GB1600125A

GB1600125A - Rotational assemblies

Info

Publication number: GB1600125A
Application number: GB9073/77A
Authority: GB
Original assignee: KAMELMACHER E
Current assignee: KAMELMACHER E
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-10-14

Description

(54) IMPROVEMENTS IN OR RELATING TO ROTATIONAL ASSEMBLIES (71) We, EDUARD KAMELMACHER, of 77 Lionel Road, Brentford, Middlesex, of Israeli nationality, and LEONARD SMITH, of 8 Brook Lane, Bexley, Kent, a British subject, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:-- This invention relates to rotational assemblies, particularly but not exclusively to bearings.

The bearings of pumps normally require lubrication, and there is always the danger that the working fluid will attack or contamin ate the lubricant, or vice versa. Thus, bearings must be separated from the pumping fluid by meams of a liquid seal, an air gap and a lubricant seal. This necessitates a complex construction. Furthermore, a complex lubricating system must 'be provided for cooling, pumping and filtering the lubricant. Complex instrumentation and control is necessary in case the lubricating system fails.

Some bearings may be lubricated by water, petrol or similar low-viscosity liquids. The main disadvantages of such bearings are their low loading capacity, high rate of wearing, particularly in even slightly contaminated liquids, and also the instability of the bearing clearance owing to swelling and temperature changes.

In a particular rotational assembly, i.e.

a stern tube bearing of a ship, oil is supplied under pressure thus giving rise to oil leakages into the water which cause pollution.

An object of the invention is to provide a bearing or any other rotational assembly in which the relatively moving parts may be ]ubricated by the working or surrounding fluid.

The invention provides a rotational assembly comprising two members arranged one within the other for relative rotational movement, wherein each member has a bearing surface in rotational contact with a bearing surface of the other member, each bearing surface comprising one or more rings of silicon-impregnated graphitic carbon (silicized graphite), each ring extend ing around the rotational axis.

Bearings formed of this material may be lubricated by liquids, which have poor lubricating properties, such as water, napthia, ammonical liquors, most known acids, sea water and even liquids containing abrasive particles.

Silicized graphite, which is formed by impregnating porous graphite at an elevated temperature with molten silicon, has a low tensile strength, a very high compressive strength and a very low coefficient of expansion.

The bearing surfaces may be radial and/ or axial.

Preferably the outer ring of a radial bearing is provided with a concentric por tion and an eccentric portion to provide suitable mounting of the outer ring in a carrier.

Preferably, the inner ring or rings are mounted with a radial clearance on a central member so as to allow for thermal expansion of the central member.

Preferably, the inner and outer rings are -tapered to provide axial-thrust and radial bearings.

Alternatively, axial-thrust bearings are provided by axially-aligned rings. Preferably, the axially-aligned rings have grooves for lubricant.

Preferably, at least one ring is formed from a plurality of pads of silicized graphite, the pads being mounted in a supporting ring.

The pads may be crush-mounted in the supporting ring, or mounted by casting the material of the supporting ring into slots or grooves in the pads. This is particularly suitable where large bearing rings are re quired, e.g. for stern tube'bearings of ships.

The rotary assembly according to the in vention may also be used for marine bear ings, rudder stock bearings, pumps, hydro electric turbines, steam turbines etc.

The invention will now be described with reference to embodiments shown by way of example in the accompanying drawings, wherein: Fig. 1 is a longitudinal sectional view of a radial journal bearing, Fig. 2 is an end view of the non-rotating ring of Fig. 1, Fig. 3 is a longitudinal sectional view of an angular contact bearing providing both radial and axial constraint, Fig. 4 is a longitudinal sectional view of a combined radial and unbalanced axial bearing, Fig. 5 is an end view of the thrust face of part of the non-rotating ring of Fig. 4, Fig. 6 is a cross sectional view along the line A-A of Fig. 5, Fig. 7 is a longitudinal sectional view of a combined radial and balanced axial bearing, Fig. 8 is a longitudinal sectional view of an angular contact bearing providing both radial and axial constraint.

Figs. 9 and 10 show respectively part cross-sectional end views of the left-and right-hand side of two journal bearings, Figs. 11 and 12 show respectively longitudinal-sectional views of the left and righthand side of the bearing of Figs. 9 and 10.

Fig. 13 is a cross-sectional view of a bearing similar to the bearing of Figs. 9 and 11.

Fig. 14 is a longitudinal sectional view of a thrust and journal bearing.

