DE102018204162A1 - Bearing bushing for a shaft of a turbocharger - Google Patents

Abstract

The invention relates to a bearing bush with a central axis for receiving a rotating shaft about this axis of a turbocharger having at least one thrust bearing surface and at least one radial bearing surface having a plurality of helical lubricant grooves for conveying lubricant.
The bushing according to the invention is characterized in that the thrust bearing surface has a number of locking surfaces in a plane perpendicular to the axis and an equal number of wedge surfaces each between the locking surfaces, wherein each at the transition of the wedge surfaces in one of the adjacent locking surfaces one from radially inward to radially outward extending keyway is formed, and wherein each of the keyways is in communication with at least one of the lubricant grooves.

Description

The invention relates to a bearing bush for a shaft with a central axis according to the closer defined in the preamble of claim 1. The invention also relates to a turbocharger with such a bushing.

Turbochargers are known from the general state of the art. Typically, they have a continuous shaft, on one end of which a turbine is mounted and on the other end of which at least one compressor wheel is mounted. For the storage of the shaft in a housing of the turbocharger bearing bushes have long been established, which in particular have thrust bearing surfaces and radial bearing surfaces. By way of example, a bearing bush of this kind in the disclosure of US 4,240,678 A be pointed out.

A crucial point in such bearing bushes is their bearing task on the one hand as a thrust bearing and in particular as a radial bearing for the typically with several 10000 rev / min very fast running shaft of the turbocharger. Such sockets can be integrally formed. This can be exemplified by the structure in the US 6,017,184 A be pointed out. It shows, for example, the EP 1 998 009 B1 a structure in which a split socket is formed. This split into two parts socket essentially has a similar structure of both the radial bearing surfaces in the interior of the two bushes and the thrust bearing surfaces on each end face of the socket.

The international patent application WO 2014/055255 A1 shows a plain bearing with a thrust bearing surface. The thrust bearing surface consists of a flat surface with pressure generating means on the inner diameter of the annular surface. These pressure-generating means do not extend to the outer diameter of the surface. They are used to bring oil as a lubricant to the flat surface. The problem with this idea is the relatively large flat surface which increases the friction. In addition, no means are provided to distribute the lubricant over the flat surface. Although this requires only a minimal amount of lubricant but on the other hand, the friction thereby further increased.

From the DE 11 2013 003 184 T5 , a translation of the international application WO 2014/003057 A1 , a bushing with thrust bearings and radial bearings for a turbocharger is also known. The thrust bearing here have continuous outwardly leading grooves, which have a curved course and expand accordingly in their course, in order to ensure the most uniform possible lubricant supply of the thrust bearing surfaces and to be able to dissipate collecting dirt. In addition, two radial bearings in the bearing bush are known from this document. These radial bearings have outwardly recessed grooves which extend so as to provide a lubricating effect to the outside as the shaft rotates relative to the bearing bushing.

From the WO 2015/167844 A1 a similar structure with spirally extending through the radial bearing surfaces grooves is known. According to the international publication, however, these grooves are not provided for lubricant supply but for acoustic optimization of the structure of the turbocharger. However, they have opposing helical configurations within the two radial bearing surfaces of the bearing bush described therein. A conveying effect on the lubricant is to be expected.

It is the object of the invention to provide an improved bushing for the shaft of a turbocharger which allows good bearing capacity along with minimal friction and acceptable lubricant consumption. It is also the object of the invention to provide a turbocharger with such a bushing.

This object is achieved by a bearing bush with the features in claim 1. The object is also achieved by a turbocharger with such a bushing.

The bushing according to the invention is constructed around a central axis about which rotates the recorded in the bearing bushing shaft of a turbocharger. The shaft forms, together with a compressor and a turbine, the so-called rotor of the turbocharger, that is, the part which rotates in the bearing bush with the speeds already mentioned at the outset. The bearing bush has comparable to the bearing bushes in the prior art at least one thrust bearing surface and at least one radial bearing surface. For example, two separate bearing bushes can be provided, so that each of the bearing bushes has a radial bearing surface and an axial bearing surface, or a common bearing bush can be provided with in each case two radial bearing surfaces and two axial bearing surfaces.

