The field of the invention

[0001] The present invention relates to an apparatus for connecting two turbine housings, a two-stage turbocharger system, and a method for assembling a two- stage turbocharger system.

Background of the invention

[0002] The basic development goals for future combustion engines make increasingly refined charging systems necessary. The design of such a turbocharger system leads to conflicting goals in terms of the power rating of the engine on the one hand and the transient response and the torque power band on the other hand. A high power rating necessitates a relatively large exhaust gas turbocharger. The desire for very high boost pressure even at low engine speeds means, however, that the turbocharger needs to be made much smaller. A combination of the two would be ideal.

[0003] Regulated two-stage turbocharging systems are being developed in order to resolve this conflict. Systems of this kind allow for the continuously variable adaptation of the turbine and compressor sides of the system for each engine operating point. The regulated two-stage turbocharger system consists of two turbochargers of different sizes connected in series that utilize bypass regulation. The exhaust gas mass flow coming from the cylinders first reaches the exhaust manifold. Here, it is possible to expand the entire exhaust mass flow using the high pressure turbine (HP) or to redirect some of the mass flow through a bypass to the low pressure turbine (LP). The entire exhaust mass flow is then utilized again by the low pressure turbine (LP). The entire fresh air flow is initially compressed by the low pressure stage. Further compression subsequently occurs in the high-pressure stage. Regulated two-stage turbocharging therefore allows for continuous adaptation on the turbine and compressor sides to the requirements of the operating engine.

[0004] As a result of the lack of space in the area surrounding an internal combustion engine, turbocharging systems of this sort must be designed to be as small as possible. In order to accomplish this, the two turbine housings are to be joined directly together. Since both the two turbine housings as well as the two compressor housings must be fluidically connected with each other, this can lead to problems during assembly. In addition, it is difficult to position the two housings correctly in relation to one another and to join them together in a fluid- tight manner.

[0005] The object of the present invention is therefore to provide an apparatus for connecting two turbine housings which permits simple assembly and, at the same time, precise positioning and fluid-tight joining of the turbine housings.

Summary of the invention

[0006] The present invention relates to an apparatus for connecting an exhaust gas outlet of a first turbine housing with an exhaust gas inlet of a second turbine housing according to claim 1, a two-stage turbocharger system according to claim 6, and a method for assembling a two-stage turbocharger system according to claim 14. [0007] The apparatus according to the invention for connecting an exhaust gas outlet of a first turbine housing with an exhaust gas inlet of a second turbine housing of a two-stage turbocharger system features a pocket, which is situated in the area of a first flange on the first turbine housing, and a projection, which is situated in the area of a second flange on the second turbine housing and is able to be inserted into the pocket. The projection is designed such that, after the projection has been inserted into the pocket, the first and second turbine housings can be tilted in relation to each other in order to establish a flush connection between the first flange and the second flange. One advantage of this apparatus is that the two turbocharger assemblies can be assembled and calibrated separately from one another. As a result of the tilting movement, significant pressure can in a simple manner be exerted against a seal between the two turbine housings. The risk of leakage is consequently reduced. In embodiments, this apparatus allows for accomplishing the connection between the turbine housings as well as the connection between the two compressor housings by way of a single motion during assembly.

[0008] In embodiments, the pocket can be situated in a wall of the first turbine housing extending from the first flange.

[0009] In embodiments able to be combined with all of the embodiments described thus far, the projection may be designed in the form of a strip extending in a linear direction from an outer wall of the second turbine housing and running approximately parallel to a plane along which lies a connection area for the second flange.

[0010] In embodiments able to be combined with all of the embodiments described thus far, the projection can have a lower side, which is disposed opposite a connection area on the first flange and features a chamfer. The chamfer may have a chamfer angle of from 2° to 7°, in particular from 4° to 5°.

[0011] In embodiments able to be combined with all of the embodiments described thus far, at least one connection means may be provided in order to attach the second turbine housing to the first turbine housing.

