GB2453041A

GB2453041A - A lubricant-stripper

Info

Publication number: GB2453041A
Application number: GB0817062A
Authority: GB
Inventors: Dierk Welz
Original assignee: Renk GmbH
Current assignee: Renk GmbH
Priority date: 2007-09-18
Filing date: 2008-09-17
Publication date: 2009-03-25
Anticipated expiration: 2028-09-17
Also published as: DE102007044496B4; GB0817062D0; GB2453041B; DE102007044496A1

Abstract

The invention relates to a lubricant-stripper for stripping lubricant from a moving surface 42 carrying lubricant in a bearing arrangement 40, in particular in a sliding-bearing arrangement for ships. The lubricant-stripper 10 has a carrier 12 for detachable securement to a fixed securement point 50 of the bearing arrangement 40 close to the moving surface 42, and a stripper element 24 which is held on the carrier 12 and cooperates with the surface 42 in order to strip and remove the lubricant. In accordance with the invention, at least the carrier 12 or the stripper element 24 is made from a material with a sufficiently high volume and surface resistivity that the lubricant-stripper 10 itself is electrically insulating.

Description

Sliding-bearing arrangement with a lubricant-stripper The invention relates to a lubricant-stripper for stripping the lubricant that is required for lubrication and cooling from a moving surface carrying lubricant in a bearing arrangement, in particular in a sliding-bearing arrangement, having a carrier for detachable securement to a fixed securement point of the bearing arrangement close to the moving surface, and having a stripper or wiper element which is held on the carrier and cooperates with the surface in order to strip and remove the lubricant, wherein the lubricant-stripper is to be electrically insulated with respect to the fixed securement point. Furthermore, the invention relates to a sliding-bearing arrangement in accordance with the preamble of claim 13.

In order to guarantee the supply of lubricant in particular in a bearing arrangement that has large dimensions, such as a sliding-bearing arrangement for stationary and off-shore installations and also for ships, there is often provided on the shaft that is mounted in the bearing arrangement close to the bearing point a lubricant-conveyor, for example a fixed lubricating ring, which takes up lubricant, for example lubricating oil or lubricating grease, from a reservoir and conveys it to the bearing point. In Figure5 4, 5 and 6 a known in-plant lubricant-stripper 100 is shown that is used, for example, on sliding-bearing arrangements 102. The lubricant-stripper 100 has a carrier 104 made from metal, to the underside of which a stripper element 106 is secured. The stripper element 106 is formed from metal sheets 108 that are connected together.

Depending on the case of application, the stripper element 106 is either fixed to the underside of the carrier 104 or is mounted on the underside in a floating manner, that is, is mounted so that it can be adjusted in relation to the carrier 104. Furthermore, provided adjacently to the stripper element 106 on the underside of the carrier 104 there is a lubricant feed 110 in the form of a chute.

In the installed state, as shown in Figure 5, the carrier 104 is supported on a fixed securement point 112 in the sliding-bearing arrangement 102 in such a way that the stripper element is arranged with its underside at a short distance from the peripheral face of a fixed lubricating ring 114; this ring is used as a lubricant-conveyor and is non-rotatably connected to the shaft, which is not shown.

On account of the short distance between the fixed lubricating ring 114, which is usually made from metal, and the stripper element 106, which is likewise made from metal, a charge-separation brought about by friction can result on account of the film of lubricant between the fixed lubricating ring 114 and the stripper element 106 that leads to electrical charging of the stripper element 106.

Electrical charging of the stripper element 106 is, however, to be prevented in all circumstances for safety reasons.

