TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to sealing devices s for sealing a bearing cover from a bearing housing. Further, embodiments of the present disclosure relate to turbomachines having such sealing devices and methods of sealing a bearing cover from a bearing housing.

BACKGROUND

[0002] Turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors. While a turbine transfers energy from a fluid to a rotor, a compressor transfers energy from a rotor to a fluid. For example, in an exhaust gas turbocharger, the exhaust gases of an internal combustion engine can be used for compressing the combustion air which is fed to the engine. With pre-compressed or charged combustion air, the capacity, and therefore also the fuel mixture in the cylinders of the engine, can be increased and a power increase for the engine is gained. A known exhaust gas turbocharger includes a rotor with a compressor impeller, a turbine wheel and a connecting shaft, a bearing arrangement, housing sections, such as compressor housing or turbine housing which are fixed and charged with a mass flow, and a bearing housing which accommodates the bearing arrangement.

[0003] Because of the mostly high process pressures in the turbine-side and also compressor-side flow regions, the turbocharger shaft is sealed in relation to the inner plenum of the bearing housing by a suitable sealing method. The internal pressure in the plenum of the bearing housing can correspond to an atmospheric pressure of 1 bar. By contrast, the gas pressure in the flow region of the compressor side and turbine side depends upon the current operating point of the turbocharger and in most cases can lie above the plenum pressure of the bearing housing. In order to counteract pressure equalization, the section of the rotor which is supported in the bearing housing is therefore guided out of the bearing housing via two seals, of which one seals the bearing housing in the direction of the compressor and the other in the direction of the turbine. In certain cases, a negative pressure in the compressor housing or in the turbine housing should be taken into consideration, for example, during partial load operation or during a shutdown period, when lubricating oil can find its way from the bearing housing into the turbine housing or compressor housing. In the compressor housing, penetrating lubricating oil could contaminate the charged compressor air and subsequently lead to unwanted emissions by combusting in the engine.

[0004] However, it has been found that conventional sealing concepts used for turbomachines, particularly turbocharging assemblies, can still be improved, particularly with respect to oil tightness, compactness, easy assembling, and cost-efficient production. Hence, there is a continuous demand for sealing devices with which at least some of the disadvantages of the prior art can be reduced or overcome.

SUMMARY

[0005] In light of the above, a sealing device for sealing a bearing cover from a bearing housing, a turbomachine and a method of sealing a bearing cover from a bearing housing according to the independent claims are provided. Further aspects, advantages, and features are apparent from the dependent claims, the description, and the accompanying drawings.

[0006] According to an aspect of the present disclosure, a sealing device for sealing a bearing cover from a bearing housing is provided. The sealing device includes a central opening for receiving a rotatable shaft supported in the bearing housing and extending through the bearing cover. Additionally, the sealing device includes a first chamber extending around the central opening. The first chamber has at least one lubricant inlet for providing lubricant into the first chamber. Additionally, the first chamber has at least one lubricant outlet for providing the lubricant to one or more bearings supporting the shaft. Further, the sealing device includes at least one gas inlet in fluid communication with at least one radial extending gas supply channel for providing gas to a radial inner sealing seat of the sealing device.

[0007] Accordingly, compared to the state of the art, an improved sealing device is provided. In particular, the sealing device as described herein provides for improved oil tightness, less complexity and the possibility of easy assembling, and more cost-efficient production compared to conventional sealing concepts. The sealing device as described herein is particularly well suited for providing a sealing in turbocharging fuel cells for which the strict requirement of zero oil contamination in the air path into the fuel cell has to be fulfilled.

[0008] According to a further aspect of the present disclosure, a turbomachine, particularly a turbocharger, is provided. The turbomachine includes at least one rotor arranged on a shaft. Additionally, the turbomachine includes a bearing housing in which the shaft is rotatably mounted. Further, the turbomachine includes a bearing cover and a sealing device according to any embodiments described herein. The sealing device is arranged between the bearing housing and the bearing cover. In particular, the sealing device is arranged between the bearing cover and a bearing cartridge.

