Sealing system for a shaft arrangement

Abstract

Sealing system for a shaft arrangement with two rotatable shafts (23, 27) guided through a housing wall bearing opening (20), namely an outer hollow shaft (23) and an inner shaft (27) guided coaxially through the outer hollow shaft (23), which sealing system has a sealing element (43) arranged in a rotationally fixed manner on the outer hollow shaft (23), which can be brought into sliding contact with an inner shaft sealing surface (55) at a radially inner sealing point with a prestressing force, wherein an annular gap (35) extending from a wet side to a dry side between the two shafts (23, 27) can be sealed by means of the sealing element (43), wherein a non-contact labyrinth seal (59) is arranged in front of the sealing element (43) on the wet side, and wherein the liquid located on the wet side in the labyrinth seal (59) is displaced radially outwards away from the radially inner sealing point into a liquid collecting contour (60), provided that a rotational speed of the outer hollow shaft (23) reaches an activation speed threshold, characterized in that that the liquid collection contour (60) in the outer hollow shaft (23) has a liquid outlet (63) through which the liquid displaced radially outwards in the labyrinth seal (59) flows in a flow direction (S) into a liquid space (31) which is located radially outside the outer hollow shaft (23), and / or that the fluid collection contour (60) of the labyrinth seal (59) on the inner circumference of the outer hollow shaft (23) has at least one circumferentially encircling annular groove (61) which is open radially inwards.

Description

[0001] The invention relates to a sealing system for a shaft arrangement according to the preamble of claim 1 or claim 16 or claim 17.

[0002] In a conventional shaft arrangement, exactly one shaft is guided through a bearing opening in a housing wall. The shaft can be supported by a rolling bearing on the inner circumference of the housing wall bearing opening, forming an annular gap in which a dynamic sealing element, such as a radial shaft seal, is arranged. The sealing element is usually pressed into the housing wall bearing opening and is preloaded with respect to the rotating shaft. Apart from this preload, the sealing element is not exposed to any external forces (e.g., centrifugal force). Such shaft arrangements are known, for example, from CH 257 507 A, DE 2 031 878 A, or AT 519 531 A1.

[0003] In contrast, an exemplary sealing system relates to a shaft arrangement with two rotatable shafts guided through a housing wall bearing opening, namely an outer hollow shaft and an inner shaft guided coaxially through the outer hollow shaft. The sealing system has a sealing element arranged non-rotatably on the outer hollow shaft. This sealing element can be brought into sliding contact with an inner shaft sealing surface at a radially inner sealing point using a preload force. In this way, the sealing element seals an annular gap extending from a wet side to a dry side, which is defined between the two shafts.

[0004] In the example sealing system, the seal contact occurs on the inner shaft to keep the sliding speed and thus the seal diameter as low as possible and to reduce material stress and friction at the sealing point. In this case, the sealing element is subject to centrifugal forces. Non-contact labyrinth seals are also known as an alternative to such a dynamic seal. With labyrinth seals, the sealing effect only begins at a minimum speed, which causes the fluid on the wet side to rotate and is thrown radially outward, i.e., away from the radially inner sealing point. In contrast, the labyrinth seal is ineffective if the minimum speed is not reached.

[0005] In order for the sealing element in the example sealing system to reliably adhere to the inner shaft at all operating points, seal reliably under all tolerances, and cover all temperature ranges, the sealing element must have an overlap with the inner shaft. The overlap is directly related to the preload force and thus to the friction at the sealing point. With rotating seals, centrifugal force is an additional component. This effect must be considered in the design (i.e., additional overlap).

[0006] Such a sealing element (e.g., a radial shaft seal) has an additional preload spring that applies a predefined preload to the seal. However, the seal can only be operated up to a certain sliding speed, since excessively high sliding speeds impair the sealing function due to the frictional power generated.

[0007] Alternatively, a PTFE ring can be used as a sealing ring. This creates less friction and therefore has a wider range of applications.

[0008] A generic sealing system is known from DE 10 2016 222 452 A1. DE 33 47 779 A1 discloses a non-contact seal.

