Shaft support assembly having a pressure reducing device and method for reducing pressure within a bearing housing supporting a shaft - Patents.com

Abstract

A shaft support assembly (10) is described having a shaft (11) supported in a bearing housing (12). The shaft support assembly (10) includes a pressure reduction device (13) for creating a reduced pressure within the bearing housing (12). The pressure reduction device (13) operates using an incompressible fluid. Additionally, a method for reducing pressure within a bearing housing (12) supporting a shaft is described. The method includes using an incompressible fluid to operate the pressure reduction device (13) for creating a reduced pressure within the bearing housing (12).

Description

[Technical field]

[0001] An embodiment of the present disclosure relates to a shaft support assembly having a shaft supported in a bearing housing, and in particular to a shaft support assembly of a turbo compound or turbocharging system, for example used in an internal combustion engine. Further embodiments of the present disclosure relate to a method of reducing pressure inside a bearing housing supporting a shaft. [Background technology]

[0002] Supercharging systems, such as exhaust gas turbochargers, are known that are used to increase the power output of internal combustion engines. In such exhaust gas turbochargers, a turbine is provided in the exhaust gas path of the internal combustion engine and a compressor is arranged upstream of the internal combustion engine and is coupled to the turbine via a common shaft. The shaft is usually supported by a bearing supported in a bearing housing. Thus, an exhaust gas turbocharger is generally composed of a rotor, a bearing assembly for the shaft, flow-guiding housing sections (compressor housing and turbine housing) and a bearing housing. The rotor includes a shaft, an impeller and a turbine wheel.

[0003] Supercharging of an internal combustion engine by means of an exhaust gas turbocharger increases the volume of the fuel mixture in the cylinder, which leads to a significant increase in the power output of the engine. Optionally, the energy stored in the exhaust gases of the internal combustion engine can be converted into electrical or mechanical energy by means of a power turbine. In this case, instead of a compressor, as in the case of an exhaust gas turbocharger, a generator or mechanical consumers are coupled to the turbine shaft.

[0004] Due to the high process pressures in the flow areas on the turbine side and the compressor side, the shaft of the exhaust gas turbocharger is sealed with a suitable sealing concept against a cavity in the bearing housing. The internal pressure of the cavity in the bearing housing usually corresponds to atmospheric pressure. However, the gas pressure in the flow passages on the compressor side and the turbine side depends on the current operating point of the exhaust gas turbocharger, most operating points being above the pressure in the cavity in the bearing housing. However, in certain cases, e.g. in part-load operation or at standstill, it is also necessary to take into account the negative pressure.

[0005] Generally, the lubricating oil supplied to the bearings and cooling holes accumulates inside the bearing casing and flows out of the bearing casing through the oil drain. A shaft seal between the bearing casing and the turbine or compressor is used to prevent oil leakage into the gas path of these components. Generally, such a shaft seal comprises non-contact sealing elements such as a pre-drain, one or more oil catch chambers, and one or more seal rings. However, it has been found that the conventional seal concepts described above are still not completely oil-tight.

[0006] Especially at idle or partial load conditions of the internal combustion engine, a slight pressure of a few millibars above atmospheric pressure may occur inside the bearing casing. In addition, when operating under such conditions, the pressure on the compressor side or turbine side may be below atmospheric pressure, which means that the pressure in the bearing casing is higher than the pressure on the compressor side or turbine side, creating a positive pressure gradient on the shaft seal. This positive pressure gradient is often the main cause of oil leakage, as air and oil are sucked from the bearing casing through the seal into the gas path of the component. Therefore, there is a high demand to avoid conditions where the pressure difference across the seal becomes positive. However, it has been found that conventional implementations of shaft support assemblies with baffle plates still have some problems with seal performance, such as undesirable axial separation of oil. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, there is a need for shaft support assemblies with improved sealing performance for a variety of applications. [Means for solving the problem]

[0008] In view of the above, there is provided a shaft support assembly for a shaft supported in a bearing housing and a method for reducing pressure inside a bearing housing supporting a shaft according to the independent claims. Further aspects, advantages and features will become apparent from the dependent claims, the description and the accompanying drawings.

