Multi-stage turbocharger arrangement

Abstract

Multi-stage turbocharger arrangement (1), - with a high-pressure turbocharger (20) comprising: - a first turbine housing (26A), - a first bearing housing (27A), - a first compressor housing (28A); and - with a low-pressure turbocharger (21) comprising: - a second turbine housing (26B), - a second bearing housing (27B), - a second compressor housing (28B); wherein a bypass (5) is formed in the first turbine housing (26A) which has a control valve (5a), characterized in that the first and second turbine housings (26A, 26B) are combined to form at least one turbine housing unit (26), and that the turbine housing unit (26) is provided with at least one cooling channel (24).

Description

[0001] The invention relates to a multi-stage turbocharger arrangement for an internal combustion engine, according to the preamble of claim 1.

[0002] EP1394380A1 describes a turbocharging system for an internal combustion engine that is designed with at least two stages. At least the exhaust-side components of an exhaust-gas turbocharger are integrated into a common housing unit.

[0003] DE3142499A1 describes an exhaust gas turbocharger arrangement for supercharging internal combustion engines with at least two turbochargers. The turbochargers are arranged parallel to each other and can be switched on, off, or switched over via valves.

[0004] DE102005025885A1 describes a charging device for an internal combustion engine with a low-pressure stage and a high-pressure stage.

[0005] Conventional multi-stage turbocharger assemblies known from the prior art are generally constructed from at least two turbochargers arranged one behind the other, with their compressor, bearing, and turbine housings connected to one another via flanges or other connecting elements. This design results in a large structural volume and increased weight, as well as the resulting high manufacturing costs of such multi-stage turbocharger assemblies. Furthermore, the multi-stage turbocharger assemblies of the prior art exhibit inadequate heat dissipation and cooling due to the large thermal mass of the assembly and the large internal surface area of ​​the exhaust gas flow channels. As a result, thermal stresses arising from the large temperature differences between the individual assemblies can only be inadequately avoided, which negatively impacts the service life of individual components.

[0006] It is therefore an object of the present invention to provide a multi-stage turbocharger arrangement having a simplified structure with more efficient cooling, which avoids the above-mentioned disadvantages of the prior art.

[0007] This problem is solved by the features of claim 1.

[0008] By combining the turbine, bearing and compressor housings of the high-pressure turbochargers and low-pressure turbochargers into a common turbine housing unit, bearing housing unit and compressor housing unit, a simpler design with a smaller installation volume can be achieved compared to the turbocharger arrangements of the state of the art.

[0009] The subclaims contain advantageous developments of the invention.

[0010] The combined housing arrangement enables an overall simpler and more cost-effective production and machining of the individual housing parts of the multi-stage turbocharger arrangement.

[0011] Due to the specific design of the turbocharger arrangement according to the invention, the amount of heat transferred from the exhaust gas into the outer housing parts is drastically reduced.

[0012] In addition, insulation is improved by an air gap between the exhaust ducts and housing parts.

[0013] In addition, the use of an expandable inner jacket arrangement for exhaust gas guidance in the flow channels is advantageous.

[0014] Furthermore, the thermal expansion / material stress can be limited by additional cooling, which ensures a nearly constant temperature in the outer housing parts, particularly through the use of a separate cooling liquid.

[0015] In addition, the individual inner and outer housing parts, which are arranged essentially parallel to one another, can be easily connected to one another by screwing, welding or clamping connections.

[0016] Furthermore, the outer housing parts can be made of housing materials that are easy to cast and / or machine, such as aluminum, steel, magnesium, plastic or combinations of other different materials.

[0017] The turbocharger arrangement according to the invention achieves a significantly smaller hot inner surface of the exhaust gas flow channels and a correspondingly lower heat radiation (particularly during the warm-up phase) due to the increased degree of integration of the arrangement.

[0018] Furthermore, the arrangement of two or more shaft / bearing assemblies in one of the housings is possible.

[0019] Furthermore, cooling of the housing containing the two / multiple shafts / bearings is possible. Furthermore, a substantially parallel arrangement of the shafts is possible.

[0020] In addition, it is possible to use a bushing (similar to a bearing cartridge) inserted into the outer shell to support the bushings and rotating shafts.

[0021] In addition, the outer housing parts can be manufactured as die-cast parts or using other known casting processes.

[0022] Furthermore, it is possible to arrange the compressor spirals with an axial offset to each other in the shaft direction.

[0023] In addition, the turbine spirals can be split perpendicular to the shafts to allow the insertion of the inner shell.

[0024] The turbine and compressor spirals can be arranged so that the projections overlap, viewed in the shaft direction, to achieve a minimum installation volume.

[0025] Furthermore, it is possible to cast or drill the oil supply and oil drain for both bearing systems in the housings.

