DE102011009564B4 - Bearing unit for turbocharger spindle units - Google Patents

Abstract

Bearing unit for a shaft (16) of a turbocharger, which comprises at least one outer ring (10; 110; 310; 410), at least one inner ring (12a,b, 112a; 312a,b; 412a) and at least two rows of bearings guided between the outer ring (10; 110; 310; 410) and the inner ring (12a,b, 112a; 312a,b; 412a), wherein at least one channel (28; 128; 328; 428) is provided for injecting lubricant into an intermediate space (14; 114; 314; 414) between the outer ring (10; 110; 310; 410) and the inner ring (12a,b, 112a; 312a,b; 412a), characterized in that that devices (32, 38, 42, 132, 138, 232, 238, 242; 320, 324; 428; 456, 458) are provided which separate the lubricant from dirt particles contained in the lubricant by utilizing centrifugal force.

Description

Field of the invention

The invention relates to a bearing unit for turbocharger spindle units, hereinafter also referred to as TLSE, according to the preamble of claims 1 and 17.

State of the art

Exhaust gas turbochargers are operated at very high speeds at high temperatures. A turbine and a compressor are arranged on a common shaft. These operating conditions place high demands on the accuracy and wear resistance of the bearing unit of the shaft bearing. Typical TLSE are, for example, in DE 20 2004 017 194 U1 and DE 38 25 326 A1 disclosed. The bearing unit is designed as a rolling bearing. The rolling bearing comprises, for example, an outer ring with two rows of bearings and two inner rings, each with one row of bearings. The distances between the raceways between the outer ring and the inner ring have a precisely defined difference in order to create an adjustment tendency; an O-arrangement is preferably used.

Due to the high temperatures and speeds, the TLSE must be permanently supplied with lubricant. The lubricant, typically oil, is fed to the TLSE through two holes in the outer ring. These two holes are inclined towards the bearing rows to ensure that the bearing rows are well supplied with lubricant. Since the turbocharger is used in combustion engines, the TLSE is advantageously included in the lubrication circuit of the combustion engine. The engine oil of the combustion engine is therefore used as the lubricant for the TLSE. In addition to lubrication, the engine oil also has a cooling function.

The quality of the engine oil in a combustion engine decreases significantly during operation. Since the oil is also used to lubricate the TLSE, contamination from abrasion and combustion residues in particular can impair the safe functioning of the TLSE. When the TLSE is in operation, very high forces, temperatures and speeds are at work, which place great strain on the TLSE. To ensure the required service life of the TLSE, a good lubricant supply with good lubricant quality is advantageous. Conventional filters for cleaning the engine oil, which are installed before the engine oil enters the TLSE, clog up very quickly and throttle the lubricant circuit. Such upstream filters have therefore not proven to be effective.

A common cause of failure for ball-bearing TLSE is the failure of the ball bearing cage. The cage is typically guided on the inboard or outboard and has the task of keeping the rolling elements, in this case balls, at a distance from each other in order to achieve the most even distribution of the balls around the circumference. The ball pockets in the circumferential direction and the respective guide surface on the inner or outer ring typically wear out. Large forces and high relative speeds increase the tendency to wear. The greatest forces and relative speeds occur particularly during the acceleration phases. Due to the impellers (turbine wheel and compressor wheel), the direction of rotation of the turbocharger is predetermined - the turbocharger only rotates in one direction. The forces on the cage, which are caused by the inertia of the cage and the friction forces in the contact points with neighboring components, as well as by the fluid friction of the lubricant, must be overcome. To do this, energy must be supplied to the cage. The energy is supplied via the balls and possibly via the inner or outer ring (if the cage is guided over the rotating ring). If the energy is supplied via the ball, the harmful "skidding effect" can be increased, whereby the balls slip on the ring due to sliding friction instead of rolling friction. By reducing or avoiding the "skidding effect", the wear of the bearing unit in general, and in particular the wear on the cage, can be reduced or avoided in order to increase the service life of the entire bearing unit or the entire turbocharger.

The DE 20 2004 017 194 U1 discloses a bearing unit for a turbocharger with the features of the preamble of patent claims 1 and 17.

US 20081 0267548 A1 and WO 2011/ 009813 A1 disclose essential features of the preamble of patent claim 17.