In the at least one radial bearing surface, a plurality of helical lubricant grooves are provided for conveying lubricant depending on the direction of rotation in one or the other axial direction. The thrust bearing surface in the bearing bush according to the invention has a number of so-called locking surfaces in a plane perpendicular to the axis and an equal number of Wedge surfaces each between the locking surfaces. In each case at the junction of the wedge surface in one of the adjacent latching surfaces of a radially inwardly to radially outwardly extending keyway is formed, each of the keyways is in communication with at least one of the lubricant grooves. The keyways, which are formed in accordance with an advantageous embodiment of the idea of radially inwardly radially outwardly increasing and preferably extending in the radial direction over only a portion of the radial width of the thrust bearing surface are thus connected to at least one of the lubricant grooves. With a corresponding direction of rotation of the shaft in the bearing bush or the shaft and the bearing bush relative to each other then there is a conveying effect of lubricant from one of the axial bearing surface side facing away from the radial bearing surface through the lubricant grooves towards the keyways of the thrust bearing surface. The lubricant is thus reliably conveyed in this area and simultaneously lubricates the radial bearing surface. The lubricant conveyed into the region of the axial bearing surface passes via the keyway into the substantially annular region of the axial bearing, in each case on the lowest point of the wedge surface, offset in the direction of the radial bearings relative to the plane of the locking surfaces. The lubricant can then accumulate in this area of the wedge surface and is increasingly compressed by the rotational movement of the counter element with respect to the thrust bearing surface of the bearing bush along the wedge surface, so that up to the point in which the wedge surface reaches the latching surface, a pressure build-up has occurred and the components do not rotate directly on top of each other but with a pressure cushion of the lubricant between them. As a result, a very efficient, low-wear and by the special structure yet very economical storage in terms of lubricant consumption possible.

According to an advantageous development of the idea, the number of lubricant grooves in the at least one radial bearing surface is greater or preferably equal to the number of keyways in the at least one axial bearing surface. Each of the helically extending lubricant grooves thus supplies one of the keyways and thus one of the wedge surfaces of the thrust bearing. If the axial bearing, for example, constructed with four locking surfaces, it has accordingly four wedge surfaces and four keyways. Each of the keyways is supplied with the lubricant via one of the helical lubricant grooves, so that practically results in a structure of the lubricant grooves in the radial bearing surface in the manner of a four-start thread. The lubricant grooves need not necessarily be formed circumferentially around the entire circumference of the radial bearing surface, so that a structure corresponding to a four-start thread with a correspondingly high pitch is conceivable, so that the lubricant grooves extend only a portion of the circumference.

Alternative forms of the lubrication grooves, which show the following courses in the state unrolled on a projection plane, for example linear, a parabola function, an e-function, a curve, an S-shaped line, a zigzag line or the like, likewise fall under the concept of the helical lubricant grooves in the invention Sense, as long as they cause a resulting conveying effect of lubricant from one axial side of the radial bearing surface to the other in each case a constant rotational direction.

A very advantageous development of the idea, it provides that the wedge surfaces adjacent to a latching surface with a step recessed in the circumferential direction, that are offset from the plane of the locking surface in the direction of the radial bearing. They then rise in the circumferential direction to the other adjacent locking surface on the level again. Such a structure allows an ideal pressure build-up in the lubricant by forming a lubricant wedge. In addition, it can be provided according to an advantageous development of the idea that between the locking surface and the wedge surface starting from the step is a parallel to the plane of the locking surfaces arranged intermediate surface, in which the keyways are arranged. The splines can thus be arranged in the wedge surfaces themselves or in between the wedge surfaces and the locking surfaces lying parallel to the locking surfaces extending intermediate surfaces. This can be advantageous in terms of manufacturing since one side edge of the keyway can then simultaneously form the radially extending boundary between the keyway and the wedge surface.

