Dynamic radial seal

Abstract

A seal arrangement for sealing a radial gap between an inner component and an outer component coaxially mounted around the inner component is provided. The inner component rotates about a rotation axis. The arrangement provides a radial seal connectably mounted to the inner component. The radial seal has a sealing lip that bears against a counterface formed by a radially inner surface of the outer component. When the seal arrangement is stationary, the sealing lip bears against the counterface with an initial lip force. The sealing lip is pivotably arranged in a radial cross section around a pivot point, and is in connection with a counterweight. The sealing lip and the counterweight are arranged in different axial regions from the pivot point and are adapted such that during rotation of the radial seal, a greater centrifugal force acts on the counterweight than on the sealing lip.

Claims

1. A seal arrangement for sealing a radial gap between an inner component and an outer component, the inner component rotates about an axis, and the outer component is non-rotational and is mounted coaxially around the inner component, the arrangement includes a radial seal mounted to the inner component, the radial seal provides a sealing lip which, under static sealing conditions, bears against a counterface formed by a radially inner surface of the outer component or of a sleeve element that is mounted to the outer component; wherein the sealing lip is pivotably arranged in a radial cross section around a pivot point, wherein the pivot point lies radially inward of the counterface; the radial seal further comprises a counterweight connected to the sealing lip, and the sealing lip and the counterweight (9) are arranged in different axial regions from the pivot point and are adapted such that, under dynamic sealing conditions, a centrifugal force acting on the counterweight is greater than the centrifugal force acting on the sealing lip.

2. The seal arrangement according to claim 1, wherein the mass of the sealing lip till to the pivot point is less that the mass of the counterweight to the pivot point.

3. The seal arrangement according to claim 1, wherein the sealing lip and the counterweight form part of an elastomeric seal body of the radial seal.

4. The seal arrangement according to claim 3, wherein the radial seal comprises a carrier element mounted to the inner component, the carrier element comprising an inner cylindrical portion and an outer cylindrical portion joined by a radially extending flange portion.

5. The seal arrangement according to claim 4, wherein the elastomeric seal body comprises a connection section that is joined to the carrier element at a radially outer surface of the outer cylindrical portion.

6. The seal arrangement according to claim 5, wherein the elastomeric body further comprises a slender region between the connection section and the sealing lip and counterweight, wherein the pivot point is established by the slender region.

7. The seal arrangement according to 1, further comprising a labyrinth seal arranged at an axially outer location relative to the sealing lip.

8. The seal arrangement according to claim 5, wherein the elastomeric seal body further comprises a non-contact lip that extends from the connection section in a radially outward direction towards the counterface, a labyrinth seal arranged at an axially outer location relative to the sealing lip, the labyrinth seal being formed by a radial gap between the counterface and the non-contact lip.

9. The seal arrangement according to claim 1, wherein the inner component is a shaft or a bearing inner ring and the outer component is a housing or a bearing outer ring.

10. A bearing unit comprising: a sealing arrangement for sealing a radial gap between an inner component and an outer component, the inner component rotates about an axis, and the outer component is non-rotational and is mounted coaxially around the inner component, the arrangement includes a radial seal mounted to the inner component, the radial seal provides a sealing lip which, under static sealing conditions, bears against a counterface formed by a radially inner surface of the outer component or of a sleeve element that is mounted to the outer component; wherein the sealing lip is pivotably arranged in a radial cross section around a pivot point, wherein the pivot point lies radially inward of the counterface; the radial seal further comprises a counterweight connected to the sealing lip, and the sealing lip and the counterweight are arranged in different axial regions from the pivot point and are adapted such that, under dynamic sealing conditions, a centrifugal force acting on the counterweight is greater than the centrifugal force acting on the sealing lip.

11. The bearing unit according to claim 10, wherein the bearing unit is a railway bearing unit comprising a double-row taper roller bearing.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0018] The drawing shows an embodiment of the invention. The single FIGURE shows a radial cross section through a seal arrangement according to the invention which is mounted in a railway bearing unit.

DETAILED DESCRIPTION OF THE INVENTION

[0019] A sealing arrangement 1 is mounted in a railway bearing unit and seals a bearing arrangement 2 (not shown in detail) against the environment E. The bearing arrangement 2 supports a rotation shaft 3 in a stationary housing 4 (the housing can also be the outer bearing ring). The shaft 3 rotates around an axis a.

[0020] The seal arrangement provides a sleeve element 7, which is mounted to the stationary housing 4. The sleeve element is made of metal and has a cylindrical inner surface 10. The seal arrangement further provides a radial seal having an elastomeric seal body 5 that is connected to a carrier element 11, which carrier element is mounted to the shaft 3. The radial seal thus rotates with the shaft.