[0012] In embodiments able to be combined with all of the embodiments described thus far, a seal can be situated between the first flange and the second flange. Through the tilting motion, both connection areas of the first and second flanges are pressed together with significant force. In the process, the seal is compressed between the two connection areas. The risk of leakage is consequently decreased.

[0013] Furthermore, in embodiments able to be combined with all of the embodiments described thus far, at least one locating pin may be provided in order to establish the position of the second turbine housing in relation to the first turbine housing during assembly. The locating pin may be situated in the connection area of the first flange and interact with the projection in order to position the first and second turbine housings in relation to one another.

[0014] The invention furthermore comprises a two-stage turbocharger system having a first exhaust gas turbocharger with a first turbine housing and having a second exhaust gas turbocharger with a second turbine housing. Situated in the area of a first flange on the first turbine housing, the first turbine housing features a pocket, into which projects a projection, which is situated in the area of a second flange on the second turbine housing. Regarding the connection between the first and the second turbine housings, the projection is designed such that, after the projection has been inserted into the pocket, the first and second turbine housings can be tilted in relation to each other in order to establish a flush connection between the first flange and the second flange.

[0015] In embodiments of the two-stage turbocharger system, the pocket can be situated in a wall of the first turbine housing extending from the first flange. [0016] In embodiments of the two-stage turbocharger system able to be combined with all of the embodiments described thus far, the projection may be designed in the form of a strip extending in a linear direction from an outer wall of the second turbine housing and running approximately parallel to a plane along which lies a connection area for the second flange.

[0017] In embodiments of the two-stage turbocharger system able to be combined with all of the embodiments described thus far, the projection can have a lower side, which is disposed opposite a connection area on the first flange and features a chamfer. The chamfer may have a chamfer angle of from 2° to 7°, in particular from 4° to 5°.

[0018] In embodiments of the two-stage turbocharger system able to be combined with all of the embodiments described thus far, at least one connection means may be provided in order to attach the second turbine housing to the first turbine housing.

[0019] In embodiments of the two-stage turbocharger system able to be combined with all of the embodiments described thus far, a seal can be situated between the first flange and the second flange.

[0020] Furthermore, in embodiments of the two-stage turbocharger system able to be combined with all of the embodiments described thus far, at least one locating pinmay be provided in order to establish the position of the second turbine housing in relation to the first turbine housing during assembly. The locating pin can be situated in the connection area of the first flange and interact with the projection in order to position the first and second turbine housings in relation to one another.

[0021] In embodiments of the two-stage turbocharger system able to be combined with all of the embodiments described thus far, the two-stage turbocharger system may furthermore feature a first compressor housing having a compressor inlet and a second compressor housing having a compressor outlet, whereby the compressor inlet and the compressor outlet are connectable with one another by way of a plug connection. The plug connection can be designed to have a tubular shape and feature a rigid center tube as well as a flexible outer casing. There can be a sealing bead at each end of the tube-shaped plug connector. The elastic outer casing has the advantage of being able to compensate for tolerances. On the other hand, it aids in sealing the connection between the two compressor housings. Due to how the plug connection is constructed (rigid center tube and flexible outer casing), rotating it at an angle of 10° can serve to connect the (compressor) housings with one another. This increases the flexibility of the design with regard to how the two turbocharger assemblies are positioned with respect to one another. The plug connection furthermore allows the two turbocharger assemblies to be connected in a single assembly step, during which a suitably tight fluidic connection is simultaneously made between both turbine housings and both compressor housings. [0022] The invention furthermore comprises a method for assembling a two-stage turbocharger system having a first exhaust gas turbocharger with a first turbine housing, and having a second exhaust gas turbocharger with a second turbine housing, whereby the method comprises the following steps: inserting a projection on the second turbine housing into a pocket on the first turbine housing; tilting the first turbine housing and the second turbine housing in relation to one another such that a first flange on the first turbine housing is situated flush against a second flange on the second turbine housing; and attaching the first turbine housing to the second turbine housing.

[0023] In embodiments, the method may furthermore comprise: connecting a compressor inlet of a first compressor of the two-stage turbocharger system with a compressor outlet of a second compressor of the two-stage turbocharger system by way of a plug connection during the insertion of the projection into the pocket.