[0009] The object of the invention is to provide a sealing system for a shaft arrangement that has a perfect sealing function in all operating modes.

[0010] The object is achieved by the features of the independent claims. Preferred developments of the invention are disclosed in the subclaims.

[0011] The core of the invention is that a seal is intended to seal the gap between two shafts. The following operating conditions exist: • The outer shaft is stationary, while the inner shaft rotates between 0 and a maximum speed. At maximum speed, the sliding speed is within the operating range of standard radial shaft seals. • The outer shaft rotates significantly faster than the inner shaft (with the gear ratios ie1 and ie2). The differential speed at the sealing point lies between 0 and a maximum value. At the maximum speed difference, the sliding speed exceeds the operating range of standard radial shaft seals.

[0012] The invention describes a combined contact and non-contact seal. When the outer shaft is stationary, the seal is not subject to centrifugal force. The seal therefore functions like a contact sealing system. The sliding speed is within a tolerable range.

[0013] As the outer shaft rotates, the centrifugal force causes the preload force to decrease proportionally with the speed, and the sealing element lifts off completely at a certain speed. However, the speed is now so high that the fluid is thrown outward and thus transported away from the (now open) sealing gap.

[0014] The new sealing system can optionally be equipped with radial stops for the spring or sealing element. This limits the expansion of the spring / sealing element. This allows the load on the spring or sealing element to be defined or limited.

[0015] The invention offers the following advantages, listed in bullet points: The preload force and thus the friction can be designed / optimized for a narrow speed range. As the outer shaft speed increases, the friction decreases continuously until liftoff, at which point it is zero. A radial shaft seal can be used in this embodiment, since sliding no longer occurs at the damaging differential speed, the friction loss is zero, and the expansion and thus the stress on the material is limited. The above principle also applies to PTFE rings.

[0016] Aspects of the invention are highlighted again in detail below: The invention is based on a sealing system which has a sealing element which is arranged on the outer hollow shaft in a rotationally fixed manner and which can be brought into sliding contact with an inner shaft sealing surface at a radially inner sealing point using a preload force. According to a first, a second, a third and a fourth embodiment of the invention, a non-contact labyrinth seal is arranged upstream of this sealing element on the wet side. If a speed of the outer hollow shaft reaches an activation speed threshold, the fluid in the labyrinth seal on the wet side is displaced away from the radially inner sealing point radially outwards into a fluid collection contour of the labyrinth seal (i.e. the sealing effect of the labyrinth seal only begins when the activation speed threshold is reached).In this way, the sealing effect is provided not only by the dynamic sealing element, but also by the labyrinth seal, which allows the dynamic sealing element to be relieved and, if necessary, designed for a smaller application range.

[0017] When the outer hollow shaft rotates, a centrifugal force builds up which acts on the dynamic sealing element in the opposite direction to the preload force. As the speed of the outer hollow shaft increases, the centrifugal force increases accordingly. According to the fourth embodiment of the invention, the sealing element lifts off the inner shaft sealing surface against the preload force and opens up a sealing gap at the sealing point, provided that the speed of the outer hollow shaft reaches a release speed threshold (i.e. the sealing effect of the dynamic seal ends when the release speed threshold is reached). With regard to perfect sealing function in all speed ranges, it is preferable if the activation speed threshold is smaller than the release speed threshold. As the speed of the outer hollow shaft increases starting from 0, the activation speed threshold is reached first, at which the sealing effect of the labyrinth seal starts.As the speed increases further, the separation speed threshold is reached, at which the dynamic sealing element lifts off from the inner shaft sealing surface due to centrifugal force.

[0018] The shaft arrangement can be designed, in particular, for the operating modes described below. In a first operating mode, the outer hollow shaft can be stationary and the inner shaft can rotate at a speed between 0 and a maximum value. In this case, the sliding speed achievable in the first operating mode between the dynamic sealing element and the inner shaft sealing surface can be within the sealing element's operating range. The dynamic sealing element can preferably be a radial shaft seal. Alternatively, the sealing element can also be implemented as a PTFE sealing ring.