[0021] The carrier element has a C-shaped profile in the depicted embodiment and provides an inner cylindrical portion 11′ that is mounted to the shaft 3. At the environmental side E of the seal arrangement, the carrier element further provides a radial flange portion 11″, from which an outer cylindrical portion 11′″ of the carrier element extends towards the bearing side of the seal arrangement 1. The elastomeric seal body 5 is connected to the carrier element 11 at a radially outer surface of the outer cylindrical portion 11′″.

[0022] The elastomeric body 5 provides a sealing lip 6 which, during rotation of the shaft, is in sliding contact with the inner cylindrical surface 10 of the sleeve element, which will be referred to as the counterface 10.

[0023] When the seal arrangement is at rest, i.e. under static sealing conditions, the sealing lip exerts a certain contact force on the counterface 10. Under dynamic sealing conditions, the centrifugal force acting on the radial seal would tend to increase the contact force, which would obviously be detrimental in terms of increasing the friction generated at the sliding contact.

[0024] To avoid this drawback, the following structure is proposed:

[0025] The sealing lip 6 is pivotably arranged in a radial cross section around a pivot point 8 (in the FIGURE, the pivot axis is thus perpendicular to the drawing plane). Furthermore, the elastomeric seal body 5 provides a counterweight 9 in connection with the sealing lip 6. As can be seen from the FIGURE, the sealing lip 6 and the counterweight 9 are arranged in different axial regions a.sup.1 and a.sup.2 respectively from the pivot point 8. The elastomeric seal body 5 further provides a connection section 12 that is joined to the outer cylindrical portion 11′″ the carrier element. The elastomeric seal body 5 may be joined to the carrier element 11 by means of vulcanization, adhesive bonding or any other suitable joining process.

[0026] The pivot point 8 is formed by a relatively slender region of the seal body 5 which joins the counterweight 9 and sealing lip 6 to the connection section 12. The bending stiffness of the sealing lip 6 together with the connection section 12 around the pivot axis is higher (at least two times as high) than the bending stiffness of the sealing lip together with the counterweight 9. Thus, it is possible for the counterweight 9 and the sealing lip 6 to pivot about the pivot point 8.

[0027] Such a pivoting action is achieved during rotation of the shaft 3 and radial seal in that the counterweight and sealing lip are designed such that the centrifugal force acting on the counterweight 9 is higher than the centrifugal force acting on the sealing lip 6. Suitably, the mass of the counterweight is greater than the mass of the sealing lip. Due to the higher centrifugal force on the counterweight 8, a pivoting movement takes place which is denoted by the two unreferenced arrows in the FIGURE. Thus, the contact force exerted by the sealing lip 6 on the counterface 10 decreases as the rotation speed increases, thereby minimizing the associated increase in sliding friction. Furthermore, at high rotation speeds, the sealing lip will lift off from the counterface 10, thereby eliminating sliding friction. The sealing arrangement 1 is thus suitable for use in a railway bearing unit which rotates at speeds in excess of 200 km/hr.

[0028] To provide additional protection against moisture and particulate contaminants from the environment E, the sealing arrangement 1 further provides a labyrinth seal 13 at an axially outer side of the arrangement. The labyrinth seal is formed by a small radial gap between the counterface 10 and a non-contact lip 14 that extends in a radial direction from the connection section 12 of the elastomeric seal body. During dynamic sealing, the radial extension of the non-contact lip 14 acts as a flinger that actively repels contamination. The non-contact lip 14 therefore helps to prevent contaminants from reaching the interface between the sealing lip 6 and the counterface 10, making it even more difficult for contaminants from the environment E to enter the bearing arrangement 2.

[0029] The invention is not restricted to the depicted embodiment, but is to be interpreted within the scope of the following claims.

REFERENCE NUMERALS

[0030] 1 Sealing arrangement

[0031] 2 Bearing arrangement

[0032] 3 Inner component (shaft)

[0033] 4 Outer component (bearing housing)

[0034] 5 Elastomeric body of radial seal

[0035] 6 Sealing lip of radial seal

[0036] 7 Sleeve element

[0037] 8 Pivot point

[0038] 9 Counterweight

[0039] 10 Counterface

[0040] 11 Carrier element of radial seal

[0041] 11′ Inner cylindrical portion of carrier element

[0042] 11″ Radial flange portion of carrier element

[0043] 11′″ Outer cylindrical portion of carrier element

[0044] 12 Connection section of elastomeric seal body

[0045] 13 Labyrinth seal

[0046] 14 Non-contact lip

[0047] 15 Gap (labyrinth seal)

[0048] E Environment

[0049] a Axis

[0050] a.sup.1 Axial region of sealing lip relative to pivot point

[0051] a.sup.2 Axial region of counterweight relative to pivot point