An extraordinarily advantageous development, it provides that the wedge surfaces are flat in the radial direction. The locking surfaces and - if present - the intermediate surfaces, which lie in a plane perpendicular to the axis, are anyway flat both in the circumferential direction and in the radial direction. According to the advantageous development of the idea, the wedge surfaces can now also be flat in the radial direction. This means that the entire step between one of the latching surfaces and the adjacent wedge surface or the transition from the intermediate surface, if present, extends in the wedge surface so that the height of the step radially inward and radially outward on the thrust bearing surface is the same. This is in terms of manufacturing of decisive advantage, since only in the circumferential direction, a change in the wedge surface takes place and this does not have to be changed in the radial direction complementary to the circumferential direction, which would represent a significant overhead in terms of manufacturing.

To an ideal oil supply of the keyways and thus the wedge surfaces and ultimately the To ensure axial bearing surface, it can also be provided according to an advantageous development of the idea that each of the grooves connected to a keyway lubricant opens on the side facing in the circumferential direction of the locking surface side of the keyway in this. Thus, the keyway is impinged on the rear in the direction of movement of a counter-element on the axial bearing surface, so that the promoted on this side in the region of the keyway lubricant ideally on the other side of the keyway and in the radial direction to the wedge surface and can contribute there to pressure build-up.

In this case, ideally, each of the keyways may be associated with exactly one of the lubricant grooves. As a result, there is no unnecessary accumulation of lubricant in the area of the radial bearing surfaces due to additional lubricant grooves, which however would also be conceivable in principle. If present, these additional lubricant grooves could end, for example, in a peripheral groove extending in the radial bearing surface. By assigning exactly one of the lubricant grooves to one of the keyways, however, a well-functioning structure, which ensures a minimum consumption of lubricant.

A very advantageous development of the idea provides it in this case that the bearing bush in this particularly favorable embodiment of the invention has a supply port for lubricant on the axial bearing surface side facing away from the radial bearing surface, so that this lubricant promoted via the conveying action of the spiral lubricant grooves in the radial bearing surface to the thrust bearing surface can be and lubricates both the radial bearings and the thrust bearing accordingly.

According to a further advantageous embodiment, an opening for receiving a fixing pin can be provided in the bearing bush. Both of these openings can be present in principle. If, for example, a hollowed-out fixing pin is used, an opening would be sufficient which allows both the technical task of the rotationally fixed fixing of the bearing bush on the one hand and by the hollow-bored fixing pin the supply of lubricant on the other hand.

According to a particularly favorable embodiment of the idea, as already mentioned above, the bushing is designed in such a way that in each case a radial bearing surface and an axial bearing surface are provided at the opposite axial ends of the bearing bush. The shaft of the rotor of the turbocharger can be stored in a single socket. In this advantageous embodiment of the idea, the spiral-shaped lubricant grooves in the two radial bearing surfaces are in opposite directions, so that they allow a conveying action in each case outwardly towards the axial bearing surfaces in the corresponding direction of rotation of the shaft in the bearing bush.

A turbocharger according to the invention comprises at least a compressor and a turbine on a common shaft. The turbocharger further includes a housing having a central opening for receiving the shaft in at least one bushing. The bushing is constructed according to one of the above-described embodiments with at least one thrust bearing surface comprising wedge surfaces and keyways and detent surfaces. In addition, the bearing bush has at least one radial bearing surface with helical lubricant grooves according to the embodiments described above. Such a turbocharger allows minimal friction in its radial and thrust bearings and allows good carrying capacity with a low consumption of lubricant or oil.

An advantageous development of the turbocharger then provides that the housing has a lubricant channel in order to supply the lubricant to the feed opening. This can ideally run radially in the housing. This significantly reduces the complexity of the housing compared to structures with several partly oblique lubricant supply lines.

Further advantageous embodiments and further developments of the bearing bush and the turbocharger also result from the exemplary embodiment, which is described in more detail below with reference to the figures.

• 1 einen Schnitt durch einen Teil eines Turboladers gemäß der Erfindung in einer möglichen Ausführungsform;
• 2 einen Schnitt durch einen Teil eines Turboladers gemäß der Erfindung in einer alternativen Ausführungsform;
• 3 eine dreidimensionale Ansicht einer Lagerbuchse in einer erfindungsgemäßen Ausgestaltung;
• 4 eine Schnittdarstellung durch die Lagerbuchse;
• 5 eine Draufsicht auf eine Ausgestaltung der Axiallagerfläche in einer erfindungsgemäßen Ausgestaltung der Lagerbuchse;
• 6 einen Teil der Axiallagerfläche von radial innen betrachtet mit einem auf der Axiallagerfläche laufenden Gegenelement;
• 7 eine Ansicht analog zu der in 6, von radial außen;
• 8 eine dreidimensionale Ansicht einer Lagerbuchse in einer weiteren Ausgestaltung gemäß der Erfindung; und
• 9 eine Draufsicht auf die Axiallagerfläche in der weiteren Ausgestaltung der Lagerbuchse gemäß der Erfindung.

