Shaft bearing

Abstract

The invention relates to a shaft bearing (10) consisting of the bearing housing (20) and a shaft (30), wherein the shaft bearing (10) has a first axial bearing (31), a second axial bearing (32) and at least one first radial bearing (41), wherein the shaft (30) has at least one thicker portion (50) in the interior of the bearing housing (20) and between the first axial bearing (31) and the second axial bearing (32), wherein the first axial bearing (31) is statically preloaded in the axial direction by means of a first pressure element (61), and wherein the second axial bearing (32) is statically preloaded in the axial direction by means of a second pressure element (62).

Description

[0001] Shaft bearings

[0002] The invention relates to a shaft bearing which is designed to absorb forces and can thus be used in a watercraft with a small supporting structure, in particular a modular, unmanned underwater vehicle.

[0003] Especially in unmanned underwater vehicles, the absence of a pressure hull allows for the use of a comparatively lightweight supporting structure. In particular, large parts of such an unmanned underwater vehicle can be flushed with water.

[0004] Furthermore, it is clear that in such unmanned underwater vehicles, due to the massive reduction in mass achieved by dispensing with the structures necessary for carrying people, comparatively simple and light engines are also used as propulsion motors.

[0005] However, geometric requirements often result in the need for a longer shaft between the engine and the propeller.

[0006] An improvement to thrust bearings or collars is known from FR 494 165 A.

[0007] A deep-sea high-temperature miniature underwater propeller with magnetic transmission and pressure compensation is known from CN 2 03 246 580 U.

[0008] An underwater propulsion unit is known from DE 10 2015 100 502 B4.

[0009] A vibration-damped ship thrust bearing is known from DE 31 12 306 A1.

[0010] A bearing arrangement is known from DE 10 2006 018 264 A1.

[0011] A hybrid radial bearing is known from JP S56-157 426 U. The object of the invention is to provide a shaft bearing that is capable of absorbing the forces, including the axial forces, of a propulsion propeller and is thus suitable for use in an unmanned underwater vehicle, particularly a modular one.

[0012] This object is achieved by the shaft bearing having the features specified in claim 1. Advantageous further developments emerge from the subclaims, the following description, and the drawings.

[0013] The shaft bearing according to the invention consists of the bearing housing and a shaft. The shaft bearing has a first axial bearing, a second axial bearing, and at least one first radial bearing. The shaft has at least one thickened portion inside the bearing housing and between the first axial bearing and the second axial bearing. This means that the diameter of the shaft is larger in the area of ​​the thickened portion. This creates the possibility of absorbing axial forces, i.e. forces directed in the direction of the longitudinal axis of the shaft. This can be a continuous thickened portion between the first axial bearing and the second axial bearing, or there can be two separate thickened portions. The second variant allows the weight of the shaft to be saved. The first axial bearing has a static preload in the axial direction by means of a first pressure element.The second axial bearing has a static preload in the axial direction by means of a second pressure element. Without this preload, the deflection typical of a propeller shaft could result in at least one of the axial bearings being over-relieved on at least one side, causing displacement in the axial bearing and subsequent damage. This is prevented by the fact that each of the axial bearings has its own preload, thus ensuring the reliability of the axial bearings.

[0014] In a further embodiment of the invention, the shaft bearing has a second radial bearing. This enables more reliable support and simultaneously ensures safe operation even when the shaft bends. In a further embodiment of the invention, the first radial bearing and preferably also the optional second radial bearing are self-aligning ball bearings. Self-aligning ball bearings are described, for example, in DIN 630 and are particularly suitable for ensuring secure support even when the shaft bends.

[0015] In a further embodiment of the invention, the first thrust element is arranged between the first axial bearing and the shaft. The second thrust element is arranged between the second axial bearing and the shaft. This allows the first axial bearing and the second axial bearing to be rigidly and thus more stably attached to the bearing housing.

[0016] In a further embodiment of the invention, the first radial bearing is arranged between the first axial bearing and the second axial bearing in the area of ​​the thickened portion. This ensures optimal force distribution, even in the event of undesired shaft deflection.