[0024] Additional details and features of the invention are described in reference to the drawings as follows.

Brief Description of the Drawings

Fig. l shows a first detail of a section of a first embodiment of the inventive two-stage turbocharger system;

Fig. 2 shows a second detail of a section of the inventive two- stage turbocharger system according to the first embodiment;

Fig. 3 shows three section views of the inventive apparatus for connecting two turbine housings in accordance with an embodiment.

Detailed Description [0025] Embodiments of the inventive apparatus for connecting two turbine housings of a corresponding two-stage turbocharger system will be described in reference to the drawings as follows. All of the following details and advantages apply to the connecting apparatus as well as to the two-stage turbocharger system having a corresponding apparatus. A method for assembling a two-stage turbocharger system will also be described.

[0026] Fig. 1 and Fig. 2 each show a detail of a section of a two-stage turbocharger system 10. The two-stage turbocharger system 10 comprises a first exhaust gas turbocharger 100 and a second exhaust gas turbocharger 200, each having a turbine and a compressor. The turbocharger system 10 has a first turbine housing 110 and a second turbine housing 210 as well as a first compressor housing 300 and a second compressor housing 400. The two turbine housings 110, 210 shown in the Fig. 1 view are not yet connected with one another. In the Fig. 2 view, the two turbine housings 110, 220 are shown connected via the inventive apparatus for connecting the exhaust gas outlet 112 of the first turbine housing 110 with the exhaust gas inlet 212 of the second turbine housing 210 in the two- stage turbocharger system 10. In Fig. 3 are three expanded section views of the connecting apparatus, whereby the process for connecting together the first and second turbine housings 110, 210 is shown in chronological sequence.

[0027] The connecting apparatus features a pocket 130 situated in the area of the first flange 120 of the first turbine housing 110 as well as a projection 230, which is situated in the area of the second flange 220 of the second turbine housing 210. The projection 230 is inserted into the pocket 130 in order to connect the two turbine housings 110, 210. The projection 230 is designed such that, after the projection 230 has been inserted into the pocket 130, the first and second turbine housings 110, 210 can be tilted in relation to each other in order to establish a flush connection between the first flange 120 and the second flange 220. This is made evident by comparing Fig. 1 with Fig. 2: a gap exists at the bottom right of Fig. 1 between the first flange 120 of the first turbine housing 110 and the second flange 220 of the second turbine housing 210. In Fig. 2, the first flange 120 and the second flange 220 are flush against one another and are providing a fluid-tight connection between the first and second turbine housings 110, 210. The movement of the two connecting apparatus components - the pocket 130 and the projection 230 - in relation to one another during the connection process, for example during the final assembly of the two-stage turbocharger system 10, is shown in Fig. 3. It is also clearly evident from Fig. 3 how the projection 230 is tilted subsequent to being inserted into the pocket 130 (middle and lower illustration). One advantage of this apparatus is that the two turbocharger assemblies can be assembled and calibrated separately from one another prior to being joined together. As a result of the tilting movement of the two turbine housings 110, 210 in relation to one another during the connecting process, significant pressure can in a simple manner be exerted against the seal 600 that is situated between the two turbine housings 110, 210, or, more specifically, between the first flange 120 and the second flange 220. The significant pressure against the seal 600 can, for example, lead to a compression of the seal leading to a reduction of its thickness measuring from 0.1 to 0.3 mm. As a result, the risk of leakage is reduced in this transitional area between the two turbine housings 110, 210. In embodiments, the connecting apparatus allows for accomplishing the connection between the turbine housings 110, 210 as well as the connection between the two compressor housings 300, 400 by way of a single movement during assembly (more regarding this hereinafter).

