Cross-Reference to Related Applications [0001] This application claims the benefit of German Patent Application No.

102017223186.6 filed December 19, 2017 the disclosure of which is herein incorporated by reference in its entirety

Field of the invention

[0002] The present invention relates to a bearing unit for a turbocharger rotor and a charger device comprising a corresponding bearing unit.

Background of the invention

[0003] An increasing number of the latest generation of vehicles are being equipped with charger devices. In order to fulfill design goals and legal requirements, it is important to develop advances optimizing reliability and efficiency in the entire powertrain and its individual components as well as in the system as a whole.

[0004] Exhaust gas turbochargers are known, for example, in which the flow of exhaust gas from a combustion engine drives a turbine comprising a turbine wheel. A compressor comprising a compressor wheel, which is arranged on a common shaft together with the turbine wheel, compresses fresh intake air for the engine that is drawn in through an intake line. Doing so increases the quantity of air, or rather oxygen, available to the engine, which in turn causes an increase in the performance of the combustion engine. [0005] Known charger devices comprise at least one compressor housing with the compressor wheel arranged therein and a bearing housing in which the rotor is mounted. In terms of radial bearing, the rotor can, for example, be mounted in a roller bearing cartridge, which is in turn located in a bore in the bearing housing. [0006] Corresponding retention means are provided in order to both radially and axially secure the bearing cartridge in the bearing housing and to prevent co- rotation of the outer bushing of the bearing cartridge. Examples of known retention means include rigid locking plates, screw-in locking bolts, or locking rings. However, all of the known solutions possess disadvantages related to the noise generated as a result of limited damping properties, the demands on installation space, and/or the relatively high costs.

[0007] Accordingly, the object of the present invention is to provide a compact and economical bearing unit for a turbocharger rotor which generates little noise.

Summary of the Invention

[0008] The present invention relates to a bearing unit according to claim 1 and a charger device according to claim 15.

[0009] The bearing unit for a turbocharger rotor according to the invention comprises a bearing housing, a bearing cartridge, which is arranged to support a turbocharger rotor in the bearing housing, a first decoupling ring, whereby said first decoupling ring is non-rotatably arranged on a first axial end of the bearing cartridge, and a fixing ring, whereby said fixing ring is non-rotatably coupled with the bearing housing. The first decoupling ring is non-rotatably coupled with the fixing ring in order to provide an anti-rotation locking means for the bearing cartridge. By means of its arrangement and design according to the invention, the first decoupling ring is able to provide both a radial damping function for the bearing cartridge and, together with the fixing ring, an anti-rotation locking function for the bearing cartridge.

[0010] In embodiments, the first decoupling ring can be arranged along an outer circumference of the bearing cartridge. In the area of the first axial end of the bearing cartridge, a first step can be provided along the outer circumference thereof. The first decoupling ring can be arranged in axial direction between said first step and the fixing ring. By means of this inventive arrangement of the first decoupling ring in relation to the bearing cartridge and the fixing ring, the first decoupling ring is able to fix the axial position of the bearing cartridge in addition to providing a damping function in an axial direction, as a result of which less movement/vibration is able to be transmitted from the turbocharger rotor to the bearing housing via the bearing cartridge and vice versa. In addition, the noise characteristics of the bearing unit are improved accordingly.

[0011] In embodiments able to be combined with all of the embodiments described thus far, a side of the first decoupling ring facing the fixing ring can comprise at least one first projection projecting in an axial direction towards the fixing ring, whereby said at least one first projection projects into a corresponding receptacle in the fixing ring, as a result of which the fixing ring and the first decoupling ring are non-rotatably coupled with one another. There may be 1 to 12, in particular 3 to 9, first projections provided on the first decoupling ring, and corresponding receptacles are provided in the fixing ring. Said receptacle(s) may be provided as recesses on an inner circumference of the fixing ring. The side of the first decoupling ring facing away from the fixing ring can comprise at least one second projection projecting in an axial direction, whereby said at least one second projection projects into a corresponding receptacle in the bearing cartridge, as a result of which the bearing cartridge and the first decoupling ring are non-rotatably coupled with one another. There may be 1 to 12, in particular 3 to 9, second projections provided on the first decoupling, and corresponding receptacles are provided in the bearing cartridge. The receptacle(s) can be provided in the form of grooves on the outer circumference of the bearing cartridge.

