WO2019213202A1

WO2019213202A1 - Bearing unit

Info

Publication number: WO2019213202A1
Application number: PCT/US2019/030122
Authority: WO
Inventors: Sebastian Mack
Original assignee: Borgwarner Inc.
Priority date: 2018-05-02
Filing date: 2019-05-01
Publication date: 2019-11-07
Also published as: CN210509302U; CN110439636B; CN110439636A

Abstract

This disclosure generally relates to charging devices. More specifically, the present invention relates to a bearing unit 10 for a rotor of a charging device. Furthermore, the invention relates to a charging device having such a bearing unit 10. The bearing unit 10 comprises a housing 100, i.e. a bearing housing 100, which has a central bore 110. The bearing unit 10 further comprises a bearing 200 arranged in the central bore 110. The bearing accommodates a rotor 500 in the housing 100. The bearing 200 is a journal bearing 200. The bearing unit 10 comprises a cartridge 300 which is arranged radially 24 between the bearing 200 and the housing 100 in the central bore 110 to reduce transmission of vibrations between the bearing 200 and the housing 100.

Description

BEARING UNIT

Technical Field

This disclosure generally relates to charging devices. More specifically, the present invention relates to a bearing unit for a rotor of a charging device. Furthermore, the invention relates to a charging device having such a bearing unit.

Background

The individual mobility sector is experiencing a disruptive change. Especially, the increasing number of electric vehicles entering the market demands higher efficiencies from traditional internal combustion engine (ICE) vehicles. Therefore, more and more vehicles are equipped with efficiency increasing measures, such as charging devices or lightweight design. Well known are, for instance, charging devices wherein a compressor, which may be driven by an e-motor or an exhaust gas powered turbine, provides compressed air to the ICE. This leads to a performance enhancement of the ICE.

Common charging devices comprise a compressor housing and an impeller which is arranged therein. As already mentioned, the compressor may be driven, for instance, by an e-motor or a turbine. The torque is transferred to the impeller via a (turbine) rotor which is mounted via a bearing in a bearing housing. Especially when the bearing is a journal bearing, vibrations and acoustic noises are amplified in the charging device. Common approaches to reduce these vibrations and acoustic noises are directed to structural modifications, specifically geometric modifications of the bearing itself. Measures such as providing grooves in the bearing or modifying the bearing clearances mostly result in a reduction of the bearing stability as the acoustic and the stability behave reciprocal.

Accordingly, the objective of the present invention is to decrease the vibrations and acoustic noise in a charging device.

Summary The present invention relates to a bearing unit as set out in claim 1, and a corresponding charging device including such a bearing unit as set out in claim 15. Other embodiments are described in the dependent claims.

The bearing unit for a rotor comprises a housing which has a central bore and a bearing arranged in the central bore. The bearing accommodates a rotor in the housing, wherein the bearing is a journal bearing. The bearing unit further comprises a cartridge which is arranged radially between the bearing and the housing in the central bore to reduce transmission of vibrations between the bearing and the housing. By providing a cartridge radially between the bearing and the housing, the bearing is not in direct contact with the housing in at least a radial direction. Thus, the housing is radially substantially decoupled from the bearing regarding vibrations. Thereby, vibrations of the bearing and the oil film in the bearing can be damped before propagating into the housing, i.e. vibrations can be cushioned by the cartridge. Thus, a propagation of vibrations from the area of the bearing to the bearing housing can be reduced or prevented. Thereby, less vibrations are propagated from the bearing housing to the adjacently arranged flow housings wherefrom acoustic noise is mainly radiated to the environment. As a result, the acoustic behavior of a charging device which comprises such a bearing unit, can be improved.

In a first embodiment of the bearing unit, the housing may comprise a first material, the bearing may comprise a second material and the cartridge may comprise a third material. The third material may be of higher elasticity than the first material and/or the second material. Preferably, the third material is a polymeric material, to reduce transmission of vibrations between the cartridge and the housing. By providing for the cartridge a material which has a higher elasticity than the material of the housing and that of the bearing, vibrations can be damped effectively and be reduced or inhibited when propagating from the bearing through the cartridge further to the housing. This can be achieved by the cartridge being able to absorb vibration energy due to its higher elasticity in comparison to the bearing and/or the housing.

According to an aspect of the first embodiment, the central bore may comprise an annular end face and the cartridge may comprise a peripheral annular protrusion. The peripheral annular protrusion may be arranged on a first end face of the cartridge axially between the cartridge and the annular end face of the housing. Additionally, the peripheral annular protrusion may extend radially inwardly to axially restrict the bearing from moving axially towards the annular end face. By implementing this advantageous feature, a movement of the bearing in an axial direction towards the annular end face of the central bore is restricted by the cartridge, more specific, by the peripheral annular protrusion as it extends radially inwardly. Thus, the bearing is not in direct contact with the housing in an axial direction. Thereby, vibrations of the bearing and the oil film in the bearing can be damped before propagating into the housing, i.e. vibrations can be cushioned by the cartridge. Thus, a propagation of vibrations from the area of the bearing to the bearing housing can be reduced or prevented. Thereby, less vibrations are propagated from the bearing housing to the adjacently arranged flow housings where from acoustic noise is mainly radiated to the environment. As a result, the acoustic behavior of a charging device which comprises such a bearing unit, can be improved.

In a second embodiment of the bearing unit, the housing may comprise a first material, the bearing may comprise a second material and the cartridge may comprise a fourth material. The fourth material may be of a similar elasticity as the first material and/or the second material.