For this reason, the lubricant-stripper has up until now been electrically insulated from the securement point at great expense. For this purpose, provided at the securement point there is a bore with an internal thread 116 into which a stud bolt 118 is screwed. Onto the stud bolt 118 are slipped an adjusting spring 120 and an insulating sleeve 122 which surrounds the latter, is made from plastics material and is received in a receiving bore 124 provided on the carrier 104. Laid on the end face of the insulating sleeve 122 are a shim disc 126 and an insulating disc 128 which is made from plastics material and on which the carrier 104 is stayed with the end face of its receiving bore 124. The stud bolt 118 projects through the two discs 126 and 128, a through-bore 130 which is formed in the carrier 104 and is in alignment with the receiving bore 124 and in which an insulating sleeve 132 made from plastics material is likewise received, and a further insulating disc 134 that is supported on the upper side of the carrier 104. A collar nut 136 is screwed onto the thread at the free end of the stud bolt 118 with the adjusting screw l2Otensioned to such an extent that the desired gap between the lubricant-stripper and the fixed lubricating ring is established. The lubricant-stripper 100 is to be electrically insulated with respect to the securement point 112 by means of this kind of securement.

As the construction which has been outlined shows, up until now a plurality of different elements have needed to be positioned at the securement point 112 in order to secure the carrier 104, which increases the outlay on production and assembly.

It is an object of the invention to provide a simplified lubricant-stripper, or a sliding-bearing arrangement that has such a lubricant-stripper, whilst maintaining sufficient electrical insulation.

The invention is directed to a lubricant-stripper or wiper according to claim 1. In accordance with the invention, at least the carrier or the stripper element is made from a material with a sufficiently high volume and surface resistivity that the lubricant-stripper itself acts in an electrically insulating manner. Furthermore, the invention is concerned with a sliding-bearing arrangement that has the features according to claim 13 and is provided with such a lubricant-stripper.

Forming the lubricant-stripper in an electrically insulating manner has the advantage, on the one hand, that the risk of electrically charging the lubricant-stripper as a result of charge-separation brought about by friction is generally reduced. On the other hand, expensive insulation between the lubricant-stripper and the securemerit point, as was previously required, is no longer necessary since the lubricant-stripper itself acts as an insulator. In this way, expensive securernent with insulating elements, such as insulating sleeves and insulating discs, as usual up until now in the prior art, is no longer required. As a result, it is not only the number of required structural parts and components that is reduced, since the insulating elements which are otherwise required are dispensed with.

Furthermore, assembly and disassembly are simplified as a result of the low number of structural parts and components in the case of the use of the lubricant-stripper in accordance with the invention. The risk that during assembly structural parts and components will fall by mistake into the bearing arrangement and need to be recovered again in order to prevent damage to the bearing arrangement, which could develop during operation as a result of lost structural parts and components, is diminished. In addition, the structural space required for the securement of the lubricant-stripper can be reduced in

comparison with the prior art.

In order to achieve sufficient insulation of the lubricant-stripper, a material is preferably used for the carrier and/or the stripper element whose volume resistivity determined in accordance with IEC 60093 lies in the range of 108 to i0 Q'm, preferably 1O'° to i' Q*m. Furthermore, it is advantageous if the surface resistivity determined in accordance with IEC 60093 of the material of the carrier and/or the material of the stripper element lies in the range of 108 to 10's, preferably 1010 to i0' Q. The materials for the carrier and the stripper element can also differ from each other in terms of their physical properties. In a particularly preferred manner, however, at least the stripper element has a sufficiently high volume resistivity and a sufficiently high surface resistivity to obtain the desired insulation effect.

The use of an electrically insulating plastics material has been shown to be particularly suitable at least for the carrier or at least for the stripper element, with not only thermosetting plastics and elastomers, but also thermoplastics being suitable as plastics materials, since these are easy to shape and process further. Of particular advantage in this case is the use of an electrically insulating thermoplastic plastics material, since this can be processed very simply by extrusion and when corresponding moulds are used can be shaped into almost any conceivable three-dimensional configuration. Furthermore, subsequent machining for definitive shaping is also possible in the case of plastics materials so that in order to reduce further the outlay that is required, basic shapes for the carrier or the stripper element can be previously produced in large piece numbers that are subsequently adapted to the respective intended purpose by means of suitable methods, such as machining. It is particularly advantageous if in particular the stripper element is made from plastics material, since the latter can come into direct contact with the surface carrying the lubricant without the surface that is often provided with corresponding surface structures for better lubricant-absorption being impaired or damaged.

