WO2002053927A1

WO2002053927A1 - Bearing arrangement

Info

Publication number: WO2002053927A1
Application number: PCT/NO2000/000430
Authority: WO
Inventors: Ole Gunnar SÖVIKNES
Original assignee: Norwegian Ballbearing Development As
Priority date: 2000-12-15
Filing date: 2000-12-15
Publication date: 2002-07-11

Abstract

Bearing arrangement with an outer ring (12) with a centrally located aperture, which ring is provided for mounting in a carrier (a bearing house, wheel or similar), and with an inner ring (14) provided for mounting on a shaft or a similar carrying member, for sliding movement between said rings. In the aperture (30) of the outer ring element (12), at least one annular rib (18) extending radially into the aperture is provided. Further it comprises a pair of inner ring elements (14a, 14b) with an outer diameter mainly equal to the inner diameter of the aperture of the first ring element (12) and with a stepped radially exposed outer surface. The steps of the inner ring elements (14a, 14b) are facing each other, to suit into the aperture (30) of the outer ring element on different sides thereof, with a sliding engagement against the rib (18) extending into the aperture (30).

Description

Bearing arrangement

The invention relates to a bearing arrangement for slowly rotating mechanisms, as stated in the introductory part of claim 1. Under "slowly rotating" is here meant a mechanism with a limited and particularly slowly rotating movement and mechanisms rotating up to some few revolutions per second,

Background

It is known various sleeve bearings with shafts journaled in sleeves of plastic. From SKG- Catalogue 3500 E from 1990 it is known to use sleeves with a radially protruding end flange as isert in a bearing, but this proposal has not been satisfying for all purposes.

Traditional bearing devices otherwise utilizes ball bearings with balls confined between mutually rotating parts to ensure smooth movement with low friction. Lubricants, such as oils or synthetical fluids, are used for further reducing the friction and avoiding direct contact between the elements. The lubricant is forced into a converging gap in the bearing device.

Traditional bearing arrangements however suffer from various drawbacks. Such devices are inclined to be heavy, relatively large and vulnerable to corrosion. Further known bearing arrangements are expensive due to the manufacturing costs demanded by the need for low tolerances for some of the parts. At low velocities these bearings are subject to damages, particularly "Brinell-damages", particularly in cases with a high impact at low velocity. This implies an undesirable rate of failure.

Object

The main object of the invention thus is to provide a bearing arrangement for slowly rotating mechanisms, eliminating one or more of said disadvantages.

It is a particular object to provide a smaller bearing arrangement which can be manufactured with simpler components than known ball bearings and which is particularly suitable for purposes with low rotating speeds and frequent starts and stops in the rotating movement.

The Invention

The invention is stated in claim 1. "Slowly rotating" may be mechanisms with a limited and particularly slow rotating movement, e.g. the fork of a bike, and mechanisms rotating up to some few revolutions per second, such as the wheel of a wheelbarrow. The invention is particularly suitable for bearing arrangements demanding frequent and limited rotation in both directions. With this design, it is possible to provide a simple bearing with both axial and radial load capacity and also with high rotational stiffness. It may well replace grooved ball bearings. The inner couple of rings are advantageously manufactured of bronze or another suitable metal and the outer ring is manufactured of polyethyleneterefthalate (PETP), even if various other materials can be used for bearings for particular purposes.

The surface of the annular components is preferably particularly plain, particularly for abutting surfaces. Coarse surfaces will reduce the service life of the bearing arrangement. This applies particularly to the surface quality of the larger ring (the first part), because this normally is manufactured of a harder material than the smaller rings, which thus would be more susceptible to a rapid wear if subjected to a coarse surface.

The tolerances may preferably be lower than 20μm for the smallest parts (the second an the third part) and less than 35μm for the larger ring (the first part). The tolerances are preferably lower than 15μm and even less than lOμm for the small rings and less than 25 μm and even 20μm for the larger. The preferred limit for avoiding an undesirable influence on the service life of the bearing arrangement is Ra 0,2% and the bearing surface should preferably not exceed this value. The inner ring typically has an inner diameter of 2,5 to 120 mm and the outer ring an outer diameter of 6 to 315 mm. Accordingly the preferred tolerances should be approximately 0,02 to 0,04% and preferably approximately 0,03%.

