Sealing device for a shaft

Abstract

The invention relates to a sealing device (16) for a shaft (14), wherein the sealing device (16) has an inlet (21) and an outlet (22) for a lubricant and is designed to be arranged between a housing (12) receiving the shaft (14) and the shaft (14) and to form a flow space (17) together with a rolling bearing (15) arranged on the shaft (14).

Description

The invention relates to a sealing device for a shaft, wherein the sealing device has an inlet and an outlet for a lubricant and is configured to be arranged between a housing receiving the shaft and the shaft and to form a flow space together with a rolling bearing arranged on the shaft. The invention also relates to an electric machine which is sealed by means of such a sealing device.Sealing devices for shafts are typically used to separate and seal an interior space, for example an electric machine, filled with a lubricant and bounded by a housing from an environment. For this purpose, such sealing devices are arranged together with a rotary bearing in a housing feedthrough in which the shaft, for example a drive shaft, is rotatably mounted by means of the rotary bearing.In order to increase the durability of such a sealing device or of a radial shaft sealing ring, active lubrications of the sealing device, such as in the form of an oil shower and / or proportional wetting, which can be influenced by a filling level of the interior, are known. Such active solutions for lubrication, in particular a combination of a pivot bearing and a radial shaft sealing ring, typically cannot be implemented simply and / or in a cost-neutral manner.Against this background, it is an object of the invention to improve lubrication of or by means of a sealing device for a shaft. In particular, the sealing device should be improved to the extent possible to enable as reliable and / or permanent lubrication as possible.This object is achieved by a sealing device for a shaft having the features of claim 1 and an electric machine having the features of claim 9.According to a first aspect, a sealing device for a shaft is specified, wherein the sealing device has an inlet and an outlet for a lubricant and is configured to be arranged between a housing accommodating the shaft and the shaft and to form a flow space together with a rolling bearing arranged on the shaft, wherein the sealing device has a reservoir which is configured to accommodate the lubricant.Because the sealing device itself has a reservoir for holding and / or holding the lubricant, it can be available for lubricating the sealing device during a rotation or rotational movement of the shaft, in particular immediately in time. This makes it possible to prevent or prevent lack of lubrication of the sealing device or of the sealing ring.According to a further aspect, an electric machine is proposed, having a housing and a shaft, wherein at least one sealing device described herein is arranged between the shaft and the housing. By providing the sealing device described herein, lubrication of the shaft bearing and the sealing device of the electric machine can be improved. In particular, more lubricant can be stored in the flow chamber by the reservoir, so that, for example, a lack of lubrication can be avoided and, in particular, a better mixing for the lubricant can be achieved at the same time, so that overheating of the sealing device, in particular at higher rotational speeds, can be avoided.The electric machine can be used, for example, as an electric traction machine for an electrically operable motor vehicle. The electric machine is in this case in particular designed as a current-excited synchronous machine (SSM) or an asynchronous machine (ASM) and can have a stator which is mounted in a fixed manner in the interior formed by the housing and a rotor which is mounted movably, in particular rotatably, with respect to the stator and is connected to the shaft in a rotationally fixed manner. In particular, when a shaft of a current-excited synchronous machine is mounted, robust sealing is necessary, since the shaft or rotor shaft can be arranged both in the oil- or lubricant-filled interior space comprising the rotor and stator and in a brush space. Brush dust must not come into contact with the oil or lubricant, because otherwise a risk of short circuit may arise. Such a secure and / or permanent seal can be provided by means of the proposed sealing device. The proposed sealing device can also be used in a separately excited synchronous machine, for example for sealing outwards, in particular in a region in which a drive shaft leaves the housing.The sealing device is in particular designed as a sealing ring or radial shaft sealing ring, which can be configured to be arranged axially adjacent to a rotary bearing or rolling bearing arranged on the shaft. Here, the rolling bearing is typically arranged in a bushing opening in the housing in order to rotatably support the shaft. The sealing device is in particular configured to be arranged on a side of the rolling bearing opposite the interior formed by the housing or can be arranged there in order to prevent an oil, coolant and / or lubricant located in the interior in which movable components the electric machine can be arranged from escaping. The shaft bearing can be designed as a rolling bearing, in particular as a ball bearing, cylindrical roller bearing, needle bearing, or can have another known rolling bearing shape.The sealing device is arranged within the electric machine, in particular in such a way that an inlet is arranged vertically above the shaft in an installed state of the electric machine, in particular in a motor vehicle, in order to thus enable the flow space to be fed with lubricant, in particular by gravity, and thus enable passive lubrication of the sealing device and / or of the rolling bearing. The outlet for the lubricant can be arranged in particular in a vertically lower third of the sealing device in order to enable passive outflow of the lubricant and thus a flow through the flow chamber. Inlet and outlet are in this case fluidically connected to the flow space formed, in order to allow a throughflow or a flow of the lubricant in the flow space.The invention is based in particular on the concept of providing a lubricant reservoir in a vicinity of the rolling bearing within the sealing device in order to enable a lubricant even over a longer service life in the sealing device. For this purpose, the sealing device has the reservoir, which is in particular designed and / or arranged in such a way that lubricant can be available from the reservoir, in particular from a first revolution of the shaft, the sealing device or the rolling bearing, by a rotation of the shaft and / or an air flow generated thereby. As a result, lack of lubrication and the formation of cracks which results therefrom can be avoided or even prevented, as a result of which durability of the sealing device can be increased.In one embodiment, the reservoir is formed as a recess on an inner periphery of a wall of the sealing device. The sealing device can be closed on one axial side and can be formed on the opposite side, in particular with circumferential opening, or can have a circumferential opening. At its periphery, the sealing device has the wall by means of which it can sealingly abut the housing recess. On an inner circumference of this wall, a recess can be provided, which is arranged in particular spaced apart from the outlet in the wall in the circumferential direction, so that lubricant can be stored.The recess can be designed to accommodate and / or keep available a predetermined volume of the lubricant, so that this can be conveyed out of the recess during a rotation of the shaft. As a result, even in a rest state, lubricant can be held in stock within and by the sealing device without the latter being able to flow completely out of the sealing device through the outlet.In