[0009] More specifically, in accordance with one aspect of the present disclosure, a shaft support assembly is provided having a shaft supported in a bearing housing, and further including a pressure reduction device for creating a reduced pressure within the bearing housing, the pressure reduction device operating using an incompressible fluid.

[0010] Thus, a shaft support assembly is provided that has improved sealing performance as compared to the prior art. In particular, embodiments of the shaft support assembly described herein advantageously avoid the creation of positive pressure gradients across the bearing housing interface, and in particular the shaft seal.

[0011] Thus, an improved turbocompound system and / or turbocharger system may be provided by using a shaft support assembly according to embodiments as described herein in the turbocompound system and / or turbocharger system. Thus, an improved internal combustion engine may be provided by providing a turbocompound system and / or turbocharger system having a shaft support assembly according to any embodiment as described herein.

[0012] According to another aspect of the present disclosure, there is provided a method of reducing pressure within a bearing housing supporting a shaft, the method including using an incompressible fluid to actuate a pressure reduction device to generate a reduced pressure within the bearing housing.

[0013] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the present disclosure briefly summarized above can be had by reference to the embodiments, the accompanying drawings of which relate to the embodiments of the present disclosure and which are described below. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 shows a schematic diagram of a shaft support assembly according to embodiments described herein including a pressure reduction device. [Diagram 2] 1 shows a schematic diagram of a shaft support assembly according to a further embodiment described herein, wherein the pressure reduction device is at least partially integrated into the bearing housing. [Diagram 3] 1 shows a schematic diagram of a shaft support assembly according to a further embodiment described herein, where the pressure reduction device is provided inside the bearing housing. [Figure 4] FIG. 2 shows a schematic diagram of a shaft support assembly according to a further embodiment described herein having a pressure reduction device and at least one additional pressure reduction device connected in series. [Diagram 5] 13 shows a schematic diagram of a shaft support assembly according to a further embodiment described herein having a pressure reduction device and at least one additional pressure reduction device connected in parallel. [Figure 6] FIG. 13 shows a schematic diagram of a shaft support assembly according to a further embodiment described herein having a pressure control device for controlling the reduced pressure generated by the pressure reduction device. [Figure 7] 1 shows a schematic diagram of an internal combustion engine including a shaft support assembly according to any embodiment described herein. [Figure 8A]FIG. 2 shows a block diagram to illustrate an embodiment of a method for reducing pressure in a bearing housing described herein. [Figure 8B] FIG. 2 shows a block diagram to illustrate an embodiment of a method for reducing pressure in a bearing housing described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Reference will now be made in detail to various embodiments, one or more examples of which are illustrated in the various figures. Each example is offered by way of illustration and not by way of limitation. For example, features illustrated or described as part of one embodiment can be used on or in combination with any other embodiment to yield yet a further embodiment. The present disclosure is intended to include such modifications and variations.

[0016] In the following description of the drawings, the same reference numbers refer to the same or similar components. Generally, only the differences with respect to the individual embodiments are described. Unless otherwise specified, the description of a part or aspect in one embodiment can be applied to the corresponding part or aspect in other embodiments as well.

[0017] A bearing assembly 10 according to the present disclosure will be described with exemplarily reference to FIG. 1. According to an embodiment, which may be combined with any other embodiment described herein, the shaft support assembly 10 comprises a shaft 11 supported in a bearing housing 12. The shaft support assembly 10 further comprises a pressure reduction device 13 for generating an underpressure inside the bearing housing 12. In this regard, the expression "underpressure inside the bearing housing" means that the pressure inside the bearing housing is lower than the outside of the bearing housing. Typically, the outside of the bearing housing is at atmospheric pressure. Thus, "underpressure" can be understood as a pressure lower than atmospheric pressure. The pressure reduction device 13 operates by using an incompressible fluid. In particular, the incompressible fluid can be oil. In this regard, the pressure reduction device 13 operating by using an incompressible fluid can be understood as the incompressible fluid being used as a working fluid for operating the pressure reduction device, in particular to provide energy for operating the pressure reduction device.

