Centrifugal separator

Abstract

The present disclosure relates to a centrifugal separator for separating a liquid phase from a crankcase gas. The separator comprises a housing (4), a separation chamber (6) inside the housing (4), a rotor shaft (8), a rotor (10) connected to the rotor shaft (8), a bearing (12) arranged at an end portion (14) of the rotor shaft (8), and a liquid outlet (20) for the separated liquid phase. The end portion (14) of the rotor shaft (8) extends through the bearing (12) to the outside of the separation chamber. An annular sealing gap (22) is formed between the housing (4) and a component (30) connected to the rotor shaft (8) outside the separation chamber (6). The liquid outlet (20) is arranged radially outside the bearing (12) and radially inside a radially outer end of the annular sealing gap (22) as seen in relation to the axial direction.

Description

Technical Field

[0001] This invention relates to a centrifugal separator for separating a liquid phase from crankcase gas. Background Technology

[0002] Crankcase gases from internal combustion engines are emitted from the crankcase of the relevant combustion engine. These gases can be treated in an environmentally friendly manner rather than being released into the atmosphere untreated. For certain types of combustion engines, legislation requires environmentally friendly treatment of crankcase gases.

[0003] Crankcase gases may include, in particular, leaking gases, oil, other liquid hydrocarbons, soot, and other solid combustion residues. To properly treat crankcase gases, the gases are separated from the oil, soot, and other residues. The separated gases may be directed to the intake of the combustion engine or vented to the atmosphere, and optionally, the oil may be directed back to the oil pan of the combustion engine via an oil filter used to remove soot and other solid residues from the oil.

[0004] Centrifuges can be used to process crankcase gases. Crankcase gases are guided into the rotor of the centrifuge, and the heavier components of the crankcase gases (such as oil and soot) are separated from the clean gas as a liquid phase. The liquid phase exits the centrifuge via a liquid outlet. The clean gas exits the centrifuge via a gas outlet.

[0005] WO 2016 / 198274 discloses a centrifugal separator for separating crankcase gases, wherein a liquid passage from the separation chamber is provided via ball bearings on the rotor shaft. Summary of the Invention

[0006] Soot and other solid particles carried by the liquid phase through the bearings can damage them and thus shorten the service life of the bearings and centrifuges.

[0007] It would be advantageous to achieve a centrifugal separator that overcomes or at least mitigates the aforementioned drawbacks. In particular, it is desirable to ensure a durable centrifugal separator for separating liquid phases from crankcase gases, where the expected rotor shaft bearing life will be maintained. To address this and other concerns, a centrifugal separator according to the present invention is provided.

[0008] According to one aspect, a centrifugal separator for separating a liquid phase from crankcase gas is provided according to the invention. The centrifugal separator includes: a housing, a separation chamber inside the housing, a rotor shaft extending axially through the separation chamber, a rotor for separating the liquid phase disposed inside the separation chamber and connected to the rotor shaft, a bearing disposed at an end portion of the rotor shaft, an inlet for crankcase gas, a gas outlet from the separation chamber for the separated gas, and a liquid outlet from the separation chamber for the separated liquid phase. The rotor shaft is connected to the housing via a bearing journal. The end portion of the rotor shaft extends through the bearing to the outside of the separation chamber. An annular sealing gap is formed between the housing and the component connected to the rotor shaft outside the separation chamber, and the liquid outlet is disposed radially outward of the bearing and radially inward of the radially outer end of the annular sealing gap, viewed relative to the axial direction.

