Taper roller bearing with grease retainer

Abstract: A taper roller bearing comprises an inner ring (2,3) and an outer ring (1) having tapered raceways, and enclosing a bearing space in which tapered rollers (4,5) are arranged as well as a cage for mutually spacing the rollers. A grease retainer means (10) is connected to the outer ring (1). The grease retainer means (10) are situated next to the inner ring part having the smallest raceway diameter. They comprise a ringshaped channel (10) in the inner space of which grease can be accommodated, which channel has apertures for communicating the channel inner space with the bearing space.

Description: The invention is related to a tapered rolling element bearing according to the preamble of claim 1 as known from US-A-2 272 757. Taper roller bearings are widely known. They are able to take both radial and axial loadings. In order to obtain a smooth operation, normally an amount of grease is filled in the bearing space between the outer and the inner ring. In service, the grease is to be gradually consumed by bleeding of the oil contained in the grease, which means that after a specific service interval a new amount of grease should be added. The specific consumption of grease is however impeded by the centrifugal forces which are exerted on the grease due to the rotational movements of the rotating ring and roller/cage set. Thereby, the grease is urged towards the largest diameter portion of the bearing space, and may finally collect in a position where it is no longer effective for lubrication purposes. A further problem which may arise in the known bearings is the inaccurate dosing of the grease into the bearing space. After filling the grease, a too large amount thereof may reach the bearing space or roller/cage sweeping space. Under the influence of centrifugal forces it will then be transported to the larger diameter end. Also the working of the grease will lead to high bearing temperatures. The object of the invention is to provide a taper rolling bearing which lacks these problems. This is achieved by the features of the second part of claim 1. The grease retaining means are able to prevent the grease from migrating too quickly into the bearing space, even under the influence of shock loads and centrifugal forces as normally generated in service. The grease retaining means are carried out in that they comprise a ringshaped channel in the inner space of which grease can be accommodated. The channel has apertures for communicating the channel inner space with the bearing space. Such channel has a U-shaped cross section, the bottom of which faces outwardly towards the outer ring. The grease can be easily retained within the U-shaped channel, as the centrifugal forces will press it against the bottom thereof. The apertures ensure a gradual delivery of grease and thereby oil into the bearing space. The taper rolling bearing may comprises two sets of tapered rollers which sets are each arranged in a separate bearing space between corresponding inner and outer rings, the ring parts having the smallest raceway diameter facing each other, wherein the grease retainer means are situated between the two inner rings. The outer rings are carried out as a unity, the grease retainer means are connected to the axially central part of said unitary outer ring. The grease retainer means are here carried out as a channel having two generally parallel flanges extending radially inwardly from the channel bottom, which flanges are provided with apertures. The channel can be easily mounted, for instance by snap-fitting. The bottom is provided with at least one radially outwardly extending pipe stub which fits in a correspondingly shaped hole in the outer ring. As usual, grease replenishments are applied through these holes. In practice, almost all the grease will assemble near the hole, and will initially not be spread out evenly. In order to obtain a quicker and more even distribution of the grease, the apertures in the channel flanges have varying mutual distances such that there are only a few apertures (15) near the pipe stub (14). A further advantage of the grease retainer means becomes apparent during storage and transport. Under such conditions, the grease may gradually sink to the lowest position, and almost all of it may end up between the raceways and the rolling elements. In such cases, high temperatures will develop as soon as the bearing in question is taken into service. The grease retainer means prevent the formation of such undesirable grease concentrations as well. According to a preferred embodiment, the channel of the grease retaining means consists of an injection moulded plastic. The invention will be explained further with reference to an embodiment as shown in the drawings. Figure 1 shows a partial cross section of a taper rolling bearing according to the invention. Figure 2 shows a grease retaining channel according to the invention in sideview. Figure 3 shows part of the grease retaining channel in perspective according to figure 2. The taper rolling bearing according to figure 1 comprises a unitary outer ring 2, as well as to separate inner rings 2, 3. Between these rings, two sets of rollers 4, 5 have been accommodated. In each set, the rollers are spaced apart by means of a cage ring 6, respectively 7. The two inner rings are spaced apart by means of spacer ring 8. A grease lubricant replenishment hole 9 has been provided in the outer ring 1. According to the invention, a grease retaining channel 10 has been connected to the outer ring 1. This grease retainer ring 10 has a bottom 11, as well as to radially inwardly extending flanges 12, 13. The bottom 11 of the grease retaining channel 10 is provided with at least one pipe stub 14, which clickfits into grease replenishment holes 9. Between channel 10 and the opposite spacer ring 8, a small gap is available. Figure 2 shows the grease retaining channel 10, having three pipe stubs 14 which each fit in a grease lubricant replenishment hole 9 in the outer ring. As is clear from figure 1 and 2 as well, the flanges 12, 13 are provided with apertures 15, which are spaced according to a particular pattern. Near each pipe stub 14, the apertures 15 are spaced apart at a greater distance than the apertures further away from a pipe stub 14. The reason therefore is the following. In replenishing the grease, a certain amount, e.g. 80 grammes, is introduced through the outer ring 1 via grease replenishment holes 9 and pipe stub 14. In practice, a large amount of grease will then sit in the vicinity of these pipe stubs 14, without initially spreading over the full channel area. However, the grease is more or less compelled to spread further over the channel by having only a few apertures 15 near the pipe stubs. Thereby, only a limited amount of grease can escape in the area near the pipe stubs; the remaining grease will flow further away from the pipe stubs and escape from the channel via the other apertures 15. Thereby, an even spreading of grease over the entire circumference of the taper roller bearing is ensured. Moreover, during transport and storage the grease retainer channel prevents the grease from sinking into the bearing space, for instance when the taper rolling bearing is stored during a longer time on one side. Figure 3 shows that the bottom 11 of the channel 10 may consist of a number of bridges 16 and openings 17. The channel may consist of a material such as plastic; also, metals such as aluminium or steel are possible.

Claims: Rolling element bearing comprising an inner ring means (2, 3) and an outer ring means (1) enclosing a bearing space in which rolling elements (4, 5) are arranged, as well as a cage (6, 7) for mutually spacing the rollers (4, 5), a grease retainer means (10) connected to the outer ring means (1), said grease retainer means comprising a ringshaped channel (10) in the inner space of which grease can be accommodated, which channel (10) has apertures (15) for communicating the channel inner space with the bearing space, said channel (10) having an U-shaped cross section, the bottom (11) of which faces outwardly, and the parallel flanges (12, 13) of which extend radially inwardly from the bottom (11), which flanges (12, 13) are provided with the apertures (15), characterised in that the rolling element bearing is a taper roller bearing whereby the inner and outer (1) ring means have tapered raceways, the outer ring means (1) being carried out as a unity, the channel (10) being connected to the axially central part of said unitary outer ring means (10), and the bottom (11) of the channel (10) being provided with at least one radially outwardly extending pipe stub (14) which fits in a correspondingly shaped hole (9) in the outer ring means (1), and in that the apertures (15) in the channel flanges (12, 13) have varying mutual distances such that there are only a few apertures (15) near the pipe stub (14). Rolling element bearing according to claim 1, wherein the channel consists of an injection moulded plastic.

Inventors: KOLLAARD NICOLAAS, PERSSON MATS JOHN, KOLLAARD, NICOLAAS, PERSSON, MATS JOHN
Applicants: SKF ENG & RES CENTRE BV, SKF ENGINEERING & RESEARCH CENTRE B.V.
Application year: 1997
Main classification: F16C33
IPC codes: F16C33, F16C19