[0012] In embodiments able to be combined with all of the embodiments described thus far, a second decoupling ring can be further provided, whereby said second decoupling ring can be non-rotatably arranged on a second axial end of the bearing cartridge. The second decoupling ring can be arranged along an outer circumference of the bearing cartridge. In the area of the second axial end of the bearing cartridge, a second step can be provided along the outer circumference thereof. The second decoupling ring can be arranged in axial direction between said second step and a radially inward extending projection of the bearing housing. By means of this inventive arrangement of the second decoupling ring, the second decoupling ring is also able to provide a damping function in both the axial and the radial directions, as a result of which less movement/vibration is able to be transmitted from the turbocharger rotor to the bearing housing via the bearing cartridge and vice versa. [0013] In embodiments able to be combined with all of the embodiments described thus far, the first decoupling ring, and the second decoupling ring if one is provided, can exhibit spring-like elastic properties.

[0014] In embodiments able to be combined with all of the embodiments described thus far, the first decoupling ring, and the second decoupling ring if one is provided, can have a conical shape in at least a central section thereof. In particular, the respective end of the decoupling ring with the smaller diameter can be oriented towards the center of the bearing cartridge and can be situated on the bearing cartridge, and the end of the decoupling ring with the larger diameter can be in contact with the fixing ring or the bearing housing.

[0015] Alternatively, the first decoupling ring, and the second decoupling ring if one is provided, can be S-shaped in cross-section. An alternative to the conical shape, the S-shape lends spring-like elastic properties to the decoupling rings which, depending on the design thereof (the exact shape, material thickness, and choice of material in order to adjust the ratio between the axial and the radial damping effects), can be adapted to the features of the respective bearing unit.

[0016] In embodiments able to be combined with all of the embodiments described thus far, the fixing ring can also comprise at least one bore for mounting it on the bearing housing. The fixing ring can be fastened to the bearing housing by means of at least one screw that extends through said at least one bore. [0017] In embodiments able to be combined with all of the embodiments described thus far, the bearing cartridge can be a roller bearing cartridge, in particular a ball bearing cartridge. Said ball bearing cartridge can comprise at least one outer bearing race, at least one inner bearing race, and a plurality of rolling elements, in particular balls, which are arranged between the outer bearing race and the inner bearing race.

[0018] By means of the arrangement according to the invention of the decoupling rings and the fixing rings, an especially compact solution is provided for anti rotation locking of the bearing cartridge while also fixing the bearing cartridge in an axial direction as well as providing an axial and radial damping function. This approach is able to both save installation space in an axial direction and reduce the weight of the bearing unit. This can ultimately lead to cost savings. In addition, the noise characteristics of the bearing unit are improved by means of the radial and axial damping function.

[0019] The invention further comprises a charger device for a combustion engine comprising a compressor with a compressor housing and a compressor wheel arranged therein as well as a bearing unit according to any of the previous embodiments. Said charger device can be an exhaust gas turbocharger and can further comprise a turbine with a turbine housing and a turbine wheel arranged therein. [0020] Additional details and features of the invention are described in reference to the following drawings.

Brief Description of the Drawings Fig. 1 shows a sectional view of the inventive bearing unit according to an exemplary embodiment; Fig. 2 shows a side view of an exemplary embodiment of a bearing cartridge in the bearing unit according to the invention; Fig. 3 shows side views of first exemplary embodiments of the first and second decoupling rings in the bearing unit according to the invention;

Fig. 4 shows a side view of a first exemplary embodiment of the fixing ring in the bearing unit according to the invention;

Fig. 5 shows a side view including a partial section of a second exemplary embodiment of the first decoupling ring in the bearing unit according to the invention;

Fig. 6 shows a side view of the second exemplary embodiment of the first decoupling ring and the second decoupling ring mounted on an exemplary embodiment of the bearing cartridge.