[0017] In a further embodiment of the invention, the first radial bearing and the second radial bearing form a force-transmitting connection between the shaft and the bearing housing. This means that forces can be transmitted directly from the shaft to the first radial bearing and from the first radial bearing to the bearing housing without any additional intervening components. This allows forces to be transmitted very reliably, especially in the event of unintentional shaft deflection.

[0018] In a further embodiment of the invention, the bearing housing is flushed with water. The advantage is that the shaft bearing does not need to be pressure-resistant to withstand external water pressure. Alternatively, the shaft bearing could be filled with a non-compressible or only slightly compressible fluid and preferably have pressure equalization with the environment. In this case, however, appropriate sealing of the shaft is required, which in turn increases frictional resistance during operation and thus wear.

[0019] In a further embodiment of the invention, the bearing housing has a water inlet. The water inlet has a filter. The main problem with a water-flushed bearing, as with any other component, is fouling. The filter is intended to enable pressure equalization, but also to prevent the ingress of sand and, above all, life forms, in order to prevent fouling within the bearing housing.

[0020] In a further embodiment of the invention, the first axial bearing and the second axial bearing are axial deep groove ball bearings.

[0021] In a further embodiment of the invention, the first axial bearing, the second axial bearing, and the first radial bearing are ceramic bearings. The use of ceramic prevents corrosion problems. Furthermore, it has proven particularly suitable for use in aqueous environments.

[0022] In a further embodiment of the invention, the first axial bearing and the second axial bearing are loaded by means of springs with an adjustable preload. The advantage is that by installing the springs, the preload can be specifically adjusted during installation and thus construction tolerances can be easily compensated. In this embodiment, it can be provided that the radial bearings are fixed to the shaft, but are not fixed with their bearing shell on the bearing housing in the axial direction, so that they can follow the movement of the springs. This can be particularly helpful for preventing tension in the radial bearings if an axial load occurs during installation or operation.

[0023] In a further aspect, the invention relates to an underwater vehicle with a traction motor, a propeller, and a shaft bearing according to the invention with a shaft. The shaft bearing is arranged between the propeller and the traction motor. The shaft bearing thus absorbs all axial forces, and in particular the forces generated by propulsion, and the traction motor is therefore not subjected to any load. This enables the use of comparatively simple and lightweight motors, such as those particularly suitable for use in an unmanned underwater vehicle. The shaft bearing is connected to the structure of the underwater vehicle. The structure is understood to mean the entirety of the load-bearing parts. In the case of an unmanned underwater vehicle, in particular a modular underwater vehicle, this can also be a simple frame structure.In particular, the propulsion motor, the shaft bearing, and the shaft are arranged in a water-surrounded area of ​​the underwater vehicle. In a manned submarine, the pressure hull always forms a massive structure that is easily subjected to forces, but this is not the case in unmanned systems. The shaft can be constructed in several parts. In particular, the shaft can be separated between the shaft bearing and the propulsion motor, so that the shaft preferably has a connecting element behind the shaft bearing and in front of the propulsion motor.

[0024] In a further embodiment of the invention, the propeller is arranged directly adjacent to the shaft bearing. The shorter the distance between the propeller and the shaft bearing, the less the shaft bends. In this case, the unmanned underwater vehicle is preferred, since in a manned underwater vehicle, the most important part of the supporting structure is usually at a greater distance from the propeller due to the pressure hull, since a flow-optimized secondary hull occupies the space between the pressure hull and the propeller, particularly in the stern area. For a shaft that is more than three times as long as the shaft bearing, the shaft bearing can preferably be arranged in the third of the shaft length assigned to the propeller.

[0025] In a further embodiment of the invention, a hollow shaft is arranged between the shaft bearing and the traction motor. Firstly, the shaft bearing protects this area from axial forces, so that this area of ​​the shaft only has to transmit the rotary motion. Secondly, this allows weight to be saved and, at the same time, the shaft torque can be reduced due to the reduced mass.

