WO2012025531A1

WO2012025531A1 - Bearing

Info

Publication number: WO2012025531A1
Application number: PCT/EP2011/064477
Authority: WO
Inventors: Heiko Schmidt
Original assignee: Schaeffler Technologies Gmbh & Co. Kg
Priority date: 2010-08-27
Filing date: 2011-08-23
Publication date: 2012-03-01
Also published as: DE102010035665A1

Abstract

The invention relates to a bearing, especially for a turbocharger, comprising a housing (2), a bearing cartridge (1) accommodated therein and a squeeze film (7) in a radial gap (13) between the bearing cartridge (1) and the housing (2). At least two piston rings (8) for throttling the outflow of oil from the squeeze film (7) are mounted in the radial gap (13) of the squeeze film (7).

Description

P105568 August 23, 2011

Description of the invention Storage

Description Field of the invention

The invention relates to a bearing, in particular for a turbocharger, with a housing, with a bearing cartridge received therein and with a squish film in a radial gap between the bearing cartridge and the housing. The bearing cartridge is in particular designed as a radial bearing, which has a rotating component, such as e.g. a shaft rotatably supports. The radial bearing is usually designed as a rolling bearing; However, it can also be given as a sliding bearing.

Background of the invention

For storage of fast rotating components, such as the shaft of a turbocharger, bearings are usually installed with a significant radial and / or axial play. For example, the resulting gap between an outer ring of a bearing cartridge and the housing forces oil to act as an oil cushion and thus as a damper. The amount of oil in such a squeeze film adjusts depending on the gap height, the gap length, the oil pressure and the oil viscosity. In a radial gap, a squeezing film dampens, in particular, rotating radial forces, as transmitted from the bearing card during a recorded imbalance during operation. P 105568 2

A storage of the aforementioned type is known for example from WO 2006004654 A1 or JP 63215830 A. If the bearing cartridge moves radially outward due to an imbalance, oil must be expelled from the radial gap, which leads to a damping force that opposes the movement.

A disadvantage of the known bearings, however, is that the squeeze film has no centering effect with a rotating component. The geometry of the squeeze film is usually matched to the needs of rotor dynamics. The oil is supplied from above, so that the pressure in an oil groove around the bearing cartridge, in particular around an outer ring of the bearing cartridge, decreases due to the flow resistance from top to bottom. Furthermore, the supply pressure decreases from top to bottom through the amount of oil draining into the squeezing film and through a spray oil bore for lubricating the bearing cartridge around the bearing cartridge. The resulting from top to bottom oil pressure gradient results in a radial force, which acts together with the force of gravity on the bearing cartridge down.

Despite the superimposition of rotating unbalance forces in the case of operation occurs in the known bearings due to the described radial, non-rotating forces such as the weight of the bearing cartridge including the stored component and the forces resulting from the pressure distribution in the squeezing, to an eccentric position of the bearing cartridge in Casing. The eccentric position in the housing further increases the oil pressure gradient from top to bottom and thus the oil drain. The distance between the bearing cartridge or an outer ring of the bearing cartridge and the housing is in consequence on the side in the direction of the described disturbing forces act, less or even zero. Although the resistance that the squeeze film opposes to the dynamic radial movements caused by imbalance increases as the gap narrows, the residual path to prevent metal contact is also reduced. P 105568 3

In the case of bearings of the known type, undesirable mechanical contacts between the bearing cartridge and the housing can thus occur, which leads to increased wear and thus to a shortened service life. In addition, the self-adjusting eccentric position of the storage cartridge increases the oil requirement for the squeeze film. In known applications, the proportion of the squeeze film in the oil requirement of the bearing cartridge is more than 50%.

Object of the invention

The object of the invention is therefore to propose a bearing with a squeeze film, which shows an improved centering effect for the bearing cartridge.

Solution of the task

According to the invention, this object is achieved for a bearing of the type mentioned above in that at least two piston rings are provided to restrict an outflow of oil from the squeezing film in the radial gap of the squeeze film.