[0009] According to another aspect of the present disclosure, a method of sealing a bearing cover from a bearing housing is provided. The method includes providing a lubricant into a first chamber extending around a central opening of a sealing device via at least one lubricant inlet. Additionally, the method includes providing the lubricant to one or more bearings supporting a rotatable shaft via at least one lubricant outlet of the first chamber. Further, the method includes providing a gas through at least one gas inlet of the sealing device into at least one radial extending gas supply channel to a radial inner sealing seat of the sealing device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

Fig. 1 shows a schematic view of a turbomachine including a sealing device according to embodiments described herein;

Fig. 2 shows a schematic perspective view of view of a sealing device according embodiments described herein;

Fig. 3 shows a schematic sectional view along plane A-A indicated in Fig. 2;

Fig. 4 shows a schematic sectional view of a sealing device according to embodiments described herein in a mounted state;

Fig. 5 shows a detailed schematic view of a radial inner portion of a sealing device according to embodiments described herein; and

Figs. 6A and 6B show block diagrams for illustrating embodiments of a method of sealing a bearing cover from a bearing housing described herein. DETAILED DESCRIPTION OF EMBODIMENTS

[0011] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0012] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment can apply to a corresponding part or aspect in another embodiment as well.

[0013] With exemplary reference to Figs. 1 to 5, a sealing device 1 according to embodiments of the present disclosure is described. According to embodiments, which can be combined with other embodiments described herein, the sealing device 1 includes a central opening 11 for receiving a rotatable shaft 31. Typically, the rotatable shaft 31 is supported in the bearing housing 3 and extends through the bearing cover 2, as exemplarily shown in Fig. 1. Additionally, the sealing device 1 includes a first chamber 12 extending around the central opening 11. The first chamber 12 has at least one lubricant inlet 121 for providing lubricant into the first chamber 12. Further, the first chamber 12 has at least one lubricant outlet 122 for providing the lubricant to one or more bearings supporting the shaft 31. Moreover, the sealing device 1 includes at least one gas inlet 131 in fluid communication with at least one radial extending gas supply channel 132 for providing gas to a radial inner sealing seat 14 of the sealing device, as exemplarily shown in more detail in Fig. 5. [0014] Accordingly, compared to the state of the art, an improved sealing device is provided. In particular, the sealing device according to embodiments described herein provides for improved oil tightness, less complexity and the possibility of easy assembling, and more cost-efficient production compared to conventional sealing concepts. In particular, the sealing device according to embodiments described herein is beneficially configured such that an active pressurization, particularly of one or more sealing rings provided at the radial inner sealing seat of the sealing device, can be provided such that lubricant leakage from an internal bearing area into an air path can be eliminated and contamination of the air path with lubricant can be avoided. The sealing device as described herein is particularly well suited for providing a sealing in turbocharging fuel cells for which the strict requirement of zero oil contamination in the air path into the fuel cell has to be fulfilled. Zero oil contamination in the air path for duel cells is of particular importance for avoiding damage of the internal fuel cell membranes due to contamination. Accordingly, employing a sealing device according to embodiments described herein for a turbocharger used for charging a fuel cell beneficially ensures that the fuel cell can operate properly.

[0015] Thus, the sealing device as described herein, provides an alternative solution for using for using oil free bearings in order to avoid oil contamination in the air path. In this regard, it is to be noted that there are various possibilities for providing oil free bearings, e.g. the use of water or air lubrication, special metals such graphite or ceramics, or the use of active magnetic bearings (AMB). However, such oil free bearings solutions, have several disadvantages. Amongst the many, one can consider the overall construct complexity, in which auxiliary supporting systems, as well as complex and stringent fluid passages in casings are required, adding cost and complexity to the overall system. A further disadvantage is the extremely high costs (across the various solutions) of the actual bearings, in some cases (such as AMB) the overall cost of the bearing surpasses the cost of the whole product. Lastly, considerations need to be made in regards the possible loads and size limitations requirements, the serviceability of the intended solutions and the reliability expectations. Hence, by employing a sealing device as described herein instead of oil free bearings, a less complex, easy retro-fitting and more cost-efficient solution is provided for avoiding oil contamination in air paths, such that turbomachines being sealed with a sealing device as described herein can beneficially be used in combination with fuel cells.

[0016] With exemplary reference to Fig. 1, according to embodiments, which can be combined with any other embodiments described herein, the at least one lubricant inlet 121 and the at least one lubricant outlet 122 are provided on the same side of the sealing device 1. Further, typically, the at least one gas inlet 131 is arranged on an opposite side of the sealing device 1 at which the at least one lubricant inlet 121 and the at least one lubricant outlet 122 are provided. According to a particular example, the sealing device 1 includes a single gas inlet 131. Similarly, a single lubricant inlet 121 and/or a single lubricant outlet 122 may be provided.