According to an aspect of the second embodiment, the central bore may comprise an annular end face and the cartridge may comprise a peripheral annular protrusion. The peripheral annular protrusion may be arranged on a first end face of the cartridge axially between the cartridge and the annular end face of the housing. The peripheral annular protrusion may comprise a third material or a coating of a third material, wherein the third material has a higher elasticity than the first material and/or the second material and/or the fourth material. Preferably, the third material is a polymeric material, to reduce transmission of vibrations between the cartridge and the housing. Additionally, the peripheral annular protrusion may extend radially inwardly to axially restrict the bearing from moving axially towards the annular end face. By implementing this advantageous feature, a movement of the bearing in an axial direction towards the annular end face of the central bore is restricted by the cartridge. More specific, a movement of the bearing in an axial direction towards the annular end face of the central bore is restricted by the peripheral annular protrusion as it extends radially inwardly. Thus, the bearing is not in direct contact with the housing in an axial direction. Thereby, vibrations of the bearing and the oil film in the bearing can be damped before propagating into the housing, i.e. vibrations can be cushioned by the cartridge. This can be achieved by the peripheral annular protrusion being able to absorb vibration energy due to its higher elasticity in comparison to the bearing and/or the housing. Thus, a propagation of vibrations from the area of the bearing to the bearing housing can be reduced or prevented. Thereby, less vibrations are propagated from the bearing housing to the adjacently arranged flow housings where from acoustic noise is mainly radiated to the environment. As a result, the acoustic behavior of a charging device which comprises such a bearing unit, can be improved.

The following aspects may be applicable to all previously presented embodiments and aspects.

In another aspect, the cartridge may axially overlap a length of the bearing. This enables the opportunity of also axially substantially decoupling the bearing from the bearing housing regarding vibrations.

In another aspect, which is combinable with any one of the previous aspects, the cartridge may comprise at least two vibration reducing members. The at least two vibration reducing members are arranged radially between the cartridge and the housing to reduce transmission of vibrations between the cartridge and the housing. One effect of providing the vibration reducing members radially between the cartridge and the housing is that a contact surface between cartridge and housing can be reduced and that the cartridge, at least in a radial direction, only stands in contact with the housing via the vibration reducing members. As a result, vibrations can be damped via the vibrations reducing members and a transmission of vibrations between the cartridge and the housing can be reduced. Furthermore, the vibration reducing members provide a possibility for securely mounting the cartridge in the central bore. Thus, the vibration reducing members enable to axially and/or radially secure the cartridge against movement to at least a certain extent. In another aspect, which is combinable with the previous aspect, the vibration reducing members may comprise a fifth material. The fifth material may have a higher elasticity than the cartridge. Preferably, the fifth material is an elastomeric material. By providing for the vibration reducing members a material which has a higher elasticity than the material of the cartridge and/or the material of the housing, vibrations can be damped effectively and be reduced or inhibited when propagating from the cartridge through the vibration reducing members further to the housing. This can be achieved by the vibration reducing members being able to absorb vibration energy due to its higher elasticity in comparison to the cartridge and/or the housing.

In another aspect, which is combinable with any the previous aspect when the cartridge comprises a material of higher elasticity than the material of the housing and/or the bearing, the vibration reducing members may be integrally formed with the cartridge. In comparison to a cartridge without vibration reducing members, the damping capacity can be increased.

In another aspect, which is combinable with any one of the three previous aspects, each of the vibration reducing members may comprise a ring shape which extends circumferentially around the cartridge to provide contacts between the cartridge and the housing.

In another aspect, which is combinable with any one of the four previous aspects, each of the vibration reducing members may be one of an O-ring or a quad ring.

In another aspect, which is combinable with any one of the five previous aspects, the cartridge may comprise a first circumferential groove and a second circumferential groove. The first circumferential groove and the second circumferential groove are formed in an outer lateral surface of the cartridge to receive the vibration reducing members therein. Additionally, the grooves may be arranged axially spaced apart on the outer lateral surface of the cartridge. By providing these advantageous features, a desired axial position of the vibration reducing members with respect to the cartridge can be ensured. This improves the mounting process and ensures the correct functionality of the device. Spacing the grooves axially apart results in that the desired position of the vibration reducing members is also spaced apart. The further the vibration reducing members are spaced apart the more stable against tilting the cartridge will be mounted in the housing.

In another aspect, which is combinable with any one of the six previous aspects, the housing may comprise a first circumferential groove and a second circumferential groove. The first circumferential groove and the second circumferential groove are formed in an inner lateral surface the housing in the central bore to receive the vibration reducing members therein. Additionally, the grooves may be arranged axially spaced apart on the inner lateral surface of the housing.

In another aspect, which is combinable with any one of the two previous aspects, the grooves may be configured such that each vibration reducing member extends radially out of the respective groove to radially preload the cartridge against the housing.

In another aspect, which is combinable with any one of the three previous aspects, a cross- section of each groove may be adapted in shape to receive and match a shape of each vibration reducing member.

In another aspect, which is combinable with any one of the previous aspects, the cartridge may further comprise at least one fluid supply bore being arranged on the outer lateral surface.

In another aspect, which is combinable with any one of the previous aspects, the cartridge may further comprise a rotation locking member to prevent rotational movement of the cartridge with respect to the housing.

In another aspect, which is combinable with the previous aspect, the rotation locking member may be arranged close to a second end face of the cartridge. Furthermore, the rotation locking mechanism may extend radially outwardly from the outer lateral surface of the cartridge to matingly engage with a corresponding recess in the housing. In another aspect, which is combinable with any one of the two previous aspects, the rotation locking member may be integrally formed with the cartridge.

In another aspect, which is combinable with any one of the three previous aspects, when the bearing unit comprises a fluid supply bore, the rotation locking member may be configured to keep the bearing cartridge in a fixed rotational position such that the at least one fluid supply bore is substantially aligned with a fluid supply bore of the housing and/or a fluid supply bore of the bearing. The present invention further relates to a charging device. The charging device comprises a compressor with an impeller and a bearing unit of any one of the previous aspects.