In a first step, the invention is based on the consideration that the oil in the squeeze film of the radial gap also has, in particular, an axial flow component. On the one hand, the oil will flow axially outwards from an oil supply bore as a result of the supply pressure in the radial gap, where it runs into the housing. On the other hand, in conventional structures for draining lubricating oil from the bearing cartridge, an approximately central oil drainage bore is provided, so that oil from the radial gap can also be pressed axially inwards, where it then flows into the housing via the oil drainage bore. P105568 4

In a second step, the invention recognizes that in the axial direction starting from the oil supply, a lower oil pressure gradient will occur when the axial outflow of the oil is throttled over the squeezing film in the radial gap. In addition, since a total of less oil flows with a throttling of the axial outflow on the way from an upper oil supply to a lower oil discharge, the vertical oil pressure gradient is reduced in the storage. Thus, the resulting disturbance force from the pressure distribution at the periphery of the bearing cartridge is significantly reduced. In a third step, the invention finally assumes that the axial oil drain in the squeeze film can be throttled by inserted piston rings which delimit the radial gap of the squeeze film. By means of the invention, the axial outflow of the oil can thus be almost completely prevented. The lower overall quantity of oil to be pumped also results in a reduced power requirement of the oil pump. In the case of a rolling bearing, the outer ring will also reach higher temperatures due to the lower cooling due to less oil flow, so that the temperature difference to the inner ring is lower. The bearing geometry is thus subject to lower fluctuations in operation.

The piston rings can seal the radial gap of the pinch film axially, for which they close the radial gap completely or partially. By means of appropriately inserted or molded piston rings can thus not only prevent the axial oil flow through the squeeze film entirely, but also set targeted and predictable. In this case, the amount of oil drainage can be influenced not only by the geometry of the piston rings or by the nature of the seal, but also by the number and by the position of the piston rings provided. Thus, for example, several piston rings can be arranged one behind the other in the radial gap. Also, the radial thickness of the piston ring may be sized so that a residual gap for adjusting an axial oil drain remains. P 105568 5

In a preferred embodiment, a piston ring is arranged in each case at an axial outer end of the radial gap. Thus, an oil drain from the squeeze film is impeded or prevented axially outward. Oil from the squeeze film will mainly only flow off axially inwards. Thus, the oil flow through the storage is already significantly reduced overall. The oil flow then occurs essentially to lubricate the bearing cartridge via a spray oil bore to the inside, from where the oil flows through a central oil drain hole. If an oil drain from the squeeze film is to be prevented axially inwards via an oil drain hole, it is advantageous to arrange a piston ring axially inward in the radial gap on both sides of an outlet opening provided for the oil drain. Such, the outlet opening respectively adjacent arranged piston ring blocks or throttles an oil drain directly towards an oil drain hole.

In a further preferred embodiment, piston rings can be arranged on both sides starting from the inlet opening of an oil supply hole, so that oil drainage from the pinch film is prevented or throttled both axially inwards and axially outwards. In this case, the oil flow through the squeezing film is drastically reduced. Oil is then mainly needed only for lubrication of the bearing cartridge. The total oil consumption is significantly reduced. Due to the fact that the axial oil drain from the squeeze film is at least throttled, a lower vertical oil pressure gradient arises over the circumference of the outer ring from top to bottom or from the oil supply to the oil discharge compared to known designs. The directed radial force on the bearing cartridge resulting from the pressure distribution is reduced. Accordingly, during operation, a rotating radial imbalance force can better center the bearing cartridge overall in the housing, since this radial force acting upward at times can then be greater than the disturbing force resulting from gravity and oil supply downwards. In addition, the squeeze film sets P 105568 6 in the lower gap of the circumferential unbalance force a greater damping force against than in the upper gap, when its gap is reduced due to the disturbing forces. In a further preferred embodiment of the bearing, the piston rings are provided with grooves. By means of the number and the cross-section of the introduced grooves, the leakage oil discharge can be specifically adjusted to the respective requirements. More preferably, the piston rings are slotted for mounting. As a result, it is possible to insert the piston rings into correspondingly provided slots, since slotted piston rings can be bent open elastically.