US 7 040 874 shows a turbocharger with lubricant filter.

EN 33 26 299 A1 reveals a gap formation between two parts rotating relative to each other.

EN 10 2008 046 582 A1 and DE 897 902 A reveal exhaust gas turbochargers with special lubricant guidance through spacer sleeves arranged on the shaft.

Disclosure of the invention

The object of the invention is to reduce the wear in a bearing unit for turbocharger spin del units, thereby increasing their service life and improving their functional reliability.

The object is achieved by a storage unit having the features of claim 1 or claim 17.

Preferred embodiments of the invention and further advantageous features are specified in the subclaims.

The bearing unit for a shaft of a turbocharger comprises at least one outer ring, at least one inner ring and at least two rows of bearings guided between the outer ring and the inner ring. At least one channel is provided for injecting lubricant into a space between the outer ring and the inner ring.

The invention is characterized in that devices are arranged within the intermediate space and/or on the inner ring and/or the outer ring which separate the lubricant from dirt particles contained in the lubricant by utilizing centrifugal force.

According to the invention, the different specific weight of the dirt particles compared to pure engine oil is exploited. After the engine oil enters the TLSE, the lubricating medium hits the rotating component, for example the inner ring, and is thereby set in rotation and finally thrown off in the direction of the non-rotating component, for example the outer ring. The trajectory of the thrown-off dirt particles, which is mainly determined by centrifugal force, differs from the trajectory of pure engine oil due to the different specific weights and the different mass inertia. By introducing suitable geometries on the rotating component and/or the non-rotating component, but also in the flow channel, the dirt particles can be completely or at least partially removed from the engine oil by utilizing centrifugal force.

According to a preferred embodiment of the invention, the lubricant containing dirt particles, for example engine oil, reaches the outer diameter of the rotating inner ring through specifically oriented feed channels. The channels preferably run at an angle of approximately 60° to 80° to the shaft axis and open near an associated row of bearings. The inner ring has a special geometry in the impact zone of the lubricant in the form of, for example, a defined groove, possibly with a spray edge. When it hits the rotating inner ring, the oil itself is set in rotation and finally thrown off and hits the rim of the stationary outer ring. Due to centrifugal forces acting on the lubricant and the dirt particles contained therein, the dirt particles are deflected at a different angle than the pure lubricant due to their higher mass inertia and hit the outer ring in a different area than the pure lubricant. The dirt particles can be separated from the oil using a suitable geometry in the outer ring, e.g. a defined groove with a separating edge. The lubricant that has been at least partially freed from dirt particles can then be fed directly to the bearing rows, while the lubricant enriched with dirt particles is fed away from the bearing rows.

According to a preferred embodiment of the invention, the lubricant is atomized/atomized. By optimizing the parameters of the oil supply, such as volume flow, pressure, direction, speed of the component that the jet hits, and introducing a spray edge to atomize the oil, a vortex flow of the atomized lubricant is generated, which transports the lubricant mist to the bearing rows. Atomization can also be achieved by appropriately designing the oil supply channels. At least part of the supplied lubricant is atomized or atomized. The bearing rows are thus lubricated with oil mist. The formation of mist (droplet formation) separates the dirt from the "clean" oil. The non-atomized, dirty part of the oil does not reach the bearing rows, leaves the TLSE through the oil outlet hole, but remains in the lubricant circuit and is available for cooling.

According to a further preferred embodiment of the invention, the flow energy of the lubricating oil can be used to reduce wear, particularly on the cage. The oil supply channels inclined towards the ball bearing are not only inclined in relation to the longitudinal axis of the shaft but also in the circumferential direction of the outer ring and positioned so that the lubricant jet hits the cage directly or indirectly and drives the cage in its intended direction of rotation.

Preferably, the lubricant flow should hit the cage in an area that drives the cage well, does not affect the cage and supports its stable running. Preferably, this can be the cage side. To better convert the flow energy of the lubricant into kinetic energy of the cage, corresponding contours or impact surfaces can be attached or incorporated on the cage or in the cage. For example, these can be fel wheels are arranged on the face of the cage facing the lubricant flow. As an alternative to the oil jet hitting the cage directly, the oil jet can first hit the rotating component (e.g. inner ring) and then hit the cage, i.e. indirectly. The lubricant is atomized and hits the cage in many small droplets, which is gentler on the cage. In addition, inconsistent volume flows of oil are made more uniform. When the oil jet hits the inner ring (or the shaft), an angular momentum is transferred to the lubricant, which helps drive the cage.