[0009] Because the liquid outlet is arranged radially outside the bearing, during the use of the centrifuge, not all the separated liquid phase will reach and flow through the bearing. Therefore, at least a major portion of the liquid phase containing particles will flow through the liquid outlet, which is arranged radially outside the bearing and separated from it. Thus, reaching the bearing with particulate matter is at least largely avoided. This reduces the risk of wear on the bearing caused by particles. Furthermore, since the liquid outlet is also arranged radially inside the radially outer end of the annular sealing gap, the liquid phase is supplied to the sealing gap via the liquid outlet. Therefore, during the use of the centrifuge, the sealing function of the sealing gap is improved by the liquid phase flowing through the sealing gap. More specifically, at the bearing, the air pressure inside the separation chamber is sealed by the air pressure outside the separation chamber and the sealing gap. The separated liquid phase in the sealing gap contributes to the sealing function of the sealing gap. Therefore, even when the liquid outlet is arranged radially outside the bearing but inside the radially outer end of the annular sealing gap, not all the separated liquid phase will flow through the bearing, and the sealing function of the sealing gap will be improved during use by the liquid phase flowing through the sealing gap.

[0010] The inventors have realized that solid particles separated from the combustion gas along with the liquid phase may cause wear on the bearings of the centrifugal separator to a certain extent, thus shortening the bearing life compared to its expected life.

[0011] The centrifugal separator is arranged to clean the crankcase gases from the internal combustion engine (ICE). This ICE can be configured to propel a vehicle, or it can be, for example, a stationary combustion engine used to drive a generator to produce electricity.

[0012] Crankcase gases (also known as leaky gases) can be vented from the crankcase of the ICE via a crankcase exhaust system. A centrifugal separator can be incorporated into the crankcase exhaust system.

[0013] Crankcase gases are the result of high pressure inside the ICE cylinders forcing some combustion gases, along with liquid and solid residues, down through the piston rings into the ICE's crankcase. If not vented, the increased pressure inside the crankcase can cause engine oil to leak out of the ICE, and the liquid and solid residues can contaminate and / or dilute the engine oil.

[0014] Centrifugal separators are configured to separate heavy components of crankcase gases (such as oil, other liquid hydrocarbons, soot, and other solid combustion residues) as a liquid phase.

[0015] In the operation of a centrifuge, crankcase gas is guided into the separation chamber and rotor via an inlet for crankcase gas. The crankcase gas enters the rotor from its central portion. As the rotor rotates, heavy components separate and are propelled as droplets from the outer periphery of the rotor against the inner wall of the separation chamber. The droplets form a separated liquid phase, which is guided out of the centrifuge via a liquid outlet. Clean gas (i.e., crankcase gas from which its heavy components have been removed) is guided out of the centrifuge via a gas outlet.

[0016] Centrifuges are constructed for parallel separation. That is, the separated phases travel through the rotor of the centrifuge in the same direction. More specifically, as discussed above, the liquid phase travels from the center of the rotor toward its periphery. The other separated phases (i.e., gases) do the same. They travel from the center of the rotor toward its periphery, while heavier components separate from them and exit the rotor at its periphery.

[0017] The rotor may include a number of separation components that improve the separation of heavy components from crankcase gases. Such separation components may take the form, for example, axially extending guide vanes oriented radially from the rotor shaft or stacked truncated conical separation disks. As the rotor rotates, heavy components are forced against the surface of the separation components, where they form droplets as they travel along the separation components toward the outer periphery of the rotor.

[0018] The centrifuge housing is fixed relative to the ICE. The rotor shaft and rotor are arranged to rotate relative to the housing. The rotor shaft can be rotated by a drive component such as a turbine impeller, electric motor, pneumatic motor, or hydraulic motor.

[0019] During operation of the centrifuge, the axial direction can be extended substantially vertically, and the liquid outlet can be located at the lower end of the separation chamber. Therefore, gravity causes the droplets of the separated liquid phase to flow along the inner wall of the separation chamber toward the liquid outlet.

[0020] During the operation of a centrifugal separator, the sealing gaps can form an hermetically tight seal or seal the separation chamber from its adjacent space. An hermetically tight seal is constructed to account for the pressure difference that typically occurs between the separation chamber and its adjacent space in a crankcase gas centrifugal separator. In the adjacent space, the pressure of the ambient environment of the ICE may be dominant or lie between the pressure inside the separation chamber and the pressure of the ambient environment. That is, the pressure inside the separation chamber is higher than the pressure of the ambient environment due to the increased pressure supplied by the rotor during the use of the centrifugal separator.