[0026] In a further embodiment of the invention, the underwater vehicle is an unmanned underwater vehicle, preferably a modular unmanned underwater vehicle.

[0027] For example, the entire drive train of the underwater vehicle can be constructed as follows: The drive motor usually has a very short shaft that protrudes from the drive motor. This drive motor shaft is connected to a hollow shaft via a connecting element. The hollow shaft is connected at the opposite end to the shaft protruding from the shaft bearing by another connecting element. The hollow shaft is further preferably supported by one, particularly preferably two radial bearings. Since the shaft bearing according to the invention absorbs all forces coming from the propeller, the radial bearings of the hollow shaft can be of simple design. The only advantage is that these radial bearings have seals, whereby these seals only serve to prevent the ingress of foreign bodies such as sand or growth.The propeller is preferably connected directly to the shaft of the shaft bearing and therefore has only a very small distance to the shaft bearing. This minimizes bending.

[0028] In a modular design of the underwater vehicle, the propulsion motor, shaft bearings, and propeller are preferably arranged in a common module. This propulsion module preferably also includes the rudder. The propulsion motor is preferably an electric propulsion motor, so that only an electrical connection to a module with an energy generation device, for example, a fuel cell device, and / or a module with an energy storage device, for example, an accumulator, needs to be established. Preferably, the entire propulsion module is water-flushed and has only a hydrodynamic outer shell.

[0029] The shaft bearing according to the invention is explained in more detail below using an embodiment shown in the drawings.

[0030] Fig. 1 Cross section

[0031] Fig. 2 Drive module

[0032] Fig. 1 shows a cross-section through an exemplary shaft bearing 10. The illustration is purely schematic and not to scale. The shaft bearing 10 has a bearing housing 20. This is, for example, directly connected to the structure of an underwater vehicle and can thus directly transmit the propulsive force generated by the propeller into the structure. The shaft 30 runs through the bearing housing 20. For example, the shaft 30 can be connected to a propeller on one side and to a traction motor on the other.

[0033] The shaft bearing 10 has a total of four bearings 31, 32, 41, 42 which are able to absorb the forces from the shaft 30. The first axial bearing 31 and the second axial bearing 32 are essential for propulsion. Through these two axial bearings 31, 32, forces acting along the shaft 30, in particular the propulsion from the shaft 30, can be transferred to the bearing housing 20 and thus ultimately to the structure to which the shaft bearing 20 is connected. The advantage is that the shaft 30 on the motor side is thus free of axial forces and thus the traction motor does not have to absorb the propulsion forces. A symmetrical design is necessary to enable both forward and reverse travel. In order to transfer the forces from the shaft 30 to the axial bearings 31, 32, the shaft 30 has a thickening 50 inside the bearing housing 20, so that a lateral support surface for the axial bearings 31, 32 is produced.

[0034] Furthermore, the shaft bearing has two radial bearings 41, 42 designed as self-aligning ball bearings. Due to the shape of the circular section of the self-aligning ball bearing, the first radial bearing 41 and the second radial bearing 42 can compensate for a certain bending of the shaft 30. However, bending of the shaft 30 could lead to the first axial bearing 31 or the second axial bearing 32 being relieved of load at certain points to such an extent that the bearing could be damaged. To prevent this, the shaft bearing 10 has a first pressure element 61 on the first axial bearing 31 and a second pressure element 62 on the second axial bearing 32. The first pressure element 61 and the second pressure element 62 each have a plurality of spring elements which ensure that the axial bearings 31, 32 always have a minimal load and thus remain stable.

