Storage facility, electric machine, pump

Abstract

Bearing device (9) for rotatably supporting a shaft (4) in a housing (7), with a rolling element bearing (11) having an inner ring (12) and an outer ring (13), wherein the shaft (4) is axially arranged in a recess (15) of the housing (7), characterized in that the inner ring (12) is arranged non-rotatably on the shaft (4), that the outer ring (13) is arranged non-rotatably on the housing (7), and that the inner ring (12) of the rolling element bearing (11) has an outer diameter (D A ) has a diameter larger than the inner diameter (D I ) the recess (15) and axially against the housing (7) with an intermediate sealing element (18).

Description

[0001] The invention relates to a bearing device for rotatably supporting a shaft in a housing, with a rolling element bearing having an inner ring and an outer ring, wherein the shaft is arranged axially in a recess of the housing, or lies in a recess.

[0002] Furthermore, the invention relates to an electric machine with a corresponding bearing device and a hydraulic pump with a corresponding electric machine. State of the art

[0003] Storage facilities of the type mentioned above are known from the prior art, for example from DE 8102255 U1.

[0004] Typically, machine shafts are rotatably mounted in housings using rolling element bearings. An inner ring of the bearing is fixed to the shaft, while an outer ring is fixed to the housing. Rolling elements, such as balls or cylinders, roll between the inner and outer rings to minimize friction between the rotating shaft and the housing. In hydraulic pumps, an electric motor is often integrated into or directly attached to the pump housing. A shaft from the electric motor typically passes through the housing to drive the pump. A recess in the housing allows fluid to flow from the pump to the electric motor via a rolling element bearing located between the pump and the electric motor.To prevent this, complex sealing devices are typically incorporated into the pump or pump assembly. For example, if fluid enters the electric motor, it can damage a commutator, potentially compromising the motor's commutation system. The pump itself usually incorporates sealing elements to prevent fluid leakage. However, if these seals become leaky over the required operating time, it must be possible to prevent the escaping fluid from reaching the electric motor. Disclosure of the invention

[0005] The bearing arrangement according to the invention, with the features of claim 1, has the advantage that a seal between the shaft and the housing is permanently ensured in a simple manner, preventing the ingress or passage of fluid, for example into a commutation system of an electric machine, even if fluid escapes from a pump containing the electric machine. According to the invention, the inner ring of the rolling element bearing has a larger outer diameter than the recess and rests axially against the housing with the sealing element interposed. The outer diameter of the inner ring is thus selected to be larger than the inner diameter of the recess in the housing in which the inner ring rests axially with the sealing element interposed.This ensures that an axial seal is formed between the inner ring and the housing by the sealing element, completely sealing the opening through which fluid could otherwise pass through the housing. Because the inner ring rests axially against the housing with the sealing element in place, no fluid can penetrate the bearing assembly. Since the inner ring of the rolling element bearing must have a relatively large outer diameter, the bearing assembly as a whole is relatively large, thus increasing its load-carrying capacity and allowing it to be used for higher loads.

[0006] According to an advantageous embodiment of the invention, the sealing element is a sealing ring. The sealing ring expediently extends around the entire recess on the housing or on the inner ring of the rolling element bearing and thus lies between the inner ring and the housing, completely surrounding the recess. Advantageously, the sealing ring is held under tension between the inner ring of the rolling element bearing and the housing to achieve a high sealing effect. The sealing ring can be, for example, an O-ring, a sleeve, or the like. The sealing ring can be made of various materials and geometries.

[0007] Preferably, the sealing element comprises an elastomer material. This ensures a flexibility of the sealing element that leads to an advantageous sealing effect.

[0008] Alternatively or additionally, it is preferably provided that the sealing element comprises polytetrafluoroethylene (PTFE). PTFE exhibits advantageous friction properties and ensures low wear even with a long service life of the bearing assembly, thus guaranteeing the seal over the entire service life of the bearing assembly.

[0009] According to an advantageous embodiment of the invention, the sealing ring is partially seated in an axial groove of the housing that surrounds the recess in an annular manner. The housing thus has an axial groove on its end face facing the inner ring, which surrounds the recess in an annular manner. The axial groove can be directly adjacent to the recess and thus be formed by a step in the recess, or it can be spaced apart from the recess in the housing. The outer diameter of the inner ring of the rolling element bearing preferably corresponds at least to the outer diameter of the axial groove.

[0010] Advantageously, the inner ring is axially preloaded or held against the housing. For this purpose, one or more spring elements can act on the shaft and / or on the inner ring of the rolling element bearing, which axially preload or press the inner ring against the housing.

[0011] The electric machine according to the invention, with the features of claim 7, comprises a housing and a shaft rotatably mounted in the housing. The electric machine is characterized by the bearing arrangement according to the invention. This results in the advantages already mentioned. In particular, the electric machine is reliably protected against liquids that could penetrate from the outside through the bearing arrangement, for example, to a commutation unit.

[0012] The hydraulic pump with the features of claim 8 is characterized by the electrical machine according to the invention. This results in the advantages already mentioned.

[0013] The invention will now be explained in more detail using an exemplary embodiment. For this purpose, the only [example] shown is... Figure of a hydraulic pump in a simplified sectional view.