In a first embodiment of the charging device, the charging device may be an exhaust gas turbocharger and may further comprise a turbine with a turbine wheel.

In another aspect of the first embodiment of the charging device, which is combinable with any one of the two previous aspects, the charging device may be an electrically assisted turbocharger and may further comprise an electrical assist device. In a second embodiment of the charging device, the charging device may be an electric charger and may further comprise an electric motor which drives the compressor.

Description of the Drawings

FIG. 1 shows a sectional view of a first embodiment of a bearing unit;

FIG. 2 shows a sectional view of a housing according the embodiment of FIG. 5A without bearing and cartridge;

FIG. 3 shows a rotated sectional view of the third embodiment of a bearing unit according to FIG. 1 wherein a rotation locking member is visible;

FIG. 4 shows an excerpt of the housing in an isometric view of the third embodiment of a bearing unit according to FIG. 3 wherein a recess of the housing is visible;

FIG. 5A shows a sectional view of a second embodiment of the bearing unit;

FIG. 5B shows a detailed view of the bearing unit of FIG. 5 A;

FIG. 5C shows an isometric view of the cartridge according the embodiment of

FIG. 5 A;

FIG. 6A shows a sectional view of a second embodiment of a bearing unit;

FIG. 6B shows a detailed view of the bearing unit of FIG. 2 A;

Detailed Description

In the context of this invention, the expressions axially, axial or axial direction is meant to be a direction parallel of or along an axis of the rotor, i.e. the rotation axis of the rotor which is mounted in the bearing housing. Thus, with reference to the figures, see, especially FIG. 1, an axial dimension is described with reference sign 22, a radial dimension extending“radially” away from the axial dimension 22 is described with reference sign 24. Furthermore, a circumferential dimension around the axial dimension 22 is described with reference sign 26. Although - for reasons of clarity - a coordinate system is not depicted in every single figure, it is clear, that corresponding parts in various figures can be analogously described with the dimensions of the just explained coordinate system.

FIGS. 1-3 show a first embodiment of a bearing unit 10 for a rotor 500. The bearing unit 10 comprises a housing 100, i.e. a bearing housing 100, which has a central bore 110. The bearing unit 10 further comprises a bearing 200 arranged in the central bore 110. The bearing accommodates a rotor 500 in the housing 100. In the present embodiments described herein after, the bearing 200 is a journal bearing 200. In other embodiments, there may be an alternative bearing such as a ball bearing. The bearing unit 10 further comprises a cartridge 300 which is arranged radially 24 between the bearing 200 and the housing 100 in the central bore 110 to reduce transmission of vibrations between the bearing 200 and the housing 100

(see, e.g., FIG. 1). By providing a cartridge 300 radially between the bearing 200 and the housing 100, the bearing 200 is not in direct contact with the housing 100 in at least a radial direction 24. Thereby, vibrations of the bearing 200 and the oil film in the bearing 200 can be damped before propagating into the housing 100, i.e. vibrations can be cushioned by the cartridge 300. Thus, a propagation of vibrations from the area of the bearing 200 to the bearing housing 100 can be reduced or prevented. Thereby, less vibrations are propagated from the bearing housing 100 to the adjacently arranged flow housings (flow housings of a compressor and/or a turbine, if applicable) or other cavities in the housing 100 wherefrom acoustic noise is mainly radiated to the environment. As a result, the acoustic behavior of a charging device which comprises such a bearing unit 10, can be improved.

The first embodiment of the bearing unit 10 is characterized in that the housing 100 comprises a first material, the bearing 200 comprises a second material and the cartridge 300 comprises a third material. The third material has a higher elasticity than the first material and/or the second material. Preferably, the third material is a polymeric material, to reduce transmission of vibrations between the cartridge 300 and the housing 100. By providing for the cartridge 300 a material which has a higher elasticity than the material of the housing 100 and that of the bearing 200, vibrations can be damped effectively and be reduced or inhibited when propagating from the bearing through the cartridge 300 further to the housing 100. This can be achieved by the cartridge 300 being able to absorb vibration energy due to its higher elasticity in comparison to the bearing 200 and/or the housing 100. The first and the second material are a similar material, for instance a metallic material. In other embodiments, the first and the second material may be an identical material or may be different materials with different properties.

