust bearing according to 1 and

3 in a cross section in the radial direction along the lines AA and BB according to a surface profile of the thrust bearing 2 ,

An exhaust gas turbocharger, not shown in more detail here, essentially has a housing with an exhaust gas guide section, a fresh air guide section and a bearing section and a running gear with a turbine wheel, a compressor wheel and a shaft that rotatably connects the turbine wheel with the compressor wheel. The power tool is rotatably received in the housing such that the turbine wheel in the exhaust guide section, the compressor in the fresh air guide section and the shaft are rotatably mounted in the bearing section. The shaft is in the bearing section by means of at least one radial bearing for receiving radial forces and at least one thrust bearing 1 rotatably supported for receiving axial forces.

The thrust bearing 1 for supporting the rotatable shaft comprises a fixedly connected to a bearing housing of the bearing portion first bearing body 2 with a first bearing body surface 3 and a second bearing body rotating with the shaft 4 with a second bearing body surface 5 , Both the first bearing body 2 as well as the second bearing body 4 each have a central opening 6 within, within which the shaft is received.

The first bearing body surface 3 is the second bearing body surface 5 positioned facing a lubrication gap. The first bearing body surface 3 is designed essentially as a flat sliding surface. The first bearing body area 3 facing positioned second bearing body surface 5 is as a storage area 7 in the form of a circular ring surface with a surface profile 8th and an outer edge 9 and an inner edge 10 educated.

Likewise, could also be the second bearing body surface 5 be designed as a substantially flat sliding surface, in which case the first bearing body surface 3 would be designed as a storage area. Also, the first bearing body surface could 3 and the second bearing body surface 5 be designed as a bearing surface, resulting in a significant improvement of running properties of the thrust bearing 1 and a substantial reduction in the wear of the thrust bearing 1 would result.

In the illustrated embodiment according to 1 indicates the storage area 7 eight lubricating oil grooves extending in the radial direction 11 on. The lubricating oil grooves 11 are configured trough-shaped and have a first Schmierölnutwandung 12 , one of the first lubricating oil groove wall 12 opposite arranged second Schmierölnutwandung 13 and a first Schmierölnutwandung 12 with the second Schmierölnutwandung 13 in the circumferential direction connecting tub bottom 14 on.

Between each of the first Schmierölnutwandung 12 and the second lubricating oil groove wall 13 two juxtaposed lubricating oil grooves 11 is a wedge surface 15 and one on the wedge surface 15 adjoining latching surface 16 educated. Both the wedge surface 15 as well as the locking surface 16 each have three boundary edges in this embodiment.

It corresponds to a radially extending formed edge of the first Schmierölnutwandung 12 one of the first Schmierölnutwandung 12 facing positioned first boundary edge of the wedge surface 15 and is hereafter referred to as the first edge 17 designated. In the circumferential direction, the wedge surface on a second boundary edge, which largely a portion of the outer edge 9 corresponds and thus further as outer edge 9 referred to as.

Furthermore, a radially extending formed edge of the second Schmierölnutwandung corresponds 13 a first boundary edge of the latching surface positioned facing it 16 and below as a second edge 18 is designated. The formed in the circumferential direction second boundary edge of the locking surface 16 largely corresponds to a section of the inner edge 10 and furthermore as inner edge 10 referred to as.

Between the wedge surface 15 and to the wedge surface 15 adjacent formed locking surface 16 is the third boundary edge of the wedge surface 15 and the locking surface 16 is formed and is further as a connecting edge 19 designated. According to the invention, the connecting edge 19 formed arcuately extending in the radial direction and circumferential direction. For the fast and safe construction of a hydrodynamic lubricant film, the formation of the arc shape has a mathematical function 2 , Order exposed in 2 is shown.

The connecting line 19 has in the embodiment according to 2 a first intersection 20 both with the inner edge 10 as well as with the first edge 17 and a second intersection 21 both with the outer edge 9 as well as with the second edge 18 on.