Preferably, polyamide is proposed as a material for the lubricant-stripper, with particularly preferably polyamide 6 (PA 6) being suitable as a plastics material for the carrier and/or the stripper element on account of its wear resistance. If the plastics material deliberately or even unintentionally comes into contact with moving parts, such as, for example, the fixed lubricating ring, the polyamide is preferably mixed with a sliding agent, preferably molybdenum disuiphide, in order to reduce the wear further.

In order to simplify production and to guarantee the desired electrical insulating effect of the lubricant-stripper in accordance with the invention it is proposed that the carrier and the stripper element be made of the same material, in which case it is particularly advantageous if the carrier and the stripper element are formed in one piece.

In order to render possible the highest possible level of flexibility when using the lubricant-stripper, it is proposed that the stripper element be secured to the carrier as a separate structural part. In this way, one and the same carrier can be used with different stripper elements that are adapted in terms of their shape to the respective intended purpose. The stripper element is preferably mounted in a floating manner on the carrier so that the stripper element is independently positioned in relation to the surface to be stripped during operation. As a result, on the one hand adjustment is simplified, whilst on the other hand possible deviations in the position and the course of the surface are compensated for.

The stripper element is provided with at least one stripper face that cooperates with the surface in order to strip the lubricant. Advantageously, at least one stripper face is configured in such a way that stripped lubricant is further removed. The stripper face can then be formed as a planar face which is inclined, for example, at a predetermined angle of inclination in relation to the stripping direction.

Alternatively, however, it is also conceivable to configure the stripper face in a curved manner, when viewed in cross section, in particular in a continuously or section-wise convex manner, concave manner and/or arched manner, with not just one circular-arc shape, but also other free-form faces being understood by arched course, such as oval, partly elliptic or parabolic courses. The stripper face is then preferably provided on the stripper element in such a way that when the lubricant-stripper is assembled the stripper face has the arched course when viewed in a plane that extends tangentially to the surface to be stripped. A particularly good stripping and removing effect is achieved in this way.

So that the lubricant-stripper can be used for opposing stripping directions, it is further proposed that the stripper element be provided with two stripper faces that extend, when the lubricant-stripper is assembled, with mirror-symmetry with respect to each other when viewed in a plane extending tangentially to the surface to be stripped.

In this way, the lubricant stripper can be used universally; this means that the running direction of the surface to be stripped in relation to the stripper element is insignificant, as a result of which the assembly is also further simplified.

In accordance with a second aspect, as defined in assembly claim 13, the invention relates to a sliding-bearing arrangement that is designed in particular for use in ships, stationary or off-shore installations and is equipped with a lubricant-stripper in accordance with the invention according to one of the previous claims.

For a better understanding of the invention, embodiments of it will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a perspective representation of an embodiment of a lubricant-stripper in accordance with the invention with a channel-shaped lubricant feed; Figure 2 shows a partly cut side view of the lubricant-stripper that is shown in Figure 1 in its installed position in a sliding-bearing arrangement; Figure 3 shows a partly cut side view, realized in accordance with Figure 2, of a modification of the embodiment shown in Figure 2 with a stripper element mounted in a floating manner; Figure 4 shows a perspective representation of a lubricant-stripper in accordance with the

prior art;

Figure 5 shows a partly cut side view of the lubricant stripper shown in Figure 4 in

accordance with the prior art in its

installed position in a sliding-bearing arrangement; and Figure 6 shows a stripper element in accordance with

the prior art that is mounted in a floating

manner.

Figure 1 shows a perspective view of a first embodiment of the invention, in the form of a lubricant-stripper 10. The lubricant stripper or wiper 10 has a substantially rectangular, plate-shaped carrier 12. Formed on the underside of the carrier 12 there is a plate-shaped elevation 14 that is arranged symmetrically between the two shorter longitudinal edges 16 of the carrier 12. Provided adjacently to the elevation 14, close to each longitudinal edge 16 on the underside, there are two receiving bores 18 that are each aligned with a through-bore 20 of smaller diameter (cf. Figure 2).

Secured to the elevation 14 -there is a likewise rectangular holding plate 22 extending transversely to the longitudinal direction of the carrier 12. Held on the underside of the holding plate 22 there is a stripper element 24 and also a lubricant feed or feedback arrangement 26 located adjacently to the stripper element and formed as a channel.