FIG. 2 depicts a housing 100 according to the invention in general but without the bearing 200, the rotor 500 and the cartridge 300 (amongst others). Apart from missing housing grooves (explained below) of the third embodiment and a missing recess (explained below) of the first embodiment, the housing 100 depicted in FIG. 2 could be a housing 100 of any one of the first, the second or the third embodiment. Thereby, it is visible that the central bore 110 comprises an annular end face 112. In other words, the bore 110 is at least partially axially restricted by the annular end face 112. In the present embodiment the annular end face 112 is integrally formed with the housing 100. In other embodiments they may be formed separately. Again with reference to FIG. 1, the cartridge 300 comprises a peripheral annular protrusion 310. The peripheral annular protrusion 310 is arranged on a first end face 312 of the cartridge 300 axially between the cartridge 300 and the annular end face 112 of the housing 100. The peripheral annular protrusion 310 extends radially inwardly to axially restrict the bearing 200 from moving axially towards the annular end face 112. In the present embodiment, the peripheral annular protrusion 310 is integrally formed with cartridge 300. Thus, in the case of this first embodiment, the first end face 312 of the cartridge is represented by an annular end face of the peripheral annular protrusion 312 which points in an axial direction towards the annular end face 112. In other, embodiments - as will be described later - the peripheral annular protrusion 310 may be a separate part from the cartridge 300. In such a case, the peripheral annular protrusion 310 extends from the first end face 312 in an axial direction 22 towards the annular end face 112, and may optionally extend radially inwardly. Thereby, the peripheral annular protrusion 310 axially extends further over the bearing 200, as the cartridge 300 itself already axially overlaps a length of the bearing 200 (see, e.g., FIG. 1 or FIG. 3). In other words, an axial length of the cartridge 300 is larger than an axial length of the bearing 200. This feature enables the opportunity of also axially decoupling the bearing 200 from the bearing housing 100 (regarding vibrations and/or direct contact). By a peripheral annular protrusion 310 axially further extending over the cartridge this effect can be further improved. Especially, by advantageously implementing the peripheral annular protrusion 310 extending radially inwardly, a movement of the bearing 200 in an axial direction towards the annular end face 112 of the central bore 110 is restricted. In other words, the cartridge 300 at least partially restricts a radial and axial movement of the bearing 200 and may thereby prevent a direct contact between the bearing 200 and housing 100 at the respective areas. Thus, the bearing 200 is not in direct contact with the housing 100 in an axial direction 22. Thereby, vibrations of the bearing 200 and the oil film in the bearing 200 can be damped before propagating into the housing 100, i.e. vibrations can be cushioned by the cartridge 300. Thus, a propagation of vibrations from the area of the bearing 200 to the bearing housing 100 can be reduced or prevented. By that, less vibrations are propagated from the bearing housing 100 to the adjacently arranged flow housings wherefrom acoustic noise is mainly radiated to the environment. As a result, the acoustic behavior of a charging device which comprises such a bearing unit 10, can be improved. Additionally, the bearing 200 press-fitted into the cartridge 300. This may further restrict or prevent an axial movement of the bearing 200. In alternative embodiments, the bearing 200 may not be press-fitted into the cartridge 300. In further alternative embodiments, the bearing 200 may be form-fittingly hold in the cartridge 300. FIGS. 5A-5C describe a second embodiment of the bearing unit 10 while FIGS. 6A-6B describe a third embodiment of the bearing unit 10. The second and the third embodiment mainly differ from the first embodiment in that the cartridge 300 is made of a different material. Apart from that similar features are marked with the same reference signs through all embodiments.

FIGS. 5B and 6B are detailed views of FIGS. 5A and 6A, respectively (see“dashed rectangle” in FIGS. 5 A and 6 A) and show that the cartridge 300 axially overlaps a length of the bearing 200. In other words, an axial length of the cartridge 300 is larger than an axial length of the bearing 200. This feature enables the opportunity of axially decoupling the bearing 200 from the bearing housing 100 (regarding vibrations and/or direct contact).

Now with reference to FIGS. 5A-6B, the housing 100 comprises the first material, the bearing 200 comprises the second material and the cartridge 300 comprises a fourth material. The fourth material has a similar elasticity as the first material and/or the second material. Analogously to the first embodiment, the central bore 110 comprises an annular end face 112. In other words, the bore 110 is at least partially axially restricted by the annular end face 112. In the present embodiment the annular end face 112 is integrally formed with the housing 100. In alternative embodiments the latter two parts may be formed separately. The cartridge 300 comprises a peripheral annular protrusion 310. The peripheral annular protrusion 310 is arranged on a first end face 312 of the cartridge 300 axially between the cartridge 300 and the annular end face 112 of the housing 100 (see, e.g., FIGS. 5B and 6B). In contrast to the cartridge 300 of the second and third embodiment, the peripheral annular protrusion 310 comprises the third material (see third material explained above with regard to the cartridge 300 of the first embodiment). The third material has a higher elasticity than the first material and/or the second material and/or the fourth material. Preferably, the third material is a polymeric material, to reduce transmission of vibrations between the cartridge 300 and the housing 100. As can be seen, especially, in FIGS. 5B and 6B, the peripheral annular protrusion 310 extends axially between the first end face 312 and the annular end face 112. Furthermore, the peripheral annular protrusion 310 extends radially inwardly from an inner lateral surface 150 of the housing 100. Thereby, the peripheral annular protrusion 310 radially extends towards the rotation axis of the rotor 500 at least until a lateral outer surface 250 of the bearing 200 such that the peripheral annular protrusion 310 overlaps at least a part of the bearing 200, i.e. the lateral outer surface 250 in a radial direction 24. In this fashion, the peripheral annular protrusion 310 axially restricts the bearing 200 from moving axially towards the annular end face 112. Additionally, the bearing 200 press-fitted into the cartridge 300. This may further restrict or prevent an axial movement of the bearing 200. In alternative embodiments, the bearing 200 may not be press-fitted into the cartridge 300. In further alternative embodiments, the bearing 200 may be form-fittingly hold in the cartridge 300.

Although in the embodiments of FIGS. 5A-6B the peripheral annular protrusion 310 is formed as a separate part from the cartridge 300, thus, similar to an annular ring axially adjacent the cartridge 300, in alternative embodiments the peripheral annular protrusion 310 may be integrally formed, and thus, may be made of the same material as the cartridge 300. In both cases (integrally formed or separately formed) the peripheral annular protrusion 310 may comprise a coating of the third material (see third material explained above). The third material has a higher elasticity than the first material and/or the second material and/or the fourth material. Preferably, the third material is a polymeric material, to reduce transmission of vibrations between the cartridge 300 and the housing 100.