[0028] As shown in Fig. 1 and in Fig. 2, the pocket 130 can be situated in a wall of the first turbine housing 110 extending from the first flange 120. The pocket 130 is formed as a groove running in a linear direction. In other words, the pocket 130 is a straight-line depression running along the border between the first flange 120 and the wall extending from the first flange 120. The cross section of the pocket 130 can be approximately rectangular or u-shaped. The projection 230 is designed in the form of a strip extending in a linear direction from an outer wall 214 of the second turbine housing 210 and running approximately parallel to a plane along which lies a connection area 222 for the second flange 220 (see Fig. 1).

[0029] The projection 230 has a lower side 232, which is disposed opposite a connection area 122 on the first flange 120 (see Fig. 1) and features a chamfer 234. The chamfer 234 is in particular evident from the illustrations in Fig. 3. The chamfer 234 may, for example, have a chamfer angle of from 2° to 7°, in particular from 4° to 5°. In other words, the projection 230 formed as a strip has a lower side 232, at least some extent of which is not exactly parallel to the connection area 222 of the second flange 220, but at least some extent of which is rather inclined slightly upward. The angle of inclination corresponds to the aforementioned chamfer angle.

[0030] Once the first flange 120 and the second flange 220 are situated flush against one another, then at least one connection means 700 can be put in place in order to attach the second turbine housing 210 to the first turbine housing 110 (see Fig. 2). In embodiments, for example two connection means 700 can be provided that are situated on the approximately opposite sides of the exhaust gas inlet 212. Suitable for use as connection means 700 are, for example, expansion pins, set screws with nuts (as shown in Fig. 2), screws, clamps, brackets, or the like.

[0031] As was already referred to above, a seal 600 can be situated between the first flange 120 and the second flange 220. Through the tilting motion, both connection areas 122, 222 of the first and second flanges 120, 220 are pressed together with significant force. In the process, the seal is compressed between the two connection areas 122, 222. This readily apparent from the illustration at the bottom of Fig. 3. As a result, the risk of exhaust gases leaking in this connection area is further reduced.

[0032] Furthermore, the apparatus for connecting the two turbine housings 110, 210 can be provided with at least one locating pin 140 in order to establish the position of the second turbine housing 210 in relation to the first turbine housing 110 during assembly. The locating pin 140 can, for example, be situated in the connection area 122 of the first flange 120 (as indicated in Fig. 1) and interact with the projection 230 (for example a recess in the projection 230) in order to position the first and second turbine housings 110 to 210 in relation to one another.

[0033] The joining of the compressor inlet 310 of the first compressor housing 300 with the compressor outlet 410 of the second compressor housing 400 will be described in reference to Fig. 1 and Fig. 2 as follows. The compressor inlet 310 is connected with the compressor outlet 410 using a so-called Plug&Seal connection unit. This comprises a tube-shaped plug connector 500 that extends from the compressor inlet 310 into the compressor outlet 410. The plug connector 500 features, for example, a rigid center tube and an elastic outer casing. In addition, a sealing bead 510 is provided at each end of the plug connector 500. The center tube can, for example, be manufactured from metal (preferably stainless steel). The outer casing can, for example, be a rubber coating. One advantage of the elastic outer casing is the ability to compensate for tolerances, because the rubber coating is flexible and can be compressed during assembly. On the other hand, the rubber coating helps in sealing the connection between the two compressor housings 300, 400. During the assembly procedure for the two-stage turbocharger system 10, the connection tube 500 in the second compressor housing 400 can, for example, be assembled in advance (see Fig. 1) as well as inserted at an appropriate angle into the first compressor housing 300. In doing so, a gap will remain between the two housings (see Fig. 1 and Fig. 2), which is also still present subsequent to the tilting movement of the two turbine housings 1 10, 210 in relation to one another. In the example shown, this gap is approximately 4-5 mm wide. Depending on the arrangement and installed location of the two-stage turbocharger system 10, the gap may be larger or smaller. The length of the connector plug 500 as well as its construction (for example, greater elasticity in order to compensate for the relevant positions of the two turbine housings with respect to each other) can be adjusted accordingly. Due to how the plug connection 500 is constructed (rigid center tube, flexible outer casing, and a sealing bead 510 at both ends), a rotation or an angle of, for example, up to 10° can serve to connect the compressor housings 300, 400 (or rather the inlet 310 and outlet 410 thereof) with one another. The rotation relates in this context to an angle between the central longitudinal axis of the compressor outlet 410 and the central longitudinal axis of the compressor inlet 310. This increases the flexibility of the design with regard to how the two turbocharger assemblies are positioned in relation to one another. The plug connection 500 furthermore allows the two turbocharger assemblies to be connected in a single assembly step, during which a suitably tight fluidic connection is simultaneously made between both turbine housings and both compressor housings. [0034] The method for assembling a two-stage turbocharger system will also be briefly discussed as follows. Initially, the two turbocharger assemblies may be assembled completely independently of one another. The first exhaust gas turbocharger 100 is then joined with the first turbine housing 1 10, and the second exhaust gas turbocharger 200 is joined with the second turbine housing 210, whereby the projection 230 of the second turbine housing 210 is inserted into the pocket 130 of the first turbine housing 1 10. This step is apparent in Fig. 1 and in the upper and middle illustrations in Fig. 3. The first turbine housing 1 10 is then tilted in relation to the second turbine housing 210 such that the first flange 120 of the first turbine housing 1 10 is situated flush against the second flange 220 of the second turbine housing 210 (see Fig. 2 and the lower illustration in Fig. 3). Finally, the first turbine housing 1 10 can then be attached to the second turbine housing 210, for example using the connection means 700.