Detailed Description

[0021] Exemplary embodiments of the bearing unit 10 according to the invention and the charger device according to the invention are described hereinafter in reference to the drawings. In the context of this application, radial surfaces/planes are based upon surfaces/planes which are essentially orthogonal with respect to the axis of rotation 600 of the turbocharger rotor 500. [0022] Fig. 1 shows a sectional view of an exemplary embodiment of the bearing unit 10 for a turbocharger rotor 500 according to the invention. The bearing unit 10 comprises a bearing housing 100 and a bearing cartridge 200, which is arranged in order to support the turbocharger rotor 500 in the bearing housing 100. A first decoupling ring 310 is non-rotatably arranged on a first axial end 210 of the bearing cartridge 200 (see Fig. 2). A fixing ring 400 is non-rotatably coupled with the bearing housing 100. According to the invention, the first decoupling ring 310 is non-rotatably coupled with the fixing ring 400 in order to provide an anti-rotation locking means for the bearing cartridge 200 in the bearing housing 100. By means of its arrangement and design according to the invention, the first decoupling ring 310 is able to provide both a radial damping function for the bearing cartridge 200 and, together with the fixing ring 400, an anti-rotation locking function for the bearing cartridge 200.

[0023] If the bearing unit 10 is being used in combination with an exhaust gas turbocharger, then the first axial end 210 of the bearing cartridge 200 is arranged on whichever end thereof is closer to a compressor of the exhaust gas turbocharger. Accordingly, the second axial end 220 of the bearing cartridge 200 is then arranged closer to a turbine of the exhaust gas turbocharger (see Fig. 2).

[0024] Referring to Fig. 1, the first decoupling ring 310 is arranged along an outer circumference of the bearing cartridge 200. In the area of the first axial end 210 of the bearing cartridge 200, a first step 212 is provided along the outer circumference thereof. The first decoupling ring 310 is arranged in an axial direction between the first step 212 (see also Fig. 2) and the fixing ring 400. Seen in an axial direction, the first decoupling ring 310 is arranged between a radial side surface, which is formed by the first step 212, and the fixing ring 400. By means of this inventive arrangement of the first decoupling ring 310 in relation to the bearing cartridge 200 and the fixing ring 400, the first decoupling ring 310 is able to fix the axial position of the bearing cartridge 200 in addition to providing a damping function in an axial direction, as a result of which less movement/vibration is able to be transmitted from the turbocharger rotor 500 to the bearing housing 100 via the bearing cartridge 200 and vice versa. In addition, the noise characteristics of the bearing unit 10 are improved accordingly. [0025] Referring to Fig. 3, a side of the first decoupling ring 310 facing the fixing ring 400 comprises a plurality of first projections 312 projecting in an axial direction towards the fixing ring 400. Said first projections 312 project into corresponding receptacles 410 in the fixing ring 400 (see Fig. 4), as a result of which the fixing ring 400 and the first decoupling ring 310 are non-rotatably coupled with one another. In embodiments, there may be 1 to 12, in particular 3 to 9, first projections 312 provided on the first decoupling ring 310, and corresponding receptacles 410 are provided in the fixing ring 400. The first projections 312 can be arranged to be evenly spaced in a circumferential direction. Alternatively, the first projections 312 can be arranged to be spaced asymmetrically. The advantage of doing so is the ability to avoid installation errors. These receptacles 410 are provided as recesses on the inner circumference of the fixing ring 400. [0026] The side of the first decoupling ring 310 facing away from the fixing ring