In general, by implementing this advantageous feature of the peripheral annular protrusion 310, a movement of the bearing 200 in an axial direction 22 towards the annular end face 112 of the central bore 110 is restricted by the cartridge 300. More specific, a movement of the bearing 200 in an axial direction 22 towards the annular end face 112 of the central bore 110 is restricted by the peripheral annular protrusion 310 as it extends radially inwardly. Thus, the bearing 200 is not in direct contact with the housing 100 in an axial direction 22. Furthermore, the cartridge 300 only contacts the housing 100 axially via the peripheral annular protrusion 310 which either is made of the third material or comprises a coating of the third material. Thereby, vibrations of the bearing 200 and the oil film in the bearing can be damped before propagating into the housing 100, i.e. vibrations can be cushioned by the cartridge 300 and/or the peripheral annular protrusion 310. This can be achieved by the peripheral annular protrusion 310 being able to absorb vibration energy due to its higher elasticity in comparison to the bearing 200 and/or the housing 100 and/or the cartridge 300 itself. Thus, a propagation of vibrations from the area of the bearing 200 to the bearing housing 100 can be reduced or prevented. Thereby, less vibrations are propagated from the bearing housing 100 to the adjacently arranged flow housings (not depicted) or cavities in the housing wherefrom acoustic noise is mainly radiated to the environment. As a result, the acoustic behavior of a charging device which comprises such a bearing unit 10, can be improved.

However, mostly described with reference to certain figures showing only one specific embodiment, the following aspects may be applicable to all previously presented embodiments and aspects.

Again, with reference to FIGS. 5A-6B, the cartridge 300 comprises two vibration reducing members 400. The vibration reducing members 400 are arranged radially between the cartridge 300 and the housing 100 to reduce transmission of vibrations between the cartridge 300 and the housing 100. One effect of providing the vibration reducing members 400 radially between the cartridge 300 and the housing 100 is that a contact surface between the cartridge 300 and the housing 100 can be reduced and that the cartridge 300, at least in a radial direction 24, only stands in contact with the housing 100 via the vibration reducing members 400. As a result, vibrations can be damped via the vibrations reducing members 400 and a transmission of vibrations between the cartridge 300 and the housing 100 can be reduced. Furthermore, the vibration reducing members 400 provide a possibility for securely mounting the cartridge 300 in the central bore 110. Thus, the vibration reducing members 400 enable to axially and/or radially secure the cartridge 300 against movement to at least a certain extent. Alternative embodiments may comprise more or less than two vibration reducing members 400. Preferably, the cartridge 300 comprises at least two vibration reducing members 400. However, the number of vibration reducing members 400 depends, inter alia, on the design of the vibration reducing members 400 and/or the design of the cartridge 300 and/or that of the housing 100 and/or on the technical requirements. One objective of providing at least two vibration reducing members 400 is to prevent tilting and to ensure a stable mounting of the cartridge 300 in the bore 110.

The vibration reducing members 400 comprise a fifth material. The fifth material has a higher elasticity than the material of the cartridge 300 and the housing 100. Preferably, the fifth material is an elastomeric material. By providing a material for the vibration reducing members 400 which has a higher elasticity than the material of the cartridge 300 and/or the material of the housing 100, vibrations can be damped effectively and be reduced or inhibited when propagating from the cartridge 300 through the vibration reducing members 400 further to the housing 100. This can be achieved by the vibration reducing members 400 being able to absorb vibration energy due to their higher elasticity in comparison to the cartridge 300 and/or the housing 100. In other words, the fifth material has a higher elasticity than the first material and/or the second material and/or the third material and/or the fourth material.

In alternative embodiments, especially those wherein the cartridge 300 comprises a material of higher elasticity than the material of the housing and/or that of the bearing, the vibration reducing members 400 may be integrally formed with the cartridge 300 (not depicted). For instance, the previously described first embodiment, wherein the cartridge 300 comprises the third material, the vibration reducing members 400 may also be formed of the third material and may further be integrally formed with the cartridge 300. In that way, in comparison to a cartridge 300 without vibration reducing members 400, the damping capacity can be increased.

In FIGS. 5A-5B and 6A-6B, the vibration reducing members 400 comprise a ring shape. The ring shape extends circumferentially 26 around the cartridge 300 to provide contacts between the cartridge 300 and the housing 100. More specific, each of the vibration reducing members 400 substantially has an O-ring shape. In alternative embodiments, the vibration reducing members 400 may comprise another shape than an O-ring shape. For instance, the cross- section of a vibration reducing member 400 may have a cross-shape like a quad-ring, or a triangle shape, or an oval shape or any other suitable shape. The skilled person will understand, that also other shapes than a substantially ring-shaped vibration reducing member 400 is suitable. For instance, vibration reducing member 400 may comprise a plurality of circumferentially distributed elements or may comprise a spiral shape.

Now with regard to FIGS. 5A-5C, in the second embodiment, the cartridge 300 comprises a first circumferential groove 352 and a second circumferential groove 354 (see, especially, FIG. 5C). The first circumferential groove 352 and the second circumferential groove 354 are formed in an outer lateral surface 350 of the cartridge 300 to receive the vibration reducing members 400 therein. The grooves 352, 354 are arranged axially spaced apart on the outer lateral surface 350 of the cartridge 300. By providing these advantageous features, a desired axial position of the vibration reducing members 400 with respect to the cartridge 300 can be ensured. This improves the mounting process and ensures the correct functionality of the device. Spacing the grooves 352, 354 axially apart results in that the desired position of the vibration reducing members 400 is also spaced apart. The further the vibration reducing members 400 are spaced apart the more stable against tilting the cartridge 300 will be mounted in the housing 100.