Fig. 15 is a part cross-sectional end view of the right-hand half of the bearing of Fig. 14, Fig. 16 is an end view of the left-hand half of the rotating thrust bearing part of the bearing of Fig. 14, Fig. 17 is a longitudinal sectional view of a radial journal bearing, Fig. 18 is a cross-sectional view along the line A-A of Fig. 17, and Figs. 19 and 20 show modified pads in cross-section.

In Figure 1, a radial journal bearing comprises a stationary component and a rotating component. The rotating component comprises a ring or rings 1 of silicized graphite which are mounted with a clearance fit on the outer surface 3 of a sleeve 2 fixed on a shaft 2'. The rings 1 are maintained concentric with the sleeve 2 by tapered rings 4 and 5 which are prevented from rotating by pins 6. Springs 7 exert pressure on the tapered rings 4 and 5 and the rings 1 via tapered faces 8 only, to provide compensation for differential thermal expansion, whilst maintaining the rings 1 concentric with axis 19 of the sleeve 2 and shaft 2'.

The stationary component comprises a ring 9 of silicized graphite the bore of which is concentric with axis 19 and a major portion 10 of its cylindrical outer surface. The remainder of its cylindrical outer surface 11 is parallel to the axis 19 but arranged eccentrically thereto (see also Figure 2). The bore of a carrier 12, which locates and supports the ring 9 is suitably machined to provide a light interference fit for the ring 9 over the concentric portion 10 and a loose fit over the eccentric portion 11.

If required, cooling of the bearing in addition to that provided by lubricating fluid can be accomplished by the provision of holes 13 in the sleeve 2, holes 14 in the tapered ring 4 and holes 15 in the tapered ring 5, thereby enabling the cooling fluid to pass through the clearance spaces between the rings 1 and the sleeve 2 to cool all the interior surfaces of the moving component of the bearing. Similarly, holes 16 and helical groove or grooves 17 and channels 18 can be provided in the stationary component for the same purpose.

In Figure 3, a thrust and journal bearing is constructed similarly to the bearing shown in Figure 1 except that the working surfaces of outer rings 20 (analogous to rings 1) are inclined and are either plane, as shown, or part-spherical in order to carry an axial load.

The stationary component comprises two rings 21, a spacer 22, two carriers 23 and a clamping flange 24. Multi-part construction is required to permit assembly. Clearance between the rings 21 and the rings 22 is adjusted by regulation of the length of the spacer ring 22.

In Figure 4, a combined thrust and journal bearing is shown which is more suitable for heavier thrust loads than the bearing shown in Figure 3.

The journal bearing assembly is almost identical with that shown in Figure 1. The thrust bearing assembly comprises a stationary component and rotating component.

The rotating component comprises a sleeve 2 extended at one end to form a flange or disc 25, which carries two rotating rings 26 and 27 which may be of different sizes and which are positioned in the disc 25 in a similar way to the ring 9 in carrier 12 in Figure 1. The stationary component comprises a ring 9 one end of which acts as one thrust face and which has small grooves 28 cut across the face width for cooling and lubrication (see also Figures 5 & 6), and which is located in carrier 12 as illustrated in Fig. 1.

Axial thrust in the opposite direction is limited by a ring 29 the thrust face of which is grooved as the thrust face of ring 9, and which is supported in a carrier 30 in the same way as ring 9 is supported in carrier 12 (i.e. with a concentric surface and a stepped eccentric surface).

The combined thrust and journal bearing illustrated in Figure 7 has the additional feature of providing hydraulic balance thereby being suitable for heavier axial loads. The general construction of this em bodiment is very similar to that of Figure 4.

Hydraulic balance is provided by increasing the diameter of a thrust disc 31 at the end of the sleeve 2 to provide the requisite area differential which is a function of the area of the disc 31 contained between the bore of the ring 9 and rings 32 and 33. The thrust face of ring 33 is grooved for cooling and lubrication.

Axial thrust in the opposite direction is limited by rings 27 and 29.

Externally pressurised fluid injected into a space 38 via a passage 39 will pass through the gaps between the rings 33 and 32 into a chamber 36, and out of the bearing through a gap 35 into a space 34, and also through the journal bearing where it will leak away through the clearance between rings 1 and 9. The nett effect is to produce an end thrust in the direction of arrow 37 opposing the applied thrust, which is in the direction of arrow 40.

The combined bearing and liquid seal illustrated in Fig. 8 comprises two stationary components and two rotating components.

The rotating components comprise rings 41 and 42, which are mounted at opposite ends of a rotating member 43 and are positioned in a way similar to rings 26, 27 in Fig. 4.

The stationary components comprise rings 44 and 50. Ring 44 is mounted in a carrier 45 similar to ring 27 in Fig. 4. The carrier 45 is a slide fit in casing 46, is sealed against liquid leakage by a resilient seal 47, and is preloaded by a spring 48.