[0018] Thus, advantageously, a shaft support assembly having improved sealing performance is provided. In particular, implementations of a shaft support assembly having a pressure reduction device as described herein are advantageously provided to avoid the creation of positive pressure gradients across a bearing-housing interface, e.g., a shaft seal.

[0019] According to an embodiment, which may be combined with any other embodiment described herein, the pressure reduction device 13 is based on the jet pump principle. In other words, the pressure reduction device can be understood as a device that operates on the jet pump principle. The pressure reduction device 13 is configured to generate and maintain a low pressure inside the bearing housing 12. In particular, the generation of a low pressure inside the bearing housing 12 by the pressure reduction device 13 is based on the effect that a jet stream is ejected with high kinetic energy (so-called driving flow), which consequently allows momentum exchange with an intake fluid, for example oil, to result in a suction flow. In particular, the suction fluid typically consists of oil (for example from the bearings and, for example, from the cooling holes) and a working fluid, in particular air or exhaust gas, of the turbocharger or turbo compound, respectively. As a result, the suction fluid is accelerated and the desired low pressure can be generated. In this respect, it is noted that typically the oil supply of an internal combustion engine is at a low pressure of a few bars, which results in a sufficient energy storage, since only a few millibars are required for the suction effect. Therefore, advantageously, the pressure reduction device does not need to operate at high efficiency, since the energy storage provided by the oil supply is significantly greater than the energy required for the operation of the pressure reduction device. In other words, if the pressure reduction device is based on the operating principle of a jet pump, it will not be very relevant whether all the basic elements of the jet pump, such as the suction chamber, the mixing throat or the diffuser, are ultimately taken into account or whether they are designed within known design criteria. In this regard, it should be noted that there are various installation possibilities for the pressure reduction device.

[0020] According to an embodiment, which may be combined with any other embodiment described herein, the pressure reduction device 13 is configured to operate by a drive oil flow and a suction oil flow. The drive oil flow is provided by oil supplied from an oil supply device for supplying oil to the bearings of the shaft support assembly. The suction oil flow is provided by oil exiting from the bearings. More specifically, the suction oil flow can be provided by oil exiting from the bearings and cooling holes. In particular, depending on the field of application (for example medium speed applications), the bearing casing on the turbine side can be provided with cooling holes or cooling bores. The cooling holes are supplied with oil of the turbocharger in order to cool the temperature level of the turbine side wall, for example by spray cooling. In other words, just like bearings, for example radial or axial bearings, the cooling holes act like additional "oil consuming elements" and consequently, if they are implemented, provide a suction flow for the pressure reduction device, for example a jet pump.

[0021] With reference to FIG. 2 by way of example, according to an embodiment that may be combined with any other embodiment described herein, the pressure reduction device 13 includes at least one nozzle 14. During operation of the pressure reduction device 13, oil is supplied from an external oil supply device via the at least one nozzle 14. In particular, oil can be understood as a working fluid for the pressure reduction device, and the at least one nozzle 14 is used to generate a jet stream. Typically, the nozzle is fed with oil from an oil supply device. For example, the oil supply device can be an oil supply device for a bearing of a shaft support assembly. More generally, the oil supply device can be an oil supply device for example of a turbo compound system and / or a turbocharging system of an internal combustion engine. The oil supply device can be an internal oil supply device or an external oil supply device.

[0022] According to an embodiment that may be combined with any other embodiment described herein, the at least one nozzle 14 is selected from the group consisting of a single jet nozzle, a multiple jet nozzle (e.g., a dual jet nozzle), an annular ring nozzle, a nozzle configured to eject the jet stream as a swirl flow, and a lobe nozzle.