[0026] The turbocharger arrangement according to the invention allows coolant to flow through some or all of the outer casings. Furthermore, the coolant can flow from one casing to another.

[0027] In addition, the bypass valve of the high-pressure turbine is integrated as part of the inner shell and in the outer casing.

[0028] In addition, the wastegate valve of the low-pressure turbine is integrated as part of the inner shell.

[0029] In addition, the bypass valve of the low-pressure turbine can be integrated into the outer casing.

[0030] Furthermore, the manually operated compressor bypass valve can be replaced by an automatic valve.

[0031] Alternatively, the wastegate valve of the low-pressure turbine, the wastegate valve of the high-pressure turbine and the bypass valve of the high-pressure compressor can be eliminated.

[0032] The bearing arrangement can also be designed so that the oil can flow in any direction, with an arrangement in a vertically mirrored position being possible.

[0033] In addition, the bearing arrangement can be designed in such a way that the arrangement in a rotated position is possible.

[0034] The scrolls and housings can be designed to accommodate many different scroll and impeller sizes.

[0035] The turbochargers of the multi-stage turbocharger arrangement according to the invention can also have a variable turbine geometry.

[0036] The multi-stage turbocharger arrangement can be used for sequential turbocharging.

[0037] The multi-stage turbocharger arrangement can be used for supercharging using two parallel turbochargers.

[0038] Further details, features and advantages of the invention will become apparent from the following description of embodiments with reference to the drawing.

[0039] It shows: Fig. 1 a schematic simplified embodiment of a multi-stage turbocharger arrangement according to the invention, and Fig. 2 a schematically simplified multi-stage turbocharger arrangement of the prior art.

[0040] With reference to Fig. 1, an embodiment of the multi-stage turbocharger arrangement 1 according to the invention is described below. As can be seen from Fig. 1, the multi-stage turbocharger assembly 1 comprises a high-pressure turbocharger 20 having a high-pressure turbine 4 connected to a high-pressure compressor 10 by a shaft 14, and a low-pressure turbocharger 21 having a low-pressure turbine 6 connected to a low-pressure compressor 9 by a shaft 15. The high-pressure turbine 4 and the low-pressure turbine 6 are arranged in a common turbine housing unit 26, which is divided into a turbine housing section 26A of the high-pressure turbocharger 20 and a turbine housing section 26B of the low-pressure turbocharger 21. Inserted inside the turbine housing unit 26 is a heat-expandable inner shell 23, within which a hot engine exhaust gas Ag flows through the high-pressure turbine 4 and the low-pressure turbine 6.An air gap 22 is formed between the inner shell 23 and the turbine housing unit 26, which insulates the inner shell 23, which is heated by the engine exhaust gas Ag, from the turbine housing unit 26. Furthermore, cooling channels 24 are formed in the turbine housing unit 26 for a coolant flowing therein, which reduces the temperature of the turbine housing unit 26 or maintains it at a level permissible in all operating states of the turbocharger arrangement 1.

[0041] Furthermore, a bypass 5 of the high-pressure turbine 4 is formed in the turbine housing section 26A of the high-pressure turbocharger 20, which bypass has a control valve 5a through which the engine exhaust gas Ag bypasses the high-pressure turbine 4 when the control valve 5a is open. Furthermore, a wastegate arrangement 7 is formed in the turbine housing section 26B of the low-pressure turbocharger 21, in the interior of which a wastegate valve 7a is arranged. When the wastegate valve 7a is open, a portion of the flow of the engine exhaust gas Ag can bypass the low-pressure turbine 6 and flow directly into an exhaust 8 (see Fig. 2) flow.

[0042] The shaft 14 of the high-pressure turbocharger 20 and the shaft 15 of the low-pressure turbocharger 21 are mounted in a common bearing housing unit 27, which is composed of a bearing housing section 27A of the high-pressure turbocharger 20 and a bearing housing section 27B of the low-pressure turbocharger 21. The bearing housing unit 27 has a cooling channel 25, the coolant flowing therein cooling the bearing housing unit 27 relative to the adjacent inner shell 23 of the turbine housing unit 26.

[0043] The high-pressure compressor 10 of the high-pressure turbocharger 20 and the low-pressure compressor 9 of the low-pressure turbocharger 21 are arranged in a common compressor housing unit 28, which is composed of a compressor housing section 28A of the high-pressure turbocharger 20 and a compressor housing section 28B of the low-pressure turbocharger 21, and is closed by means of a compressor cover 29. As can be seen from the illustration of Fig. 1, the high-pressure compressor 10 is also partly formed in the bearing housing unit 27 and the low-pressure compressor 9 is also partly formed in the compressor cover 29.