[0021] Within the sealed gap, as the rotor rotates, a pumping effect is achieved by components connected to the rotor shaft. This pumping effect helps to transport the separated liquid phase through the sealed gap.

[0022] According to an embodiment, the liquid outlet can be located 0-20 mm radially outward from the outer radial ring surface of the bearing. In this way, the liquid outlet can be positioned close to the bearing, and therefore the sealing clearance can be positioned close to the bearing and close to the rotor shaft. This, in turn, provides a small-diameter sealing clearance with a small friction-generating surface close to the axis of rotation, thus reducing frictional torque compared to a larger diameter sealing clearance. Furthermore, tighter manufacturing tolerances are easier to achieve with a smaller diameter than with a larger diameter.

[0023] According to an embodiment, the liquid outlet may include a number of through holes extending through the housing and arranged circumferentially around the bearing. In this way, the separated liquid phase can flow out of the separation chamber at a number of circumferentially arranged locations. Therefore, it can be ensured that the separated liquid phase is discharged uniformly circumferentially from the separation chamber, and the storage of liquid phase in areas far from the liquid outlet can be avoided.

[0024] The liquid outlet may include at least two through holes, such as at least four, such as at least eight through holes.

[0025] The centrifuge housing may include surrounding sidewalls enclosing the separation chamber, as well as a first end wall and a second end wall. A liquid outlet may be disposed in the end wall. Furthermore, the end wall may include recesses for guiding the separated liquid to the liquid outlet. As an example, the liquid outlet may include a number of through-holes as discussed above, and individual recesses may be disposed radially outward of at least one of these through-holes, such as radially outward of each through-hole. The recesses may be arranged such that their bottom surface is radially inwardly inclined to guide the separated liquid toward the corresponding through-hole.

[0026] According to an embodiment, at least one of the numerous through-holes has a larger cross-sectional area at a distance from the separation chamber than near the separation chamber. Therefore, at least one through-hole (such as all of the through-holes) can be in the form of a funnel, with a narrow portion near or at the separation chamber and a wider portion at a distance from the separation chamber. In this way, it is ensured that the separated liquid phase flows through at least one through-hole, and that solid particles in the liquid phase entering at least one through-hole do not become trapped therein.

[0027] According to an embodiment, each of the number of through holes may have a substantially circular or elliptical cross-section. In this way, the through holes can be arranged close to the bearing and can be configured to provide a liquid outlet on the radially inner side of the radially outer end of the annular sealing gap, while maintaining a small-diameter annular sealing gap. Therefore, the advantages of the aforementioned small-diameter sealing gap, low frictional torque, and tight manufacturing tolerances can be provided.

[0028] According to an embodiment, an annular protrusion may be provided on the housing. The axial surface of the annular protrusion may form a surface defining an annular sealing gap, and the surface of the component may form an opposing surface defining the annular sealing gap. In this way, a sealing gap can be conveniently provided between the housing and the component connected to the rotor shaft on the outer side of the separator.

[0029] According to an embodiment, the liquid outlet can be arranged to emerge from an annular protrusion. In this way, the separated liquid phase can be directly guided into the sealing gap, which helps the sealing function of the sealing gap. Moreover, compared with the case where the separated liquid phase is guided radially inward of the sealing gap, the separated liquid phase can be transported / pumped through the sealing gap a shorter distance.

[0030] Regarding the latter point, compared to the prior art disclosed in WO 2016 / 198274 (where the separated liquid phase is guided to a radial position inside the sealing gap via ball bearings), by arranging the liquid outlet to be led out in an annular protrusion, the separated liquid phase is supplied into the sealing gap to aid its sealing function, while having a shorter distance to leave the sealing gap. Therefore, the separated liquid phase is efficiently handled from the sealing gap.

[0031] According to an embodiment, the annular sealing gap can form a labyrinth seal. In this way, good sealing performance can be provided by the annular sealing gap. The labyrinth seal can be a single-stage labyrinth seal, i.e., it includes only one directional change of the sealing gap, or it can be a multi-stage labyrinth seal, i.e., it includes more than one directional change of the sealing gap. Such directional changes of the sealing gap can be between a substantially radial direction and a substantially axial direction relative to the axial direction defined by the direction of the rotor shaft extending through the separation chamber.