Advantageous features of the invention are stated in the sub claims.

Example

The invention is further described with reference to the drawings, wherein: Fig. 1 shows an exploded perspective view of a bearing arrangement according to the invention,

Fig. 2 shows a plane view from above of the bearing arrangement in Fig. 1, Fig. 3 shows a section along the line A-A in Fig. 2,

Fig. 4 shows an exploded axial view of the bearing arrangement in Fig. 3, while Fig. 5 shown an axial section through a further embodiment of a bearing arrangement according to the invention.

In Fig. 1 a bearing arrangement 10 for slow rotation is shown, which comprises three parts: a ring 12 and two rings 14a, 14b which are of a smaller diameter than the first ring and which are arranged on different sides thereof, to have the first ring confined in between.

In Fig. 1 the design of each ring is clearly shown, and description will be given with reference to this Figure. The larger ring 12 has a radially outward facing circumferential surface 20 and a surface 16 facing radially inward to an aperture 30. The surface 16 is divided in right part 16a in the Figure and a left part 16b by a radially extending flange 18 forming a rib coaxial with the ring 12. The smaller rings 14a and 14b have uniform radially extending cylindrical surfaces 22a and 22b and stepped radially facing cylindrical surfaces 29a and 29b.

In Fig. 2 the bearing arrangement is shown in front view seen from the right side in Fig. 1. The right smaller ring 14a is fitting closely into the aperture 30 of the larger ring, with the step of the radially outward facing surface 29a shown with a broken line 32. This view would be identical from the left side of Fig. 1, with the left smaller ring 14b arranged in the aperture 30 of the larger ring 12 on the left side.

In fig. 3 the assembly of the parts is shown more clearly. The smaller rings 14 and 14b is fitting into the aperture 30 of the larger ring 12 and are abutting opposite sides of the flange 16. The larger ring 12 has an outer diamter Dy and an inner diameter outside the flange 16 of Di. The outer diameter of the smaller rings 14a and 14b is denoted dy and the inner diameter di. The smaller rings 14a and 14b are mutually abutting with the facing surfaces 33a and 33b. (Fig. 1). In Fig. 4 the geometry of the parts is shown more clearly. The larger ring 12 has an inner diameter ds (counted from the face of the flange 18). Each of the smaller rings 14a and 14b has an outer cylindrical surface 28 with a width t and a diameter Di (see Fig. 3) and an inner cylindrical surface 24 with a width i and a diameter Dn, separated bu the radial step 6. The steps 26 are abutting the respective sides of the flange 18.

The flange 18 may have different designs, the steps of the smaller rings 14a and 14b may be fitted correspondingly. A bearing arrangement can thus be manufactured according to the invention, which for certain purposes need less maintenance, has a longer service life and is less subject to corrosion and failure than comparable known bearing arrangements. This applies particularly for purposes with slow rotation. The novel bearing arrangement can be manufactures relatively cheaply and with a weight reduction of 30-40% to comparable known radial wheel-bearings. The novel bearing arrangement is suitable for uses with frequent knocks and few and varied rotations, e.g. with several starts and stops, such a bearing arrangement can act as an axial and as an radial bearing, even if it is most suited for uses with mainly radial load and with a demand for radial load stiffness. It may replace a radial sleeve bearing without increasing the size.

The parts of this bearing may be manufactured of various suitable materials, but it is preferred to use a combination of bronze or another metal in the inner rings. An example of suitable material for the outer ring is polyethyleneterefthalate (PETP).

This bearing arrangement has the ability to endure dynamic load variations. Further it is suitable for replacing existing bearings.

The design of the bearing arrangement allows to utilize the smaller rings as emitting rings and the bearing thus will be suitable for use in contaminated or chemically affected environments. On the other side the bearing arrangement has a drainage property in resting position, independent of the inclination of its mounting, e.g. on a vehicle. The bearing arrangement may also be usesd in the electrotechnical industry.

The performance of the novel bearing arrangement is relatively insensitive to the temperature.