The carrier 45 is prevented from rotating by pin 49.

The ring 50 is mounted in a carrier 51 similar to ring 27 in Fig. 4. The carrier 51 is mounted in a casing 52 so that the carrier cannot rotate.

Where the liquid pressure in spaces 54 and 55 is above that in spaces 56 and 57 no provision for lubrication is required.

Where the liquid pressure in spaces 54 and 55 is less than the spaces 56 and 57 or the spaces 54 and 55 are filled with a gas, lubricating fluid must be supplied to spaces 56 and 57 from an external supply. In this case the space 57 must be sealed against leakage.

As can be seen from Fig. 8 the contacting rings 41, 50 and 43, 44 contact via inclined bearing surfaces. The angle of the inclined surfaces is chosen such that the intersection of the perpendiculars to the working surfaces of rings 41 and 42 with the axis 53 of the rotating member 43 are external to the bearing assembly to provide stability. The inclined working surfaces may be plane or part-spherical.

The journal bearing illustrated in Figures 10 and 12 comprises an inner rotating part and an outer stationary part. The rotating component comprises a plurality of silicized graphite pads 58, the ends of which are rebated to form keys 59. The pads 58 are mounted in a rotating member 60 by crushing rings 61. Before crushing the rings 61 are in a position 62 indicated by broken lines. After positioning the pads 58, the rings 61 are crushed down to trap the pads 58. The stationary component comprises a ring 9 and a carrier 12 as described for the embodiment of Figure 1. The bearing surfaces are machined after assembly to provide plane cylindrical surfaces with a desired bearing clearance between them.

The journal bearing illustrated in figures 9 and 11 comprises a rotating component, and a stationary component similar to that described in Figures 10 and 12. The rotating component comprises a plurality of silicized graphite pads 63, the sides of which are provided with grooves 64. A rotating ring 65 is cast between and around the inside surface - of the pads 63, which are secured by end rings 67 and spacers 66 integral with the ring 65. The pads 63 stand proud of the outer surface of the ring 65 by a clearance 68. The bearing surfaces are machined after assembly to provide plane cylindrical surfaces with the desired bearing clearance between them.

The journal bearing illustrated in figure 13 is similar to that illustrated in Figures 9 and 11 except that the pads 69 are shaped to provide an almost continuous radially outer surface.

The combined thrust and journal bearing illustrated in Figures 14 to 16 is constructed on the same principles as the bearing illustrated in Figures 10 and 12. The rotating part of the journal bearing is identical with that shown in Figure 13.

A rotating part 71 of the thrust bearing comprises a thrust disc 74 which is cast around silicized graphite pads 72, the radi ally-outer faces of which are provided with a groove 73 to secure the pads in the disc 74.

A stationary part 68 comprises a flanged mounting ring 69, which is cast around siliconised pads 70, the sides of which are provided with grooves 76, and the tops of the pads are relieved with cut-outs 75 in order to secure the pads 70 in the ring 69.

The bearing surfaces are machined after assembly to provide plane surfaces with the desired clearance between them.

The cast inner and outer rings can be made from any material with a melting point less than that of Silicon.

The bearing shown in Figures 17-20 comprises a stationary ring 81 mounted in a casing 2 and a rotating ring 83 mounted on a shaft 84. The rotating ring 83 is formed by means of casting between the inside sur face of silicized graphite pads 85 which are connected to each other to form a continuous ring by means of flexible joints 86 having the same length as the pads 85.

The flexible joints 86 are stamped out of thin plate, the material of which is similar to that of the ring 83, so that the flexible joints 86 become integrated into the ring 83 during casting.

The pads 85 have a channel-shaped crosssection with the sides 87 diverging in a direction towards the associated web portion to form a key preventing radial movement of the pads 85 under the influenced centrifugal forces. External side surfaces 8 of the pads 85 are similarly divergent to provide sufficient space between the pads to be filled in by the material of the supporting ring 83. The radial depth of the joints 86 is less than the radial depth of the sides 87 whereby grooves 89 between the pads 85 and the flexible joints 86 are retained to provide access for cooling and lubricating fluid.

As shown in Fig. 18 the base 90 of the channel is substantially flat.

As shown in Fig. 19 the base 90 of the channel has a conclave-concave shape to provide greater thickness of the pad 5 at the middle.

As shown in Fig. 20 the base 90 of the channel has a corrugated shape to increase the grip between the pads 85 and the supporting ring 83.

The construction of the stationary ring 81 is similar to that of the rotating ring 83.