[0032] According to an embodiment, the centrifugal separator may include a drive chamber and a turbine impeller disposed within the drive chamber and connected to an end portion of a rotor shaft. A sealing gap may be provided in the drive chamber and may be configured to seal the drive chamber from the separation chamber. In this manner, the separation chamber may be sealed within the drive chamber to the outside of the separation chamber.

[0033] The turbine impeller may be a component, with a sealing gap formed between the component and the housing. Alternatively, the component forming the sealing gap between itself and the housing may be a component separate from the turbine impeller.

[0034] According to one embodiment, the separator rotor may include a stack of separation discs, each disc having a truncated conical shape. In this way, efficient separation of the liquid phase from the crankcase gas can be ensured.

[0035] A gap is formed between these separation discs arranged in a disc stack. As the rotor rotates together with the disc stack, heavy components are forced against the inner surface of the separation discs and form droplets as they travel along the separation discs toward the outer periphery of the disc stack.

[0036] According to one embodiment, a ridge may surround the bearing inside the separation chamber and extend radially between the bearing and the liquid outlet. The ridge may extend axially from the bearing into the separation chamber. In this way, the ridge prevents the separated liquid phase from reaching the bearing, and thus prevents solid particles in the separated liquid phase from causing wear on the bearing.

[0037] According to an embodiment, the ridge may include at least one opening. In this way, a small amount of separated liquid phase can reach the bearing through at least one opening. The at least one opening may have a circumferential extension less than half of the circumferential extension of the ridge (such as less than 25%, less than 10%, or less than 5%). Therefore, the bearing can be lubricated by the oil content of the liquid phase, but the ridge still prevents a large number of solid particles in the liquid phase from reaching the bearing.

[0038] According to one embodiment, the bearing may be sealed toward the separation chamber. In this way, any separated liquid phase reaching the bearing is prevented from flowing through the bearing, and thus solid particles are prevented from causing wear on the bearing.

[0039] Further features and advantages of the invention will become clear when the specification and the following detailed description are studied. Attached Figure Description

[0040] Various aspects and / or embodiments of the invention, including its specific features and advantages, will be readily understood from the exemplary embodiments discussed in the following detailed description and accompanying drawings, in which:

[0041] Figure 1 A cross-section of a centrifuge according to an embodiment is shown.

[0042] Figure 2a and Figure 2b The lower portion of the housing of a centrifuge according to an embodiment is shown, and

[0043] Figure 3-5 A cross-section of the lower portion of a centrifugal separator according to various embodiments is shown. Detailed Implementation

[0044] The aspects and / or embodiments of the invention will now be described more fully. Throughout the text, similar numbers denote similar elements. For the sake of brevity and / or clarity, well-known functions or constructions will not be described in detail.

[0045] Figure 1 A cross-section of a centrifugal separator 2 according to an embodiment is shown. The centrifugal separator 2 is configured to separate the liquid phase from crankcase gas from an internal combustion engine.

[0046] The centrifuge 2 includes a housing 4, a separation chamber 6 inside the housing 4, a rotor shaft 8 extending through the separation chamber 6 in the axial direction, and a rotor 10 arranged inside the separation chamber 6 for separating liquid phases.

[0047] The housing 4 may be formed from one or more parts. The separation chamber 6 is defined by at least a portion of the housing 4. For example, the housing 4 may include an enclosing sidewall 5 surrounding the separation chamber 6, a first end wall 3, and an opposing second end wall 7. The rotor 10 is connected to the rotor shaft 8.

[0048] Bearing 12 is disposed at the end portion 14 of rotor shaft 8. Rotor shaft 8 is journal-connected to housing 4 by bearing 12. Bearing may be, for example, ball bearing, roller bearing or plain bearing. Rotor shaft 8 may be journal-connected to another bearing at the opposite end portion of rotor shaft 8.

