Rolling bearing for linear movement

In a roller bearing (1) for the straightline movement of a supporting component (2) along a guide rail (6), the quantity of re-lubrication is to be minimized regardless of the installation position of the roller bearing (1). This is acheived by the invention in that a separate lubricant line (13) is inserted in a channel (10) of a head (8) for the lubricant supply which takes the form of a single-lipped seal (16) in a region in which lubricacant exiet points are desired.

The invention concerns a rolling bearing for linear movement of a carrier 
along a guide rail, said rolling bearing comprising pairs of rolling 
element circuits supported on raceways on the carrier and the guide rail, 
a head piece comprising a region for deflecting the rolling elements being 
arranged at each front end of the carrier, and at least one of said head 
pieces comprising a canal for feeding lubricant to the rolling elements. 
Such a rolling bearing is known from DE-PS 0 120 093. 
This document also shows a rolling bearing for linear movement comprising a 
carrier mounted longitudinally displaceably on a rail on four pairs of 
recirculating rolling element rows. The front ends of this generic type of 
rolling bearing are closed by head pieces. A canal for feeding lubricant 
to the rolling elements is provided in at least one of these head pieces. 
This canal is supplied with lubricant by a feed duct and a lubricating 
nipple. 
The disadvantage of the pre-cited rolling bearing is that the lubricant 
feed canal in the head piece has no valve-like closures or apertures at 
its exit openings, and moreover, due to unevennesses in the head piece, 
this canal cannot bear in an absolutely leak-tight manner against the 
carrier so that undesired lubricant losses can occur. Such lubricant 
losses necessitate higher minimum amounts of re-lubrication of the rolling 
bearing, and in the most unfavorable of cases, they can cause 
discontinuities in the lubricant film so that higher wear and premature 
failure of the described rolling bearing is to be expected. 
Moreover, the arrangement and the configuration of the lubricant canals 
concerned do not assure a uniform and reliable supply of lubricant to the 
intended points of lubrication of the rolling bearing in the different 
installed positions, i.e. a deficiency of lubricant would occur at first 
in the parts of the lubricant canals which are either furthest away from a 
central lubricant feed canal or situated in a region located in opposition 
to the direction of gravity. 
The object of the invention is therefore to provide a rolling bearing of 
the type initially described in which the above-mentioned disadvantages 
are eliminated and in which particularly, independent of the installed 
position of the rolling bearing, only minimum amounts of re-lubrication 
are required to assure a uniform and reliable lubricant supply to the 
rolling bearing. 
The invention achieves this object according to the characterizing part of 
claim 1 by the fact that a separate lubricant duct comprising radial 
openings for lubricant exit is inserted into the canal of the head piece. 
By means of this separate lubricant duct, the head piece is sealed on the 
carrier with respect to escaping lubricant. Due to the valve-like 
configuration of the openings, the amount of re-lubrication required can 
be considerably reduced because lubricant is transferred through the 
openings only under pressure and thus an exit of lubricant under the 
action of gravity is prevented. Moreover, the lubricant feed according to 
the invention is independent of the installed position of the roller 
bearing even when low-viscosity oil is used as a lubricant. 
Further developments of the invention are described more closely below. 
The lubricant duct has a substantially U-shaped cross-section and its 
lengthwise end which forms an opening bears against the carrier via 
contact surfaces. 
Such a U-shaped lubricant duct is easy to manufacture and its mounting on 
the head piece also does not present any problems. 
The lubricant duct can be made of an elastic polymeric material or any 
other elastic material. 
These materials are readily available and their shaping can be accomplished 
relatively simply. 
It is likewise advantageous to make the lubricant duct out of a 
light-weight material. 
By virtue of this material, and this can also apply to the other materials 
mentioned above, the total mass of the rolling bearing of the invention is 
only minimally increased. 
The contact surfaces of the lubricant duct bearing against the carrier are 
configured as double elastic sealing lips which, in the regions of 
intended lubricant exit points merge into single-lip elastic sealing lips. 
This embodiment is an advantageous development of the embodiment of claim 
1. By reason of the double elastic sealing lips, an excellent sealing 
between the head piece and the carrier is assured by simple means. 
The elasticity of the single-lip portions of the sealing lip is chosen so 
that when lubricant is required on the rolling element-side, the sealing 
lip yields to form an opening of adequate cross-section for the required 
transfer of lubricant, and when a state of pressure equilibrium prevails 
between the lubricant duct-side and the rolling element-side of the 
sealing lip, the sealing lip retains its central position, i.e. it remains 
closed and thus prevents an undesired continued flow of lubricant. 
It is appropriate, to arrange lubricant exit regions in the lubricant duct 
so that they register respectively with the raceways of the carrier. 
In conjunction with the previously mentioned measures, this configuration 
assures a minimum consumption of lubricant, i.e. the lubricant is only fed 
to the points where it is required. 
The radial openings of the lubricant duct are made in the form of slits 
which register respectively with the raceways of the carrier. 
These simple-to-make slits likewise enable a controlled lubricant supply. 
The sealing lips of these slits open only when a sufficient overpressure 
has been built-up in the lubricant duct, and in a slate of approximate 
pressure equilibrium, they keep the lubricant duct closed. This variant is 
also conceivable in combination with the embodiment of claim 4. 
The lubricant duct has a substantially annular cross-section. 
In this variant, the aforesaid sealing measures are not required. It is 
possible to use a hose of a readily available standard commercial quality. 
The lubricant duct comprises slits extending at a slant to its center line 
and arranged so as to register with raceway regions of the carrier. 
Similar to the aforementioned measures, these slits guarantee a controlled 
and economic supply of lubricant to the desired points of lubrication and 
can also be cut into the lubricant duct subsequent to its fabrication in a 
simple manner. 
It is advantageous, to make the lubricant duct so that it is closed at both 
ends. This simple measure makes the provision of additional and 
complicated sealing means on the carrier and the head pieces superfluous. 
The solution described here is not limited to linear guides only. It is 
conceivable to use it in all cases, for example also with rolling bearings 
for rotary motion, in which a lubricant or the like is transported through 
canals to respective points of consumption where a controlled and economic 
lubrication is required. 
The scope of the invention is not limited only to the features of the 
claims, there existing also the possibility of combining individual 
features of the claims with the disclosure contained in the statement of 
advantages and in the description of the example of embodiment.