one embodiment, the reservoir is formed as a circumferentially extending groove. In this way, a transport of the lubricant from the reservoir and in the circumferential direction can be promoted, whereby a distribution of the lubricant within the rolling bearing or the sealing device can be made possible or improved. In other embodiments, the recess can have a different geometry and can be designed, for example, as a ball segment or transverse groove in order to be able to receive and / or reserve lubricant according to requirements.In one embodiment, the inlet and / or the outlet is arranged on a periphery of the sealing device. This makes it possible to promote the supply and / or discharge of the lubricant, because a radial inflow and outflow of the lubricant can be made possible. In other embodiments, it can be provided that the inlet and / or outlet is arranged on a side wall of the sealing device.In one embodiment, the outlet and the inlet form an angle, in particular with respect to a central axis of the sealing device. As a result, the inlet and the outlet are not arranged on one axis, so that a direct flow of lubricant can be avoided. In addition, this allows optimized placement for the reservoir.In one embodiment, the angle is about 150° to about 120°. As a result, the outlet is arranged offset with respect to a vertical and can enclose an angle of approximately 30° to approximately 60° with the latter. As a result, an opening of the drain, in particular in an installed state in an electric machine or a motor vehicle, can be arranged higher relative to the reservoir, as a result of which it is possible to retain lubricant in the reservoir or in a lower region of the sealing device.In one embodiment, the reservoir is arranged on an axis with the inlet. As a result, the reservoir and the inlet can be arranged opposite one another with respect to a central axis of the sealing device, such that the reservoir can be placed vertically at a lowermost position of the sealing device in an installed state in an electric machine, in particular in an operating position in a motor vehicle, as a result of which it is possible to promote the holding of lubricant, in particular as a result of gravity effects. As a result, a supply of lubricant to the sealing device or the rolling bearing can be improved.In one embodiment, the sealing device has a circumferentially formed flow channel. The flow channel is arranged in particular as an annular groove on a flat side of the sealing device, which groove can be arranged adjacent to the rolling bearing. As a result, a flow through the sealing device, in particular by means of lubricant from the reservoir, can be promoted during operation or during a rotation of the shaft, because lubricant in the flow channel can be distributed over the circumference of the sealing device. In this case, the flow channel is in particular configured such that it is formed opposite and / or together with the rolling bearing in the region of the flow chamber or delimits the latter.In one embodiment, the flow channel is arranged axially spaced apart from the inlet and / or the outlet. In this case, it can be provided that the inlet and / or outlet encloses an angle with the central axis of the sealing device and is arranged correspondingly obliquely in the sealing device. In this case, the inlet and / or the outlet can open into the flow channel, as a result of which a feeding of the flow channel or a discharge of lubricant into or from the flow channel is made possible, in particular by means of a direct fluidic connection.In one embodiment, the outlet is arranged offset from the reservoir counter to a rotational direction of the shaft. As a result, lubricant which is conveyed from the reservoir by a rotation of the shaft can first flow around the shaft before it reaches a region of the outlet in order to be able to leave the sealing device there. In this way, utilization of the lubricant stored in the reservoir can be improved because a dwell time within the sealing device can be extended.Further advantages and possible applications of the invention will become apparent from the following description in conjunction with the figures. FIG. 1 shows a schematic sectional view of an exemplary embodiment of an electric machine according to the invention with a sealing device according to the invention. FIG. 2 shows a schematic sectional view of an exemplary embodiment of a sealing device according to the invention.FIG. 1 shows a schematic sectional view along an axis of rotation M of an electric machine 10 according to the invention according to an exemplary embodiment.The electric machine 10 has a rotor 11 and a stator, not shown here. The rotor 11 is arranged in an interior 13 of the electric machine 10 enclosed by a housing 12, which interior can be filled at least partially with an oil, coolant and / or lubricant. The rotor 11 is connected in a rotationally fixed manner to an (anti-Ebs) shaft 14 for driving at least one wheel of a motor vehicle.The shaft 14 is rotatably mounted by means of a rolling or ball bearing 15 in a housing passage for the shaft 14. A sealing device 16 is arranged axially adjacent to the bearing 15. The sealing device 16 is designed as a radial shaft sealing ring and has an inlet 21 and an outlet 22 for a lubricant, which are configured to conduct the lubricant into a flow chamber 17 or to conduct it out of it. The flow chamber 17 is formed in particular between the sealing device 16, the housing 12, the rolling bearing 15 and the shaft 14. In addition, the sealing device 16 has a reservoir 18 which is configured to receive the lubricant. The reservoir 18 is formed as a recess or a groove extending in the circumferential direction of the sealing device 16 on an inner circumference of a circumferential wall 23 of the sealing device 16.The inlet 21 and the outlet 22 are arranged on a periphery of the sealing device 16 and, in the exemplary embodiment shown, each open into a flow channel 20 formed in the sealing device 16. the flow channel 20 is formed here in a circumferential manner on a side of the sealing device 16 which adjoins the rolling bearing 15 in order to convey lubricant, in particular by means of an air flow generated by a rotation of the shaft 14, and to provide it to the sealing device 16 and to the rolling bearing 15.FIG. 2 shows the sealing device 16 of FIG. 1 in a sectional illustration in a plane intersecting perpendicularly the axis of rotation M or central axis M (cf. FIG. 1 ) of the sealing device 16. The rolling bearing 15 is illustrated in a dashed illustration.In this illustration, it can be seen that the reservoir 18 is arranged on an axis A with the inlet 21, wherein the axis A runs through the central axis of the sealing device 16 running perpendicular to the drawing plane. In addition, the inlet 21 and the outlet 22 enclose an angle α of approximately 150°. In other embodiments, this angle α may be about 150° to about 120°. As a result, the outlet is arranged offset with respect to the vertical, which on the one hand enables the reservoir 18 to be positioned at a lowest point of the sealing device 18 in an installation situation in an electric machine 10 in a motor vehicle. This may promote the retention of lubricant in the reservoir. On the other hand, the outlet 22 of the sealing device 16 can be arranged offset with respect to the reservoir 18 counter to a rotational direction D of the shaft 14, as a result of which the lubricant can flow around the shaft 14 first during a rotation thereof, in order then to pass into a region of the outlet 22. As a result, a lubricating effect can be improved and wear of the sealing device 16 can be reduced.LIST OF REFERENCE CHARACTERS10 Electric machine 11 Rotor 12 Housing 13 Interior 14 Shaft 15 Rolling bearing 16 Sealing device 17 Flow chamber 18 Reservoir 20 Flow channel 21 Inlet 22 Outlet 23 Wall A Axis D Direction of rotation M Central axis α Angle