[0049] The centrifuge 2 further includes an inlet 16 for crankcase gases into the separation chamber 6, a gas outlet 18 for separated gases from the separation chamber 6, and a liquid outlet 20 for separated liquid phases from the separation chamber 6. Figure 1 Only liquid outlet 20 is indicated in the diagram. Liquid outlet 20 is disposed in the first end wall 3 of housing 4. Various embodiments of liquid outlet 20 are described in... Figure 2a-5 As shown in the image.

[0050] The end portion 14 of the rotor shaft 8 extends through the bearing 12 to the outside of the separation chamber 6. Component 24 is connected to the rotor shaft 8 at the end portion 14 of the rotor shaft 8 outside the separation chamber 6.

[0051] An annular sealing gap 22 is formed between the housing 4 and the component 24 connected to the rotor shaft 8 on the outside of the separation chamber 6, and the liquid outlet 20 is arranged on the radially outer side of the bearing 12 and the radially inner side of the radially outer end of the annular sealing gap 22, relative to the axial direction.

[0052] An annular protrusion 26 is provided on the housing 4. The axial surface of the annular protrusion 26 forms a surface defining an annular sealing gap 22. The surface of the component 24 facing the axial surface of the annular protrusion 26 forms an opposing surface defining the annular sealing gap 22. That is, the annular sealing gap 22 is formed between the axial surface of the annular protrusion 26 and the surface of the component 24.

[0053] The separator rotor 10 includes a stack 32 of separation discs 34, each disc 34 having a truncated cone shape. Gaps are formed between the separation discs in the stack 32, and as the rotor 8 rotates, crankcase gas travels through these gaps from the inner periphery to the outer periphery, simultaneously separating into liquid and gas phases. Figure 1 Only some of the separation disks 34 are indicated.

[0054] In these embodiments, the truncated conical separation discs 34 are stacked with their wide ends facing downwards. In an alternative embodiment, the truncated conical separation discs may be stacked with their wide ends facing upwards.

[0055] As an example only, the rotor shaft 8 may have an outer diameter in the range of 8-14 mm, the bearing 12 may be a ball bearing with an inner diameter in the range of 8-14 mm, an outer diameter in the range of 18-36 mm, and a thickness / height in the range of 5-12 mm, the annular sealing gap 22 may have a width between the housing 4 and the component 24 in the range of 0.1-0.5 mm, and the number of separation discs 34 may be in the range of 50-150, which may have an outer diameter in the range of 60-130 mm and may be arranged at a distance from each other in the range of 0.25-0.7 mm.

[0056] The rotor shaft 8 is rotated about the rotation axis 9 by a drive component. Figure 1 In the embodiment shown, the driving component is an electric motor 11 connected to the rotor shaft 8.

[0057] The centrifuge 2 is configured to be positioned such that its axis of rotation 9 extends substantially vertically during use. Therefore, the liquid outlet 20 is located at the lower end of the housing 4. Thus, the separated liquid phase can be transported towards the liquid outlet 20 by gravity.

[0058] Figure 2a and Figure 2b A centrifugal separator (such as) according to an embodiment is shown. Figure 1The end wall 3 of the housing of the centrifugal separator 2 shown. Figure 2a This is a view showing the lower part from the inside of separation chamber 6, and Figure 2b The lower section is shown in a view from the outside of the separation chamber.

[0059] In these embodiments, the liquid outlet 20 includes a number of through holes 36 extending through the end wall 3 and arranged circumferentially around the bearing 12. Thus, the separated liquid phase is uniformly discharged from the separation chamber around the bearing 12 via these through holes 36.

[0060] In these embodiments, each of the number of through holes 36 has a substantially elliptical cross-section. Therefore, the through holes 36 of the liquid outlet 20 can be arranged close to the bearing 12.

[0061] According to an alternative embodiment, each of the through holes 36 may have a substantially circular cross-section, or a substantially rectangular cross-section, or a substantially square cross-section.

