GB2539648A

GB2539648A - Labyrinth seal

Info

Publication number: GB2539648A
Application number: GB1510729.5A
Authority: GB
Inventors: Bongaerts Jeroen; Organisciak Michel
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 2015-06-18
Filing date: 2015-06-18
Publication date: 2016-12-28
Also published as: GB201510729D0

Abstract

The present invention resides in a seal assembly (2) for sealing a radial gap between an inner component (10) and an outer component (20) which are relatively rotatable about a rotation axis (11). The assembly comprises an annular first seal member (30) and an annular second seal member (40), wherein: the first seal member is mountable to the inner component (10), and the second seal member is mountable to the outer component (20); or the first seal member (30) is mountable to the outer component, and the second seal member (40)is mountable to the inner component. The first seal member comprises a main body (32) and at least one lamella (34) extending generally radially. The second seal member comprises a main body (42) and a plurality of axially-spaced lamellae (44) extending generally radially, whereby the at least one lamella of the first seal member extends between two adjacent lamellae of the second seal member; and the lamellae (44, 144) of the second seal member have a greater flexibility than the lamella (34, 134, 234) of the first seal member.

Description

Labyrinth seal The present invention relates to a seal for use on e.g. a rotating shaft. The seal may be used to prevent contamination 5 from passing the seal towards, for example, a bearing rotatably supporting a shaft. Preferably, the seal may be used on a shaft to protect a bearing within an enclosed space in which the bearing is continually re-lubricated, such that the seal allows egress of lubricant whilst substantially 10 preventing ingress of contaminants.

Labyrinth seals are useful for such an application. These seal by virtue of providing a long narrow channel from one side of the seal to the other. These are typically difficult 15 to manufacture and install accurately.

According to the invention there is provided a seal assembly according to claim 1.

In the following description, the phrase "extending radially" means extending away from the rotation axis, but not necessarily extending in a plane perpendicular thereto unless explicitly specified.

For a better understanding of the invention and to show how the same may be put into effect, reference is now made, by way of example only, to the accompanying drawings in which: Figure 1 shows a first embodiment of a seal assembly in 30 accordance with the invention; Figure 2 shows a second embodiment of a seal assembly in accordance with the invention; and -2 -Figure 3 shows a third embodiment of a seal assembly in accordance with the invention.

Figure 1 shows a schematic representation of a first embodiment of a seal assembly 1 in accordance with the invention. The seal assembly 1 surrounds a rotatable shaft 10 having a rotation axis 11 and substantially seals a gap between the shaft 10 and a housing 20 surrounding the shaft 10.

The seal assembly 1 comprises an annular first seal member 30 and an annular second seal member 40.

In all embodiments described below, the first seal member 30 15 forms an inner seal member, and this is surrounded by the second seal member 40, which is an outer seal member.

However, the opposite arrangement is possible -the first seal member 30, 130, 230 may form the outer seal member, while the second seal member 40, 140 may form the inner seal member.

The first seal member 30 comprises a main body 32. At least one lamella 34 extends from the main body 32 generally in the radial direction. In this embodiment, the first seal member 30 comprises multiple (two or more) lamellae 34. In the embodiment of Figure 1, the lamellae 34 extend perpendicular to the rotation axis 11. In other words, they are parallel with a plane extending perpendicular to the rotation axis 11.

The second seal member 40 comprises a main body 42. A plurality of axially-spaced lamellae 44 extend from the main body 42 generally radially. The plurality of axially spaced lamellae 44 extend from the main body 42 at an acute angle (i.e. non perpendicular) to the rotation axis 11. In other words, the plurality of lamellae 44 of the second seal member 40 are inclined in an axially outward direction relative to a plane extending perpendicular to the rotation axis 11.

Preferably, the lamellae 44 extend at an angle of between 30 and 30 degrees from the rotation axis (when considered in cross-section). yore preferably, the angle would be in the range 50 to 70 degrees.