The stripper element 24 has a substantially triangular basic body, with one of the faces of the stripper element, the face 28, extending substantially parallel to the shorter longitudinal side of the holding plate 22. The two other faces 30 and 32 are formed with mirror-symmetry with respect to each other and have a circular-arc-shaped course. The tip of the stripper element 24 points in the direction of an opening 36 of the lubricant-feedback 26 that is delimited by a bent-over section 34.

The stripper element 24 is made from a plastics material that is mixed with a sliding agent, in the present case from polyamide 6 (PA6) mixed with MoS2. The polyamide 6 used for the stripper element 24 has a volume resistivity determined in accordance with IEC 60093 in the range of 1010 to Q*rn, whilst its specific surface resistance determined in accordance with IEC 60093 lies in the range 1010 to 1013 C). The carrier 12, the plate 22 and also the lubricant-feedback 26 are made from a metal material, in the present case from a steel sheet, and welded together. The stripper element 24 is secured to the plate 22, for example by adhesion or screwing.

The lubricant-stripper 10 that is shown in Figure 1 is represented in its installed position in Figure 2 in a partly cut-away side view. In the case of application shown in Figure 2, the lubricant-stripper 10 is used in a sliding-bearing arrangement 40. The sliding-bearing arrangement 40, which is only partly represented, serves to mount a shaft (not shown) which extends perpendicularly to the drawing plane and on which a fixed lubricating ring 42 is provided in a non-rotatable manner. The fixed lubricating ring 42 is used as a lubricant-conveyor and conveys lubricant out of a reservoir below the shaft into the region of the sliding-bearing point (not shown). Provided on the housing 44 of the sliding-bearing arrangement 40 there is an assembly opening 46 that is closed by means of a cover 48 secured with screws. Formed underneath the cover 48 on the housing 44 there is a securement point in the form of a shoulder 50. The lubricant-stripper 10 with its carrier 12 is supported on this shoulder 50.

In order to secure the carrier 12, provided in the shoulder 50 there are a plurality of internal threads 52, only one of which is shown in Figure 2. A stud bolt 54 that projects through the receiving bore 18 and the through-bore 20 is screwed into the thread. Furthermore, slipped onto the stud bolt 54 there is an adjusting spring 56 which is received in the receiving bore 18. Screwed onto the end of the stud bolt 54 projecting out of the through-bore 20 there is a collar nut 58 with which carrier 12 is secured on the shoulder 50 and spaced with respect to the biased adjusting spring 56.

The lubricant-stripper io is positioned on the shoulder 50 in the housing 44 in such a way that the stripper element 24 is arranged at a short distance (for example 0.3 to 0.5 mm) from the lateral surface of the fixed lubricating ring 42 at the highest point of the ring. When the shaft is rotated, as indicated by the arrow F, the fixed lubricating ring 42 takes up lubricant. The lubricant is subsequently removed from the lateral surface by the stripper element 24 and subsequently brought into the lubricant feed 26 and conveyed to the sliding-bearing point. By using polyamide 6 for the stripper element 24 no charge-separation results and with that there is also no longer any charging of the lubricant-stripper 10; hence electrical insulation, as was previously required in the case of the known lubricant-strippers, is no longer necessary. Furthermore, the electrical connection between the fixed lubricating ring 42 and the lubricant-stripper 10 is interrupted by the stripper element 24 acting in an insulating manner.

A modified version of the lubricant-stripper io of Figures 1 and 2 is shown in Figure 3. In the case of this modified embodiment, the plate 22 is detachably connected to the carrier 12 by means of a screw connection 38, with the screw connection 38 being designed in such a way that the plate 22 together with the stripper element 24 can execute compensating movements.

The embodiments shown, with the modification, only represent one of many possible variants. it thus also lies within the scope of the invention to make not only the carrier 12 and the stripper element 24, but also just the carrier 12 or just the stripper element 24 out of an electrically insulating material.