[0035] While the projection 230 on the second turbine housing 210 is being inserted into the pocket 130 of the first turbine housing 1 10, the compressor inlet 310 of the first compressor is able to be connected with the compressor outlet 410 of the second compressor of the two-stage turbocharger system 10. This can take place, for example, by way of the plug connector 500. The plug connector 500 can, for example, have been previously inserted into the compressor outlet 410 of the second compressor housing 400. As a consequence, the two compressor housings 300, 400 as well as the two turbine housings 1 10, 210 can then be joined together. This approach not only simplifies assembly, but also reduces assembly time considerably. In addition, it is thereby possible to completely assemble the two turbocharger assemblies separately from one another. [0036] Although the present invention has been described above and is defined in the attached claims, it should be understood that the invention may alternatively be defined in accordance with the following embodiments: 1. Apparatus for connecting an exhaust gas outlet (112) of a first turbine housing (110) with an exhaust gas inlet (212) of a second turbine housing (210) in a two-stage turbocharger system (10) having

a pocket (130) situated in the area of a first flange (120) on the first turbine housing (110), and

a projection (230), which is situated in the area of a second flange (220) on the second turbine housing (210) and can be inserted into the pocket (130), characterized in that the projection (230) is designed such that, after the projection (230) has been inserted into the pocket (130), the first and second turbine housings (110, 210) can be tilted in relation to one another in order to establish a flush connection between the first flange (120) and the second flange (220).

2. Apparatus according to embodiment 1, characterized in that the pocket (130) is situated in a wall of the first turbine housing (110) extending from the first flange (120).

3. Apparatus according to embodiment 1 or embodiment 2, characterized in that the projection (230) is designed in the form of a strip, which extends in a linear direction from an outer wall (214) of the second turbine housing (210) and runs approximately parallel to a plane along which lies a connection area (222) for the second flange (220).

4. Apparatus according to any of the preceding embodiments, characterized in that the projection (230) has a lower side (232), which is disposed opposite a connection area (122) on the first flange (120) and features a chamfer (234).

5. Apparatus according to embodiment 4, characterized in that the chamfer (234) has a chamfer angle of from 2° to 7°, in particular from 4° to 5°. 6. Apparatus according to any of the preceding embodiments, characterized in that at least one connection means (700) is provided in order to attach the second turbine housing (210) to the first turbine housing (110).

