DOUBLE-ROW BALL BEARING

Abstract

A double-row ball bearing, in particular for adjusting the blades of a tail rotor of a helicopter, including an inner ring and an outer ring as the bearing rings, and balls rolling off between the bearing rings and designed to transmit axial forces between the bearing rings in both directions, the outer ring being tiltably supported in a housing part.

Claims

1. A double-row ball bearing comprising: an inner ring and an outer ring, and balls which roll between the inner ring and outer ring and configured to transmit axial forces between the inner ring and outer ring in both axial directions, wherein the outer ring is tiltably mounted in a housing part, and wherein the outer ring has two annular, mutually spaced, convexly curved surface sections defining sliding surfaces which describe one and the same spherical surface.

2. The ball bearing according to claim 1, wherein the outer ring and the housing part comprise a tilting bearing configured as a plain bearing.

3. The ball bearing according to claim 2, wherein a lubricant chamber is formed between the sliding surfaces of the outer ring, an outer circumferential surface of the outer ring, lying between said sliding surfaces in the axial direction, and an inner circumferential surface of the housing part.

4. The ball bearing according to claim 3, wherein the inner circumferential surface, delimiting the lubricant chamber, of the housing part is at least partially cylindrical.

5. The ball bearing according to claim 1, wherein the mounting of the outer ring is supported in the housing part to allow a tilting between the outer ring and the housing part of at least 2.

6. The ball bearing according to claim 1, wherein the housing part is configured as a housing ring coupled to the outer ring in a rotationally fixed manner, whereby during operation the inner ring can rotate freely relative to the outer ring.

7. The ball bearing according to claim 6, further comprising a predetermined breaking element rotationally coupling the housing ring to the outer ring, the predetermined breaking element allowing limited tilting, between the outer ring and the housing ring, the predetermined breaking element configured to release a relative rotation between the outer ring and the housing part when a maximum torque acting between the inner ring and the outer ring is exceeded.

8. The ball bearing according to claim 1, configured as a double-row bearing in an O-arrangement.

9. A method comprising: providing a double-row ball bearing having an inner ring and an outer ring, and balls which roll between the inner ring and outer ring and configured to transmit axial forces between the inner ring and outer ring in both axial directions, wherein the outer ring is tiltably mounted in a housing part, and wherein the outer ring has two annular, mutually spaced, convexly curved surface sections defining sliding surfaces which describe one and the same spherical surface; and using the double-row ball bearing in a tail rotor of a helicopter which has a blade adjustment system.

10. The method according to claim 9, wherein the outer ring and the housing part comprise a tilting bearing configured as a plain bearing.

11. The method according to claim 10, wherein a lubricant chamber is formed between the sliding surfaces of the outer ring, an outer circumferential surface of the outer ring lying between said sliding surfaces in the axial direction, and an inner circumferential surface of the housing part.

12. The method according to claim 11, wherein the inner circumferential surface, delimiting the lubricant chamber, of the housing part is at least partially cylindrical.

13. The method according to claim 9, wherein the outer ring is supported in the housing part to allow a tilting between the outer ring and the housing part of at least 2.

14. The method according to claim 9, wherein the housing part is configured as a housing ring coupled to the outer ring in a rotationally fixed manner, whereby during operation the inner ring can rotate freely relative to the outer ring.

15. The method according to claim 14, further comprising a predetermined breaking element rotationally coupling the housing ring to the outer ring, the predetermined breaking element allowing limited tilting, between the outer ring and the housing ring, the predetermined breaking element configured to release a relative rotation between the outer ring and the housing part when a maximum torque acting between the inner ring and the outer ring is exceeded.

16. The method according to claim 9, wherein the double-row bearing is in an O-arrangement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In the following, an exemplary embodiment of the disclosure is explained in more detail with reference to a drawing. In the drawings:

[0026] FIG. 1 shows a double-row ball bearing in a sectional view.

DETAILED DESCRIPTION

[0027] A rolling bearing 1 designed as a double-row ball bearing is part of a blade adjustment system, denoted overall by 10, of a tail rotor of a helicopter. The rolling bearing 1 has an inner ring 2 and an outer ring 3 as bearing rings, with the inner ring 2 being formed in two parts in the present case, namely consisting of a first inner ring part 4 and an identically shaped inner ring part 5 arranged in a mirror-inverted manner in relation thereto. Each inner ring part 4, 5 provides an inner ring raceway 9, on which balls roll as rolling bodies 6. The balls 6, which are also in contact with the outer ring raceways 14, are thus arranged in the form of two rows of rolling bodies 7, 8. A center plane ME, which is placed between the inner ring parts 4, 5, is located in the middle between the rows of rolling bodies 7, 8. Pressure lines through the centers of the rolling bodies 6 are denoted by DL. For example, the rolling bearing 1 is a double-row bearing in an O-arrangement. In contrast to the inner ring 2, the one-piece outer ring 3 has an annular central web 15, to which the outer ring raceways 14 are connected. The rolling bodies 6 are guided in a cage 11. Seals disposed on both end faces of the rolling bearing 1 are denoted by 12, 13.