[0017] According to embodiments, which can be combined with any other embodiments described herein, the first chamber 12 can have at least one of a circular axial cross-section, an elliptical axial cross-section, a rectangular axial cross-section, or any other suitable axial cross-section. The axial cross-section of the first chamber 12 may have a constant geometry around the central opening 11. Alternatively, the geometry of the axial cross-section of the first chamber 12 may vary around the central opening 11. . In other words, the cross- sectional shape of the first chamber 12 may vary around the central opening 11. According to an example, the first chamber 12 can be a torus-like or tubular chamber.

[0018] With exemplary reference to Fig. 4, according to embodiments, which can be combined with any other embodiments described herein, the sealing device 1 further includes a second chamber 13 separated from the first chamber 12. The second chamber 13 extends around the central opening 11. Further, the second chamber 13 is provided between the at least one gas inlet 131 and the at least one radial extending gas supply channel 132. Accordingly, the gas may enter through the at least one gas inlet 131, then be provided through the second chamber 13 into the at least one radial extending gas supply channel 132, and guided to the radial inner sealing seat 14.

[0019] According to embodiments, which can be combined with any other embodiments described herein, the second chamber 13 can have at least one of a circular axial cross-section, an elliptical axial cross-section, a rectangular axial cross-section, or any other suitable axial cross-section. The axial crosssection of the second chamber 13 may have a constant geometry around the central opening 11. Alternatively, the geometry of the axial cross-section of the second chamber 13 may vary around the central opening 11. In other words, the cross-sectional shape of the second chamber 13 may vary around the central opening 11. According to an example, the second chamber 13 can be a toruslike or tubular chamber.

[0020] According to embodiments, which can be combined with any other embodiments described herein, the sealing device 1 is an integral one-piece structure. For instance, the sealing device may be produced by additive manufacturing. In particular, the integral one-piece structure of the sealing device can be produced by additive manufacturing. Alternatively, the sealing device 1 as described herein can be made of two or more parts connected to each other. The two or more parts may be produced by additive manufacturing. Accordingly, a method of manufacturing the sealing device according to any embodiments described herein by using an additive manufacturing process can be provided.

[0021] With exemplary reference to Fig. 4, according to embodiments, which can be combined with any other embodiments described herein, the first chamber 12 is provided at a first radial distance R| from a central axis 111 of the central opening 11. Further, the second chamber 13 is provided at a second radial distance R ₂ from the central axis 111. Typically, the second radial distance R ₂ is different from the first radial distance Rx For instance, the second radial distance R ₂ can be larger than the first radial distance R Alternatively, the second radial distance R ₂ may be smaller than the first radial distance R

[0022] According to embodiments, which can be combined with any other embodiments described herein, the at least one gas inlet 131 is configured for receiving gas from a compressor 20 of a turbomachine 10. In particular, typically the at least one gas inlet 131 of the sealing device 1 faces a back side 2 IB of a compressor wheel 21. During operation of the compressor, at least one sealing ring 15 provided at the radial inner sealing seat 14 of the sealing device 1 is pressurized by gas provided from the compressor.

[0023] According to embodiments, which can be combined with any other embodiments described herein, the radial inner sealing seat 14 includes a first sealing ring reception 141 and a second sealing ring reception 142, as exemplarily shown in Fig. 4. Typically, the first sealing ring reception 141 and the second sealing ring reception 142 are separated by the at least one radial extending gas supply channel 132. In particular, radial inner walls of the at least one radial extending gas supply channel 132 can provide axial stops for sealing elements (e.g. sealing rings as described herein) to be mounted in the first sealing ring reception 141 and the second sealing ring reception 142, respectively.

[0024] With exemplary reference to Fig. 4, according to embodiments, which can be combined with any other embodiments described herein, the at least one sealing 15 inlcudes a first sealing ring 151 and a second sealing ring 152. The first sealing ring 151 can be mounted to the first sealing ring reception 141. Further, the second sealing ring 152 can be mounted to the second sealing ring reception 142. According to embodiments, which can be combined with any other embodiments described herein, at least one of the first sealing ring 151 and the second sealing ring 152 is selected from a lip seal ring, a piston ring, and a labyrinth seal ring. [0025] According to embodiments, which can be combined with any other embodiments described herein, at least one of the first sealing ring 151 and the second sealing ring 152 is a lip seal ring comprising one or more notches 153. The one or more notches 153 are configured for receiving gas provided through the at least one radial extending gas supply channel 132. In particular, as exemplarily shown in Fig. 5, the one or more notches 153 are oriented towards the at least one radial extending gas supply channel 132. Accordingly, beneficially the lip seal ring can be pushed against the rotatable shaft 31 by the gas exiting the gas supply channel 132. In other words, the lip seal rings may be actively pressurized to improved tightness of the sealing.