In a further preferred embodiment of the bearing, the bearing cartridge comprises an outer ring which forms the radial gap of the pinch film to the housing, wherein the piston rings are each inserted into a groove of the outer ring and project radially beyond. About the radial projection, the axial sealing of the radial gap of the pinch film is carried out. If the grooves are deeper than the radial width of the piston rings, a radial movement of the outer ring or of the bearing cartridge in the housing of the bearing is made possible. In this respect, the damping and centering effect of the squeeze film is retained without restriction.

Conversely, it would also be possible to introduce the grooves for holding the piston rings in the bearing cartridge receiving bore of the housing, in which the bearing cartridge is received. However, this represents a greater outlay in terms of production technology since, for example, the outer ring of a bearing cartridge can be processed more easily as a smaller and geometrically simpler component. Also, the processing of the storage cartridge is in the hands of the bearing manufacturer, while the housing in which the bearing cartridge is received, is usually made by another manufacturer. Appropriately, a circumferential groove is introduced into the outer ring of the bearing cartridge in each case at the axial height of the inlet openings. From the oil supply hole oil is pressed into this circumferential groove and pressed axially along the circumference in the radial gap of the squeeze film. Such a groove P 105568 7 leads to an improved distribution of oil in the squeeze film and a more homogeneous vertical pressure gradient along the circumference of the bearing cartridge.

In another preferred embodiment of the storage Lagerkartu- see is surrounded by a guide ring. Through the use of such a guide ring of the squish film defining radial gap can be pre-assembled separately from the mounting of the bearing cartridge or the bearing cartridge housing. In this case, the guide ring preferably forms the radial gap relative to the housing, wherein the piston rings are each inserted into a groove of the guide ring and radially project beyond it. It is expediently introduced into the guide ring at the axial height of the inlet openings a circumferential groove for oil distribution and oil supply of the pinch film.

Short description of the drawing

Further advantages and advantageous embodiments of the invention are the subject of the following figures and their description parts.

They show in detail:

Fig. 1 shows an embodiment with four piston rings, Fig. 2 shows a section A - A of the embodiment with four piston rings

Fig. 3 shows a detail of the embodiment with four piston rings

4 shows an embodiment with two axially inner piston rings, a section A - A of the embodiment with two axially inner piston rings, P105568

6 shows an embodiment with two axially outer piston rings, Fig. 7 shows a section A - A of the embodiment with two axially outer piston rings,

Fig. 8 shows an embodiment with four piston rings and grooves, Fig. 9 shows a section A - A of the embodiment with four piston rings with

grooves

10 shows an embodiment of a spring-loaded bearing cartridge with four piston rings and one embodiment of a spring-loaded bearing cartridge with four piston rings, wherein the outer rings of the bearing cartridge bear directly against the pinch film.

Detailed description of the drawing

FIGS. 1-3 show, in a first embodiment of the bearing, a bearing cartridge 1 of a turbo roller bearing which is received in a housing 2 via a pinch film 7. The dash-dotted lined for clarity bearing cartridge 1 comprises an outer ring 6 and an inner ring 1 1, wherein the outer ring 6 and the inner ring 1 1 are rotatably supported by rolling elements 12 relative to each other. The inner ring 11 is split in two in the axial direction and serves to receive the shaft of a rotor, not shown, of a turbocharger. The bearing axis or axis of rotation is shown.

The bearing cartridge 1 is inserted with its outer ring 6 with radial clearance in the housing 2. Between the outer ring 6 and the housing 2 results P105568 9, a radial gap 13 which acts as a squeeze film 7 by pressed-in oil and damps radial movements of the bearing cartridge 1 relative to the housing 2 during operation. For oil supply two oil supply holes 4 are provided in the housing, which open into the storage cartridge 1 towards the inside into a respective inlet opening 14. At the axial height of the inlet openings 14, a circumferential oil groove 3 is arranged on the outer ring 6 of the bearing cartridge 1, is pressed into the oil from the oil supply holes 4.

