Linear bearing element

The invention concerns a linear bearing element mounted on the running race of a guide rail and comprising, on at least one of its two front ends, a wiper which bears by an end region against the running face to retain lubricant in the linear bearing element, at lease one lubricant supply device, with its inlet end connected to an outer supply duct and its outlet, end connected with the bearing region being arranged on or in the bearing element.

The invention concerns a linear bearing element mounted on the running face 
of a guide rail and comprising, on at least one of its two front ends, a 
wiper which bears by an end region against the running face to retain 
lubricant in the linear bearing element, at least one lubricant supply 
device, with its inlet end connected to an outer supply duct and its 
outlet end connected with the bearing region being arranged on or in the 
bearing element. 
From DE-C-2 130 420 a bearing element is known which comprises a wiper unit 
permitting a constantly dosed lubrication of a rolling bearing by simple 
and inexpensive means. This device comprises a wiper made of a polymeric 
material with a wiping edge which is intended to clean the running face 
during the reciprocating motion of a bearing element made in the form of a 
recirculating roller shoe and thus keep away impurities from the rolling 
bearing while, at the same time, preventing lubricant from escaping from 
the bearing element. In this device, lubricant is transferred into the 
bearing element from the outside via an element made of an absorbent 
material surrounding the wiping edge which is in contact with the running 
face. However, it is possible that undesired emulsions present on the 
running face be transported into the bearing together with the lubricant. 
Another linear bearing element of the initially cited type is known from 
U.S. Pat. No. 4,927,272 whose lubricant supply device is a lubricant 
injection unit with a complicated elongate structure comprising an adaptor 
housing, an injection pipe, a lubricant reservoir, a measuring and 
filtering element and distributing canals which are connected to supply 
canals. The supply canals are arranged in the wiper giving it a 
complicated structure for a spare part so that when the wiper lip is worn 
out, a relatively expensive component has to be replaced. Moreover, the 
supply device of this prior art linear bearing element is screwed directly 
into a threaded bore of the bearing element with a part of its length 
protruding out of a front end thereof and this results in large dimensions 
of the bearing in the longitudinal direction of the guide rail. 
It is an object of the invention to provide a linear bearing having a 
compact wiper unit which prevents the ingress of dirt and permits the 
supply of defined, minimum quantities of lubricant to the running faces 
and bearing regions without leakage losses. 
It is intended that with such a wiper unit the lubricant should be retained 
as far as possible completely in the bearing element so that the 
quantities of lubricant required for re-lubrication can be drastically 
reduced. Users of equipment comprising bearings having wiper units should 
thus be enabled to better comply with laws concerning environmental 
protection. 
The invention achieves this object by the fact that the supply device is 
configured as a dosing valve and arranged in a chamber of an attachment 
body comprising distributing canals which are connected to the outer 
supply duct and open into the chamber, the attachment body being fixed on 
an end face of the bearing element. 
Dosing valves are standard commercial components used in central 
lubrication systems. They open and close as a function of the pressure of 
the lubricant delivered. 
Each attachment body of the bearing element can be made as a component 
having a U-shaped cross-section surrounding the guide rail and comprising 
a plurality of chambers in which dosing valves are arranged. 
The wiper can be made as a plate-shaped component arranged between the 
attachment body and the bearing element. It is appropriate, in this case, 
to arrange a transfer opening in the wiper to connect the dosing valve at 
its outlet end with the bearing region. However, it is also possible to 
arrange the wiper on the end face of the attachment body away from the 
bearing element. 
A simple method of fabrication comprises making the chambers for the dosing 
valves in the form of pocket bores in the attachment body. 
The dosing valve can be configured as a bush-type component comprising 
spaces arranged axially behind one another to form the inlet opening, the 
dosing chamber, the discharge chamber and the outlet opening. Within the 
chamber of the attachment body, the valve can be surrounded by a sealing 
ring separating the inflow region of the chamber from the discharge 
region. A securing of the dosing valve against axial displacement can be 
assured by a cylindrical pin pressed into a bore of the attachment body 
and engaging into an annular groove of the dosing valve. An axial fixing 
of the dosing valve can also be obtained by screwing it into the chamber 
which, in this case, is made at least partially as a threaded bore. 
It is also possible to make the dosing valve, for instance, out of two 
bush-type components arranged next to each other with parallel axes and to 
arrange one behind the other, an inlet opening and a dosing chamber in one 
of the components, and a discharge chamber and an outlet opening in the 
other component, the components being provided with a front end connection 
between the dosing chamber and the discharge chamber. The two components 
of the dosing valve may also be disposed one on the attachment body and 
one on the bearing element. 
Examples of embodiment of the invention are represented in the drawings and 
will be described more closely in the following.