FIG. 1 is a top view of a rolling bearing 1 according to the invention 
comprising a carrier 2 on which parts, not represented, to be moved 
linearly can be fixed by screw connections 3. The carrier 2 is 
longitudinally displaceably mounted on pairwise arranged circuits of 
rolling elements 4 which are supported on raceways 5, 5a provided on the 
carrier 2 and on a guide rail 6. 
The carrier 2 is closed at each of its front ends 7 by a head piece 8 made 
in this case of a plastic material. The head pieces 8 comprise deflecting 
regions 9 for the deflection of the rolling elements 4. At least one of 
the head pieces 8 comprises a canal 10 for supplying lubricant from a 
lubricating nipple 11 and a feed duct 12 to the rolling elements 4. 
A separate lubricant duct 13 is inserted into the canal 10 of at least one 
of the head pieces 8. In the present embodiment, the lubricant duct 13 has 
a U-shaped cross-section and its lengthwise end which forms a radial 
opening 14 bears against the front end 7 of the carrier 2 by double 
elastic sealing lips 15. In a region of intended lubricant exit, namely in 
the region of the raceways 5, 5a for the rolling elements 4, the lubricant 
duct 13 is made as a single-lip sealing tip 16. 
The mode of functioning of the rolling bearing 1 comprising the lubricant 
duct 13 of the invention will now be elucidated with the help of FIG. 2 
which is a cross-sectional view taken along line II--II of FIG. 1. 
It can be seen that the lubricant duct 13 is closed at its axial ends 17. 
Lubricant is pressed into the lubricant duct 13 via a lubricating nipple 11 
(s. FIG. 1) and a feed duct 12. This lubricant spreads out in a cavity 18 
which, when lubricant is continued to be fed, builds up an overpressure in 
the lubricant duct 13. This overpressure causes the single-lip sealing lip 
16 to yield by reason of its elasticity. The lubricant can now exit from 
the lubricant duct 13 in the regions of intended lubricant exit in the 
vicinity of the rolling elements 4 until the overpressure has been reduced 
to an extent that the single-lip sealing lip 16 is again closed, i.e. 
until the lubricant pressure in the lubricant duct 13 is similar to the 
lubricant pressure on the rolling element-side. 
Since the rolling bearing 1 is sealed all around, the lubricant remains in 
the lubricant duct 13 until a subsequent lubrication pulse causes a 
renewed increase of pressure in the lubricant duct 13 and the process is 
repeated. 
This also means that lubricant is transported only to the points where it 
is required, that is to say, to the points where the lubricant pressure on 
the rolling element-side is less than in the lubricant duct 13. Thus 
lubricant consumption is strongly minimized by using the rolling bearing 
1. 
FIG. 3 is a view of a lubricant duct 13 having a double elastic sealing lip 
15. The structure of this is similar to that described with reference to 
FIGS. 1 and 2. However, the double elastic sealing lip 15 extends along 
the entire lengthwise end 20 of the lubricant duct 13. A controlled 
lubricant supply to the raceways 5, 5a of the rolling bearing 1 (s. FIGS. 
1 and 2)is assured in this case with the help of slits 21. 
FIG. 4 is a cross-sectional view taken along line IV--IV of FIG. 3. It can 
be seen that the lubricant duct 13 is made of a plastic material. 
As can be seen in FIGS. 5 and 6, it is also possible for the lubricant duct 
13 to have an annular cross-section 22. Advantageously, this lubricant 
duct 13 of the invention is provided with slits 23 extending at a slant to 
the center line of the lubricant duct 13. These slits 23 are likewise 
arranged in the region of the raceways 5, 5a of the rolling elements 4. 
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List of Reference Numbers 
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1 Rolling bearing 
2 Carrier 
3 Screw connection 
4 Rolling element 
5 Raceway 
5a Raceway 
6 Guide rail 
7 Front end 
8 Head piece 
9 Region 
10 Canal 
11 Lubricating nipple 
12 Feed duct 
13 Lubricant duct 
14 Opening 
15 Sealing lip 
16 Sealing lip 
17 Ends 
18 Cavity 
19 not used 
20 Lengthwise end 
21 Slits 
22 Cross-section 
23 Slits 
24 Cross-section 
25 not used 
26 Contact surface 
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