CN112564381A

CN112564381A - Assembly for supporting and sealing a rotor shaft

Info

Publication number: CN112564381A
Application number: CN202011026483.4A
Authority: CN
Inventors: V·弗拉什基夫斯基
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2019-09-26
Filing date: 2020-09-25
Publication date: 2021-03-26
Also published as: DE102019214793A1

Abstract

The invention relates to an assembly for mounting and sealing a rotor shaft (1) in a housing (2), on which assembly a rotor (4) of an electric machine (5) is arranged in a rotationally fixed manner, wherein the rotor shaft (1) is supported relative to the housing (2) by means of at least one rolling bearing (3) and is sealed relative to the housing (2) by means of a sealing element (8) arranged between the rotor (4) and the rolling bearing (3), and wherein a protective element (9) which suppresses heat conduction and/or diverts the flow of heat is arranged between the at least one rolling bearing (3) and the rotor (4) in the region of the sealing element (8).

Description

Assembly for supporting and sealing a rotor shaft

Technical Field

The invention relates to an assembly for mounting and sealing a rotor shaft in a housing, on which assembly a rotor of an electric machine is arranged in a rotationally fixed manner, wherein the rotor shaft is supported relative to the housing by means of at least one rolling bearing.

Background

DE 102011076530 a1 discloses an assembly for mounting an electric machine, in particular for mounting a rotor shaft, on which the rotor of the electric machine is arranged in a rotationally fixed manner. The rotor shaft is supported by two rolling bearings relative to the housing. Since heat is introduced from the rotor of the electric machine to the rotor shaft, the inner ring of the rolling bearing is thermally insulated from the rotor shaft by an insulating material. Preferably, an adhesive should be used as an insulating material, which adhesive, in addition to the heat-insulating function, also performs the function of fixing the rolling bearing to the rotor shaft. Due to the insulating layer having a low thermal conductivity, the heat conduction between the rotor shaft and the bearing inner ring is reduced to such an extent that the temperature rise of the rolling bearing is small.

Therefore, there is a problem in terms of thermal stress of the members when supporting the rotor shaft of the electric machine.

Disclosure of Invention

The aim of the invention is to avoid inadmissibly high thermal stresses of the hazardous components when supporting and sealing the rotor shaft.

According to the invention, in the assembly for supporting and sealing the rotor shaft, a sealing element is provided which is arranged between the rotor and the rolling bearing and seals the rotor shaft relative to the housing; in this case, a protective element is arranged in the region of the sealing element, which element suppresses heat conduction in the rotor shaft and/or diverts the heat flow in the rotor shaft. The direction of the heat flow is influenced by the arrangement and design of the protective element in such a way that the heat flow is directed away from the sealing element and at a distance from the sealing element, so that impermissibly high temperatures do not occur in the region of the sealing element. The following advantages are thus achieved: impermissible thermal stresses of the sealing element and also of the rolling bearing are avoided.

According to a preferred embodiment, the protective element diverting the heat flow is designed as a ring or as a ring. The protective element surrounds the entire circumference of the rotor shaft as a ring and thus deflects the heat flow, which is first spread axially on the surface of the rotor shaft between the rotor and the ring, radially inward, so that the spacing of the higher-temperature region from the sealing element increases.

According to another preferred embodiment, the protective element is made of a material having a low thermal conductivity (expressed in the specialist literature as material value λ). Such a material with low thermal conductivity may be, for example, a ceramic material or a plastic.

According to a further preferred embodiment, the protective element has a surface which is at least partially coated with a substance having a low thermal conductivity. The protective element or ring can therefore be made of a material with a high thermal conductivity, for example steel, while the coating has a very low thermal conductivity and thus effects a diversion of the heat flow in the rotor shaft. The heat cannot therefore reach the steel ring and therefore also cause an impermissible temperature rise of this steel ring.

According to a further preferred embodiment, the annular protective element or ring engages with the rotor shaft, i.e. the ring and the rotor shaft are fixedly connected to one another by a mechanical or material connection. For example, the ring may be pressed or shrunk onto the rotor shaft or glued to the rotor shaft.

According to a further preferred embodiment, the annular protective element is clamped between the rotor shaft (i.e. an axial stop on the rotor shaft) and the at least one rolling bearing (i.e. its inner ring). The ring is thus fixed in the axial direction and also in the tangential direction.

According to a further preferred embodiment, at least one rolling bearing has an inner ring, and the annular protective element is formed in one piece with the inner ring, i.e. integrated into the inner ring. A simplified assembly is thus obtained, since fewer components are to be assembled.