[0062] At least one of the through holes 36 has a larger cross-sectional area at a certain distance from the separation chamber 6 than closer to the separation chamber. That is, in Figure 2a In the view shown, one or more of the through holes 36 have a larger diameter than the through holes 36. Figure 2b The smaller cross-sectional area is shown in the view. In this way, it is ensured that the separated liquid phase will flow through the through-hole 36, and any solid particles entering the through-hole 36 will not get stuck in the through-hole 36.

[0063] All of the through holes 36 can have a larger cross-sectional area at a certain distance from the separation chamber than at a closer distance from the separation chamber.

[0064] The number of through holes 36 can be more than two, such as at least four, such as in the range of 6-16, such as at least 10. In the example shown, the end wall 3 is provided with 12 through holes 36.

[0065] The total area of ​​the liquid outlet 20 can be 18-75 mm. 2 Within the range, the number of through holes 36 is divided. As an example, the elliptical cross-section of the through hole can be 2×3.6 mm, the diameter of the circular cross-section through hole 36 can be 2 mm, the square cross-section through hole 36 can be measured as 2×2 mm, and the rectangular cross-section through hole 36 can be measured as 2×3.5 mm.

[0066] The end wall 3 includes a recess 15 for guiding the separated liquid to the liquid outlet 20. Individual recesses 15 are arranged radially outward in each of the through holes 36.

[0067] Figure 3A cross-section of the lower portion of the centrifuge 2 according to an embodiment is shown. The centrifuge 2 is similar in many respects to a combined centrifuge. Figure 1-2b The centrifugal separator 2 is discussed.

[0068] In these embodiments, the drive component arranged to rotate the rotor shaft 8 includes a turbine impeller 30 instead of an electric motor. The turbine impeller 30 is configured to be driven by oil sprayed onto a shovel. For example, engine oil from the ICE (centrifugal separator 2 configured to clean its crankcase gases) can be directed toward the turbine impeller 30 via nozzles.

[0069] Therefore, the centrifuge 2 includes a drive chamber 28 and a turbine impeller 30 disposed in the drive chamber 28 and connected to the end portion 14 of the rotor shaft 8. An annular sealing gap 22 is provided in the drive chamber 28 and configured to seal the drive chamber 28 with the separation chamber 6.

[0070] In these embodiments, the component 24 that forms an annular sealing gap 22 between itself and the housing 4 is composed of a turbine impeller 30.

[0071] Furthermore, an annular protrusion 26 is provided on the housing 4, and the annular sealing gap 22 is at least partially defined by two axially facing surfaces: the axial surface of the annular protrusion 26 and the opposing surface of the component 24 / turbine impeller 30.

[0072] Liquid outlet 20 is arranged to emerge from an annular protrusion 26. That is, the through hole 36 forming liquid outlet 20 terminates in the annular protrusion 26, and thus terminates in the annular sealing gap 22. In this way, the liquid phase flowing from separation chamber 6 through through hole 36 reaches the annular sealing gap 22.

[0073] Furthermore, the end wall 3 of the housing 4 includes a recess 15, which is arranged radially outward of the through hole 36 and configured to guide the separated liquid into the through hole 36.

[0074] Figure 4 A cross-section of the lower portion of the centrifuge 2 according to an embodiment is shown. The centrifuge 2 is similar in many respects to a combined centrifuge. Figure 1-3 One or more of the centrifugal separators 2 discussed.

[0075] Furthermore, the centrifuge 2 includes a drive chamber 28 and a turbine impeller 30 connected to the end portion 14 of the rotor shaft 8. The turbine impeller 30 forms a drive component for rotating the rotor shaft 8 during operation of the centrifuge 2.

[0076] Furthermore, the axial surface and the opposing surface of the annular protrusion 26 of the housing 4 define at least a portion of the annular sealing gap 22. In these embodiments, the opposing surface is provided by a component 24 separate from the turbine impeller 30. That is, the component 24, connected to the rotor shaft 8, is arranged between the turbine impeller 30 and the protrusion 26.

[0077] Furthermore, the through-hole 36 of the liquid outlet 20 is arranged to extend out of the annular protrusion 26.