[0019] In a second operating mode, the outer hollow shaft can rotate at a speed that is considerably higher than the inner shaft speed by a speed difference. The speed difference can range from 0 to a maximum value. At a speed difference that reaches the maximum value, the sliding speed between the sealing element and the inner shaft sealing surface can be outside the sealing element's operating range, provided that the sealing element is out of sealing contact with the inner shaft sealing surface due to centrifugal force.

[0020] Preferred geometric features of the labyrinth seal are described below: According to the first embodiment of the invention, the fluid collection contour of the labyrinth seal in the outer hollow shaft has a fluid outlet. When the labyrinth seal is effective (i.e., the rotational speed of the outer hollow shaft is at least at the activation speed threshold), the fluid displaced radially outward in the labyrinth seal flows in one flow direction into a fluid chamber located radially outside the outer hollow shaft.

[0021] In a technical implementation, the fluid chamber can be a radially outer annular gap between the outer hollow shaft and an inner circumference of the housing wall bearing opening. The radially outer annular gap can be sealed axially outward by a second dynamic sealing element.

[0022] In addition to the sealing system, the shaft arrangement according to the invention can also comprise a rotary bearing, in which the outer hollow shaft is supported on the inner circumference of the housing wall bearing opening via at least one outer radial bearing, forming the radially outer annular gap. Similarly, the outer hollow shaft can be supported on the inner shaft via at least one inner radial bearing, forming the radially inner annular gap in which the radially inner dynamic sealing element is arranged.

[0023] In the second embodiment of the invention, the fluid collection contour of the labyrinth seal on the inner circumference of the outer hollow shaft has at least one circumferentially extending annular groove that is open radially inward, in which the fluid displaced radially outward can collect. To enhance the sealing effect, the fluid outlet can open directly into the bottom of the annular groove.

[0024] According to the third embodiment, the labyrinth seal has at least one circumferentially extending annular land on the inner circumference of the outer hollow shaft. This land protrudes radially inward from the inner circumference of the outer hollow shaft by a land height. The annular land can be arranged at an axial distance from the sealing element, with the annular groove being arranged axially between the annular land and the sealing element.

[0025] In addition, the labyrinth seal can have a fluid deflection contour on the outer circumference of the inner shaft. This can be formed approximately in the negative form of the fluid collection contour (positioned on the inner circumference of the outer hollow shaft). The fluid deflection contour on the outer circumference of the inner shaft can have a circumferentially circumferential annular ridge. This can protrude into the annular groove of the radially outer fluid collection contour. Alternatively or additionally, the radially inner fluid deflection contour on the outer circumference of the inner shaft can have a circumferentially circumferential annular groove into which the annular ridge of the radially outer fluid collection contour can protrude.

[0026] An embodiment of the invention is described below with reference to the attached figures.

[0027] They show: Fig. 1 a section of a transmission structure with a shaft arrangement consisting of an outer hollow shaft and an inner shaft guided coaxially through the outer hollow shaft; Fig. 2 to 4 are views illustrating a sealing system and a rotary bearing of the shaft arrangement.

[0028] In the Fig. 1 shows a vehicle transmission structure as far as is necessary for understanding the invention. The transmission structure is arranged in a transmission housing, of which Fig. 1 only a housing wall 1 is shown. The transmission structure is shown in Fig. 1 shows a transmission shaft 3 on which fixed gears are arranged in a rotationally fixed manner. The transmission structure also includes a differential 5. Its input side 7 is connected to a transmission output shaft 9. From the differential output side 11, an output shaft 13 leads to a vehicle rear axle (HA), while another output shaft 15 leads to a vehicle front axle (VA).

[0029] The Fig. The vehicle transmission structure shown in Figure 1 has a combustion engine connection (not shown), in which a drive torque generated by the combustion engine is introduced into the transmission structure via an engine shaft and is routed via the transmission output shaft 9 to the vehicle's front axle VA and / or the vehicle's rear axle. Furthermore, the vehicle transmission has an electric motor connection, in which a drive torque generated by the electric motor 17 is introduced into the transmission structure via an electric motor shaft 19 and is routed via the transmission output shaft 9 to the vehicle's front axle VA and / or the vehicle's rear axle. Fig. 1, the electric machine 17 with its housing 18 is flanged to the gearbox housing wall 1. The electric machine shaft 19 is in the Fig. 1 or Fig. 2 is guided through a bearing opening 20 of the housing wall 1 and is drivingly connected to the gear shaft 3.