In most cases identical silicized graphite pads 85 can be used for the ring 83 and the ring 81. The bearing surfaces are machined after casting to provide plain cylindrical surfaces with the desired bearing clearance between them.

WHAT WE CLAIM IS: - 1. A rotational assembly comprising two members arranged one within the other for relative rotational movement, wherein each member has a bearing surface in rotational contact with a bearing surface of the other member, each bearing surface comprising one or more rings of silicon-impregnated graphitic carbon (silicized graphite), each ring extending around the rotational axis.

2. A rotational assembly as claimed in claim 1, wherein radial bearing surfaces are provided.

3. A rotational assembly as claimed in claim 1 or claim 2, wherein axial bearing surfaces are provided.

4. A rotational assembly as claimed in claim 2, wherein the outer ring of a radial bearing is provided with a concentric portion and an eccentric portion to provide suitable mounting of the outer ring in a carrier.

5. A rotational assembly as claimed in claim 2, wherein the inner ring or rings are mounted with a radial clearance on a central member so as to allow for thermal expansion of the central member.

6. A rotational assembly as claimed in claim 2, or claim 4, or claim 5, wherein the inner and outer rings are tapered to provide axial-thrust and radial bearings.

7. A rotational assembly as claimed in claim 3, wherein axial-thrust bearings are provided by axially-aligned rings.

8. A rotational assembly as claimed in claim 7, wherein the axially aligned rings have grooves for lubricant.

9. A rotational assembly as claimed in claim 1, wherein at least one ring is formed from a plurality of pads of silicized graphite, the pads being mounted in a supporting ring.

10. A rotational assembly as claimed in claim 9, wherein the pads are of channel shaped cross-section.

11. A rotational assembly as claimed in claim 10, wherein the sides of each pad diverge in a radially outward direction towards the associated web portion which defines part of the bearing surface to form a key thereby preventing loading of the bearing surface by centrifugal forces acting, in use, on rotating pads.

12. A rotational assembly as claimed in claim 11, wherein the pads are connected together by means of flexible joints.

13. A rotational assembly as claimed in claim 12, wherein the radial depth of the flexible joints is less than the radial depth of the sides of the channel-shaped pads, so as to define grooves between adjacent pads.

14. A rotational assembly as claimed in claim 9, wherein the pads are crush-mounted in the supporting ring.

15. A rotational assembly as claimed in any one of claims 9-13, wherein the pads are mounted by casting the material of the supporting ring into slots or grooves between the pads.

16. A rotational assembly as claimed in claim 14, wherein the sides of the pads are provided with grooves.

17. A rotational assembly substantially as herein described with reference to and as shown in Figs. 1 and 2, Fig. 3, Figs. 4, 5 and 6, Fig. 7, Fig. 8, Figs. 9 and 11, Figs. 10 and 12, Fig. 13, Figs. 14, 15 and 16, Fig. 17 and 18, Fig. 19 or Fig. 20, of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. face of silicized graphite pads 85 which are connected to each other to form a continuous ring by means of flexible joints 86 having the same length as the pads 85. The flexible joints 86 are stamped out of thin plate, the material of which is similar to that of the ring 83, so that the flexible joints 86 become integrated into the ring 83 during casting. The pads 85 have a channel-shaped crosssection with the sides 87 diverging in a direction towards the associated web portion to form a key preventing radial movement of the pads 85 under the influenced centrifugal forces. External side surfaces 8 of the pads 85 are similarly divergent to provide sufficient space between the pads to be filled in by the material of the supporting ring 83. The radial depth of the joints 86 is less than the radial depth of the sides 87 whereby grooves 89 between the pads 85 and the flexible joints 86 are retained to provide access for cooling and lubricating fluid. As shown in Fig. 18 the base 90 of the channel is substantially flat. As shown in Fig. 19 the base 90 of the channel has a conclave-concave shape to provide greater thickness of the pad 5 at the middle. As shown in Fig. 20 the base 90 of the channel has a corrugated shape to increase the grip between the pads 85 and the supporting ring 83. The construction of the stationary ring 81 is similar to that of the rotating ring 83. In most cases identical silicized graphite pads 85 can be used for the ring 83 and the ring 81. The bearing surfaces are machined after casting to provide plain cylindrical surfaces with the desired bearing clearance between them. WHAT WE CLAIM IS: -

1. A rotational assembly comprising two members arranged one within the other for relative rotational movement, wherein each member has a bearing surface in rotational contact with a bearing surface of the other member, each bearing surface comprising one or more rings of silicon-impregnated graphitic carbon (silicized graphite), each ring extending around the rotational axis.