List of reference numerals Lubricant-stripper 58 Collar nut 12 Carrier 100 Lubricant-stripper 14 Elevation 102 Sliding-bearing 16 Longitudinal edges arrangement 18 Receiving bores 104 Carrier Through-bores 106 Stripper element 22 Holding plate 108 Metal sheets 24 Stripper element 110 Lubricant-feed 26 Lubricant-feed 112 Securement point 28 Face 114 Fixed lubricating ring Face extending in an 116. Thread arched manner 118 Stud bolt 32 Face extending in an 120 Adjusting spring arched manner 122 Insulating sleeve 34 Bent-over section 124 Receiving bore 36 Opening 126 Shim disc 38 Screw connectIon 128 Insulating disc Sliding-bearing 130 Through-bore arrangement 132 Insulating sleeve 42 Fixed lubricating ring 134 Insulating disc 44 Housing 136 Collar nut 46 Assembly opening 48 Cover Shoulder 52 Thread 54 Stud bolt 56 Adjusting spring

Claims

Claims 1. A lubricant-stripper for stripping lubricant from a moving surface (42) carrying lubricant in a bearing arrangement (40), having a carrier (12) for detachable securement to a fixed securement point (50) of the bearing arrangement (40), and a stripper element (24) which is held on or integral with the carrier (12) and cooperates with the surface (42) in order to strip the lubricant, wherein the lubricant-stripper (10) is to be electrically insulated with respect to the fixed securement point (50), characterised in that the carrier (12) and/or the stripper element (24) are made from a material with such a high volume resistivity and such a high surface resistivity that the lubricant-stripper (10) itself acts substantially in an electrically insulating manner.
2. A lubricant-stripper according to claim 1, in which the volume resistivity determined in accordance with IEC 60093 lies in the range 108 to 1015 *m, preferably in a range 1010 to 1013 Q'm.
3. A lubricant-stripper according to claim 1 or 2, in which the surface resistivity determined in accordance with IEC 60093 lies in the range 108 to 1015 Q, preferably in the range 1010 to 1013 �=.
4. A lubricant-stripper according to any preceding claim, in which the carrier (12) and/or the stripper element (24) is/are made from an electrically insulating plastics material, preferably a thermoplastic plastics material.
5. A lubricant-stripper according to claim 4, in which the plastics material is polyamide, preferably polyamide 6 (PA 6), which if applicable is mixed with a sliding agent, preferably molybdenum disuiphide or PTFE.
6. A lubricant-stripper according to any preceding claim, in which the carrier (12) and the stripper element (24) are made from the same material.
7. A lubricant-stripper according to claim 6, in which the carrier (12) and the stripper element (24) are formed in one piece.
8. A lubricant-stripper according to any of claims 1 to 6, in which the stripper element (24) is mounted on the carrier (12) in a floating manner.
9. A lubricant-stripper according to any of claims 1 to 6, in which the stripper element (24) has at least one stripper face (30, 32) which when the lubricant-stripper (10) is assembled has an arched or curved course when viewed in a plane extending tangentially to the surface (42) to be stripped.
10. A lubricant-stripper according to any preceding claim, in which the stripper element (24) has two stripper faces (30, 32) which when the lubricant-stripper (10) is assembled extend with mirror-symmetry with respect to each other when viewed in a plane extending tangentially to the surface (42) to be stripped.
11. A lubricant-stripper according to any preceding claim, in which the lubricant-stripper has at least one lubricant feed (26) that is arranged adjacently to the stripper element (24) and is preferably held on the carrier (12).
12. A lubricant-stripper substantially as described herein with respect to any of Figures 1 to 3.
13. A sliding-bearing arrangement having a sliding-bearing point for mounting a shaft, a lubricant-conveyor (42) which is fixed with respect to rotation on the shaft, and a lubricant-stripper (10) which co-operates with the lubricant-conveyor (42) and is formed in accordance with any preceding claim.
14. A sliding-bearing arrangement according to claim 13, in which the lubricant-conveyor is a fixed lubricating ring (42) that is fixed with respect to rotation on the shaft and with which the stripper element (24) cooperates in order to strip the lubricant.
15. A sliding-bearing arrangement according to claim 13 or 14 and installed in a ship or a stationary or off-shore installation.