[0026] With exemplary reference to Fig. 3, according to embodiments, which can be combined with any other embodiments described herein, the at least one radial extending gas supply channel 132 includes two or more gas supply channels separated by radially extending walls 133. As an example, six radial extending gas supply channels 132 are shown in Fig. 3. However, it is to be understood that more or less than six radial extending gas supply channels 132 can be provided.

[0027] According to embodiments, which can be combined with any other embodiments described herein, the two or more gas supply channels are evenly distributed in a circumferential direction around the central opening 11, as exemplarily shown in Fig. 3. However, it is to be understood that alternatively, the two or more gas supply channels may be unevenly distributed in a circumferential direction around the central opening 11.

[0028] With exemplary reference to Fig. 5, according to embodiments, which can be combined with any other embodiments described herein, radial inner ends 134 of the least one radial extending gas supply channel 132 include a labyrinth seal 135. In particular, the labyrinth seal 135 is provided circumferentially around the central opening 11.

[0029] With exemplary reference to Fig. 1, it is to be understood that according to a further aspect of the present disclosure a turbomachine, particularly a turbocharger, can be provided. The turbomachine, includes at least one rotor 21 arranged on a shaft 31, a bearing housing 3 in which the shaft 31 is rotatably mounted, a bearing cover 2, and a sealing device 1 according to any embodiments described herein. The sealing device 1 is arranged between the bearing housing 3 and the bearing cover 2. In particular, the sealing device 1 is arranged between the bearing cover 2 and a bearing cartridge 32. Although Fig. 1 shows an example in which the sealing device 1 is provided between a compressor and the bearing housing, it is to be understood that the sealing device 1 can also be provided between the turbine and the bearing housing.

[0030] According to embodiments, which can be combined with any other embodiments described herein, the at least one gas inlet 131 of the sealing device 1 faces a back side 21B of the at least one rotor 21. Typically, the at least one rotor 21 is a compressor wheel of a compressor 20. Further, typically the at least one gas inlet 131 of the sealing device 1 is configured for receiving gas from the compressor 20 for pressurizing at least one sealing ring 15 provided at the radial inner sealing seat 14 of the sealing device 1 during operation of the compressor 20.

[0031] Accordingly, the sealing device 1 may be referred to as active pressurizable sealing device or active pressurized sealing device. Typically, the sealing device 1 includes a housing 16 including the first chamber 12, the at least one gas inlet 131, the gas supply channel 132, and optionally the second chamber 13 according to embodiments described herein. The housing 16 may be an integral one-piece structure and can be produced by additive manufacturing.

[0032] Accordingly, it is to be understood that typically the housing incorporates a controlled volume (i.e. the at least one gas inlet 131, the gas supply channel 132, and optionally the second chamber 13) for pressurization of the sealing device 1, particularly at least one sealing ring 15 provided at the radial inner sealing seat 14 the sealing device 1. Further, typically the housing incorporates an oil circuit (i.e. at least one lubricant inlet 121, the first chamber 12, and at least one lubricant outlet 122) configured for controlling the feed and direction of lubricant to the one or more bearings.

[0033] Typically, the sealing device is placed between a rotor (e.g. a compressor wheel) and a bearing. In view of the embodiments described herein it is to be understood that the sealing device has the following functionalities: active sealing of lubricant (e.g. oil) through a controlled pressurization integrated air circuit; provide internal passages (circuit) for oil flow to the turbocharger shaft bearing arrangement; prevent, through the use of seals (energized by controlled air pressure circuit), the oil leakage to the air path; provide internal passages for a compressed air chamber actively energizing the shaft seals; scalability via the use of additive manufacturing construct approach; serviceability ease: allowing quick access to replaceable seals; and

- use of seal devices on the turbomachine rotating shaft (such as lip seal rings) actively pressurized to minimize leakage between internal bearing area and air path as well as maintain and control lubricant tightness and contamination

[0034] With exemplary reference to the block diagram of Figs. 6A and 6B, a method 40 of sealing a bearing cover 2 from a bearing housing 3 according to the present disclosure is described. According to embodiments, which can be combined with any other embodiments described herein, the method 40 includes providing (represented by block 41 in Figs. 6A and 6B) a lubricant into a first chamber 12 extending around a central opening 11 of a sealing device 1 via at least one lubricant inlet 121. Further, the method includes providing (represented by block 42 in Fig. 6A and 6B) the lubricant to one or more bearings supporting a rotatable shaft 31 via at least one lubricant outlet 122 of the first chamber 12. For instance, the lubricant can be oil.