[0014] The figure shows a simplified longitudinal section of a hydraulic pump 1 comprising a pump assembly 2 and an electric machine 3. The pump assembly 2 includes, for example, a piston or gear pump driven by the electric machine 3. The electric machine has a shaft 4 on which a rotor 5 is fixedly mounted. The rotor 5 interacts with a stator 6, which is fixedly mounted in a housing 7, to drive the shaft 4. This can be achieved in a conventional manner, for example, by a mechanical commutation system. Two bearing arrangements 8 and 9 are also provided for the rotatable mounting of the shaft 4 in the housing 7.

[0015] Both bearing assemblies have a rolling element bearing 10 or 11, respectively, which provides rotatable support for the shaft 4 in the housing 7. The rolling element bearing 10 is of conventional design and is located at a first shaft end of the shaft 4. The second rolling element bearing 11 is situated between the electric motor 3 and the pump assembly 2. An inner ring 12 of the rolling element bearing 11 is fixed to the shaft 4, at least against rotation. An outer ring 13 of the rolling element bearing 11 is fixed to the housing 7, at least against rotation. Rolling elements 14, which in this embodiment are designed as balls, run or roll between the inner ring 12 and the outer ring 13. The shaft 4 penetrates the housing 7 and projects partially into the pump assembly 2 to drive it. For this purpose, the housing 7 has a recess 15 through which the shaft 4 projects.

[0016] The inner ring 12 of the rolling element bearing 11 has an outer diameter D A on, which is larger than the inner diameter D I the recess 15. This causes the inner ring 12 to overlap with an end wall 16 of the housing 7. In the overlap area, the end wall 16 of the housing 7 has an annular axial groove 17 that extends around the recess 15. A small gap is provided between the recess 15 and the axial groove 17. A sealing element 18, which in this case is an O-ring made of an elastomeric plastic and / or polytetrafluoroethylene, is partially embedded in the axial groove 17. The sealing element 18 is designed as a sealing ring that surrounds the recess 15 in an annular and, in particular, coaxial manner.

[0017] The inner ring 12 of the rolling element bearing 11 rests axially against the sealing element 18. In particular, the inner ring 12 is pressed axially against the housing 7, so that the sealing element 18 is clamped or pre-tensioned between the housing 7 and the inner ring 12. This creates a reliable seal between the inner ring 12 and the sealing ring 18, or the housing 7, preventing fluid from the pump assembly 2 to the electric motor 3 through the bearing assembly 9. By advantageously constructing the sealing element 18 at least partially from polytetrafluoroethylene, the frictional forces between the inner ring 12 and the sealing element 18 are minimized, thus ensuring a long service life for the bearing assembly 9.

[0018] Due to the large outer diameter D compared to conventional rolling element bearings ABy increasing the size of the inner ring 12, particularly its inner diameter, the load rating of the rolling element bearing 11 is simultaneously increased, allowing the electric machine 3 to be designed or used for higher loads. The outer ring 13 of the rolling element bearing 11 is advantageously pressed into the housing 7, thus eliminating the need for a bearing cap and a bulkhead. The housing 7 can be designed as a two-piece unit, as shown, or alternatively as a single piece. An eccentric bearing 19 of the pump assembly 2 runs smoothly against the inner ring 12, preventing tilting. The appropriately dimensioned rolling element bearing 11 thus replaces a bearing cap and a bulkhead. The axial preload of the outer ring 13 of the rolling element bearing 11 is advantageously achieved by the geometry of the housing 7 or the pump assembly 2.Advantageously, the geometry of the housing 7 or the pump assembly 2 is also selected such that frictional contact with the inner ring 12 occurs only between the inner ring 12 and the sealing element 18, but not between the inner ring 12 and the housing 7 itself. This can be achieved, for example, by making the sealing element 18 so large and protruding from the axial groove 17 that contact between the inner ring 12 and the housing 7 is prevented.

[0019] Preferably, the outer ring 13 has an opening for the connector (not shown), which is preferably sealed to seal the entire electric machine 3. Connectors for electrical contact with the electric machine 3 can be inserted through this opening.

Claims

[1] Bearing device (9) for rotatably supporting a shaft (4) in a housing (7), with a rolling element bearing (11) having an inner ring (12) and an outer ring (13), wherein the shaft (4) is arranged axially in a recess (15) of the housing (7), characterized by , that the inner ring (12) is arranged non-rotatably on the shaft (4), that the outer ring (13) is arranged non-rotatably on the housing (7), and that the inner ring (12) of the rolling element bearing (11) has an outer diameter (D A ) has a diameter larger than the inner diameter (D I ) the recess (15) and axially against the housing (7) with an intermediate sealing element (18). [2] Storage device according to claim 1, characterized by , that the sealing element (18) is a sealing ring. [3] Storage device according to one of the preceding claims, characterized by , that the sealing element (18) has an elastomeric material. [4] Storage device according to one of the preceding claims, characterized by , that the sealing element (18) has Teflon. [5] Storage device according to any one of the preceding claims, characterized by , that the sealing element (18) is partially embedded in an axial groove (17) which surrounds the recess (15) in a ring shape. [6] Storage device according to any one of the preceding claims, characterized by , that the inner ring (12) is axially preloaded against the housing (7). [7] Electric machine (3) with a housing (7) and a shaft (4) rotatably mounted in the housing (7), characterized by a bearing device (9) for rotatably mounting the shaft (4) in the housing (7) according to one or more of the preceding claims. [8] Hydraulic pump (1) with an electric machine (3) according to claim 7.

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