400 in the example shown in Fig. 3 comprises a plurality of second projections 314 projecting in an axial direction, whereby said second projections 314 extend into corresponding receptacles 230 (see Fig. 2) in the bearing cartridge 200, as a result of which the bearing cartridge 200 and the first decoupling ring 310 are non-rotatably coupled with one another. In embodiments, there may be 1 to 12, in particular 3 to 9, second projections 314 provided on the first decoupling ring 310, and corresponding receptacles 230 are provided in the bearing cartridge 200. The second projections 314 can be arranged to be evenly spaced in a circumferential direction. Alternatively, the second projections 314 can be arranged to be spaced asymmetrically. The advantage of doing so is the ability to avoid installation errors. The receptacles 230 can be provided in the form of grooves on the outer circumference of the bearing cartridge 200. The first and second projections 312, 314 can, for example, be in the form of rounded teeth (see Fig. 3). The receptacles 410, 230 in the fixing ring 400 (see Fig. 4) and in the bearing cartridge 200 (see Fig. 2) can be in the form of rounded or angular, e.g. milled or stamped, recesses or grooves. [0027] Referring to Fig. 1 and Fig. 2, the bearing unit 10 comprises a second decoupling ring 320. The second decoupling ring 320 is non-rotatably arranged on a second axial end 220 of the bearing cartridge 200 (see Fig. 2). The second decoupling ring 320 is also arranged along the outer circumference of the bearing cartridge 200. In the area of the second axial end 220 of the bearing cartridge 200, a second step 222 is provided along the outer circumference thereof (see Fig. 2). The second decoupling ring 320 is arranged in axial direction between the second step 222 and a radially inward extending projection 120 (see Fig. 1) of the bearing housing 100. By means of this inventive arrangement of the second decoupling ring 320, the second decoupling ring 320 is also able to provide a damping function in both the axial and the radial directions, as a result of which less movement/vibration is able to be transmitted from the turbocharger rotor 500 to the bearing housing 100 via the bearing cartridge 200 and vice versa. [0028] In order to provide said damping function, both the first decoupling ring

310 and the second decoupling ring 320 can exhibit spring-like elastic properties.

[0029] Like the exemplary embodiments shown in Fig. 3, the first decoupling ring 310 and the second decoupling ring 320 can have a conical shape in at least a central section thereof. In this case, the respective end of the decoupling ring 310, 320 with the smaller diameter is oriented towards the center of the bearing cartridge and is situated on the bearing cartridge 200. The end of the decoupling ring 310, 320 with the larger diameter is in contact with the fixing ring 400 or the bearing housing 100 (see Fig. 1).

[0030] A cross-section of the decoupling rings 310, 320 can have at least a partially conical shape, for example a conical section between two cylindrical sections (see also Fig. 2). The (partially) conical shape of the first and the second decoupling rings 310, 320 represents a particularly advantageous option for how the functional combination of axial and radial damping can be accomplished. The ratio between the axial and the radial damping action can be adjusted by way of the angles a and b (see Fig. 3) in the decoupling rings 310, 320 of conical design. [0031] Said angles a and b can, for example, measure between 10° and 80°, in particular between 20° and 70°. The degree of damping can be adjusted by the choice of material as well as the wall thickness of the decoupling rings 320, 310. For example, spring steel can be chosen as a material.