[0035] For example, the lubricant can be pumped in at the lubricant inlet 121 and flows to the lubricant chamber (i.e. the first chamber 12 as described herein. From the first chamber 12, the lubricant is distributed to the bearings in the opposite direction to the air path side (i.e. away from the rotor, particularly the compressor). Accordingly, direct splash of oil towards the air path section of the turbomachine, particularly the turbocharger, can be avoided.

[0036] Additionally, the method includes providing (represented by block 43 in Fig. 6 A and 6B) a gas through at least one gas inlet 131 of the sealing device 1 into at least one radial extending gas supply channel 132 to a radial inner sealing seat 14 of the sealing device. For better understanding, the gas flow GF and the lubricant flow LF are indicated in Fig. 5.

[0037] According to embodiments, which can be combined with any other embodiments described herein, providing (represented by block 43 in Fig. 6A and 6B) the gas through the at least one gas inlet 131 of the sealing device 1 includes providing the gas from a compressor 20.

[0038] According to embodiments, which can be combined with any other embodiments described herein, the method 40 of sealing a bearing cover 2 from a bearing housing 3 further includes pressurizing (represented by block 45 in FIG. 6B) at least one sealing ring 15 provided at the radial inner sealing seat 14 of the sealing device 1 during operation of the compressor 20.

[0039] According to embodiments, which can be combined with any other embodiments described herein, the method 40 includes providing (represented by block 44 in Fig. 6B) a gas into a second chamber 13 separated from the first chamber 12 and extending around the central opening 11 via the at least one gas inlet 131. Additionally, the method may include, guiding (represented by block 45) the gas from the second chamber 13 to the radial inner sealing seat 14 of the sealing device via the at least one radial extending gas supply channel 132. Further, the method can include pushing (represented by block 46 in Fig. 6) a flexible portion of at least one of a first sealing ring 151 and a second sealing ring 152 provided at the radial inner sealing seat 14 towards the rotatable shaft 31 by employing gas exiting the gas supply channel 132.

[0040] It is to be understood that embodiments of the method 40 of sealing a bearing cover 2 from a bearing housing 3 as described herein, typically is conducted by using a sealing device 1 according to any embodiments described herein.

[0041] According to embodiments, which can be combined with any other embodiments described herein, providing the gas through at least one gas inlet 131 of the sealing device 1 includes feeding compressed air, particularly from a compressor 20 as described herein. It is to be understood that the compressed air (which may also be referred to as pressurized air) can be provided from the compressor in a controlled manner, for example, pressure and/or flow rate of the compressed air can be adjusted. The compressed air may be led into the air chamber (i.e. the second chamber 13 as described herein). From the air chamber, the compressed air then pressurizes the internal passages (i.e. the least one radial extending gas supply channel 132 as described herein) of the housing 16 to energize at least one sealing ring 15 provided at the radial inner sealing seat 14 of the sealing device 1, as described herein. Thereby, oil leakage from the shaft into the compressed air path of the compressor wheel is avoided.

[0042] Accordingly, in view of the embodiments described herein, it is to be understood that compared to the state of the art, an improved sealing device, an improved turbomachine, and an improved method of sealing can be provided. In particular, the embodiments as described herein beneficially provide for improved oil tightness, less complexity, easy assembly, easy retrofitting and improved cost-efficiency compared to the state of the art. Further, the embodiments as described herein are beneficially configured for providing an active pressurization, particularly of one or more sealing rings provided at the radial inner sealing seat of the sealing device, such that lubricant leakage from an internal bearing area into an air path can be eliminated and contamination of the air path with lubricant can be avoided.

[0043] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.

REFERENCE NUMBERS

1 sealing device

10 turbomachine

11 central opening

111 central axis

12 first chamber

121 lubricant inlet

122 lubricant outlet

13 second chamb er

131 gas inlet

132 gas supply channel

133 walls

134 radial inner ends of gas supply channel

135 labyrinth seal

14 radial inner sealing seat

141 first sealing ring reception

142 second sealing ring reception

15 sealing ring

151 first sealing ring

152 second sealing ring

153 notches

16 housing

2 bearing cover

20 compressor

21 rotor / compressor wheel

2 IB back side of rotor / compressor wheel

3 bearing housing

31 rotatable shaft

32 bearing cartridge

30 turbine

40 method of sealing a bearing cover from a bearing housing 41-46 blocks of block diagram for illustrating the method of sealing a bearing cover from a bearing housing

GF gas flow

LF lubricant flow