According to a further preferred embodiment, the annular protective element has an outer, preferably cylindrical sliding surface which is in sliding contact with the sealing element. The sealing element thus indirectly seals the rotor shaft with respect to the housing by means of the annular protective element. The annular protective element is therefore arranged next to the sealing element or its sealing lip.

According to a further preferred embodiment, the sealing element is designed as a radial shaft sealing ring with a sealing lip which slides on a rotating sliding surface of the annular protective element. The sealing function of the sealing element is to seal the dry interior space in which the rotor runs outwardly, in particular to prevent the ingress of oil which is supplied to the rolling bearing for its lubrication.

According to a further preferred embodiment, the annular protective element is sealed with respect to the rotor shaft by means of a further sealing element, preferably an O-ring, because the tightness achieved by the joining process is insufficient.

Drawings

An embodiment of the invention is shown in the drawings and will be described in more detail below, wherein other features and/or advantages may be obtained from the description and/or drawings. In the drawings:

fig. 1 shows the mounting of the rotor shaft in the housing for the bearing on the left in a sectional view, and

fig. 2 shows the mounting of the rotor shaft for the right-hand bearing in a reduced detail.

Detailed Description

Fig. 1 shows, in an axial section, a detail of the mounting of a rotor shaft 1 in a housing 2 by means of a first (left-hand) rolling bearing 3 having an inner ring 3a and an outer ring 3 b. The rotor 4 of the electric machine 5 is arranged on the rotor shaft 1, while the stator 6 of the electric machine 5 is arranged radially outside the rotor 4. The rotor 4 runs in a dry interior space 7 which is arranged within the housing 2 and is sealed off from the outside. The rotor shaft 1 has a rotational axis a and an axial bore 1a for supplying lubricating oil. The radial bore 1b (on the left in the drawing) is arranged next to the inner ring 3a of the roller bearing 3 and is connected to the axial bore 1 a. The rolling bearing 3 is supplied with lubricating oil through the axial hole 1a and the radial hole 1 b. A sealing element 8, which is preferably designed as a radial shaft sealing ring 8, is arranged on the right side of the rolling bearing 3 in the drawing (i.e. on the side of the rolling bearing 3 facing the rotor 4) and is fixed in the housing 2. According to the invention, an annular protective element 9 is arranged radially within the radial shaft sealing ring 8, which engages with the rotor shaft 1 and exerts a thermal protection function on the sealing element 8. The annular protective element 9 has a cylindrical outer surface 9a designed as a sliding surface, which is in sliding contact with the sealing element 8, in particular the sealing lip of the radial shaft sealing ring 8. The annular protective element 9 has a cylindrical inner surface 9b, which is arranged on a corresponding outer surface of the rotor shaft 1 and is sealed by a ring (rundshrring) 10 (also called O-ring 10). An annular protective element 9 having an end face 9c is fixed in the axial direction between an axial stop of the rotor shaft 1 and the inner ring 3a of the rolling bearing 3. The inner space 7 is sealed off by means of a sealing element 8; in particular, the lubricant supplied to the rolling bearing 3 is prevented from penetrating into the inner space 7 by the sealing element 8. In case a small amount of lubricating oil, so-called leakage, may still penetrate into the inner space 7, a collecting device 11 is provided for receiving lubricating oil thrown off by a shoulder (not referenced) of the rotor shaft 1.

The annular protective element 9 according to the invention has the following object: in particular, the sealing element 8 is protected against impermissibly high thermal stresses, i.e. impermissibly high temperatures as a result of the heat introduction into the rotor 4. The heat generated in the rotor 4 during operation reaches the rotor shaft 1 radially inwards from the rotor 4 and, as illustrated by the heat flow arrows P1, P2, flows first in the axial direction and in the region of the radially outer region of the rotor shaft 1 in the direction of the rolling bearing 3 and in the direction of the protective element 9. The protective element 9 (in order to fulfill its function as a thermal protection element) is made of a material having a low thermal conductivity (denoted by the letter λ in the specialist literature). Alternatively, the annular protective element 9 can also be designed as a steel ring which, although having a relatively high thermal conductivity, is provided with an outer coating having a low thermal conductivity. The coating is applied in particular in the region of the contact surface between the protective element 9 and the rotor shaft 1, i.e. on the inner surface 9b and the end face 9 c. The coating with low thermal conductivity prevents heat from the rotor 4 from reaching the coated steel ring 9 or the annular protective element 9 in the region of the

contact surfaces

9b, 9c between the annular protective element 9 and the rotor shaft 1. Instead, the diversion of the heat flow or heat flow according to the heat flow arrows P1, P2 is achieved by the design of the protective element 9 according to the invention. The heat flows around the contour of the annular protective element 9. Due to the protective element, the temperature in the region of the sealing element 8 is kept within the permitted range, thus increasing the service life of the sealing element.