[0032] Shown in Fig. 5 and Fig. 6 are alternative exemplary embodiments of the first and second decoupling rings 310, 320. In this example, the first decoupling ring 310 and the second decoupling ring 320 are S-shaped in cross-section. An alternative to the conical shape, the S-shape lends spring-like elastic properties to the decoupling rings 310, 320 which, depending on the design thereof (the exact shape, material thickness, and choice of material in order to adjust the relationship between axial and radial damping effects), can be adapted to the features of the respective bearing unit. [0033] As depicted in Fig. 4, the fixing ring 400 further comprises a plurality of bores 420 used for mounting it on the bearing housing 100. The fixing ring 400 can, for example, be fastened to the bearing housing 100 by means of screws that extend through the at least one bore 420. For example, 2 to 8, in particular 3 to 6, and for example 5 screws as well as the corresponding holes 420 can be provided in the fixing ring 400. Said bores 420 can, for example, be arranged to be evenly or unevenly spaced along the fixing ring 400. Alternatively, the fixing ring 400 can also be affixed to the bearing housing 100 via other fastening means as long as this fixing is able to transmit both rotary forces and forces acting in an axial direction from the fixing ring 400 to the bearing housing 100. This manner of fastening advantageously avoids contact with portions of the compressor (the compressor housing or the rear wall of the compressor) so that vibrations are unable to be transmitted from the bearing cartridge 200 to the compressor via the fixing ring 400. The radial side wall of the bearing housing 100, to which the fixing ring 400 is fastened, can be designed in such a way that the fixing ring 400 is accommodated in a pocket 110 (see Fig. 1) such that the fixing ring 400 is flush with the rest of the radial side wall. [0034] As a further alternative, the fixing ring 400 can also be clamped to a radially outward end between the bearing housing 100 and a further component that is coupled with the bearing housing 100 (a compressor housing or a rear wall of a compressor, for example). In order to keep the contact surface for this manner of fastening as small as possible, radially projecting teeth which are clamped between the bearing housing 400 and said further component can be provided for this purpose on a radially outward area of the fixing ring 400 (not shown in the drawings). [0035] The bearing cartridge 200 can be designed as a roller bearing cartridge, for example in the form of a ball bearing cartridge. The ball bearing cartridge comprises at least one outer bearing race 240 as well as at least one inner bearing race. For example, the outer and/or the inner bearing races can be designed as one piece or as multiple pieces, e.g. two pieces. Fig. 1 shows only the outer bearing race 240, which is one piece in this case. A plurality of rolling elements, for example balls, are arranged between the outer bearing race 240 and the inner bearing race. The outer bearing race(s) 240 and the inner bearing race(s) are arranged essentially concentric to one another as well as concentric to the axis of rotation 600 of the turbocharger rotor 500. As can be gathered from Fig. 1, the first decoupling ring 310 and the second decoupling ring 320 are non-rotatably coupled with the outer bearing races 240.

[0036] By means of the arrangement according to the invention of the decoupling rings 310, 320 and the fixing rings 400, an especially compact solution is provided for anti-rotation locking of the bearing cartridge 200 while also fixing the bearing cartridge 200 in an axial direction as well as providing an axial and radial damping function. This approach is able to both save installation space in an axial direction and reduce the weight of the bearing unit 10. This can ultimately lead to cost savings. In addition, the noise characteristics of the bearing unit 10 are improved by means of the radial and axial damping function. [0037] The invention furthermore includes a charger device for a combustion engine comprising a compressor with a compressor housing and a compressor wheel arranged therein as well as a bearing unit 10 according to any of the previously described embodiments. Said charger device can be an exhaust gas turbocharger and can further comprise a turbine with a turbine housing and a turbine wheel arranged therein. Alternatively, the charger device may also be an electrically driven compressor or an electrically assisted exhaust gas turbocharger.

Although the present invention has been described above and is defined in the appended claims, it should be understood that the invention may, as an alternative, also be defined in accordance with the following embodiments: 1. A bearing unit (10) for a turbocharger rotor (500) comprising

a bearing housing (100);

a bearing cartridge (200), which is arranged to support a turbocharger rotor (500) in said bearing housing (100);

a first decoupling ring (310), wherein said first decoupling ring (310) is non-rotatably arranged on a first axial end (210) of said bearing cartridge (200); and

a fixing ring (400), wherein said fixing ring (400) is non-rotatably coupled with the bearing housing (100),

characterized in that the first decoupling ring (310) is non-rotatably coupled with the fixing ring (400) in order to provide an anti-rotation locking means for the bearing cartridge (200).

2 The bearing unit according to embodiment 1, characterized in that the first decoupling ring (310) is arranged along an outer circumference of the bearing cartridge (200).

3. The bearing unit according to embodiment 2, characterized in that, in the area of the first axial end (210) of the bearing cartridge (200), a first step (212) is provided along the outer circumference thereof, and in that the first decoupling ring (310) is arranged in an axial direction between said first step (212) and the fixing ring (400).