Cages guided by the inner ring tend to heat up on the side facing away from the lubricant application and wear out quickly because too little lubricant reaches the sliding guide. The heat application with heating of the bearing row to a very high temperature level is detrimental to the function and service life of the bearing. Better lubrication to reduce friction and a reduction in the temperature of the bearing row are therefore advantageous. Cooling using engine oil is only insufficiently effective for the turbine-side bearing row.

A further preferred embodiment of the invention provides for the geometry of the cage to be asymmetrical. This allows friction on the cage guide to be significantly reduced. The new cage geometry uses centrifugal forces to bring the lubricant completely over the bearing point via an incline and then spins it outwards in order to lubricate the bearing point via the rolling elements. It also reaches the opposite guide of the cage in order to ensure sufficient lubrication there too, particularly if the lubricant can only be introduced on one side. The measures and effects described typically transport lubricant to areas of the ball bearing that have previously been poorly supplied with lubricant.

In addition, the "open" cross-sections, i.e. those that are free for the flow of lubricant, are enlarged. This reduces the "filtering effect" of the bearing row, which reduces the probability of contamination from the lubricating oil remaining in the bearing row. Contaminants could get into the raceway - ball contact or into the contact points of the cage with neighboring components and cause increased running noise or high mechanical stresses. Reducing or avoiding the ingress of contamination into the bearing rows is therefore very beneficial for trouble-free operation and the longevity of the bearing.

In addition, the new geometry reduces the weight of the cage by reducing the cage volume. This reduces the moment of inertia, which promotes rapid acceleration and braking.

Furthermore, the weight of the cage is balanced with the new geometry, as despite the asymmetrical cage geometry (cross section) the masses are distributed symmetrically, so that the probability of dynamic imbalance occurring is reduced. To avoid the bearing point heating up to an excessively high temperature level, the bearing row is supplied with more lubricant and better in terms of temperature flow due to the special geometry of the cage. This transfers the heat to the lubricant and transports it away from the bearing point. In addition, the efficient removal of the lubricant prevents or reduces "splashing losses" in the bearing row. The asymmetrical ball cage achieves improved lubrication and greater heat dissipation of the bearing row, which increases the service life and function of the entire unit.

As an additional feature, the sliding guides of the cage (e.g. cage-bearing ring contact and cage-ball contact) can be provided with a friction-reducing layer, such as a silver layer, a DLC layer or similar.

In a further preferred embodiment of the invention, the lubricant contaminated with dirt particles can be given a swirl (angular momentum), which results in an eddy current and the dirt particles are transported outwards to the edge of the eddy current by centrifugal force. The lubricant contaminated with dirt particles that is transported radially outwards by centrifugal force can then be drained off through drainage devices mounted radially on the outside, for example in the simplest case through a bore. The "cleaned" lubricant remains in the middle of the eddy current, i.e. in the core of the lubricant supply flow, and can then be fed to the bearing system or the row of ball bearings for lubrication. The angular momentum in the lubricant flow can be generated, for example, by guide vanes positioned at an appropriate angle to the flow, by tangential flow, by threaded channels or oblique flow. The swirl generation can be arranged both in the bearing unit itself and in the channels for the lubricant supply, for example in the housing of the turbocharger. The cleaning of the lubricant by means of rotary impulse is thus possible within the dimensions of the turbocharger, ie it can be integrated into the turbocharger or its bearing unit, so that no additional component to be installed outside the bearing unit or turbocharger is required.

The invention is explained in more detail below using several embodiments with reference to the drawings. Further features and advantages of the invention emerge from the drawings and the description of the drawings.