In a further, not shown embodiment, the connecting line 19 so positioned, or the wedge surface 15 and the catch area 16 such that the first point of intersection 20 as an intersection only between the connecting line 19 and the inner edge 10 is trained. That is, the first point of intersection 20 is not on the first edge 17 but in an area on the inside edge 10 between the first edge 17 and the second edge 18 , where the area between two adjacent oil holes 11 is positioned. Thus, an effective area of the wedge surface has 15 unlike in 2 illustrated wedge surface 15 enlarged, wherein the locking surface 16 Similarly, another, not shown embodiment, a connecting line 19 which is positioned so that the second intersection 21 as an intersection only between the connecting line 19 and the outer edge 9 is trained. That is, the second intersection 21 is not on the second edge 18 but in an area on the outer edge 9 between the first edge 17 and the second edge 18 , this area between two adjacent oil holes 11 is positioned. Thus, an effective area of the locking surface 16 unlike in 2 shown locking surface 16 enlarged, with the wedge surface 15 is formed reduced.

In an embodiment, also not shown, the first point of intersection 20 and the second intersection 21 positioned according to a combination of the two previously described embodiments not shown.

In the in 2 illustrated embodiment is in a direction of rotation provided for the shaft (see arrow in 1 ) the second intersection 21 the first intersection 20 following positioned.

In 3 is in a cross section in the radial direction along the lines AA and BB the Flä chenprofil 8th of the thrust bearing 1 shown. The surface profile 8th has a maximum tread depth H, wherein the tread depth H of a height of the first Schmierölnutwandung 12 , which in this embodiment perpendicular to the tub bottom 14 is formed corresponds.

Starting from a virtual level along the tub bottom 14 as a reference surface has in this embodiment, the connecting line 19 a constant distance to this virtual plane, which corresponds to the maximum tread depth H. Not shown in detail is another embodiment, the connecting edge 19 has a variable distance from the virtual plane. For example, this variable distance is formed extending arcuately in the radial direction and / or circumferential direction. Likewise, the slope of the wedge surface 15 be variable in the radial direction and / or circumferential direction.

In an embodiment not shown, the slope of the wedge surface 15 a transition from a positive to a negative slope.

To supply the thrust bearing 1 with lubricant has in a non-illustrated embodiment, the thrust bearing 1 at least one oil supply hole, which opens into a central bore. The oil supply bore has a non-circular, asymmetrical and / or free-formed outlet opening in the bearing surface 7 , wherein the surface transition from the outlet opening to the bearing surface 7 elastohydrodynamically improved is formed.

To further positively influence the flow-directing and micro-dynamic effect on the lubricating medium are the bearing surface 7 and / or sliding surface 3 . 5 at least partially with a microstructuring, in particular in the region of at least one wedge surface 15 and / or locking surface 16 fitted. Also have the sliding surfaces 3 . 5 and / or the storage area 7 at least partially a friction and / or wear-reducing surface coating.

The number of lubricating oil grooves 11 as well as the number of wedge and locking surfaces 15 . 16 are freely variable. Indicates the storage area 7 three lubricating oil grooves 11 and respectively three wedge and locking surfaces 15 . 16 up, that's the thrust bearing 1 production technology can be produced in a short time. Indicates the storage area 7 a larger number of lubricating oil grooves 11 and a correspondingly larger number of wedge and locking surfaces 15 . 16 on, so is with increasing the number a more uniform load on the locking surfaces 16 and thus expect a further reduction of wear. Overall, for example, in a number of twelve lubricating oil grooves 11 and respectively twelve wedge and locking surfaces 15 . 16 a hydrodynamic state in the instationary operation reached faster than with a number of three lubricating oil grooves 11 , respectively three wedge and locking surfaces 15 . 16 , However, in terms of manufacturing technology, this increases with the increasing number of lubricating oil grooves 11 , Wedge and locking surfaces 15 . 16 the time expenditure.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1644647 B1 [0002]

Claims (15)