4. The bearing unit according to any of the previous embodiments, characterized in that a side of the first decoupling ring (310) facing the fixing ring (400) comprises at least one first projection (312) projecting in an axial direction towards the fixing ring (400), wherein said at least one first projection (312) projects into a corresponding receptacle (410) in the fixing ring (400), as a result of which the fixing ring (400) and the first decoupling ring (310) are non-rotatably coupled with one another.

5. The bearing unit according to embodiment 4, characterized in that 1 to 12, in particular 3 to 9, first projections (312) are provided on the first decoupling ring (310), and corresponding receptacles are (410) provided in the fixing ring (400).

6. The bearing unit according to embodiment 4 or embodiment 5, characterized in that said receptacle(s) (410) are provided as recesses on an inner circumference of the fixing ring (400).

7. The bearing unit according to any of embodiments 4 to 6, characterized in that a side of the first decoupling ring (310) facing away from the fixing ring (400) comprises at least one second projection (314) projecting in an axial direction, wherein said at least one second projection (314) projects into a corresponding receptacle (230) in the bearing cartridge (200), as a result of which the bearing cartridge (200) and the first decoupling ring (310) are non-rotatably coupled with one another.

8. The bearing unit according to embodiment 7, characterized in that 1 to 12, in particular 3 to 9, second projections (314) are provided on the first decoupling ring (310), and corresponding receptacles are (230) provided in the bearing cartridge (200).

9. The bearing unit according to embodiment 7 or embodiment 8, characterized in that said receptacle(s) (230) are provided as recesses on an outer circumference of the bearing cartridge (200). 10. The bearing unit according to any of the previous embodiments, characterized in that a second decoupling ring (320) is further provided, wherein said second decoupling ring (320) is non-rotatably arranged on a second axial end (220) of the bearing cartridge (200).

11. The bearing unit according to embodiment 10, characterized in that the second decoupling ring (320) is arranged along an outer circumference of the bearing cartridge (200).

12. The bearing unit according to embodiment 11, characterized in that, in the area of the second axial end (220) of the bearing cartridge (200), a second step (222) is provided along the outer circumference thereof, and in that the second decoupling ring (320) is arranged in an axial direction between said second step (222) and a radially inward extending projection (120) of the bearing housing (100). 13. The bearing unit according to any of the previous embodiments, characterized in that the first decoupling ring (310), and the second decoupling ring (320) if one is provided, exhibit spring-like elastic properties. 14 The bearing unit according to any of the previous embodiments, characterized in that the first decoupling ring (310), and the second decoupling ring (320) if one is provided, have a conical shape in at least a central section thereof, in particular wherein the respective end of the decoupling ring (310, 320) with the smaller diameter is oriented towards the center of the bearing cartridge and is situated on the bearing cartridge (200), and the end of the decoupling ring (310, 320) with the larger diameter is in contact with the fixing ring (400) or the bearing housing 100 15. The bearing unit according to any of embodiments 1 to 13, characterized in that the first decoupling ring (310), and the second decoupling ring (320) if one is provided, are S-shaped in cross-section. 16. The bearing unit according to any of the previous embodiments, characterized in that the fixing ring (400) further comprises at least one bore (420) for mounting it on the bearing housing (100).

17. The bearing unit according to embodiment 16, characterized in that the fixing ring (400) is fastened to the bearing housing (100) by means of at least one screw that extends through said at least one bore (420). 18. The bearing unit according to any of the previous embodiments, characterized in that the bearing cartridge 200 is a roller bearing cartridge, in particular a ball bearing cartridge.

19. The bearing unit according to embodiment 18, characterized in that said ball bearing cartridge comprises at least one outer bearing race (240), at least one inner bearing race, and a plurality of rolling elements, in particular balls, which are arranged between the outer bearing race (240) and the inner bearing race. 20. A charger device for a combustion engine comprising

a compressor with a compressor housing and a compressor wheel arranged therein; and

a bearing unit (10) according to any of the preceding embodiments. 21. The charger device according to embodiment 20, characterized in that said charger device is an exhaust gas turbocharger further comprising a turbine with a turbine housing and a turbine wheel arranged therein.