On the opposite side of the oil supply holes 4, the outer ring 6 of the bearing cartridge 1 approximately axially centrally has a bore 5 which corresponds to an outlet opening 15 of a Ölabfuhrbohrung in the housing 2. The oil supply holes 4 in the housing 2 supply the oil grooves 3 with oil. The oil is distributed over the oil grooves 3 on the circumference of the outer ring 6 and is pressed axially inwardly and axially outwardly into the surrounding radial gap 13 due to the existing pressure gradient. Between the outer ring 6 and the housing 2, a squeezing film 7 results adjacent to the inlet openings 14.

From the squeeze film 7, oil can flow axially outward between the bearing cartridge 1 and the housing 2 as well as axially inside via the bore 5 and the outlet opening 15 into the housing. In each case, piston rings 8 are provided in such a way that throttling of the outflow from the squeezing film 7 is ensured both axially inwards and axially outwards. For this purpose, two piston rings 8 at the axial outer ends of the radial gap 13 and two piston rings 8 axially inwardly disposed between the inlet openings 14 and the outlet opening 15. Overall, four piston rings 8 are thus placed along the radial slot 13.

To accommodate the piston rings 8 1 grooves 16 are provided in the outer ring 6 of the bearing cartridge. From Fig. 3 it will be seen that in these grooves P105568 10

16, the piston rings 8 are each used with a radial projection. In this case, the radial depth of the grooves 16 is in each case greater than the radial thickness of the piston rings 8. Also in the section A - A shown in FIG. 2 is visible that the piston rings 8 are each inserted into a groove of the outer ring 6. For assembly, the piston rings 8 are each slotted and have at their respective lower end accordingly a break 9. In the exemplary embodiment according to FIGS. 1-3, the axial flow of oil through the squeeze film 7 is almost completely prevented. Oil for lubrication also reaches the interior of the bearing cartridge 1 1 via a non-drawn spray oil bore through the outer ring 6. From there it flows via the bore 5 or the outlet opening 15 into the housing.

Due to the fact that the axial oil drainage from the squeeze film 7 is almost completely prevented, a lower oil pressure gradient arises over the circumference of the outer ring 6 from top to bottom or from the inlet openings 14 of the oil supply holes 4 to the outlet opening 15 compared to known designs without piston rings 8. The resulting from the oil supply directed radial force on the bearing cartridge 1 down is thus reduced. In operation, a rotating radial force acting on the bearing cartridge 1 due to a recorded in the inner ring 1 1 imbalance, the bearing cartridge 1 overall in the housing 2 center better. The temporarily upward radial unbalance force will then be greater than the force resulting from gravity and oil supply disturbance down. In addition, the squeeze film 7 sets in the lower gap between the outer ring 6 and housing 2 of the circumferential unbalance force a greater damping force than the upper gap, when its gap is reduced due to the downwardly acting disturbance force.

4 and 5 show in a further embodiment of the bearing in the axial gap 3 a total of only two axially inner piston rings 8. The two piston rings 8 are axially between the inlet openings 14 and the approximately axial P 105568 11 centrally disposed outlet opening 15 is placed. In this embodiment, the oil drain from the squeezing film 7 is throttled axially inwardly by the piston rings 8. Axially outward, oil can flow out of the squeeze film 7 over the housing. In section A - A corresponding to FIG. 5 through the rolling elements 12, no piston ring 8 can be seen.

6 and 7 show in a further variant of the storage only two axially outer piston rings 8. In this embodiment, oil drain from the squeeze film 7 is allowed axially inwardly into the outlet opening 15. An oil flow axially outwards is throttled by the piston rings 8. FIG. 7 is identical to FIG. 2.

Fig. 8 and 9 show a further embodiment of the storage, in turn, four piston rings 8 are provided axially inwardly and axially outboard. The embodiment corresponds to that shown in Fig. 4, however, have the introduced piston rings 8 axially continuous grooves 10. By the number and the cross section of the grooves 10 can be adjusted to the specific needs of the targeted leakage oil flow. The grooves 10 for adjusting the flow of oil can also be provided in the already illustrated other embodiments of the storage. The grooves 10 need not be provided in accordance with Fig. 8 in all piston rings 8. In particular, it is conceivable to provide only a few of the four piston rings 8 shown with such grooves 10. 10 shows a spring-loaded bearing cartridge 1. In contrast to the previously described embodiments, the bearing cartridge 1 shown here comprises a continuous inner ring 1 1 and a two-part outer ring 6, wherein the two parts of the outer ring 6 are biased against each other in the axial direction.