Preferably, when the seal assembly 1 is installed on a shaft to seal a housing 20 or the like, the distal annular edge (the free edge) of each of the lamellae 44 of the second seal member 40 is disposed more outwardly in the axial direction with respect to the housing 20 than its proximal annular end (its radially outermost circumference, where it meets the main body 42). In other words, when installed in a housing 20, the direction X denotes the axially outward direction.

In all embodiments, the seal assembly 1, 2, 3 may be used to seal a bearing (not shown) within the housing 20. The bearing would be arranged in the Y direction in each Figure, and so the outward direction (the X direction) corresponds to the direction away from the bearing, while the inward direction (the Y direction) corresponds to the direction towards the bearing. The sealing effect of the seal assembly 1 is to allow grease to move in the X direction, whilst hindering contaminants from moving in the Y direction.

The first and second seal members 30, 40 are arranged such that the lamellae 34, 44 of each seal member 30, 40 are interspersed. That is, at least one lamella 34 of the first seal member 30 extends between two adjacent lamellae 44 of the second seal member 40. Preferably, with the exception of -4 -the axially outermost lamellae 34, 44, each lamella 34, 44 of each seal member 30, 40 is inserted between a pair of lamellae 34, 44 of the other seal member 30, 40.

It is preferred (but not essential) that the lamellae 44 of the second seal member 40 contact the main body 32 of the first seal member 30. Preferably, the lamellae 34 of the first seal member 30 do not contact the main body 42 of the second seal member 40.

Most preferably, the lamellae 34, 44, 134, 144, 234 of opposing seal members 30, 40, 130, 140, 230 do not contact when in their free state (i.e. not deformed by an external force).

The lamellae 34 of the first seal member 30 are axially-spaced. Preferably, the lamellae 34 of the first seal member 30 are spaced apart from each other by a distance in the range 5mm. to 40mm.

The lamellae 44 of the second seal member 40 are axially-spaced. Preferably, the lamellae 44 of the second seal member 40 are spaced apart from each other by a distance in the range 5mm. to 40mm.

The lamellae 44 of the second seal member 40 have a greater flexibility than the lamellae 34 of the first seal member 30. That is, the lamellae 44 of the second seal member 40 will deform by a greater amount under a load (for example, when in a flow of grease) than the lamellae 34 of the first seal member 30. For example, the lamellae 44 of the second seal member 40 (or the whole second seal member 40) have a Young's modulus in the range of 5 to 50 MPa. -5 -

Optionally, the lamellae 34 of the first seal member 30 (or the whole first seal member 30) have a Young's modulus of at least 100 MPa (e.g. 100 to 30,000 MPa).

The lamellae 44 of the second seal member 40 comprise or are formed of one or more of: rubber; natural rubber; fluorinated rubber; a thermoplastic; Teflon; thermoplastic elastomer (TPE); thermoplastic polyurethane (TPU); polytetrafluoroethylene (=FE); nitrile butadiene rubber (NBR); hydrogenated nitrile butadiene rubber (HNBR); and/or fluoroelastomers, such as FKM.

Indeed, the entire second seal member 40 may be made of the same material. In which case, the second seal member 40 is preferably provided with an insert 50 to increase the rigidity of the rain body 42 of the second seal member 40 and to hold the main body 42 to the housing 20 or shaft 10 to which it is mounted. In Figure 1 is shown a single rigid insert 50 in the form of a cylinder, extending from one lamella 44 to an adjacent lamella 44. When more than two lamellae 44 are provided, an insert 50 may be provided between each pair of adjacent lamellae 44.

The lamellae 34 of the first seal member 30 may be rigid. Indeed, the entire first seal member 30 may be rigid. The lamellae 34 of the first seal member 30 (or the entire first seal member 30) may comprise or are formed of one or more of: steel; aluminium; copper; brass; and/or some other metal; and/or alloys thereof. In embodiments in which lamellae 34 do not contact the second seal member 40, the lamellae 34 (or the entire first seal member 30) may be made from plastic, such as rigid plastic. -6 -

The/each insert 50 may comprise or is formed of one or more of: steel; aluminium; or some other metal; alloys thereof; and/or plastic.