Short description of the drawings

• 1 : shows a section through a first embodiment of the bearing unit according to the invention.
• 2 : shows an enlarged section in the area of the left bearing row.
• 2a : shows a modified design of the groove 32 from 2 .
• 3 : shows a section through a second embodiment of the bearing unit according to the invention.
• 4 : shows an enlarged section in the area of the left bearing row.
• 5 : shows a simplified section through part of a bearing unit according to a third embodiment of the invention.
• 6 : shows a simplified section through part of a bearing unit according to a fourth embodiment of the invention.
• 7 : shows a section through a fifth embodiment of a bearing unit according to the invention.
• 7a , b: shows a bearing cage in perspective and in section
• 8th : shows a schematic section through a bearing unit according to a further embodiment of the invention.
• 9 : shows an enlarged view of the channel for supplying the lubricant according to 8th .
• 10 : shows schematically a section through the channel for supplying the lubricant according to a further embodiment for generating a swirl of the lubricant.
• 11 : shows a schematic section through the channel for supplying the lubricant with tangential flow to generate a swirl.
• 12 : shows a schematic section through a channel with spiral geometry to generate a swirl of the lubricant.

Description of preferred embodiments of the invention

In 1 a bearing unit with two rows of ball bearings, which are designed here as shoulder ball bearings, is shown according to the invention. The bearing unit comprises a one-piece outer ring 10 and a two-piece inner ring 12a, b spaced apart from it. Between the outer ring 10 and the inner ring 12a, b there remains a gap 14 in which the rows of bearings are arranged, which are arranged at a large distance from one another. The inner ring 12a, b is firmly connected to a shaft 16 which rotates about a shaft axis 18.

A first bearing row comprises a ball cage 20 which contains a plurality of balls 22. The second bearing row also comprises a ball cage 24 which contains a plurality of balls 26. The balls 22, 26 run in corresponding raceways of the outer ring 10 and the inner rings 12a, 12b, respectively.

The bearing unit is lubricated and simultaneously cooled by a lubricant that is injected via corresponding channels 28 into the intermediate space 14 near the bearing rows. The lubricant used is preferably an engine oil from an oil circuit of an internal combustion engine. The channels 28 are provided at an angle of approximately 60° to 80° in relation to the shaft axis 18 of the shaft 16 in the outer ring 10, so that the lubricant is injected obliquely in the direction of the respective bearing rows.

2 shows an enlarged view of the storage unit from 1 in the area of the left bearing row. The outer ring 10, the inner ring 12a and the balls 22 arranged between them, which are held by the ball cage 20, can be seen. The inner ring sits on the shaft 16, which rotates about a shaft axis 18. The lubricant is injected at an oblique angle in the direction of the inner ring 12a via the channel 28. The lubricant flow 40 hits the inner ring 12a in a first area 30, in which, according to this embodiment, a defined groove 32 is arranged. As can be seen in 2a recognizes, this groove 32 can also be provided with a spray edge 32a. Since the inner ring 12a and thus also the groove 32 rotate with the shaft 16, the lubricant flow 40 is also set in rotation and is deflected by the groove 32 and thrown off in the direction of the outer ring 10. The lubricant flow then hits the inner diameter of the outer ring 10. Due to the centrifugal forces acting on the lubricant and the dirt particles contained therein, the dirt particles are deflected more strongly in the clockwise direction as shown in the drawing than the pure lubricant, so that the pure lubricant is impacts the outer ring 10 in a second region 34 in accordance with the flow path 40a, while the dirt particles are deflected more clockwise and impact the outer ring 10 in a third region 36 in accordance with the flow path 40b. In order to be able to better separate the pure oil from the dirty oil, a separating edge 38 is provided on the inner diameter of the outer ring 10.

The 3 and 4 show a storage unit that essentially corresponds to the one in the 1 and 2 The same components are provided with the same reference numerals and the general description of the bearing unit also applies to the bearing unit of the 3 and 4 .

In contrast to the first embodiment, in the embodiment according to 3 No groove is provided on the inner ring 12a, 12b, but corresponding baffles 42 are provided on the outer diameter of the inner ring 12a, b.