[0028] The outer ring 3 is accommodated in a housing part 16, which is designed as a housing ring. A tilting bearing in the form of a plain bearing 17 is formed between the housing ring 16 and the outer ring 3. In the non-tilted setting of the rolling bearing 1 shown in FIG. 1, the annular components 2, 3, 16 have a uniform central axis MA. If the inner ring 2 and the outer ring 3 with it also are tilted relative to the housing part 16, which means a misalignment, the result is an angle , shown exaggerated in FIG. 1, between an axis FL and the central axis MA. The tilting by the angle is completely absorbed by the tilting bearing 17 and can be up to 2.

[0029] When the blade adjustment system 10 is operated as intended, the outer ring 3 rotates together with the housing ring 16, while the inner ring 2 constitutes a stationary bearing ring. A blade of the tail rotor is adjusted by the inner ring 2 being displaced in the adjustment direction VR, i.e. along the central axis MA. In this case, the outer ring 3 and the housing ring 16 rotating with it are inevitably also displaced. Any slight tilting between the outer ring 3 and the housing ring 16 is insignificant in this adjustment process on account of the tilting bearing 17.

[0030] The tilting bearing 17 comprises two annular sliding surfaces 18, 19 which are provided by the outer ring 3 and define a spherical shape SP. The two mutually spaced sliding surfaces 18, 19 adjoin the end faces of the outer ring 3 and are arranged mirror-symmetrically with respect to the center plane ME. A substantially cylindrical outer circumferential surface 20 of the outer ring 3 is disposed between the two sliding surfaces 18, 19. The outer circumferential surface 20 is concentrically surrounded by an inner circumferential surface 21 of the housing ring 16. The plain bearing sections denoted by 22, 23, which are each formed on the one hand by one of the sliding surfaces 18, 19 and on the other hand by a sliding lining 24 on the housing ring 16, adjoin the inner circumferential surface 21. A lubricant chamber 25 filled with grease is formed between the outer circumferential surface 20 of the outer ring 3 and the inner circumferential surface 21 of the housing part 16.

[0031] As long as the outer ring 3 is freely rotatable relative to the inner ring 2, the plain bearing 17 has the sole function of a tilting bearing. Each rotation of the outer ring 3 about the central axis MA is accompanied by a corresponding rotation of the housing ring 16 about the central axis MA. For this purpose, a pin 26 is firmly inserted into a bore 27 in the outer ring 3. The pin 26 simultaneously engages in an opening 28 which is disposed in the housing part 16.

[0032] As can be seen from FIG. 1, the pin 26 in the opening 28 has significant play in the longitudinal direction of the central axis MA. This play enables the described tilting of up to 2 between the outer ring 3 and the housing ring 16. On the other hand, in the direction orthogonal to this, that is to say in the circumferential direction of the outer ring 3 and of the housing ring 16, there is no or only minimal play of the pin 26. Relative rotations between the outer ring 3 and the housing ring 16 are thus excluded. However, if excessive forces occur between the outer ring 3 and the housing part 16, which in extreme cases can be attributed to a blockage between the inner ring 2 and the outer ring 3, the pin 26 breaks, thus representing a predetermined breaking element. At this moment, rotation between the outer ring 3 and the housing ring 16 is released, which means that the plain bearing 17 is converted into a rotary bearing. In this state, the lubricant supply disposed in the lubricant chamber 25 contributes significantly to heat dissipation. The kinematics of the blade adjustment system 10 are retained even in the case of this emergency function of the plain bearing 17, which otherwise only serves as a tilting bearing.

LIST OF REFERENCE SIGNS

[0033] 1 Rolling bearing, double-row ball bearing [0034] 2 Inner ring [0035] 3 Outer ring [0036] 4 Inner ring part [0037] 5 Inner ring part [0038] 6 Rolling body, ball [0039] 7 Row of rolling bodies [0040] 8 Row of rolling bodies [0041] 9 Inner ring raceway [0042] 10 Blade adjustment system [0043] 11 Cage [0044] 12 Seal [0045] 13 Seal [0046] 14 Outer ring raceway [0047] 15 Central web [0048] 16 Housing part, housing ring [0049] 17 Plain bearing, tilting bearing [0050] 18 Sliding surface of the outer ring [0051] 19 Sliding surface of the outer ring [0052] 20 Outer circumferential surface [0053] 21 Concave inner circumferential surface [0054] 22 Plain bearing section [0055] 23 Plain bearing section [0056] 24 Sliding lining [0057] 25 Lubricant chamber [0058] 26 Pin, predetermined breaking element [0059] 27 Bore in the outer ring [0060] 28 Opening in the housing part [0061] Angle [0062] DL Pressure line [0063] FL Axis of the inner ring with misalignment [0064] MA Central axis [0065] ME Center plane [0066] SP Spherical shape [0067] VR Adjustment direction