[0023] According to an embodiment, which may be combined with any other embodiment described herein, the pressure reduction device 13 is coupled to the bearing housing 12. In particular, the pressure reduction device 13 may include a suction chamber that may be coupled to the bearing housing via a fitting.

[0024] With exemplarily reference to Fig. 3, according to an embodiment that may be combined with any other embodiment described herein, the pressure reduction device 13 is at least partially integrated into the bearing housing 12. In other words, the pressure reduction device 13 may be fully or partially integrated into the bearing housing 12. Thus, advantageously, a more space-saving design may be provided. Alternatively, as shown diagrammatically in Fig. 4, the pressure reduction device 13 may be provided inside the bearing housing 12. Thus, the pressure reduction device 13 may be arranged and configured to generate a localized lower pressure inside the bearing housing 12.

[0025] According to an embodiment, which may be combined with any other embodiment described herein, the shaft support assembly 10 may further include one or more additional pressure reduction devices 15, as shown diagrammatically in Figure 4. For example, the one or more additional pressure reduction devices 15 may be connected in series with the pressure reduction device 13, as shown in Figure 4. Additionally or alternatively, the one or more additional pressure reduction devices 15 may be connected in parallel with the pressure reduction device 13, as shown exemplarily in Figure 5.

[0026] 6, according to an embodiment that may be combined with any other embodiment described herein, the shaft support assembly 10 may include a controller 16 for controlling the reduced pressure generated by the pressure reduction device 13 and / or one or more additional pressure reduction devices 15. The controller may be an actively driven controller or a passively driven controller. For example, the controller may be configured to set the suction pressure of the pressure reduction device. Additionally, the controller may be configured to switch the pressure reduction device on or off.

[0027] Thus, in light of the embodiments of the shaft support assembly described herein, it should be appreciated that an improved turbocompound system and / or turbocharger system may be provided by using the shaft support assembly described herein in a turbocompound system and / or turbocharger system. Thus, an improved internal combustion engine may be provided by providing a turbocompound system and / or turbocharger system having a shaft support assembly according to any embodiment described herein. Figure 7 illustrates generally an internal combustion engine 20 including a shaft support assembly 10 according to any embodiment described herein.

[0028] 8A and 8B, an embodiment of a method 30 for reducing pressure inside a bearing housing 12 supporting a shaft 11 according to the present disclosure will be described. According to an embodiment, which may be combined with any other embodiment described herein, the method 30 includes using an incompressible fluid to actuate a pressure reduction device 13 for generating a reduced pressure inside the bearing housing 12 (represented by block 31 in FIG. 8A).

[0029] According to an embodiment of the method 30, which may be combined with any other embodiment described herein, using an incompressible fluid to operate the pressure reduction device 13 (represented by block 31 in FIG. 8A ) includes providing a drive oil flow and a suction oil flow to operate the pressure reduction device 13 (represented by block 32 in FIG. 8B ). The drive oil flow is provided by oil from an oil supply for the bearing. The suction oil flow is provided by oil exiting the bearing.

[0030] According to an embodiment that may be combined with any other embodiment described herein, the method 30 further includes using the incompressible fluid to actuate one or more additional pressure reduction devices 15 (represented by block 33 in FIG. 8B ). As exemplarily described with reference to FIGS. 4 and 5 , the one or more additional pressure reduction devices 15 may be connected in parallel and / or in series with the pressure reduction device 13.