In the enlarged view of the left bearing part according to 4 it can be seen that the baffle plate 42 is arranged and angled in such a way that the lubricant injected through the channel 28 hits the rotationally symmetrical baffle plate 42 in accordance with the lubricant flow 44 shown and is atomized by the injection pressure. The degree of atomization can be controlled by various parameters, in particular by the volume flow, the pressure, the direction of the injected lubricating oil and the speed of the inner ring 12a, b and thus the speed of the baffle plate 42. Because the lubricant is injected obliquely in the direction of the baffle plate 42, it experiences both a speed component in the direction of the balls 22 and a speed component in the circumferential direction due to the rotation of the inner ring 12a or the baffle plate 42 about the shaft axis 18. A first flow path 44a of the atomized lubricant is generated, which transports the lubricant mist to the bearing row. The bearing rows are thus lubricated with atomized lubricant. The dirt particles follow the flow path 44b and are deflected by centrifugal forces in a clockwise direction as shown in the drawing and do not reach the area of the bearing rows.

5 shows schematically a further embodiment of a bearing unit according to the invention with an outer ring 110, an inner ring 112a and balls 122 with ball cage 120 arranged between them. A lubricant is injected into the intermediate space 114 via a channel 128 in accordance with the lubricant flow 140 and strikes a rib 132 arranged on the inner ring 112a in a first region 130. Due to the oblique injection and the rotation of the inner ring 112a with the rib 132, the injected lubricant is swirled and exposed to centrifugal forces, with the lighter components, i.e. the pure lubricant, flowing in the direction of the bearing row in accordance with the flow path 140a, while the heavier dirt components are deflected clockwise according to the drawing representation following the flow path 140b and do not overcome the rib 132. In the direction of the shaft axis 18, offset from the rib 132, a further rib 138 is arranged on the outer ring 110, which slows down the lubricant flow 140 in the flow path 140a and, if necessary, retains further dirt particles, which are then held in the region of this rib 138 by the centrifugal forces acting radially outward in the direction of the outer ring 110.

6 shows an embodiment of a storage unit according to the invention in detail, which essentially corresponds to the embodiment according to 5 Identical components are designated by the same reference numerals.

In contrast to 5 is at 6 on the inner ring 112a a rib 232 with an approximately rectangular cross-section is arranged, which essentially fulfils the same function as the rib 132 in 5 . In 5 Rib 132 was provided with rounded edges.

On the outer ring 110, according to 6 There is also a rib 238 which is offset from the rib 232 and has an undercut 242 which is open in the direction of the rib 232. This undercut is intended to collect any dirt particles which overcome the first rib 232 in the direction of the bearing row and are held in this undercut 242 by the centrifugal forces acting radially outwards and do not reach the bearing row. The flow path 240a of the lubricant and the flow path 240b of the dirt particles are shown by the arrows.

In particular, when designing according to the 1 and 2 There is also the further advantage that the flow 40a of the cleaned lubricant directed onto the bearing row uses this flow energy of the lubricant to drive the ball cage 20 in its intended direction of rotation.

It is advantageous if the channel 28 for injecting the lubricant is not only inclined towards the shaft axis 18 of the shaft 16, but is also inclined in the circumferential direction of the outer ring 10, so that the lubricant is deflected by the inner ring 12a onto the separating edge and then hits the ball cage 20 and drives the ball cage 20 in the direction of rotation.

It can of course also be provided that the channel 28 or the outlet of the channel 28 is directed directly at the ball cage, so that the ball cage is accelerated much more strongly due to the higher flow speed compared to indirect flow. However, in this embodiment the groove 32 in the inner ring 12a or the separating edge 38 on the outer ring would have to be omitted, so that the dirt particle separating effect of these devices would no longer be present.

In 7 A bearing unit with two ball bearings is shown, which in its construction is essentially the same as the bearing units from the 1 and 3 The bearing unit comprises a one-piece outer ring 310 and a two-piece inner ring 312a, 312b spaced apart from it. Between the outer ring 310 and the inner ring 312a, b there remains a gap 314 in which the rows of bearings are arranged at a large distance from one another. The inner ring 312a, b can be firmly connected to a shaft (not shown) and rotates about a shaft axis 318. A first row of bearings comprises a ball cage 320 which contains a plurality of balls 322. The second row of bearings also comprises a ball cage 324 which contains a plurality of balls 326. The balls 322, 326 run in corresponding raceways of the outer ring 310 and the inner rings 312a, 312b, respectively.

The lubricant is injected via corresponding channels 328 into the gap 314 near the two rows of bearings and can leave the gap via an outlet 346.