[0030] As from the Fig. 2, the electric machine shaft 19 is constructed in two parts, comprising an electric machine-side shaft section 21 and a transmission-side shaft section 23, which are plug-in connected to one another. In the same way, the output shaft 13 is constructed in two parts, comprising an electric machine-side shaft section 25 and a transmission-side shaft section 27, which are plug-in connected to one another. The transmission-side shaft section 25 of the output shaft 13 and the transmission-side shaft section 23 of the electric machine shaft 19 form a shaft arrangement according to the invention, in which the transmission-side shaft section 23 of the electric machine shaft 19 is implemented as an outer hollow shaft and the transmission-side shaft section 25 of the output shaft 13 is implemented as an inner shaft, which is guided coaxially through the outer hollow shaft 23.

[0031] The following are based on the Fig. 2 to 4 the structural design of the sealing system and the rotary bearing of the shaft arrangement guided through the housing wall 1 is described: Accordingly, the outer hollow shaft 23 is in the Fig. 2 is supported on the inner circumference of the housing wall bearing opening 20 via two axially spaced-apart rolling bearings 29, specifically forming a radially outer annular gap 31. In addition, the outer hollow shaft 23 is supported on the inner shaft 27 via an inner radial bearing 33, specifically forming a radially inner annular gap 35. The radially outer annular gap 31 between the bearing opening 20 and the outer hollow shaft 23 is sealed axially outward in a liquid-tight manner by a radially outer sealing element 37. In addition, a sealing system is provided which seals the radially inner annular gap 35 between the outer hollow shaft 23 and the inner shaft 27 axially outward. The end face of the outer hollow shaft 23 is supported on a shaft flange 41 of the inner shaft 27 via an axial bearing 39.

[0032] The sealing system has a radial shaft seal 43 as a dynamic sealing element, which fits into a sealing seat 44 ( Fig. 4) of the outer hollow shaft 23. The radially inner sealing element 43 is constructed from a circumferential sheet metal ring 45, which has an angular profile in cross-section, with a circumferential, radially outer ring leg 47, which merges at a sheet metal edge into a radially inwardly projecting ring flange 49. A sealing lip 51 is vulcanized onto the ring flange 49 and pressed into sliding contact with an inner shaft sealing surface 55 by a preload spring 53. In addition, the radially inner sealing element 43 has a radial stop 57, which limits a centrifugal force-induced movement of the sealing lip 51 radially outwards in order to prevent overstretching of the sealing lip 51 under centrifugal force stress. In the Fig. In the rest position shown in Figure 4, the sealing lip 51 is spaced from the radial stop 57 by a free travel path.

[0033] A non-contact labyrinth seal 59 is located in front of the radially inner sealing element 43 on its wet side. Its geometry is determined by the Fig. 2 and Fig. 3: Accordingly, the labyrinth seal 59 has a fluid collection contour 60 on the inner circumference of the outer hollow shaft 23. This is shown in the Fig. 3 is formed with an annular groove 61 circumferentially extending on the inner circumference of the outer hollow shaft 23 and open radially inward. A fluid outlet 63 opens at the bottom of the annular groove 61, which fluidically connects the radially inner annular gap 35 with the radially outer annular gap 31. The annular groove 61 is in the Fig. 3 is arranged between an annular web 65 and the radially inner sealing element 43. The annular web 65 is also circumferentially formed and protrudes radially inward from the inner circumference of the outer hollow shaft 23 by a web height.

[0034] The labyrinth seal 59 further has a fluid deflection contour 67 on the outer circumference of the inner shaft 27, which is formed approximately in negative form to the fluid collection contour 60. Accordingly, the fluid deflection contour 67 is formed on the outer circumference of the inner shaft 27 with a circumferential, radially outwardly projecting annular ridge 69, which projects into the annular groove 61 of the radially outer fluid collection contour 60. Furthermore, the fluid deflection contour 67 is formed on the outer circumference of the inner shaft 27 with a circumferentially circumferential annular groove 71, into which the annular ridge 65 of the radially outer fluid collection contour 60 projects.