7. Apparatus according to any of the preceding embodiments, characterized in that a seal (600) is situated between the first flange (120) and the second flange (220). 8. Apparatus according to any of the preceding embodiments, characterized in that furthermore at least one locating pin (140) is provided in order to establish the position of the second turbine housing (210) in relation to the first turbine housing (110) during assembly. 9. Apparatus according to embodiment 8, characterized in that the locating pin (140) is situated in the connection area (122) of the first flange (120) and interacts with the projection (230) in order to position the first and second turbine housings (110, 210) in relation to one another. 10. Two-stage turbocharger system (10) having

a first exhaust gas turbocharger (100) with a first turbine housing (110), and

a second exhaust gas turbocharger (200) with a second turbine housing (210),

wherein, situated in the area of a first flange (120) on the first turbine housing (110), the first turbine housing (110) features a pocket (130), into which projects a projection (230), which is situated in the area of a second flange (220) on the second turbine housing (210), characterized in that the projection (230) is designed such that, during the connection of the first and second turbine housings (110, 210), after the projection (230) has been inserted into the pocket (130), the first and second turbine housings (110, 210) can be tilted in relation to one another in order to establish a flush connection between the first flange (120) and the second flange (220). 11. Two-stage turbocharger system according to embodiment 10, characterized in that the pocket (130) is situated in a wall of the first turbine housing (110) extending from the first flange (120). 12. Two-stage turbocharger system according to embodiment 10 or embodiment 11, characterized in that the projection (230) is designed in the form of a strip, which extends in a linear direction from an outer wall (214) of the second turbine housing (210) and runs approximately parallel to a plane along which lies a connection area (222) for the second flange (220).

13. Two-stage turbocharger system according to any of the embodiments 10 to 12, characterized in that the projection (230) has a lower side (232), which is disposed opposite a connection area (122) on the first flange (120) and features a chamfer (234).

14. Two-stage turbocharger system according to embodiment 13, characterized in that the chamfer (234) has a chamfer angle of from 2° to 7°, in particular from 4° to 5°.

15. Two-stage turbocharger system according to any of the embodiments 10 to

14, characterized in that at least one connection means (700) is provided in order to attach the second turbine housing (210) to the first turbine housing (110).

16. Two-stage turbocharger system according to any of the embodiments 10 to

15, characterized in that a seal (600) is situated between the first flange (120) and the second flange (220). 17. Two-stage turbocharger system according to any of the embodiments 10 to

16, characterized in that also at least one locating pin (140)is provided in order to establish the position of the second turbine housing (210) in relation to the first turbine housing (110) during assembly. Two-stage turbocharger system according to embodiment 17, characterized in that the locating pin (140) is situated in the connection area (122) of the first flange (120) and interacts with the projection (230) in order to position the first and second turbine housings (110, 210) in relation to one another. Two-stage turbocharger system according to any of the embodiments 10 to 18, characterized in that the two-stage turbocharger system (10) furthermore features a first compressor housing (300) having a compressor inlet (310) and a second compressor housing (400) having a compressor outlet (410), wherein the compressor outlet (410) and the compressor inlet (310) are connectable with one another by way of a plug connection (500). Two-stage turbocharger system according to embodiment 19, characterized in that the plug connection (500) is designed to have a tubular shape and feature a rigid center tube as well as a flexible outer casing. Two-stage turbocharger system according to embodiment 20, characterized in that there is a sealing bead (510) at each end of the tube- shaped plug connection (500). Method for assembling a two-stage turbocharger system having a first exhaust gas turbocharger (100), which features a first turbine housing (110), and

a second exhaust gas turbocharger (200), which features a second turbine housing (210), comprising:

inserting a projection (230) on the second turbine housing (210) into a pocket (130) in the first turbine housing (110);

tilting the first turbine housing (110) and the second turbine housing (210) in relation to one another such that the first flange (120) of the first turbine housing (110) is situated flush against the second flange (220) of the second turbine housing (210); and attaching the first turbine housing (110) to the second turbine housing (210).

Method according to embodiment 22, furthermore comprising connecting a compressor inlet (310) of a first compressor of the two-stage turbocharger system with a compressor outlet (410) of a second compressor of the two-stage turbocharger system by way of a plug connection (500) during the insertion of the projection (230) into the pocket (130).