Fig. 2 shows a further bearing arrangement, in particular for the second bearing of the rotor shaft 101 or the right-hand bearing 103. However, reference numerals 100 greater than those in fig. 1 are used for the same or similar components. The rotor 104 is arranged on the rotor shaft 101. The introduction of heat by the rotor 104 to the rotor shaft 101 is illustrated by heat flow arrows P1, P2. The annular protective element 109 achieves, due to its above-described characteristics according to the invention (i.e. its thermal protection function): the heat flow is diverted in the region of the protective element 9 and is prevented from flowing into the region of the sealing element 108. In an alternative embodiment, the protective element 109 designed as a ring, which engages with the rotor shaft 101 according to the above-described embodiments (for example by pressing, shrinking or clamping and sealing by means of the O-ring 110), can be integrated into the inner ring 103a of the rolling bearing 103, i.e. be formed in one piece with the inner ring 103 a. In this alternative solution, the rolling bearing 103 is assembled simultaneously with the annular protective element 109. The integrated protective element 109 is therefore made of the same material as the inner ring 103a, in particular steel, but is provided with a coating having a low thermal conductivity.

List of reference numerals

1 rotor shaft

1a axial hole

1b radial hole

2 casing

3 rolling bearing (left side)

3a inner ring

3b outer ring

4 rotor

5 electric machine

6 stator

7 inner space

8 sealing element/radial shaft sealing ring

9-Ring-shaped protective element

9a outer surface

9b inner surface

9c end face

10 toroidal ring/O-ring

11 collecting device

101 rotor shaft

102 shell

103 rolling bearing (Right side)

103a inner ring

104 rotor

105 electric machine

106 stator

107 inner space

108 sealing element/radial shaft sealing ring

109 ring-shaped protective element

110 toroidal ring/O-ring

a axis of rotation

Directional arrows for P1 heat flow

Directional arrows for P2 heat flow

Claims

1. An assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102), on which assembly a rotor (4, 104) of an electric machine (5, 105) is arranged in a rotationally fixed manner, wherein the rotor shaft (1, 101) is supported relative to the housing (2,102) by means of at least one rolling bearing (3, 103) and is sealed relative to the housing (2,102) by means of a sealing element (8, 108) arranged between the rotor (4, 104) and the rolling bearing (3, 103), and wherein a protective element (9, 109) which inhibits heat conduction and/or diverts heat flow is arranged between the at least one rolling bearing (3, 103) and the rotor (4, 104) in the region of the sealing element (8, 108).

2. Assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102) according to claim 1, characterized in that the protective element (9, 109) is designed annular.

3. The assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102) according to claim 2, characterized in that the protective element (9, 109) is made of a material having a low thermal conductivity.

4. An assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102) according to claim 1, 2 or 3, characterized in that the protective element (9, 109) has a surface (9b, 9c) which is at least partially coated with a substance having a low thermal conductivity.

5. Assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102) according to claim 2, 3 or 4, characterized in that the annular protective element (9, 109) engages with the rotor shaft (1, 101).

6. Assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102) according to claim 2, 3 or 4, characterized in that the annular protective element (9, 109) is clamped between the rotor shaft (1, 101) and the at least one rolling bearing (3, 103).

7. Assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102) according to one of claims 2 to 5, characterized in that the at least one rolling bearing (3, 103) has an inner ring (3a, 103a) and the annular protective element (9, 109) is formed in one piece with the inner ring (3a, 103 a).

8. Assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102) according to one of claims 2 to 7, characterized in that the annular protective element (9, 109) has an outer sliding surface (9a) which is in sliding contact with the sealing element (8, 108).

9. Assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102) according to one of the preceding claims, characterised in that the sealing element is designed as a radial shaft sealing ring (8, 108).

10. Assembly for supporting and sealing a rotor shaft (1, 101) in a housing (2,102) according to one of claims 2 to 9, characterized in that the annular protective element (9, 109) is sealed with respect to the rotor shaft (1, 101) by means of a further sealing element, in particular a circular ring (10, 110).