[0078] exist Figure 4 In the middle, the larger cross-sectional area of ​​the through hole 36 at a certain distance from the separation chamber 6 compared to that closer to the separation chamber 6 is also clearly visible. That is to say, Figure 4 The funnel shape of the through-hole 36 is shown. For example, one or more of the through-holes 36 may have a conical broadened cross section in the range of 0.5-5 degrees in the direction from the separation chamber 6 toward the annular sealing gap 22.

[0079] According to these embodiments, ridge 38 surrounds bearing 12 inside separation chamber 6 and extends radially between bearing 12 and liquid outlet 20. Ridge 38 extends axially from bearing 12 into separation chamber 6. Ridge 38 may form part of housing 4.

[0080] Therefore, in addition to the liquid outlet being arranged radially outward of the bearing 12 to discharge the separated liquid from the separation chamber at point 6 before reaching the bearing 12, the ridge 38 also prevents a large portion of the main flow of the separated liquid that might overflow from the liquid outlet 20 from reaching the bearing 12. Thus, solid particles in the separated liquid phase can be prevented from reaching the bearing 12, thereby preventing wear on the bearing 12.

[0081] Ridge 38 may have a height h in the range of 1-5 mm. In this way, the most anticipated large influx of the separated liquid phase can be prevented from reaching bearing 12.

[0082] The height h of the ridge 38 extends axially from the bottom surface of the separation chamber formed by the shell 4 into the separation chamber 6.

[0083] According to some embodiments, the ridge 38 may include at least one opening 40. In this way, a small amount of separated liquid phase can reach the bearing through the opening 40. This small amount of separated liquid can lubricate the bearing 12.

[0084] Each of at least one of the openings 40 may have a circumferential width in the range of 0.1-1 mm. In this way, larger solid particles contained in the separated liquid phase may not flow through the opening 40, and thus larger solid particles are prevented from reaching the bearing 12.

[0085] As an example, ridge 38 may be provided with one to six openings 40.

[0086] According to these embodiments, at least one opening 40 can be provided in the ridge 38 in the form of a slit arranged substantially vertically. In this way, at least one opening can be easily manufactured, for example, during injection molding of the housing portion including the ridge 38.

[0087] Figure 5 A cross-section of the lower portion of the centrifuge 2 according to an embodiment is shown. The centrifuge 2 is similar in many respects to a combined centrifuge. Figure 1-4 One or more of the centrifugal separators 2 discussed.

[0088] Furthermore, the centrifuge 2 includes a drive chamber 28 and a turbine impeller 30 connected to the end portion 14 of the rotor shaft 8. The turbine impeller 30 forms a drive component for rotating the rotor shaft 8 during operation of the centrifuge 2.

[0089] Furthermore, the axial surface of the annular protrusion 26 of the housing 4 and the opposing surface defined by the component 24 define at least a portion of the annular sealing gap 22.

[0090] According to these embodiments, the bearing 12 is sealed toward the separation chamber 6. Therefore, any separated liquid phase reaching the bearing 12 is prevented from flowing through the bearing 12, and thus solid particles are prevented from causing wear on the bearing 12.

[0091] In all embodiments of the centrifuge 2 discussed herein, especially with reference to Figure 1-5 The liquid outlet 20 can be arranged within a range of 0-20 mm radially outward from the radial outer ring surface 13 of the bearing 12, for example, see Figure 1 , Figure 3 and Figure 5 In other words, the through hole 36 forming the liquid outlet 20 can be arranged within a range of 0-20 mm radially outward from the outer radial ring surface 13 of the bearing 12.

[0092] Referring again to all embodiments, the annular sealing gap 22 can form a labyrinth seal. In the illustrated embodiment, a single-stage labyrinth seal means that the annular sealing gap 22 includes only one directional change between the radial extension 22' and the axial extension 22'', such as... Figure 5 As indicated in the document. However, a multi-stage labyrinth seal may be alternatively provided, which includes more than one directional variation of the sealing gap.