Furthermore, in the embodiment according to FIG. 10, a guide ring 17 is provided between the outer ring 6 and the housing 2, wherein the radial gap 13 is formed between the guide ring 17 and the housing 2. accordingly P 105568 12 speaking piston rings 8 are inserted into grooves 18 of the guide ring 17, which throttle the oil drain from the squeezing 7 both axially inwardly and axially outward. The rolling elements 12 are guided in cages 20. Fig. 1 1 shows a further embodiment of a spring-loaded bearing cartridge 1, which is formed according to the bearing cartridge 1 according to FIG. In contrast to FIG. 10, however, the outer rings 6 form the radial gap relative to the housing 2. A guide ring 17 is not provided. On the outer ring 6 of the bearing cartridge 1 according to FIG. 1 1, four piston rings 8 are provided. The two outer rings 6 are biased to each other. The outer rings 6 are in the assembled state directly to the squeezing 7.

The invention with its embodiments can be used in particular as a bearing for a turbocharger as a so-called turbo rolling bearing. Likewise, the invention can be applied to other bearings in which a pinch film is provided. The bearing cartridge can also be designed as a sliding bearing. Another application is, for example, the storage of air conditioning compressors.

List of Reference Numbers Storage Cartridge

casing

Oil groove outer ring

Oil supply hole

drilling

outer ring

squeeze film

piston ring

interruption

Groove piston ring

inner ring

rolling elements

radial gap

inlet opening

outlet

Groove for piston ring

guide ring

Groove for piston ring

Oil groove guide ring

Cage

Claims

P105568 August 23, 2011 Claims

1. Bearing, in particular for a turbocharger, with a housing (2), with a bearing cartridge (1) accommodated therein and with a squeeze film (7) in a radial gap (13) between the bearing cartridge (1) and the housing (2), characterized in that in the radial gap (13) of the pinch film (7) at least two piston rings (8) are provided for throttling an outflow of oil from the squeeze film (7).

2. Storage according to claim 1,

characterized in that a piston ring (8) is arranged in each case at an axial outer end of the radial gap (13).

3. Storage according to claim 1 or 2,

characterized in that axially approximately centrally in the housing (2) an outlet opening (15) of a Olabflussbohrung (5) is arranged, and that axially inside the radial gap (13) on both sides of the outlet opening (15) each have a piston ring (8) is arranged.

4. Storage according to claim 3,

characterized in that axially in each case between the outlet opening (15) and the respective outer end of the radial gap (13) in the housing (2) an inlet opening (14) of an oil supply hole (4) is arranged.

5. Storage according to one of the preceding claims,

characterized in that the piston rings (8) are provided with grooves (10). P 105568

6. Storage according to one of the preceding claims,

characterized in that the piston rings (8) are slotted for mounting.

7. Storage according to one of the preceding claims,

characterized in that the bearing cartridge (1) comprises an outer ring (6) which forms the radial gap (13) to the housing (2), and that the piston rings (8) in each case in a groove (16) of the outer ring (6) are inserted and project radially beyond this.

8. Storage according to claim 7,

characterized in that in the outer ring (6) of the bearing cartridge (1) in each case at the axial height of the inlet openings (14) a circumferential oil groove (3) is introduced.

9. Storage according to one of claims 1 to 6,

characterized in that the bearing cartridge (1) is surrounded by a guide ring (18), that the guide ring (17) forms the radial gap (13) to the housing (2), and that the piston rings (8) in each case in a groove (18) of the guide ring (17) are inserted and project radially beyond.

10. Storage according to claim 9,

characterized in that in the guide ring (17) in each case at a- xialer height of the inlet openings (14) a circumferential groove (19) is introduced.