Showing:

• 1 a section through a portion of a turbocharger according to the invention in a possible embodiment;
• 2 a section through a portion of a turbocharger according to the invention in an alternative embodiment;
• 3 a three-dimensional view of a bearing bush in an embodiment of the invention;
• 4 a sectional view through the bushing;
• 5 a plan view of an embodiment of the thrust bearing surface in an embodiment of the bearing bush according to the invention;
• 6 a part of the thrust bearing surface, as viewed radially from the inside, with a counter element running on the thrust bearing surface;
• 7 a view analogous to in 6 , from radially outside;
• 8th a three-dimensional view of a bearing bush in a further embodiment according to the invention; and
• 9 a plan view of the thrust bearing surface in the further embodiment of the bearing bush according to the invention.

In the presentation of the 1 is a section of a turbocharger 1 to recognize how it can be used in particular as an exhaust gas turbocharger. The core of the turbocharger 1 form a turbine 2 and on a common wave 4 with this turbine 2 a compressor 3 , at the other end of the wave 4 , The turbocharger 1 itself consists of a central housing 5 in which a bearing bush 6 for storage of the shaft 4 is arranged. The central housing 5 is then laterally in the area of the compressor 3 through an attached compressor housing and in the area of the turbine 2 completed by a turbine housing (both not shown). For the following invention is now in particular the central region of the housing 5 as well as the bearing bush 6 for axial and radial mounting of the so-called rotor from shaft 4 , Turbine 2 and compressors 3 significant.

The housing 5 has a radial lubricant channel 7 for the supply of lubricant in the area of one in the bearing bush 6 arranged feed opening 8th on. The lubricant thus preferably passes centrally into the interior of the bearing bush 6 to both sides of the bearing bush 6 to supply evenly. It then passes from the bearing bush 6 over their radial bearing surfaces 14 , which will be described in detail below, to the at both ends of the bearing bush 6 arranged thrust bearing surfaces 15 , From there, the lubricant passes in their entirety designated 9 discharge channels, through which it is collected and discharged again. This is known so far for a specialist in the field of turbochargers.

In addition, the bearing bush has 6 an opening 10 for receiving a fixation pin 11 on which the bearing bush 6 fixed, in particular prevents rotation. The opening can be 10 correspondingly larger than the diameter of the fixing pin 11 be executed so that the bearing bush 6 both in the circumferential direction and in the axial direction of a central axis 12 as they are in the presentation of 1 to recognize, is movable.

In the presentation of the 2 the same structure is shown again. The only difference is that the opening 10 and the feed opening 8th are folded together by a fixing pin 11 ' is used, which has a central bore 13 has, so that he can take on the one hand the task of fixing and on the other hand, the task of lubricant supply. All other elements are analogous to the elements described above 1 designated and understood.

In the presentation of the 3 is now a first embodiment of the bearing bush 6 in a three-dimensional view and below in the 4 and 5 in a sectional view and in plan view of one of the thrust bearing surfaces 15 the bearing bush 6 to recognize. The structure is such that the bearing bush 6 Radial bearing surfaces at both axial ends 14 and thrust bearing surfaces 15 having. In the three-dimensional view of 3 is one of the thrust bearing surfaces 15 and one of the radial bearing surfaces 14 to recognize. The view of 5 shows the top view of just this thrust bearing surface 15 , About the feed opening 8th Lubricant gets inside the bearing bush 6 , The two radial bearing surfaces 14 have several, in the embodiment shown here four, helically through the radial bearing surfaces 14 running lubricant grooves 16 on. These lubricant grooves 16 ensure the corresponding direction of rotation of the shaft 4 in the bearing bush 6 for that over the feed opening 8th into the interior of the bearing bush 6 supplied lubricant through the lubricant grooves 16 outwards, towards the thrust bearing surfaces 15 , is promoted. This is enough through the lubricant grooves 16 in the radial bearing surfaces 14 flowing lubricant for adequate lubrication of the radial bearing surfaces 14 even out.