[0093] However, according to an alternative embodiment, in its simplest form, the annular sealing gap 22 may extend only in the radial direction or only in the axial direction.

[0094] It will be understood that various exemplary embodiments have been shown above, and the invention is defined only by the appended claims. Those skilled in the art will recognize that the exemplary embodiments may be modified without departing from the scope of the invention as defined by the appended claims, and different features of the exemplary embodiments may be combined to produce embodiments other than those described herein.

Claims

1. A centrifugal separator (2) for separating a liquid phase from crankcase gas, the centrifugal separator (2) comprising: Shell (4) The separation chamber (6) inside the shell (4). The rotor shaft (8) extends through the separation chamber (6) in the axial direction. A rotor (10) for separating the liquid phase is arranged inside the separation chamber (6) and connected to the rotor shaft (8). A bearing (12) is arranged at the end portion (14) of the rotor shaft (8). Inlet (16) for the crankcase gas. The gas outlet (18) from the separation chamber (6) for the separated gas, and The liquid outlet (20) from the separation chamber (6) for separating the liquid phase, wherein The rotor shaft (8) is connected to the housing (4) via the bearing (12) journal, wherein The end portion (14) of the rotor shaft (8) extends through the bearing (12) to the outside of the separation chamber (6), wherein An annular sealing gap (22) is formed between the housing (4) and the component (24) connected to the rotor shaft (8) outside the separation chamber (6), and wherein... Viewed relative to the axial direction, the liquid outlet (20) is arranged radially outward of the bearing (12) and radially inward of the radially outer end of the annular sealing gap (22). The liquid outlet (20) includes a number of through holes (36) that extend through the housing (4) and are arranged circumferentially around the bearing (12), and at least one of the number of through holes (36) has the form of a funnel, wherein the narrow portion is close to or at the separation chamber (6) and the wider portion is at a distance from the separation chamber (6).

2. The centrifuge (2) according to claim 1, wherein, The liquid outlet (20) is located within a radially outer range of 0-20 mm on the radially outer ring surface (13) of the bearing (12).

3. The centrifuge (2) according to claim 1, wherein, Each of the number of through holes (36) has a substantially circular or elliptical cross section.

4. The centrifugal separator (2) according to any one of claims 1-3, wherein, An annular protrusion (26) is provided on the housing (4), the axial surface of the annular protrusion forming a surface defining the annular sealing gap (22), and the surface of the component (24) forming an opposing surface defining the annular sealing gap (22).

5. The centrifuge (2) according to claim 4, wherein, The liquid outlet (20) is arranged to extend out of the annular protrusion (26).

6. The centrifuge (2) according to claim 4, wherein, The annular sealing gap (22) forms a labyrinth seal.

7. The centrifugal separator (2) according to claim 4, comprising a drive chamber (28) and a turbine impeller (30) disposed in the drive chamber (28) and connected to an end portion (14) of the rotor shaft (8), wherein a sealing gap (22) is provided in the drive chamber (28) and configured to seal the drive chamber (28) from the separation chamber (6).

8. The centrifugal separator (2) according to any one of claims 1-3, wherein, The rotor (10) of the centrifugal separator includes a stack (32) of separation discs (34), each of which has a truncated cone shape.

9. The centrifugal separator (2) according to any one of claims 1-3, wherein, A ridge (38) surrounds the bearing (12) inside the separation chamber (6), extends radially between the bearing (12) and the liquid outlet (20), and wherein the ridge (38) extends from the bearing (12) into the separation chamber (6) in the axial direction.

10. The centrifuge (2) according to claim 9, wherein, The ridge (38) has a height (h) in the range of 1-5 mm.

11. The centrifuge (2) according to claim 9, wherein, The ridge (38) includes at least one opening (40).

12. The centrifuge (2) according to claim 11, wherein, The at least one opening (40) has a circumferential width in the range of 0.1-1 mm.

13. The centrifuge (2) according to claim 11 or claim 12, wherein, The at least one opening (40) is provided in the ridge (38) in the form of a slit arranged substantially vertically.

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