Figure 2 shows a schematic representation of a second embodiment of a seal assembly 2 in accordance with the invention. As with the first embodiment, the seal assembly 2 surrounds a rotatable shaft 10 having a rotation axis 11 and substantially seals a gap between the shaft 10 and a housing surrounding the shaft 10. Components described with reference to the first embodiment are denoted with the same reference numerals in Figure 2, while similar components have reference numerals preceded by a "1".

The second embodiment differs in that the at least one lamella 134 of the first seal member 130 is inclined relative to a plane extending perpendicular to the rotation axis 11.

The lamellae 134, 44 of the first and second seal members 30, are all inclined at the same or substantially the same angle relative to a plane extending perpendicular to the rotation axis 11.

The spacing between adjacent lamellae 134, 44 on each seal member 130, 40 may the same as in the first embodiment.

Preferably, the lamellae of the first and second seal members 130, 40 are all inclined at an angle in the range 30 to 80 degrees (more preferably, 50 to 70 degrees) relative to the rotation axis 11 in a cross-section passing through the rotation axis 11. -7 -

Preferably, when the seal assembly 2 is installed on a shaft to seal a housing or the like, the distal annular edge (the free edge) of each of the lamellae 44 of the second seal member 40 are disposed more outwardly in the axial direction with respect to the housing 20 than its proximal annular end (where it meets the main body 42), while the distal annular edge (the free edge) of each of the lamellae 134 of the first seal member 30 are disposed more inwardly in the axial direction with respect to the housing 20 than its proximal annular end (where it meets the main body 132).

As with the first embodiment, the lamellae 44 the second seal member 40 have a greater flexibility than the lamellae 134 of the first seal member 130 and are angled towards the rotation axis 11 in an axially outward direction. Thus, when contamination from the environment side of the seal tries to enter the seal and exerts a force on the lamellae 44 of the second seal member in the Y direction, the lamellae 44 are urged towards a radially outer surface of the main body 132 of the first seal member 130. This reduces a gap therebetween, enhancing the sealing ability of the seal 2. When a force acts on the lamellae 44 of the second seal member in the X direction, the gap increases. Therefore, when the bearing is filled with fresh grease during a re lubrication event, the escape of used grease via the seal 2 is facilitated.

Figure 3 shows a schematic representation of a third embodiment of a seal assembly 3 in accordance with the invention. As with the second embodiment, the seal assembly 3 surrounds a rotatable shaft 10 having a rotation axis 11 and substantially seals a gap between the shaft 10 and a housing 20 surrounding the shaft 10. Components described with reference to the first or second embodiments are denoted with the same reference numerals in Figure 3, while similar components have reference numerals preceded by a "2".

The third embodiment differs in that both of the first and second seal members 230, 140 include a plurality of lamellae. The main bodies 142, 232 of either seal member 230, 140 preferably extend axially beyond the outermost lamella 144, 234 of the respective pluralities.

Preferably, each of the first and second seal members 230, 140 include between 2 and 20 lamellae. An insert 150 extends between each of the adjacent lamellae 144 of the second seal member 140. Preferably, an insert 150 is also provided at either end of the main body 142 either side of the plurality of lamellae 144 in order to firmly attach the second seal member 140 to the housing 20 (or shaft 10).

An insert 250 extends between each of the adjacent lamellae 234 of the first seal member 230. Preferably, an insert 250 is also provided at either end of the main body 232 either side of the plurality of lamellae 234 in order to firmly attach the first seal member 230 to the shaft 10 (or housing 20).