With regard to FIGS. 6A-6B, in the third embodiment, the housing 100 comprises a first circumferential groove 152 and a second circumferential groove 154. The first circumferential groove 152 and the second circumferential groove 154 are formed in the inner lateral surface 150 of the housing 100 in the central bore 110 (see, FIG. 6B). Thus, the first circumferential groove 152 and the second circumferential groove 154 are configured to receive the vibration reducing members 400 therein. Additionally, the grooves 152, 154 may be arranged axially spaced apart on the inner lateral surface 150 of the housing 100. Spacing the grooves 152, 154 axially apart results in that the desired position of the vibration reducing members 400 is also spaced apart. The further the vibration reducing members 400 are spaced apart the more stable against tilting the cartridge 300 will be mounted in the housing 100.

In alternative embodiments, the bearing unit 10 may comprise at least one groove in the outer lateral surface 350 of the cartridge 300 as well as at least one groove in the inner lateral surface 150 of the housing 100 (not depicted). Thereby, the grooves may be configured such that a vibration reducing member 400 is partly in a groove of the cartridge 300 and partly in a groove of the housing 100. Alternatively, each respective groove may be configured to receive a vibration reducing member 400, i.e. one vibration reducing member 400 is received by a groove of the cartridge 300 and another vibration reducing member 400 is received by a groove of the housing 100. That means, a groove of the cartridge 300 and a groove of the housing 100 both may be located at a same axial position or at different axial positions. Also, the depth in a radial direction 24 of the respective groove (of the cartridge 300 or of the housing 100) may be configured correspondingly to receive a vibration reducing member 400 alone or to receive a vibration reducing member 400 in conjunction with the respective other groove (of the cartridge 300 or of the housing 100). In alternative embodiments, there may be, additionally or alternatively, grooves arranged on other suitable surfaces to damp vibrations between the bearing 200 and the housing 100. Corresponding vibration reducing members 400 may be arranged in the latter grooves analogously the explanations hereinabove and below.

As can be seen from the FIGS. 5A-6B, the grooves 152, 154, 352, 354 are configured such that each vibration reducing member 400 extends radially out of the respective groove 152, 154, 352, 354 to radially preload the cartridge 300 against the housing 100. In other words, the grooves are configured such that the cartridge is press-fitted into the bore 110 via each vibration reducing member 400 being compressed between the cartridge 300 and the housing 100. Depending on the material of a vibration reducing member 400 and/or the amount of how much each vibration reducing member 400 is compressed between the cartridge 300 and the housing 100, the amount of damping vibrations can be adjusted. Thus, on the one hand, the damping capability of the bearing unit 10 and on the other hand, the amount stabilization capability can be adjusted by, inter alia, one or more of the following: compression capability/design/material of vibration reducing member 400, the amount of how much a vibration reducing member 400 extends radially out of the respective groove, the design of the grooves and/or the radial clearance between outer lateral surface 350 of the cartridge 300 and inner lateral surface 150 of the housing 100.

In the present embodiments, a cross-section of each groove 152, 154, 352, 354 is shaped substantially rectangular (see FIGS. 5B and 6B). A radial depth of each groove 152, 154, 352, 354 is configured such that each vibration reducing member 400 extends radially out of the respective groove 152, 154, 352, 354. In alternative embodiments the cross-section of one or more grooves 152, 154, 352, 354 may comprise another shape such as an oval shape, a triangular shape, a circular shape, a splined shape, a zig-zag shape or any other suitable shape. The cross-section of one or more grooves 152, 154, 352, 354 may be adapted in shape to receive and/or match a shape of a respective vibration reducing member 400. Some embodiments may also comprise different shapes of the grooves 152, 154, 352, 354 and/or different shapes of the vibration reducing members 400. As can be seen, especially in FIG. 5C, the cartridge 300 comprises two fluid supply bores 357. The two fluid supply bores 357 are arranged on the outer lateral surface 350 of the cartridge 300. Each of the fluid supply bores 357 radially extends through the cartridge 300. In other words, each of the fluid supply bores 357 is located between the outer lateral surface 350 and an inner lateral surface 360 of the cartridge 300. The two fluid supply bores 357 are arranged 180 degrees circumferentially spaced apart on cartridge 300. Thus, the two fluid supply bores 357 are arranged vis-a-vis at the same axial position and radially spaced apart. Each of the fluid supply bores 357 is configured such that they - when looking in a radial direction 24 - overlap with a respective housing supply bore and a respective bearing supply bore. Thereby, the two fluid supply bores 357 are adapted in size and/or their position relative to the housing 100 and/or the bearing 200. Thus, in alternative embodiments, the two fluid supply bores 357 may be arranged at other positions, relative to the housing 100 and/or the bearing 200 and/or the cartridge 300 (relative to each other). In other embodiments, the cartridge 300 may comprise less or more than two fluid supply bore 357. Preferably, the cartridge 300 comprises at least one fluid supply bore 357.

Back with reference to FIG. 3, the cartridge 300 comprises a rotation locking member 320. The rotation locking member 320 is configured to prevent rotational movement of the cartridge 300 with respect to the housing 100. The rotation locking member 320 is arranged close to a second end face 314 of the cartridge 300. In other words, the rotation locking member 320 is arranged substantially at the second end face 314 of the cartridge 300. Thus, one side of the rotation locking member 320 is axially aligned with the second end face 314. In other embodiments, the rotation locking member 320 may be arranged at another position on the cartridge 300, particularly at another axial position on the cartridge 300. The rotation locking mechanism 320 extends radially outwardly from the outer lateral surface 350 of the cartridge 300 to matingly engage with a corresponding recess 120 in the housing 100 (see recess 120 in Fig. 4). The rotation locking member 320 is integrally formed with the cartridge 300. In other embodiments, rotation locking member 320 and the cartridge may be separate parts and connected with each other by frictional connection, form-fit or by an adhesive bond. In further alternative embodiments, the rotation locking member 320 may be attached to the housing 100 or integrally formed with the housing 100. In such a case, the cartridge 300 may comprise a corresponding recess to matingly engage with the rotation locking member 320. Although only shown in figures with regard to the first embodiment, the rotation locking member 320 may be comprised analogously in the bearing unit 10 of the second and the third embodiment. The rotation locking member 320 is configured to keep the bearing cartridge 300 in a fixed rotational position. Thereby, the fluid supply bores 357 are substantially axially aligned with the respective fluid supply bore of the housing 100 the respective fluid supply bores of the bearing 200. More specific, the relative circumferential and/or axial positions of the recess 120, the rotation locking member 320 and the fluid supply bores 357 is adapted such that the fluid supply bores 357 are at their designated position, when the rotation locking member 320 matingly engages the recess 120.