[0035] The sealing lip 51 of the radially inner sealing element 43 can lift off the inner shaft sealing surface 55 against the preload force if the rotational speed of the outer hollow shaft 23 reaches a separation speed threshold. Furthermore, in the labyrinth seal 59, the hydraulic oil in the radially inner annular gap 35 can be displaced radially outward, away from the radially inner sealing point, if the rotational speed of the outer hollow shaft 23 reaches an activation speed threshold. To ensure proper sealing function of the sealing system, the activation speed threshold is dimensioned smaller than the separation speed threshold.

[0036] The sealing system must be designed for both pure combustion engine operation and electric motor operation, which places extreme demands on the sealing system: In the first operating mode (i.e., pure combustion engine operation), the outer hollow shaft 23 remains stationary, while the inner shaft 27 rotates at a speed correlated with the driving speed. The achievable sliding speed between the sealing lip 51 of the radially inner sealing element 43 and the inner shaft sealing surface 55 in the first operating mode lies within the sealing element's operating range.

[0037] Alternatively, in a second operating mode (i.e., electric motor operation), both the outer hollow shaft 23 and the inner shaft can rotate in the same direction of rotation, with the outer hollow shaft 23 rotating at a speed (e.g., 16,000 rpm) that is greater than the inner shaft speed (correlating with the vehicle speed) by a considerable speed difference. When the speed difference reaches a maximum, the sliding speed between the sealing lip 51 of the radially inner sealing element 43 and the inner shaft sealing surface 55 can lie outside the sealing element's range of application, provided that the sealing element 43 (at the maximum speed difference) is lifted off the inner shaft sealing surface 55, i.e., is no longer in sliding contact with the inner shaft sealing surface 55.

[0038] In the second operating mode, a Fig.3 oil flow S indicated by arrows, in which hydraulic oil from the differential 5 is guided via an inlet bore 58 into the radially inner annular gap 33 and there lubricates the axial bearing 39 and the radial bearing 33 and is then guided or thrown off in the flow direction through the labyrinth seal 59 and through the outlet bore 63 to the radially outer annular gap 31. LIST OF REFERENCE SYMBOLS: 1 housing wall 3 Gear shaft 5 Differential 7 Entrance page 9 Gearbox output shaft 11 Exit page 13 Output shaft to the vehicle rear axle 15 Output shaft to the vehicle front axle 17 Electric machine 18 Electrical machine housings 19 Electric machine shaft 20 Warehouse opening 21, 23 Shaft sections of the electric machine shaft 25, 27 Shaft sections of the output shaft 13 29 outer radial bearings 31 radial outer annular gap 33 inner radial bearing 35 radial inner annular gap 37 radial outer sealing element 39 thrust bearings 41 Shaft flange 43 radial inner sealing element 44 Sealing seat 45 sheet metal ring 47 ring shanks 49 Ring flange 50 Coverage 51 Sealing lip 53 Preload spring 55 Inner shaft sealing surface 57 Radial stop 58 Inflow 59 Labyrinth seal 60 Fluid collection contour 61 ring groove 63 Drain 65 Ringsteg 67 Liquid deflection contour 69 Ringsteg 71 Ring groove VA vehicle front axle HA vehicle rear axle S Oil flow direction