[0035] In order to achieve pressure equalization, the bearing housing 20 has a water inlet with a filter 70. This allows ambient water to penetrate into the interior, thus creating pressure equalization. The filter 70 largely prevents growth within the bearing housing 20. In order to nevertheless achieve a sufficient service life of the bearings 31, 32, 41, 42, these are ceramic bearings. Fig. 2 shows an example of a drive module. The drive module has a supporting structure 140, for example a steel frame. The drive motor 100 and the shaft bearing 10 are fastened to the structure 140. A hollow shaft 150 is arranged between the drive motor 100 and the shaft bearing 10, which is connected to the shaft of the drive motor 100 via a connecting element 120 and, on the opposite side, to the shaft 30 of the shaft bearing 10 via a connecting element 120.For support, the hollow shaft 150 is held by two radial bearings 130, which are designed as simple, sealed ceramic roller bearings. The sealing of the radial bearings 130 serves only to prevent the ingress of foreign matter and to prevent growth. The propeller 110 is arranged on the shaft 30 of the shaft bearing 10, in close proximity to the shaft bearing 10. All propulsive forces generated by the propeller 110 are transmitted directly to the shaft bearing 10 and from there into the structure 140. The traction motor 100 thus remains unloaded by the propulsive forces.

[0036] Reference symbol

[0037] 10 shaft bearings

[0038] 20 bearing housings

[0039] 30 wave

[0040] 31 first axial bearing

[0041] 32 second axial bearing

[0042] 41 first radial bearing

[0043] 42 second radial bearing

[0044] 50 Thickening

[0045] 61 first printing element

[0046] 62 second pressure element

[0047] 70 filters

[0048] 100 traction motor

[0049] 110 propellers

[0050] 120 connecting element

[0051] 130 radial bearings

[0052] 140 Structure 150 Hollow shaft

Claims

Patent claims 1. Shaft bearing (10) consisting of the bearing housing (20) and a shaft (30), wherein the shaft bearing (10) has a first axial bearing (31), a second axial bearing (32) and at least one first radial bearing (41), wherein the shaft (30) has at least one thickened portion (50) in the interior of the bearing housing (20) and between the first axial bearing (31) and the second axial bearing (32), wherein the first axial bearing (31) has a static preload in the axial direction by means of a first pressure element (61), wherein the second axial bearing (32) has a static preload in the axial direction by means of a second pressure element (62).

2. Shaft bearing (10) according to claim 1, characterized in that the shaft bearing (10) has a second radial (42) bearing.

3. Shaft bearing (10) according to one of the preceding claims, characterized in that the first pressure element (61) is arranged between the first axial bearing (31) and the shaft (30), wherein the second pressure element (62) is arranged between the second axial bearing (32) and the shaft (30).

4. Shaft bearing (10) according to one of the preceding claims, characterized in that the first radial bearing (41) is arranged between the first axial bearing (31) and the second axial bearing (32) in the region of the thickening (50).

5. Shaft bearing (10) according to one of the preceding claims, characterized in that the first radial bearing (41) is a self-aligning ball bearing.

6. Shaft bearing (10) according to one of the preceding claims, characterized in that the bearing housing (20) is flushed with water.

7. Shaft bearing (10) according to claim 6, characterized in that the bearing housing (20) has a water inlet, wherein the water inlet has a filter (70).

8. Shaft bearing (10) according to one of the preceding claims, characterized in that the first axial bearing (31) and the second axial bearing (32) are axial deep groove ball bearings.

9. Shaft bearing (10) according to one of the preceding claims, characterized in that the first axial bearing (31), the second axial bearing (32) and the first radial bearing (41) are ceramic bearings.

10. Shaft bearing (10) according to one of the preceding claims, characterized in that the first axial bearing (31) and the second axial bearing (32) are loaded by means of springs with an adjustable preload.

11. Underwater vehicle with a traction motor (100), a propeller (110) and a shaft bearing (10) according to one of the preceding claims, wherein the shaft bearing (10) is arranged between the propeller (110) and the traction motor (100), wherein the shaft bearing (10) is connected to the structure of the underwater vehicle.

12. Underwater vehicle according to claim 11, characterized in that the propeller (110) is arranged directly adjacent to the shaft bearing (10).

13. Underwater vehicle according to one of claims 11 to 12, characterized in that a hollow shaft (150) is arranged between the shaft bearing (10) and the drive motor (100).

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