The axially outward to the thrust bearing surfaces 15 subsidized lubricant then passes into each one with each of the lubricant grooves 16 connected keyway 17 , Next to this keyway 17 are located on the one side each so-called locking surfaces 18 which are in a plane perpendicular to the axis 12 lie, and which for the improvement of the recognizability in the representation of the 5 hatched are marked, even if it is not, as usual in hatching usual, is a cut. These locking surfaces 18 are just formed both in the circumferential direction and in the radial direction. Between them wedge surfaces extend 19 , in whose area the keyways 17 lead. The transition between the wedge surfaces 19 and the locking surfaces 18 on one side in the circumferential direction, in this case on the side in whose area the keyways 17 are arranged, is formed in the form of a step. This has radially inward and radially outward the same height h, so that the wedge surface is configured in the radial direction just. It then rises to on the other side in the circumferential direction adjacent locking surface 18 and goes there in this catch area 18 above.

The keyway 17 is in connection with one of the lubricant grooves 16 in the range of this step-like transition from the locking surface 18 in the wedge surface 19 incorporated into this and takes in the direction radially outward steadily in terms of their depth from. After about two-thirds of the radial width of the thrust bearing surface 15 seen from radially inward to the outside ends the keyway 17 at the level of the wedge surface 19 , The keyway 17 itself is only radially aligned at one of its peripheral side edges or, for example, with its center line. The other side edge or both side edges, if the center line is radially aligned, is / are parallel to each other, so that the keyway 17 very easy to make with a router. The lubricant groove 16 ends in the direction of the adjacent locking surface 18 in the keyway 17 , so that it can be supplied from this direction with lubricant, which then by the rotation of the counter element 20 on the inside of the case 5 of the turbocharger 1 fixed bearing bush 6 over the wedge surface 19 ideally spreads. The height h of the step may for example be on the order of a few 10 microns, with an outer diameter of the bearing bush 6 for example 10 to 30 mm.

In the presentation of the 6 is a rolled-out section of a part of the thrust bearing surface seen from radially inside seen; in 7 the same section seen from radially outside. In 6 the height h of the step is shown; as well the keyway 17 as well as in the keyway 17 opening lubricant groove 16 , A counter element 20 to the thrust bearing surface 15 moves relative to the thrust bearing surface 15 according to the indicated arrow, so that the over the lubricant groove 16 incoming lubricant in the direction from which it flows over the wedge surface 19 spreads and provides for the lubrication of the components. In the presentation of the 7 is the same construction from the radially outside, and therefore with the reverse orientation as in the illustration of 6 represented. It can be seen that the keyway 17 does not lead to the radially outer region, so here essentially only the wedge surface 19 can be seen. Essentially, because in the embodiment in the 6 and 7 and also in the 8th and 9 , which will be described below, the structure is slightly different than previously described. Instead of the mouth of the keyway 17 in the wedge surface 19 located in this embodiment, a 21 marked with intermediate surface, which is parallel to the locking surfaces 18 runs, and a section between the actual wedge surface 19 and the stage represents. In this interface 21 then is the keyway 17 incorporated so that the transition of the keyway 17 in a plane and not wedge-shaped rising surface, as in the embodiment shown above, takes place. The technical effect is essentially the same, in terms of production, one or the other variant, depending on the tools used, be beneficial. The two variants can be in both described embodiments of the bearing bush 6 can thus be reversed compared to the examples described. It would also be conceivable a bushing 6 with two different thrust bearing surfaces 15 build according to the embodiments.