The present invention further relates to a charging device (not fully depicted). The charging device comprises a compressor with an impeller 22 and a bearing unit 10 of any one of the previous aspects. In a first embodiment of the charging device, the charging device may be an exhaust gas turbocharger and may further comprise a turbine with a turbine wheel 32 (see impeller 22 and turbine wheel 32 FIG. 5A). The charging device may be an electrically assisted turbocharger and may further comprise an electrical assist device (not depicted). In a second embodiment of the charging device, the charging device may be an electric charger and may further comprise an electric motor which drives the compressor (not depicted).

It should be understood that the present invention can also alternatively be defined in accordance with the following embodiments:

1. A bearing unit (10) for a rotor (500) comprising:

a housing (100) having a central bore (110);

a bearing (200) arranged in the central bore (110) for accommodating a rotor (500) in the housing (100), wherein the bearing (200) is a journal bearing (200);

characterized in that

the bearing unit (10) further comprises a cartridge (300) arranged radially between the bearing (200) and the housing (100) in the central bore (110) to reduce transmission of vibrations between the bearing (200) and the housing (100).

2. The bearing unit (10) of embodiment 1, wherein the cartridge (300) axially overlaps a length of the bearing (200).

3. The bearing unit (10) of any one of embodiments 1 or 2, wherein the housing (100) comprises a first material, the bearing (200) comprises a second material, the cartridge (300) comprises a third material and wherein the third material has a higher elasticity than the first material and/or the second material, preferably wherein the third material is a polymeric material, to reduce transmission of vibrations between the cartridge (300) and the housing (100).

4. The bearing unit (10) of embodiment 3, wherein the central bore (110) comprises an annular end face (112) and wherein the cartridge (300) comprises a peripheral annular protrusion (310) being arranged on a first end face (312) of the cartridge (300) axially between the cartridge (300) and the annular end face (112) of the housing (100).

5. The bearing unit (10) of embodiment 4, wherein the peripheral annular protrusion (310) extends radially inwardly to axially restrict the bearing (200) from moving axially towards the annular end face (112). 6. The bearing unit (10) of anyone of embodiments 1 or 2, wherein the housing (100) comprises a first material, the bearing (200) comprises a second material, the cartridge (300) comprises a fourth material and wherein the fourth material has a similar elasticity as the first material and/or the second material.

7. The bearing unit (10) of embodiment 6, wherein the central bore (110) comprises an annular end face (112) and wherein the cartridge (300) comprises a peripheral annular protrusion (310) being arranged on a first end face (312) of the cartridge (300) axially between the cartridge (300) and the annular end face (112) of the housing (100) and wherein peripheral annular protrusion (310) comprises a third material or a coating of a third material, wherein the third material has a higher elasticity than the first material and/or the second material and/or the fourth material, preferably wherein the third material is a polymeric material, to reduce transmission of vibrations between the cartridge (300) and the housing (100).

8. The bearing unit (10) of embodiment 7, wherein the peripheral annular protrusion (310) extends radially inwardly to axially restrict the bearing (200) from moving axially towards the annular end face (112).

9. The bearing unit (10) of any one of the previous embodiments, wherein the cartridge (300) comprises at least two vibration reducing members (400) which are arranged radially between the cartridge (300) and the housing (100) to reduce transmission of vibrations between the cartridge (300) and the housing (100).

10. The bearing unit (10) of embodiment 9, wherein the vibration reducing members (400) comprise a fifth material having a higher elasticity than the cartridge (300), preferably wherein the fifth material is an elastomeric material.

11. The bearing unit (10) of embodiment 9, if dependent of embodiment 3, wherein the vibration reducing members (400) are integrally formed with the cartridge (300). 12. The bearing unit (10) of any one of embodiments 9 - 11, wherein each of the vibration reducing members (400) comprises a ring shape extending circumferentially around the cartridge (300) to provide contacts between the cartridge (300) and the housing (100).

13. The bearing unit (10) of any one of embodiments 9 - 12, wherein each of the vibration reducing members (400) is one of an O-ring or a quad ring.

14. The bearing unit (10) of any one of embodiments 9 - 13, wherein the cartridge (300) comprises a first circumferential groove (352) and a second circumferential groove (354) formed in an outer lateral surface (350) of the cartridge (300) to receive at least one vibration reducing member (400) therein.

15. The bearing unit (10) of 14, wherein the grooves (352, 354) are arranged axially spaced apart on the outer lateral surface (350) of the cartridge (300).

16. The bearing unit (10) of any one of embodiments 9 - 15, wherein the housing (100) comprises a first circumferential groove (152) and a second circumferential groove (154) formed in an inner lateral surface (150) the housing (100) in the central bore (110) to receive at least one vibration reducing member (400) therein.

17. The bearing unit (10) of 16, wherein the grooves (152, 154) are arranged axially spaced apart on the inner lateral surface (150) of the housing (100).