As can be seen in FIGS. 1 to 7, a bearing element 1 of the invention has a 
wiper unit fixed on a front end thereof. The bearing element 1 comprises a 
carrier body with two deflector bodies arranged adjacent to front ends 
thereof. Bearing regions 2 of the bearing element 1 comprising rolling 
elements 3 are supported on running faces 4 of a guide rail 5. The wiper 
unit comprises an attachment body 6 which is configured as a carrier body 
for lodging dosing valves and which has a plate-shaped wiper 7 arranged 
thereon. During the reciprocating motion of the bearing element 1 along 
the guide rail 5, the end of a wiper lip 8 slides on the running faces 4 
of the guide rail 5 thereby preventing an escape of lubricant from the 
bearing region 2 and a penetration of dirt into the bearing. 
The wiper 7 of FIG. 2 is fixed on the front end of the attachment body 6 
away from the bearing element 1 while the wiper 7 of the wiper unit of 
FIG. 3 is arranged between front ends of the attachment body 6 and of the 
bearing element 1. 
Lubricant is supplied to the wiper unit from the outside via a supply duct 
9. Distributing canals 10 in the form of bores are arranged for this 
purpose in the attachment body 6 and can be sealed from the outside by 
sealing screws 11. The distributing canals 10 open into chambers 12 made 
in the form of pocket bores in each of which a dosing valve 13 is 
arranged. 
A dosing valve 13 can be configured as a bush-type component comprising 
axially behind one another, an inlet opening 14, a dosing chamber 15, a 
discharge chamber 16 and an outlet opening 17. Between the dosing chamber 
15, in which is disposed a spring-loaded piston 18, and the discharge 
chamber 16, there is arranged a non-return valve having a closing element 
in the form of a spring-loaded ball 19. 
In the embodiment represented in FIGS. 3 to 6, each dosing valve 13 is 
arranged in a chamber 12 so that its inlet opening 14 is downstream of the 
adjacent distributing canal 10, while its outlet opening 17 adjoins the 
wiper 7 where lubricant can flow out of the attachment body 6 through a 
transfer opening 20 into the bearing element 1 which is composed of a 
carrier body 29 and two deflector bodies 21. These deflector bodies 21 for 
the rolling elements 3 of the bearing element 1 adjoin the carrier body 29 
and likewise comprise transfer openings 22 which communicate with the 
transfer openings 20 of the wiper 7. In the embodiment of FIG. 2, the 
transfer openings 22 of the deflector bodies 21 are connected directly 
with the transfer opening 17 of the dosing valves 13. 
Each dosing valve 13 arranged in a chamber 12 is sealed with a sealing ring 
23 which seals the inlet opening-end of the chamber 12 from its outlet 
opening-end. The sealing ring 23 is an O-ring seal inserted into a 
peripheral groove of the dosing valve 13. 
The dosing valve 13 further comprises a second annular groove 24 on its 
outer surface into which a cylindrical pin 25 arranged in a bore of the 
attachment body 6 engages at one peripheral point to secure the dosing 
valve 13 against axial displacement. 
The supply of lubricant to the bearing regions 2 is effected by the fact 
that lubricant is transported under pulsating pressure via the supply duct 
9 and the distributing canals 10 into the chambers 12 and the inlet 
openings 14 of the dosing valves 13. This causes the piston 18 to be 
displaced in the dosing chamber 15 against the action of its pressure 
spring, and lubricant present in the dosing chamber 15 is thereby 
transported towards the non-return valve so that the ball 19 is lifted 
from its seat against the action of its pressure spring thus allowing 
lubricant to enter into the discharge chamber 16. Such a pressure pulse 
therefore causes the piston which is guided with play in the housing bore 
of the dosing valve to leave its position of rest so that the lubricant 
present in front of the piston is displaced through the non-return valve 
into the discharge chamber 16 and from there, through the outlet opening 
17, into the bearing region. When the piston reaches its end position, the 
piston tip seals the dosing chamber 15 in the direction of the non-return 
valve. Upon a relief of pressure, the piston spring pushes the piston 18 
back into its position of rest and the dosing chamber 15 is refilled with 
lubricant via the annular gap between the piston 18 and the housing bore 
of the dosing valve. The non-return valve prevents a back-flow of 
lubricant. 
The inner contour of the attachment body 6 facing the guide rail 5 can be 
configured so as to form a small gap on the guide rail 5 to serve as a 
pre-segregator for chips and other coarse impurities. As shown in FIG. 6, 
the sealing of the transfer openings 20 and of the joint between the 
attachment body 6 and the wiper 7 can be effected by a sealing plate 26 
arranged between the attachment body 6 and the wiper 7. 
It is also possible to additionally support the dosing valves 13 at their 
outlet opening-end by an additional plate 27 fixed on a front end of the 
attachment body 6. To absorb the thrust forces of the dosing valves 13, 
the plate 27 can be screwed to the attachment body 6. In this embodiment, 
which is shown in FIG. 3, it is appropriate to arrange a sealing ring 28 
between the plate 27 and the dosing valve 13. The embodiment of FIG. 2 
likewise comprises a sealing ring 28 for the dosing valve 13. 