In the representations of the 8th and 9 is now the second described construction of the thrust bearing surface 15 to recognize again, otherwise analogous to the representations in 3 and 5 , Another difference of the construction is that in the 3 to 5 the bearing bush 6 a relatively large outer diameter in the region of the radial bearing surfaces 14 has, for example, the adaptation to a corresponding central opening of the housing 5 to accomplish, without the inner diameter, the radial bearing surfaces 14 and the thrust bearing surfaces 15 to have to change. The construction in the 8th and 9 shows the same structure, without the material bulges on the bearing bush 6 so this bushing 6 designed for a correspondingly smaller diameter. Otherwise, the structures largely correspond. One in the bearing bush 6 indicated groove 22 has no technical functionality in the true sense, but only serves the direction in which the bearing bush 6 during assembly must be symbolized, since a directional mounting is necessary to the conveying effect of the helical lubricant grooves 16 from the center of the bearing bush 6 towards the thrust bearing surfaces 15 in any case.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4240678 A [0002]
• US 6017184 A [0003]
• EP 1998009 B1 [0003]
• WO 2014/055255 A1 [0004]
• DE 112013003184 T5 [0005]
• WO 2014/003057 A1 [0005]
• WO 2015/167844 A1 [0006]

Claims (14)

Bearing bush (6) having a central axis (12) for receiving a shaft (4) of a turbocharger (1) rotating about said axis (12), having at least one axial bearing surface (15) and at least one radial bearing surface (14) which has a plurality of helical lubricant grooves (12). 16) for conveying lubricant, characterized in that the thrust bearing surface (15) has a number of locking surfaces (18) in a plane perpendicular to the axis (12) and an equal number of wedge surfaces (19) between the locking surfaces (18) , wherein in each case at the transition of the wedge surfaces (19) in one of the adjacent latching surfaces (18) from radially inside to radially outwardly extending keyway (17) is formed, and wherein each of the keyways (17) with at least one of the lubricant grooves (16) in Connection stands. Bearing bush (6) to Claim 1 , characterized in that the number of helical lubricant grooves (16) in the at least one radial bearing surface (14) is greater than or preferably equal to the number of keyways (17) in the at least one thrust bearing surface (15). Bearing bush (6) to Claim 1 or 2 , characterized in that the wedge surfaces (19) adjacent to the one latching surface (18) are set back with a step in the axial direction and then increase in the circumferential direction to the other adjacent latching surface (18). Bearing bush (6) to Claim 3 , characterized in that between the latching surface (18) and the adjacent wedge surface (19) starting from the step a parallel to the plane of the locking surfaces (18) arranged intermediate surface (21), in which the keyway (17) is arranged. Bearing bush (6) according to one of Claims 1 to 4 , characterized in that the wedge surfaces (19) are planar in the radial direction. Bearing bush (6) according to one of Claims 1 to 5 , characterized in that the splines (17) extend from radially inward to radially outward and preferably extend in the radial direction only over part of the radial width of the thrust bearing surface (15). Bearing bush (6) according to one of Claims 1 to 6 , characterized in that each of the one of the keyway (17) connected helical lubricant grooves (16) opens on the circumferential direction of the locking surface (18) facing side of the keyway (17) in this. Bearing bush (6) according to one of Claims 1 to 7 , characterized in that each of the keyways (17) is associated with exactly one of the helical lubricant grooves (16). Bearing bush (6) according to one of Claims 1 to 8th characterized by a supply opening (8) for lubricant on the axial bearing surface (15) facing away from the radial bearing surface (14). Bearing bush (6) according to one of Claims 1 to 9 characterized by an opening (10) for receiving a fixing pin (11 '). Bearing bush (6) according to one of Claims 1 to 10 , characterized in that the keyways (17) have side edges aligned parallel to one another in the radial direction. Bearing bush (6) according to one of Claims 1 to 11 , characterized in that at each axial end a respective radial bearing surface (14) and an axial bearing surface (15) are provided, wherein the helical lubricant grooves (16) in the two radial bearing surfaces (14) are formed in opposite directions. Turbocharger (1) with at least one compressor (3) and a turbine on a common shaft (4) with a housing (5), which has a central opening for receiving the shaft (4) in at least one bearing bush (6), characterized by the bearing bush (6) according to one or more of Claims 1 to 12 , Turbocharger (1) after Claim 13 and with a bearing bush (6) according to one of Claims 9 to 12 , characterized in that in the housing (5) a, in particular radially extending, lubricant channel (7) for supplying lubricant to the supply opening (8) of the bearing bush (6) is provided.

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