18. The bearing unit (10) of any one of embodiments 14 - 17, wherein the grooves (152, 154, 352, 354) are configured such that each vibration reducing member (400) extends radially out of the respective groove (152, 154, 352, 354) to radially preload the cartridge (300) against the housing (100).

19. The bearing unit (10) of any one of the previous embodiments, if dependent from embodiment 13, wherein a cross-section of each groove (152, 154, 352, 354) is adapted in shape to receive and match a shape of each vibration reducing member (400).

20. The bearing unit (10) of any one of the previous embodiments, wherein the cartridge (300) further comprises at least one fluid supply bore (357) being arranged on the outer lateral surface (350).

21. The bearing unit (10) of any one of the previous embodiments, wherein the cartridge (300) further comprises a rotation locking member (320) to prevent rotational movement of the cartridge (300) with respect to the housing (100).

22. The bearing unit (10) of embodiment 21, wherein the rotation locking member (320) arranged close to a second end face (314) of the cartridge (300) and extends radially outwardly from the outer lateral surface (350) of the cartridge (300) to matingly engage with a corresponding recess (120) in the housing (100).

23. The bearing unit (10) of any one of embodiments 21 or 22, wherein the rotation locking member (320) is integrally formed with the cartridge (300).

24. The bearing unit (10) of any one of embodiments 21 to 23, if dependent of embodiment 20, wherein the rotation locking member (320) is configured to keep the bearing cartridge (300) in a fixed rotational position such that the at least one fluid supply bore (357) is substantially aligned with a fluid supply bore of the housing (100) and a fluid supply bore of the bearing (200).

25. A charging device comprising a compressor with an impeller (22) and a bearing unit (10) of any one of the previous embodiments.

26. The charging device of embodiment 25, wherein the charging device is an exhaust gas turbocharger and further comprises a turbine with a turbine wheel (32). 27. The charging device of any one of embodiments 25 or 26, wherein the charging device is an electrically assisted turbocharger and further comprises an electrical assist device. 28. The charging device of embodiment 25, wherein the charging device is an electric charger and further comprises an electric motor which drives the compressor.

Claims

1. A bearing unit (10) for a rotor (500) comprising:

a housing (100) having a central bore (110);

characterized in that

2. The bearing unit (10) of claim 1, wherein the cartridge (300) axially overlaps a length of the bearing (200).

3. The bearing unit (10) of any one of claims 1 or 2, wherein the housing (100) comprises a first material, the bearing (200) comprises a second material, the cartridge (300) comprises a third material and wherein the third material has a higher elasticity than the first material and/or the second material, preferably wherein the third material is a polymeric material, to reduce transmission of vibrations between the cartridge (300) and the housing (100).

4. The bearing unit (10) of claim 3, wherein the central bore (110) comprises an annular end face (112) and wherein the cartridge (300) comprises a peripheral annular protrusion (310) being arranged on a first end face (312) of the cartridge (300) axially between the cartridge (300) and the annular end face (112) of the housing (100).

5. The bearing unit (10) of any one of claims 1 or 2, wherein the housing (100) comprises a first material, the bearing (200) comprises a second material, the cartridge (300) comprises a fourth material and wherein the fourth material has a similar elasticity as the first material and/or the second material.

6. The bearing unit (10) of claim 5, wherein the central bore (110) comprises an annular end face (112) and wherein the cartridge (300) comprises a peripheral annular protrusion (310) being arranged on a first end face (312) of the cartridge (300) axially between the cartridge (300) and the annular end face (112) of the housing (100) and wherein peripheral annular protrusion (310) comprises a third material or a coating of a third material, wherein the third material has a higher elasticity than the first material and/or the second material and/or the fourth material, preferably wherein the third material is a polymeric material, to reduce transmission of vibrations between the cartridge (300) and the housing (100).

7. The bearing unit (10) of claim 4 or claim 6, wherein the peripheral annular protrusion (310) extends radially inwardly to axially restrict the bearing (200) from moving axially towards the annular end face (112).

8. The bearing unit (10) of any one of the previous claims, wherein the cartridge (300) comprises at least two vibration reducing members (400) which are arranged radially between the cartridge (300) and the housing (100) to reduce transmission of vibrations between the cartridge (300) and the housing (100).

9. The bearing unit (10) of claim 8, wherein the vibration reducing members (400) comprise a fifth material having a higher elasticity than the cartridge (300), preferably wherein the fifth material is an elastomeric material.

10. The bearing unit (10) of any one of claims 8 - 9, wherein each of the vibration reducing members (400) comprises a ring shape extending circumferentially around the cartridge (300) to provide contacts between the cartridge (300) and the housing (100).

11. The bearing unit (10) of any one of claims 8 - 10, wherein the cartridge (300) comprises a first circumferential groove (352) and a second circumferential groove (354) formed in an outer lateral surface (350) of the cartridge (300) to receive at least one vibration reducing member (400) therein.

12 The bearing unit (10) of any one of claims 8 - 11, wherein the housing (100) comprises a first circumferential groove (152) and a second circumferential groove (154) formed in an inner lateral surface (150) the housing (100) in the central bore (HO) to receive at least one vibration reducing member (400) therein.

13. The bearing unit (10) of any one of claims 11 - 12, wherein the grooves (152, 154, 352, 354) are configured such that each vibration reducing member (400) extends radially out of the respective groove (152, 154, 352, 354) to radially preload the cartridge (300) against the housing (100).

14. The bearing unit (10) of any one of the previous claims, wherein the cartridge (300) further comprises a rotation locking member (320) to prevent rotational movement of the cartridge (300) with respect to the housing (100).

15. A charging device comprising a compressor with an impeller (22) and a bearing unit (10) of any one of the previous claims.