Axial bearing for supporting a rotatable shaft, with a fixedly connected to a bearing housing first bearing body ( 2 ) and a shaft rotatable with the second bearing body ( 4 ), with at least one substantially flat sliding surface ( 3 . 5 ) and at least one with this an intermediate lubrication gap forming bearing surface ( 5 . 3 . 7 ) in the form of a circular ring surface with a surface profile ( 8th ), whereby the storage area ( 7 ) at least three lubricating oil grooves extending in the radial direction ( 11 ), and the surface profile ( 8th ) between the lubricating oil grooves ( 11 ) each have a wedge surface ( 15 ) as well as to the wedge surface ( 15 ) adjacent formed locking surface ( 16 ), wherein the wedge surface ( 15 ) at least in the circumferential direction has at least one slope, and between the wedge surface ( 15 ) and the wedge surface ( 15 ) adjacent formed locking surface ( 16 ) a connecting edge ( 19 ), characterized in that the connecting edge ( 19 ) is formed extending arcuately in the radial direction and / or circumferential direction. Thrust bearing according to claim 1, characterized in that the arcuately formed connecting edge ( 19 ) is formed according to a mathematical function of second order. Thrust bearing according to claim 1 or 2, characterized in that that the connecting edge ( 19 ) over a profile depth (H) of the surface profile ( 8th ) is formed extending arcuately. Thrust bearing according to one of the preceding claims 1 to 3, characterized in that the connecting line ( 19 ) a first intersection ( 20 ) with an outer edge ( 9 ) of the storage area ( 7 ) and a second intersection ( 21 ) with an inner edge ( 10 ) of the storage area ( 7 ), wherein the first intersection ( 20 ) and the second intersection ( 21 ) in a region of the bearing surface between two adjacently positioned lubricating oil grooves ( 11 ) are arranged. Thrust bearing according to claim 4, characterized in that the first intersection ( 20 ) on a first edge ( 17 ) of the wedge surface ( 15 ) and the second intersection ( 21 ) on a second edge ( 18 ) of the locking surface ( 16 ), the first edge ( 17 ) as far as possible a first Schmierölnutwandung ( 12 ) a lubricating oil groove ( 11 ) associated with a lubricating oil groove ( 11 ) comprising a second lubricating oil groove wall ( 13 ), which of the second edge ( 18 ) corresponds as far as possible, is positioned adjacent. Thrust bearing according to claim 4 or 5, characterized in that in a direction of rotation provided for the second cutting point ( 21 ) the first intersection ( 20 ) is positioned next. Thrust bearing according to one of claims 1 to 6, characterized in that the slope of the wedge surface ( 15 ) is variable in the radial direction and / or circumferential direction. Thrust bearing according to one of claims 1 to 7, characterized in that the slope of the wedge surface ( 15 ) has a transition from a positive to a negative slope. Thrust bearing according to one of claims 1 to 8, characterized in that the thrust bearing ( 1 ) has at least one oil supply hole which in the bearing surface ( 7 ) and a non-circular, asymmetrical and / or free-form outlet opening in the storage area ( 7 ), wherein the surface transition from the outlet opening to the bearing surface ( 7 ) Elastohydrodynamically improved is formed. Thrust bearing according to one of claims 1 to 9, characterized in that the bearing surface ( 7 ) and / or sliding surface ( 3 . 5 ) at least partially a microstructuring, in particular in the region of at least one wedge surface ( 15 ) and / or latching surface ( 16 ), which has a flow directing and microdynamic effect on a lubricating medium. Thrust bearing according to one of claims 1 to 10, characterized in that the sliding and / or bearing surface ( 3 . 5 . 7 ) has at least partially a friction and / or wear-reducing surface coating. Exhaust gas turbocharger with a housing and a running gear, in particular comprising a compressor wheel and a turbine wheel rotatably connected by means of a shaft, characterized in that for supporting a shaft of the running tool the housing has a thrust bearing ( 1 ) according to claims 1 to 11. Method for producing a thrust bearing according to one of claims 1 to 11, characterized in that the bearing surface ( 7 ) is processed in a first step by means of a material-removing process and is processed in a second step by means of an electrochemical process. Process for producing a thrust bearing according to Claim 13, characterized in that the electrochemical method is a pulsed electrochemical process. Method for producing a thrust bearing according to claim 13 or 14, characterized that the processing of the storage area ( 7 ), alternatively or cumulatively, the structuring of the storage area ( 7 ), the production of lubricating oil grooves ( 11 ), the production of the wedge and locking surfaces ( 15 . 16 ) and the production of the outlet openings of the oil supply holes, combined in one processing step will take place.