According to this embodiment of the invention, the ball cages 320 and 324 are asymmetrical in cross-section. The cross-section of the ball cage comprises a longer leg and a shorter leg, which are arranged at an obtuse angle to one another. The tip of the angle points in the direction of the outer ring 310. The longer leg is in the direction of the channel 328 through which the lubricant is introduced. The lubricant flow 340 introduced through the channels 328 first strikes the inner ring 312a, 312b. Since the inner ring 312a, 312b rotates during operation of the bearing, the lubricant flow 340 is set in rotation and thrown off the inner ring 312a, 312b in the direction of the outer ring 310. The lubricant flow then hits the inner diameter of the outer ring 310. Due to the asymmetry of the ball cages 320, 324, a continuous gap remains between the legs of the ball cages 320, 324 and the outer ring 310. The lubricant flow can now easily penetrate into the gap and wash around the balls, thus reaching all important lubrication points.

The design of the ball cages 320, 324 has another effect. Due to the centrifugal forces acting on the lubricant and the dirt particles contained therein, the lubricant and the dirt particles are deflected to different degrees. The pure lubricant is preferentially directed to the lubrication points, while the dirt particles are largely deflected away from the bearing rows.

In 7a and 7b A possible design of the ball cages 320, 324 is shown as an example.

8th shows a schematic section through a further embodiment of a bearing unit according to the invention. The bearing unit comprises an outer ring 410 and an inner ring 412a spaced therefrom, with a gap 414 remaining between the outer ring 410 and the inner ring 412a, in which rolling elements, in this case balls 422, are arranged. The balls 422 are preferably held in a ball cage 420 and run on corresponding raceways that are arranged in the inner ring 412a or outer ring 410. The inner ring 412a sits, for example, on a shaft that is not shown in this drawing.

The bearing unit or the balls 422 are lubricated and simultaneously cooled by a lubricant that is injected into the intermediate space 414 via a corresponding channel 428, with an engine oil from an oil circuit of an internal combustion engine preferably being used as the lubricant. The channel 428 for injecting the lubricant is arranged at an angle with respect to the longitudinal axis of the bearing unit, so that the lubricant is supplied obliquely in the direction of the respective rolling elements 422.

The outer ring 410 is arranged in a housing 448. The lubricant is introduced into the channel 428 in the outer ring 410 via a channel 450. Either in the channel 450 or at the beginning of the channel 428 there are devices that give the inflowing lubricant flow 440 a swirl. This angular momentum of the lubricant around the flow axis causes a centrifugal force acting on the lubricant. The lubricant contains dirt particles, in particular metallic abrasion due to wear or combustion residues, whose specific density is greater than the density of the lubricant. Due to the centrifugal force acting on the lubricant mixed with dirt particles, these "heavier" dirt particles are dispersed due to the centrifugal force acting on the lubricant. gal forces from the pure lubricant. The dirt particles with a higher density migrate outwards in the rotating lubricant flow due to the higher centrifugal forces. In doing so, they displace the components with a lower density, i.e. the pure lubricant, which thereby reaches the centre, while the dirt particles migrate outwards. In channel 428, the pure lubricant is separated from the dirt-laden lubricant. While the pure lubricant reaches the intermediate space 414 through a central bore 452 and can be used to lubricate the balls 422, the dirt-laden lubricant, which is located radially on the outside in channel 428, is discharged via another bore 454 and fed to the intermediate space 414 at a different angle so that it does not reach the area to be lubricated.

The generation of angular momentum of the lubricant can be achieved in different ways.

9 shows, for example, the supplied lubricant flow 440, which is fed to the channel 428. Guide vanes 456 arranged at an angle to the axis of the channel are provided on the outer wall of the channel, onto which the lubricant flow 440 strikes and is thereby converted into a lubricant flow with angular momentum 440a. The angular momentum transports the heavier dirt particles radially outwards, while the pure lubricant remains in the center of the lubricant flow and can flow out via the bore 452 as lubricant flow 441, while the lubricant flow 444 enriched with dirt particles can flow out via a lateral bore 454.