Claims

[1] Sealing system for a shaft arrangement with two rotatable shafts (23, 27) guided through a housing wall bearing opening (20), namely an outer hollow shaft (23) and an inner shaft (27) guided coaxially through the outer hollow shaft (23), which sealing system has a sealing element (43) arranged in a rotationally fixed manner on the outer hollow shaft (23), which can be brought into sliding contact with an inner shaft sealing surface (55) at a radially inner sealing point with a prestressing force, wherein an annular gap (35) extending from a wet side to a dry side between the two shafts (23, 27) can be sealed by means of the sealing element (43), wherein a non-contact labyrinth seal (59) is arranged in front of the sealing element (43) on the wet side, and wherein the liquid located on the wet side in the labyrinth seal (59) is displaced radially outwardly away from the radially inner sealing point into a liquid collecting contour (60), provided that a rotational speed of the outer hollow shaft (23) reaches an activation speed threshold, characterized by , that the liquid collection contour (60) in the outer hollow shaft (23) has a liquid outlet (63) through which the liquid displaced radially outwards in the labyrinth seal (59) flows in a flow direction (S) into a liquid space (31) which is located radially outside the outer hollow shaft (23), and / or that the fluid collection contour (60) of the labyrinth seal (59) on the inner circumference of the outer hollow shaft (23) has at least one circumferentially encircling annular groove (61) which is open radially inwards. [2] Sealing system according to claim 1, characterized bythat when the outer hollow shaft (23) rotates, a centrifugal force builds up which acts on the sealing element (43) in the opposite direction to the preload force and / or which increases with increasing speed of the outer hollow shaft (23). [3] Sealing system according to claim 2, characterized by that the sealing element (43) lifts off the inner shaft sealing surface (55) over an adjustment path against the preload force, provided that the speed of the outer hollow shaft (23) reaches a detachment speed threshold, and that a radial stop (57) is assigned to the sealing element (43), which limits the adjustment path of the sealing element (43) to the outside in order to avoid damage to the sealing element. [4] Sealing system according to one of the preceding claims, characterized by that with increasing speed of the outer hollow shaft (23) the friction of the sealing element (43) on the inner shaft sealing surface (55) becomes smaller and smaller, until the sealing element (43) lifts off due to centrifugal force, at which the friction is zero. [5] Sealing system according to one of the preceding claims, characterized by that the sealing element (43) is designed with an overlap (50) which is a diameter difference between the inner diameter of the undeformed sealing element (43) and the outer diameter of the inner shaft sealing surface (55). [6] Sealing system according to claim 5, characterized by that the overlap (50) is designed such that the sealing element (43) is in sealing contact with the inner shaft sealing surface (55) only in a small, lower speed range of the outer hollow shaft (23), and that in a subsequent upper speed range of the outer hollow shaft (23) the sealing element (43) is lifted off the inner shaft sealing surface (55), and that in the upper speed range of the outer hollow shaft (23) the sealing effect of the labyrinth seal (59) is activated. [7] Sealing system according to claim 5 or 6, characterized bythat the sealing element (43) is not designed with an excessively large overlap (50) in order to develop a sealing effect both in the lower speed range and in the upper speed range, but rather the sealing element (43) is designed with a comparatively smaller overlap (50) in order to develop a sealing effect only in the lower speed range. [8] Sealing system according to one of claims 3 to 7, characterized by that the activation speed threshold is smaller than the separation speed threshold. [9] Sealing system according to claim 8, characterized bythat in a first operating mode, i.e. in a purely internal combustion engine operation, the outer hollow shaft (23) is stationary and the inner shaft (27) rotates at a speed between 0 and a maximum value, and that the sliding speed that can be achieved in the first operating mode between the sealing element (43) and the inner shaft sealing surface (55) lies within the sealing element application range, and / or that the sealing element (43) is a radial shaft sealing ring or a PTFE sealing ring. [10] Sealing system according to claim 8 or 9, characterized bythat in a second operating mode, i.e. purely electromotive operation, both the outer hollow shaft (23) and the inner shaft (27) rotate in the same direction of rotation, and the speed of the outer hollow shaft (23) is greater than the inner shaft speed by a considerable speed difference, and that the speed difference lies between 0 and a maximum value, and that when the speed difference assumes the maximum value, the sealing element (43) is lifted off the inner shaft sealing surface (55) and the sliding speed between the sealing element (43) and the inner shaft sealing surface (55) lies outside the range of use of the sealing element (43). [11] Sealing system