[0031] According to an embodiment that may be combined with any other embodiment described herein, the method 30 further includes a step of controlling the reduced pressure generated by the pressure reduction device 13 using the controller 16 (represented by block 34 in FIG. 8B). In addition, the method may include controlling the reduced pressure generated by the one or more additional pressure reduction devices 15. In particular, the control of the pressure reduction device 13 and / or the control of the one or more additional pressure reduction devices 15 may be performed, for example, by using mechanically actuated valves (e.g., spring valves) for controlling the differential pressure across the seal. Thus, the occurrence of the above-mentioned positive pressure gradient may be avoided. Furthermore, the pressure increase of the pressure reduction device 13 and / or the one or more additional pressure reduction devices 15 may be directly controlled by using mechanical valves. It is noted that instead of a mechanical operation controller, an electrical device may be used. Furthermore, it is understood that there are several possibilities for controlling the pressure reduction device 13 and / or the one or more additional pressure reduction devices 15. For example, a purely hydraulic control by differential pressure at the bearings may be used depending on the operating point of the turbocharger.

[0032] Furthermore, for example in the driving flow supply of the pressure reduction device 13 and / or the one or more additional pressure reduction devices 15, a purely electric control valve can be used to control the pressure reduction device 13 and / or the one or more additional pressure reduction devices 15. In this case, the driving flow is controlled by the turbocharger speed or the turbocharger operating point, which has the advantage that for non-critical turbocharger operating points, a switching off of the pressure reduction device 13 and / or the one or more additional pressure reduction devices 15 can be easily realized.

[0033] In light of the embodiments described herein, it should be appreciated that a shaft support assembly and method is provided that advantageously provides improved sealing performance as compared to the prior art. In particular, the embodiments as described herein advantageously avoid the creation of positive pressure gradients across the bearing-housing interface, and in particular across the shaft seal.

[0034] While the forgoing is directed to exemplary embodiments, other and further embodiments may be devised without departing from the basic scope, which is determined by the claims that follow. [Explanation of symbols]

[0035] 10 axis support assembly 11 Axis 12 Bearing housing 13 Pressure Relief Device 14 Nozzles 15 One or more additional pressure reducing devices 16 Pressure Controller 20 Internal Combustion Engine 30 How to reduce pressure inside a bearing housing 31-34 Block diagram of a method for reducing pressure in a bearing housing

Claims

1. A shaft support assembly (10) having a shaft (11) supported in a bearing housing (12) and including a pressure reducing device (13) for creating a reduced pressure inside the bearing housing (12), comprising: The pressure reducing device (13) operates by using oil, said pressure reduction device (13) being based on the jet pump principle, A shaft support assembly (10).

2. the pressure reduction device (13) is configured to operate with a drive oil flow and a suction oil flow, the drive oil flow being provided by oil supplied from an oil supply device for a bearing of the shaft support assembly (10), and the suction oil flow being provided by oil exiting from the bearing. The shaft support assembly (10) of claim 1.

3. the pressure reducing device (13) comprises at least one nozzle (14), and oil from an external oil supply device is supplied through the at least one nozzle (14) when the pressure reducing device (13) is activated. A shaft support assembly (10) according to claim 1 or 2.

4. the at least one nozzle (14) is selected from the group consisting of a single jet nozzle, a multiple jet nozzle, an annular ring nozzle, a nozzle configured to eject the jet stream as a swirl flow, and a lobe nozzle. The shaft support assembly (10) of claim 3.

5. The pressure reducing device (13) is coupled to the bearing housing (12). A shaft support assembly (10) according to any one of claims 1 to 4.

6. the pressure reduction device (13) is at least partially integrated into the bearing housing (12) or the pressure reduction device (13) is provided inside the bearing housing (12); A shaft support assembly (10) according to any one of claims 1 to 5.

7. further comprising one or more additional pressure reduction devices (15), said one or more additional pressure reduction devices (15) being connected in parallel and / or in series with said pressure reduction device (13); A shaft support assembly (10) according to any one of the preceding claims.

8. a controller (16) for controlling the reduced pressure generated by the pressure reduction device (13); A shaft support assembly (10) according to any one of the preceding claims.

9. An internal combustion engine (20) equipped with a turbo compound system and / or a turbocharging system comprising a shaft support assembly (10) according to any one of claims 1 to 8.

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