In 10 Another possibility for generating an angular momentum on the lubricant is shown. The outer ring 410 with the channel 428 for introducing the lubricant and a part of the housing 448, which rests on the outer ring, can be seen schematically. The lubricant flow 440 is introduced at an angle to the channel 428 via a further channel 450, so that the lubricant is thereby set into a swirl and forms a lubricant flow with angular momentum 440a. The heavier dirt particles thus migrate radially outwards and to the edge of the channel 428, while the lighter lubricant remains in the middle of the channel 428. The two components can be separated, for example, as in 9 carried out and is in 10 not shown.

11 shows an embodiment of the swirl generation by tangential flow. The outer ring 410 with channel 428 is shown schematically from above, with the lubricant flow 440 being fed tangentially to the channel 428 through the channel 450 and thereby forming a rotating lubricant flow with angular momentum 440a. This lubricant flow with angular momentum 440a can then be used further accordingly.

12 shows schematically a section through the outer ring 410 in the area of the supply of the lubricant flow 440, wherein the lubricant flow is supplied via a threaded bore 458 and thereby receives an angular momentum (twist) and forms a lubricant flow with angular momentum.

List of reference symbols

10

Outer ring

12a, b

Inner ring

14

Space

16

Wave

18

Shaft axis

20

Ball cage

22

Bullet

24

Ball cage

26

Bullet

28

channel

30

first area

32

groove

32a

Spray edge

34

second area

36

third area

38

Separating edge

40

Lubricant flow

40a, b

Flow pattern

42

Baffle plate

44

Lubricant flow

44a, b

Flow pattern

110

Outer ring

112a

Inner ring

114

Space

120

Ball cage

122

Bullet

128

channel

130

first area

132

rib

138

rib

140

Lubricant flow

140a, b

Flow pattern

232

rib

238

rib

240

Lubricant flow

240a, b

Flow pattern

242

Undercut

310

Outer ring

312a, b

Inner ring

314

Space

318

Shaft axis

320

Ball cage

322

Bullet

324

Ball cage

326

Bullet

328

channel

340

Lubricant flow

346

Outlet

410

Outer ring

412a

Inner ring

414

Space

420

Ball cage

422

Bullet

428

channel

440

Lubricant flow

440a

Lubricant flow with angular momentum

441

Lubricant flow (cleaned)

444

Lubricant flow (contaminated)

448

Housing

450

channel

452

drilling

454

drilling

456

vane

458

Threaded hole

Claims (20)