To reduce the overall length of the attachment body 6, the dosing valve can 
be comprised of two bushes arranged next to each other with parallel axes, 
in which case, the dosing chamber 15 is arranged in one of the bushes and 
the discharge chamber 16 in the other bush. An overflow canal is then 
required to connect the two chambers to one another. The bush with the 
dosing chamber 15 and the bush with the discharge chamber 16 can both be 
pressed into their respective lodging bores. 
The attachment body 6 and the wiper 7 can be made together in the form of 
an inseparable unit of a high strength plastic material, for example, 
glass fiber reinforced polyamide. These two elements can be joined 
together by ultrasonic welding, in which case, no sealing is required 
between them. The wiper lip 8 can be spray-molded on the wiper 7 but it is 
equally possible to arrange this lip in a receiving groove and clamp it 
between two parts or fix it there by positive engagement in some other 
way. 
The dosing chamber and the discharge chamber may be arranged optionally in 
series or parallel to one another, and the non-return valve can be 
constituted by a ball with a compact diaphragm spring. A particularly 
economic structural unit is obtained if the dosing valves 13 are not 
comprised of separate bushes but the dosing chamber and the discharge 
chamber are formed in the material of the attachment body or of the 
deflector body. In lieu of the known types of commercial dosing valves, it 
is also possible to use valves of other known types, for example plate 
valves or solenoid valves. The attachment body 6, the wiper 7 with the 
wiper lip 8 and the deflector body 21 can all be made together as a 
one-piece component. 
Monitoring elements in the form of pressure sensors, microswitches or 
proximity switches can be integrated in the dosing valve 13 in the dosing 
chamber 15 or the discharge chamber 16 thereof, or in the canal connecting 
these chambers to one another or in the canal leading to the outlet 
opening 17. 
The modified wiper unit shown in FIGS. 8 to 10 comprises an attachment body 
30 and two wipers 31 with wiper lips 32 adjoining the front ends of the 
attachment body 30. The wipers 31 and the attachment body 30 are jointly 
fixed on the bearing element 1 by one central screw 33 and by further 
screws 34. The lubricant distributing canals 10 extending within the 
attachment body 30 can be optionally connected with the supply duct 9 by a 
plurality of bores leading to the outside. In the example of embodiment, 
two of these bores extending in a horizontal direction are sealed by 
sealing screws 11 while a vertical bore 36 surrounded by a sealing ring 35 
is connected via a large annular groove 37 of a reversible bush 38 with a 
horizontal distributing canal 10 leading to the dosing valves 13. 
The reversible bush 38 is fitted into a bore of the attachment body 30 and 
surrounds the central screw 33. In addition to the large annular groove 
the reversible bush 38 comprises two further, small annular grooves 39 on 
its outer surface which are arranged spaced axially behind one another so 
that when the reversible bush 38 is taken out of the attachment body 
turned through 180.degree. about an axis perpendicular to its own axis and 
then re-placed in its new position into the attachment body 30, no annular 
groove is located under the bore 36. In this way, the connection between 
the bore 36 leading to the outside and the distributing canals 10 is 
interrupted. 
This arrangement can be used when, after the removal of a sealing screw 11, 
lubricant is to be fed into the attachment body 30 via the thus obtained 
opening of the distributing canal 10 concerned. In this new position of 
the reversible bush 38, the two small annular grooves 39, which are 
disposed next to the bore 36 but not connected with it, establish a 
connection between the two distributing canals 10 extending on either side 
of the central screw 33. Lubricant flowing in from the supply duct 9 can 
thus be transferred from a single location on the attachment body 30 to 
all the dosing valves 13 arranged in the attachment body 30. 
The embodiments of the invention are not limited to linear elements mounted 
on rolling bearings but can be used equally well in bearing elements 
having sliding bearings. 
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Reference Numbers 
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1 Bearing element 21 Deflector body 
2 Bearing region 22 Transfer opening 
3 Rolling element 23 Sealing ring 
4 Running face 24 Annular groove 
5 Guide rail 25 Cylindrical pin 
6 Attachment body 26 Sealing plate 
7 Wiper 27 Plate 
8 Wiper lip 28 Sealing ring 
9 Supply duct 29 Carrier body 
10 Distributing canals 
30 Attachment body 
11 Sealing screw 31 Wiper 
12 Chamber 32 Wiper lip 
13 Dosing valve 33 Central screw 
14 Inlet opening 34 Screw 
15 Dosing chamber 35 Sealing ring 
16 Discharge chamber 
36 Bore 
17 Outlet opening 37 Large annular groove 
18 Piston 38 Reversible bush 
19 Ball 39 Small annular groove 
20 Transfer opening 
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