according to one of the preceding claims, characterized bythat the fluid space (31) is a radially outer annular gap between the outer hollow shaft (23) and an inner circumference of the housing wall bearing opening (20), and that the radially outer annular gap (31) is sealed outwards in the axial direction by means of a further sealing element (37). [12] Sealing system according to one of the preceding claims, characterized by that the labyrinth seal (59) has at least one circumferentially encircling annular web (65) on the inner circumference of the outer hollow shaft (23), which protrudes radially inwards from the inner circumference of the outer hollow shaft (23) by a web height, and that the annular web (65) is arranged at an axial distance from the sealing element (43). [13] Sealing system according to one of the preceding claims, characterized by that the annular groove (61) is arranged in the axial direction between the annular web (65) and the sealing element (43). [14] Sealing system according to one of claims 12 or 13, characterized bythat the labyrinth seal (59) has a liquid deflection contour (67) on the outer circumference of the inner shaft (27), which is formed in negative form to the liquid collection contour (60) on the inner circumference of the outer hollow shaft (23), and that the liquid deflection contour (67) has a circumferentially surrounding annular web (69) on the outer circumference of the inner shaft (27) which projects into the annular groove (61) of the radially outer liquid collection contour (60), and / or that the liquid deflection contour (67) has a circumferentially surrounding annular groove (71) on the outer circumference of the inner shaft (27), into which the annular web (65) of the radially outer liquid collection contour (60) projects. [15] Sealing system according to one of the preceding claims, characterized bythat the outer hollow shaft (23) is supported on the inner circumference of the housing wall bearing opening (20) via at least one outer radial bearing (29), specifically forming the radially outer annular gap (31), and / or that the outer hollow shaft (23) is supported on the inner shaft (27) via at least one inner radial bearing (33), specifically forming the radially inner annular gap (35). [16] Sealing system for a shaft arrangement with two rotatable shafts (23, 27) guided through a housing wall bearing opening (20), namely an outer hollow shaft (23) and an inner shaft (27) guided coaxially through the outer hollow shaft (23), which sealing system has a sealing element (43) arranged in a rotationally fixed manner on the outer hollow shaft (23), which can be brought into sliding contact with an inner shaft sealing surface (55) at a radially inner sealing point with a prestressing force, wherein an annular gap (35) extending from a wet side to a dry side between the two shafts (23, 27) can be sealed by means of the sealing element (43), wherein a non-contact labyrinth seal (59) is arranged in front of the sealing element (43) on the wet side, and wherein the liquid located on the wet side in the labyrinth seal (59) is displaced radially outwardly away from the radially inner sealing point into a liquid collecting contour (60), provided that a rotational speed of the outer hollow shaft (23) reaches an activation speed threshold, characterized by , that the labyrinth seal (59) has at least one circumferentially encircling annular web (65) on the inner circumference of the outer hollow shaft (23), which protrudes radially inward from the inner circumference of the outer hollow shaft (23) by a web height. [17] Sealing system for a shaft arrangement with two rotatable shafts (23, 27) guided through a housing wall bearing opening (20), namely an outer hollow shaft (23) and an inner shaft (27) guided coaxially through the outer hollow shaft (23), which sealing system has a sealing element (43) arranged in a rotationally fixed manner on the outer hollow shaft (23), which can be brought into sliding contact with an inner shaft sealing surface (55) at a radially inner sealing point with a prestressing force, wherein an annular gap (35) extending from a wet side to a dry side between the two shafts (23, 27) can be sealed by means of the sealing element (43), wherein a non-contact labyrinth seal (59) is arranged in front of the sealing element (43) on the wet side, and wherein the liquid located on the wet side in the labyrinth seal (59) is displaced radially outwardly away from the radially inner sealing point into a liquid collecting contour (60), provided that a rotational speed of the outer hollow shaft (23) reaches an activation speed threshold, and wherein, when the outer hollow shaft (23) rotates, a centrifugal force builds up which acts on the sealing element (43) in the opposite direction to the preload force and / or which increases with increasing speed of the outer hollow shaft (23), characterized by , that the sealing element (43) lifts off the inner shaft sealing surface (55) over an adjustment path against the preload force, provided that the speed of the outer hollow shaft (23) reaches a detachment speed threshold, and that a radial stop (57) is assigned to the sealing element (43), which limits the adjustment path of the sealing element (43) to the outside in order to avoid damage to the sealing element.

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