Bearing unit for a shaft (16) of a turbocharger, which comprises at least one outer ring (10; 110; 310; 410), at least one inner ring (12a,b, 112a; 312a,b; 412a) and at least two rows of bearings guided between the outer ring (10; 110; 310; 410) and the inner ring (12a,b, 112a; 312a,b; 412a), wherein at least one channel (28; 128; 328; 428) is provided for injecting lubricant into an intermediate space (14; 114; 314; 414) between the outer ring (10; 110; 310; 410) and the inner ring (12a,b, 112a; 312a,b; 412a), characterized that devices (32, 38, 42, 132, 138, 232, 238, 242; 320, 324; 428; 456, 458) are provided which separate the lubricant from dirt particles contained in the lubricant by utilizing centrifugal force. Storage unit according to Claim 1 , characterized in that the devices (32, 38, 42, 132, 138, 232, 238, 242; 320, 324) are arranged within the intermediate space (14; 114; 314; 414) between the outer ring (10; 110; 310; 410) and the inner ring (12a,b, 112a; 312a,b; 412a). Storage unit according to Claim 1 , characterized in that the devices (32, 38, 42, 132, 138, 232, 238, 242; 428; 456; 458) are arranged in or on the inner ring (12a,b, 112a; 312a,b; 412a) and/or in or on the outer ring (10; 110; 310; 410). Storage unit according to Claim 1 , characterized in that the devices (32, 38, 42, 132, 138, 232, 238, 242; 428; 456; 458) are part of a ball cage (320, 324) arranged in the intermediate space (314). Storage unit according to one of the Claims 1 until 4 , characterized in that the channel (28; 128; 328; 428) for injecting the lubricant into the intermediate space (14; 114; 314; 414) is arranged in the fixed outer ring (10; 110; 310; 410). Storage unit according to one of the Claims 1 until 5 , characterized in that the channel (28; 128; 328; 428) runs at an angle of approximately 60° to 80° to the longitudinal axis of the outer ring (10; 110; 310; 410) and opens near a row of bearings. Storage unit according to one of the Claims 1 until 6 , characterized in that the channel (28; 128; 328; 428) is directed towards the rotating inner ring (12a,b; 112a,b; 312a,b), and the lubricant impinges on the inner ring (12a,b; 112a; 312a,b; 412a) in a first region (30; 130) and is accelerated in the circumferential direction by the rotation of the inner ring (12a,b; 112a; 312a,b; 412a). Storage unit according to one of the Claims 1 until 7 , characterized in that the inner ring (12a,b) in the first region (30) has a substantially perpendicular to the shaft axis (18) of the shaft (16) has a groove (32) which diverts the lubricant in the direction of the outer ring (10). Storage unit according to Claim 8 , characterized in that the groove (32) has a spray edge (32a) at which the deflected lubricant detaches from the inner ring (12a,b). Storage unit according to Claim 8 or 9 , characterized in that due to the acceleration of the lubricant and the deflection through the groove (32), centrifugal forces act on the lubricant, whereby the lubricant is deflected at a first angle in the direction of the outer ring (10) and strikes the outer ring (10) in a second region (34), while lubricant enriched with dirt particles is deflected at a second angle in the direction of the outer ring (10) and strikes the outer ring (10) in a third region (36). Storage unit according to one of the Claims 1 until 10 , characterized in that the outer ring (10) has a separating edge (38) extending substantially perpendicular to the shaft axis (18) of the shaft between the second region (34) and the third region (36). Storage unit according to Claim 11 , characterized in that the separating edge (38) is arranged and designed such that the lubricant impinging in the second region (34) is deflected in the direction of the bearing row, while the lubricant impinging in the third region (36) and enriched with dirt particles is deflected away from the bearing row. Storage unit according to one of the Claims 1 until 7 , characterized in that the channel (28, 128) is designed such that the injected lubricant is atomized and a flow path (140a; 240a) of the atomized lubricant is generated in the direction of the bearing row, while lubricant enriched with dirt particles is separated from the pure lubricant by a flow path (140b; 240b) and guided away from the bearing row. Storage unit according to one of the Claims 1 until 7 or 13 , characterized in that the inner ring (12a,b; 112a) in the first region has a geometric contour (132, 232) running substantially perpendicular to the shaft axis (18) of the shaft (16) or a baffle plate (42) or a baffle edge onto which the lubricant strikes and is thereby atomized. Storage unit according to one of the Claims 1 until 6 , characterized in that the channel (428) is designed in such a way or has devices (456; 458) which impart a rotational impulse (twist) to the injected lubricant, whereby lubricant enriched with dirt particles is separated and drained off from the pure lubricant due to centrifugal forces, while the pure lubricant is supplied to the bearing row. Storage unit according to one of the Claims 1 until 15 , characterized in that the channel (28; 128; 328; 428) is aligned such that the lubricant directly or indirectly impacts a ball cage (20, 24; 120; 320; 324; 420) of a bearing row and drives the ball cage (20, 24, 120, 320) in its direction of rotation. Bearing unit for a shaft (16) of a turbocharger, which comprises at least one outer ring (310), at least one inner ring (312a,b) and at least two rows of bearings guided between the outer ring (310) and the inner ring (312a,b), wherein at least one channel (328) is provided for injecting lubricant into an intermediate space (314) between the outer ring (310) and the inner ring (312a,b), wherein the channel (328) is aligned such that the lubricant directly or indirectly impinges on a ball cage (320; 324) of a row of bearings, characterized in that the cross section of the ball cage (320, 324) comprises a longer leg and a shorter leg, which are arranged at an obtuse angle to one another, wherein the tip of the angle points in the direction of the outer ring (310), and the longer leg is arranged in the direction of the channel (328), by into which the lubricant is introduced. Storage unit according to Claim 17 , characterized in that the ball cage (320; 324) has impact surfaces onto which the lubricant impinges directly or indirectly. Storage unit according to Claim 17 or 18 , characterized in that the ball cage (320, 324) is asymmetrical in cross-section. Turbocharger with a turbine and a compressor arranged on a common shaft (16), wherein the shaft (16) is supported by means of a bearing unit according to one of the Claims 1 until 19 is pivotally mounted.

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