In Fig. 5 is shown an alternative embodiment providing some of the most important advantages when used on a wheel. On a wheel shaft 41, a spacing sleeve 44 is arranged between two inner rings 42, 43. These part may be manufactured of stainless steel and be pressed against a step 45 on the wheel shaft 41 by a nut 46 on a threaded outer end 47 of the shaft. The rings 42, 43 have a substantially larger outer diameter than the spacing sleeve 44. The rings 42, 43 correspond to the rings 14a and 14b of the above example, the step of the former being omitted.

This embodiment may have been used with an enclosing ring corresponding to the ring 12 of the above example. But in this case it is divided in two part 48, 49, each with a radial step 50 which corresponds to the outer surface for each of the inner rings 42, 43. Therby each of the outer rings 48, 49 will provide a cylindrical surface 51 which will have a sliding contact with the outer surface 52 of each of the inner rings 42, 43, and an axially facing annular surface 53 making a sliding engagement against the exposed part of the inner side of adjoining inner ring 42 and 43 respectively.

The outer rings 48, 49 have an outer radial step 54 provided by a axially seen outer flange 55, 56. The stepped part of said outer rings 48, 49 are introduced from opposite sides into the aperture 57 of a wheel 58. In this example, the wheel 58 is annular and solid, but is may be suitably modfied. It is a provision that the wheel can keep the outer rings without rotation in a defined distance with low tolerances. The outer rings 48, 49 may be manufactured in a suitable plastic material, with tolerances as stated above. On the outer side of each of the inner rings 42, 43 an inner, axially extending collar or flange 59 is provided. The inner annular flange provided on each of the outer rings 48, 49 is given the reference numeral 60.

This embodiment will be more complicated to manufacture and more demanding to mount on a wheel or another arrangement than the former embodiment, but it will still provide a substantial gain to prior art.

Modifications

The invention may be modified in different ways relatively to the above examples. The rib or flange in the aperture in the outer ring is preferably integrated therewith. But it is possible by dividing the outer ring to arrange the rib as a joining part between the two inner rings. For some purposes it is also conceivable to reverse the structure of the embodiment of Fig. 1. The outer rings may be arranged in the aperture of a wheel differently from the shown manner, but it is preferred that each ring has a radially protruding flange with a mutual distance corresponding to the hub length of the wheel.

The shaft 41 can be modifid to different suspensions, e.g.in a fork. The rings 48, 49 can be attached to a carrier in other ways than shown, provided that a fixed distance is provided.

Claims

Claims: 6

1. Bearing arrangement with an outer ring (12) with a centrally located aperture, which ring is provided for mounting in a carrier (a bearing house, wheel or similar), and with an inner ring (14) provided for mounting on a shaft or a similar carrying member, for sliding movement between said rings, characterized in

- that the aperture (30) of an outer ring element (12) has at least one annular rib (18) extending radially into the aperture, and - that it further comprises a pair of inner ring elements (14a, 14b) with an outer diameter mainly equal to the inner diameter of the aperture of the first ring element (12) and with a stepped radially exposed outer surface, and

- that the steps of the inner ring elements (14a, 14b) are facing each other, to suit into the aperture (30) of the outer ring element on different sides thereof, with a sliding engagement against the rib (18) extending into the aperture (30).

2. Bearing arrangement according to claim 1, characterized in that the rib (18) consists of a flange (18) with parallel, radially extending sides facing into the aperture (30), said flange being integrated with the outer ring element (12).

3. Bearing arrangement according to claim 1 or 2, characterized in that the outer ring element comprises two rings (48, 49) with mirror symmetry, each of which has a radially inward step (50) to provide an annular flange (60) on each.

4. Bearing arrangement according to claim 3, characterized in that the inner ring elements (42, 43) are spaced by an axial sleeve (44) engaging the outer ring elemetns (48, 49).

5. Bearing arrangement according to claim 3 or 4, characterized in that to outer ring elements (48, 49) are attached to a common carrier in a fixed mutual distance.

6. Bearing arrangement according to claim 5, characterized in that the outer ring elements (48, 49) are arranged in an aperture (53) in a wheel (58), each of them having a radially outward protruding flange (55, 56) with a mutual axial distance corresponding to the hub length of the wheel.