Claims

Sealing device (16) for a shaft (14), wherein the sealing device (16) has an inlet (21) and an outlet (22) for a lubricant and is configured to be arranged between a housing (12) receiving the shaft (14) and the shaft (14) and to form a flow space (17) together with a rolling bearing (15) arranged on the shaft (14), wherein the sealing device (16) has a reservoir (18) configured to receive the lubricant.Sealing device (16) according to claim 1, wherein the reservoir (18) is formed as a recess on an inner periphery of a wall (23) of the sealing device (16).Sealing device (16) according to one of the preceding claims, wherein the reservoir (18) is formed as a groove extending in the circumferential direction.Sealing device (16) according to one of the preceding claims, wherein the inlet (21) and / or the outlet (22) is arranged on a periphery of the sealing device (16).Sealing device (16) according to one of the preceding claims, wherein the outlet (22) and the inlet (21) enclose an angle (α).The sealing device (16) according to the preceding claim, wherein the angle (α) is about 150° to about 120°.Sealing device (16) according to one of the preceding claims, wherein the reservoir (18) is arranged on an axis (A) with the inlet (21).Sealing device (16) according to one of the preceding claims, wherein the sealing device (16) has a circumferentially formed flow channel (20).Electric machine (10), comprising a housing (12) and a shaft (14), wherein at least one sealing device (16) according to at least one of the preceding claims is arranged between the shaft (14) and the housing (12).Electric machine (10) according to the preceding claim, wherein the outlet of the sealing device (16) is arranged offset from the reservoir (18) counter to a rotational direction (D) of the shaft (14).

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