In any of the embodiments described above, the lamellae of one or both of the first or second seal members 30, 40, 140, 230 may be sized (i.e. such that it extends sufficiently far radially) to contact the main body 32, 42, 132, 232 of the other of the first and second seal members 30, 40, 140, 230.

Alternatively, the lamellae of one or both of the first or second seal members 30, 40, 140, 230 may be sized (i.e. such that it extends sufficiently far radially) to contact the inserts 50, 150, 250 mounting the main body 32, 42, 132, 232 of the other of the first and second seal members 30, 40, 140, 230.

Additionally, a lubricating and sealing grease can be added to the space in between the lamellae 34, 44, 134, 144, 234 before installation. This can ensure good lubrication of the seal and a more difficult path for potential contamination entering the bearing side. Any contamination can be captured by the grease.

Claims

-10 -CLAIMS: 1. A seal assembly (1,2, 3) for sealing a radial gap between an inner component (10) and an outer component (20) which are relatively rotatable about a rotation axis (11), the assembly comprising an annular first seal member (30, 130, 230) and an annular second seal member (40, 140), wherein: the first seal member forms an inner seal member that is mountable to the inner component (10), and the outer seal member is formed by the second seal member, which is mountable to the outer component (20); or the first seal member forms an outer seal member that is mountable to the outer component, and the inner seal member is formed by the second seal member, which is mountable to the inner component wherein: the first seal member comprises a main body (32, 132, 232) and at least one lamella (34, 134, 234) extending 20 generally radially; the second seal member comprises a main body (42, 142) and a plurality of axially-spaced lamellae (44, 144) extending generally radially; the at least one lamella of the first seal member 25 extends between two adjacent lamellae of the second seal member; and the lamellae (11, 144) of the second seal member have a greater flexibility than the lamella (34, 134, 234) of the first seal member.
2. The seal assembly of claim 1, wherein the plurality of lamellae (44, 144) of the second seal member (40, 140) are inclined relative to a plane extending perpendicular to the rotation axis (11), in an axially outward direction (X).
3. The seal assembly of claim 1 or claim 2, wherein the at least one lamella (34, 134, 234) of the first seal member is inclined relative to a plane extending perpendicular to the rotation axis.
4. The seal assembly of claim 2 and claim 3, wherein the 10 lamellae of the first and second seal members are all inclined at the same angle, so as to be essentially parallel to each other.
5. The seal assembly of claim 2 and claim 3, wherein the lamellae of the first and second seal members are all inclined at an angle in the range 30 to 80 degrees relative to the rotation axis in a cross section passing through the rotation axis.
6. The seal assembly of any preceding claim, wherein the second seal member (40, 140) comprises one or more inserts (50, 150) extending between adjacent lamellae thereof.
7. The seal assembly of claim 6, wherein the insert(s) comprise(s) or is/are formed of one or more of: steel; aluminium; metal; metal alloys; and/or plastic.
8. The seal assembly of any preceding claim, wherein the first seal member comprises a plurality of axially spaced 30 lamellae.

-12 -
9. The seal assembly of claim 3, wherein the first seal member comprises an insert (250) extending between the adjacent lamellae thereof.
10. The seal assembly of any preceding claim, wherein the lamellae of the first and second seal members are axially spaced apart.
11. The seal assembly of any preceding claim, wherein the lamellae (44, 144) of the second seal member comprise or are formed of one or more of: rubber; natural rubber; fluorinated rubber; a thermoplastic; Teflon; nitrile butadiene rubber; hydrogenated nitrile butadiene rubber; and/or fluoroelastomers.
12. The seal assembly of any preceding claim, wherein the at least one lamellae (34, 134, 234) of the first seal member comprise(s) or is/are formed of one or more of: steel; aluminium; copper; brass; metal; metal alloy; and/or plastic.
13. The seal assembly of any preceding claim, wherein the at least one lamella of the first seal member contact(s) the second seal member.
14. The seal assembly of any preceding claim, wherein the plurality of lamellae of the second seal member contact the first seal member.