[0044] As from Fig. 1, air L is supplied to the low-pressure compressor 9 from the outside via a channel 16 formed in the compressor cover 29, which channel 16 extends further between the low-pressure compressor 9 and the high-pressure compressor 10 in the compressor housing unit 28 and, after the high-pressure compressor 10, runs through the bearing housing unit 27, the compressor housing unit 28 and the compressor cover 29. Furthermore, a compressor bypass channel 11 is formed in the compressor cover 29 in the region of the high-pressure compressor 10, which compressor bypass channel includes a compressor bypass valve 118. The charge air L can be completely or partially bypassed around the high-pressure compressor 10 through this compressor bypass channel 11 in order to prevent throttling of the high-pressure compressor 10 at large air flow rates.

[0045] The connecting surfaces of the common turbine housing unit 26, bearing housing unit 27 and compressor housing unit 28, which are formed essentially parallel to one another, are, although in Fig. 1 not shown, connected to each other by means of screw, welding, adhesive and / or clamp connections.

[0046] The high-pressure turbine 4 and the low-pressure turbine 6 or the low-pressure compressor 9 and the high-pressure compressor 10 can each have a variable turbine geometry, which in Fig. 2 in the case of the high-pressure turbine 4, is identified by reference numeral 4a, for example. Furthermore, the compressor bypass valve 11a may be an automatic or controlled valve, and the wastegate valve 7a may be omitted in some arrangements to save costs.

[0047] At the Fig. In the multi-stage turbocharger arrangement according to the invention shown in Figure 1, the hot exhaust gas flows only in the inner shell 23, which is sandwiched between the turbine housing unit 26 and the bearing housing unit 27, which have the cooling channels 24 and 25, respectively, to prevent overheating of the turbine housing unit 26 and the bearing housing unit 27, respectively. The cooling channels 24 and 25 can alternatively also be connected to one another. In other conceivable embodiments, the housing units 26, 27, and 28 can also be divided differently than in the embodiment shown here. Furthermore, alternatively, all housing units can be cooled, or only parts of the exhaust gas flow channels can be insulated by an air gap.

[0048] Fig. Figure 2 shows a simplified schematic representation of a multi-stage turbocharger arrangement of the prior art, such as is used in a conventional two-stage turbocharger system of a diesel engine. The same components are identified by the same reference numerals as in Fig. 1. The Fig. The multi-stage turbocharger arrangement 10 shown in Figure 2 illustrates the flow path of the exhaust gas Ag of an engine 2 from an exhaust manifold 3 to its discharge through an exhaust 8, as well as the flow path of the intake air L through an intake line 16 to an intake manifold 13 of the engine 2. This conventional turbocharger arrangement is known in many similar designs or variations, the structure of which, however, will not be described in detail here.

[0049] Compared to known prior art turbocharger arrangements, the multi-stage turbocharger arrangement according to the invention has a significantly smaller number of components and a lower overall weight. Furthermore, the comparatively significantly smaller installation volume of the turbocharger systems is a major advantage.

[0050] To supplement the disclosure, explicit reference is made to the graphic representation of the invention in Fig. 1.

Claims

[1] Multi-stage turbocharger arrangement (1), - with a high-pressure turbocharger (20) which features: - a first turbine housing (26A), - a first bearing housing (27A), - a first compressor housing (28A); and - with a low-pressure turbocharger (21) which features: - a second turbine casing (26B), - a second bearing housing (27B), - a second compressor housing (28B); wherein a bypass (5) is formed in the first turbine housing (26A) which has a control valve (5a), characterized by , that the first and second turbine casings (26A, 26B) are combined to form at least one turbine casing unit (26), and that the turbine housing unit (26) is provided with at least one cooling channel (24). [2] Multi-stage turbocharger arrangement (1) according to claim 1, characterized by, that the first and second bearing housings (27A, 27B) are combined to form at least one bearing housing unit (27). [3] Multi-stage turbocharger arrangement (1) according to claim 2, characterized by , that the bearing housing unit (27) is provided with at least one cooling channel (25). [4] Multi-stage turbocharger arrangement (1) according to any one of claims 1 to 3, characterized by , that the first and second compressor housings (28A, 28B) are combined to form at least one compressor housing unit (28). [5] Multi-stage turbocharger arrangement (1) according to claim 3 or claim 4, if dependent on claim 2, characterized by , that the turbine housing unit (26), bearing housing unit (27) and compressor housing unit (28) are connected to each other via a screw, weld, adhesive or clamp connection. [6] Multi-stage turbocharger arrangement (1) according to any one of claims 1 to 5, characterized by, that the turbine housing unit (26) is provided with an integrated inner shell (23) for exhaust gas routing. [7] Multi-stage turbocharger arrangement (1) according to claim 6, characterized by , that the inner shell (23) is surrounded by an air gap (22). [8] Multi-stage turbocharger arrangement (1) according to any one of claims 1 to 7, characterized by , that a low-pressure turbine (6) of the low-pressure turbocharger (21) has an integrated wastegate arrangement (7).

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