EP0634576B1

EP0634576B1 - Transmission with revolving bearing and seal used hereby

Info

Publication number: EP0634576B1
Application number: EP19940201679
Authority: EP
Inventors: Jozef Segers
Original assignee: Atlas Copco Airpower NV
Current assignee: Atlas Copco Airpower NV
Priority date: 1993-07-14
Filing date: 1994-06-11
Publication date: 1997-09-10
Anticipated expiration: 2014-06-11
Also published as: ES2109592T3; DE69405490D1; EP0634576A1; DE69405490T2

Description

The invention concerns a transmission with revolving bearing containing a main shaft, a main bearing house in which said main shaft is supported on bearings, a secondary shaft connected to the main shaft and revolving around the geometrical axis of the main shaft, whose geometrical axis is parallel to but eccentrically in relation to the geometrical axis of the main shaft, and a revolving bearing house in which the secondary shaft revolving together with the bearing house is supported on the revolving bearing in a revolving manner according to its geometrical axis.
Such transmissions are used among others to drive a scroll compressor. The fixed scroll is fixed in relation to the stationary main bearing house, whereas the moveable scroll working in conjunction with it is fixed in relation to the revolving bearing house.
A scroll compressor comprising a transmission of the above kind is disclosed in DE-A-4.100.328.
There is no hermetic separation between the bearings around the main shaft and the revolving bearing around the secondary shaft.
Among others in such applications, the bearings of the transmission are greased and sealed separately. At very high rotary speeds of the transmission, whereby the scroll compressors can work with a greater capacity and a greater output, the centrifugal load on the revolving bearing largely increases.
Very thorough greasing becomes necessary. Grease can no longer guarantee this. Oil lubrication is not applied because of sealing problems due to the special movement of the revolving bearing.
The invention aims to remedy this disadvantage and to provide a transmission with revolving bearing whereby oil lubrication can be applied and subsequently a very good lubrication and a very high speed can be obtained.
This aim is reached according to the invention because the transmission contains a seal which is situated between the inside of the main bearing house and the outside of the revolving bearing house, seals the opening between these bearing houses and is fixed in relation to the whole consisting of the main shaft and the secondary shaft.
In a particular embodiment according to the invention, the seal contains a ring which is fixed on a radially protruding part which extends into or opposite the opening between the inside of the main bearing house and the outside of the revolving bearing house and which stands on the whole consisting of the main shaft and the secondary shaft.
In a particular embodiment according to the invention, screw thread is provided on one of the sides formed by the inside of the main bearing house opposite the seal and the opposite outside of the seal.
In another peculiar embodiment of the invention, the screw thread is provided on one of the sides formed by the outside of the revolving bearing house opposite the seal and the opposite inside of the seal.
The invention also concerns the seal as such from the transmission according to any of the previous embodiments.
In order to better explain the characteristics according to the invention, the following preferred embodiment of a transmission with revolving bearing and of a seal used hereby is given as an example only without being limitative in any way, with reference to the accompanying drawings, where:

figure 1 shows a cross section of a transmission with revolving bearing according to the invention, mounted in a scroll compressor;
figure 2 shows a section according to line II-II in figure 1;
figure 3 shows the part indicated by F2 in figure 1 to a larger scale;
figure 4 shows the part indicated by F4 in figure 1, but with reference to another embodiment of the invention;
figure 5 shows the part indicated by F5 in figure 4 to a larger scale;
figure 6 shows a part analogous to that in figures 3 and 5, but with reference to a third embodiment of the invention;
figure 7 shows a part analogous to that in figures 3, 5 and 6, but with reference to a fourth embodiment of the invention;
figure 8 shows a part analogous to that in figures 3, 5, 6 and 7, but with reference to a fifth embodiment of the invention.

Figure 1 shows a coil compressor which mainly consists of a two-part housing 1 with a fixed scroll 2, an element 3 revolving in this housing with the moveable scroll 4 which works in conjunction with the above-mentioned fixed scroll 2, and a drive for this moveable element 3, consisting of an engine which is not represented in the figures and a transmission 5 according to the invention.
The housing 1 turns into a main bearing house 6 on one side which is part of the transmission 5. On a flat part of the inside of the opposite side of the housing 1 stands the fixed scroll 2.
The revolving element 3 is situated between the above-mentioned flat part and the main bearing house 6 and provided on the flat side diverted from the main bearing house 6 with a scroll 4 which works in conjunction with a scroll 2. This moveable element 3 makes a circular movement around a geometrical axis 7 inside the housing 1. Said element 3 is hereby lead by among others three crankshafts 8 of which one shaft part in the element 3 and the other shaft part in the housing 1, next to the main bearing house 6, is supported on bearings. The housing 1 is provided next to the scroll 2 with an entrance 9 for the air to be compressed and provided in the middle of the scroll 2 with an exit 10 for the compressed air.
The transmission 5 which causes the circular movement of the element 3 contains a main shaft 11 which is supported on two ball bearings 12 in the main bearing house 6. The geometrical axis of the main shaft 11 coincides with the above-mentioned geometrical axis 7.
To one end of the main shaft 11 is eccentrically connected a secondary shaft 13 whose geometrical axis 14 is parallel to but situated at a short distance from the above-mentioned geometrical axis 7. The revolving element 3 can rotate around the geometrical axis 14 and is mounted on the secondary shaft 13 by means of a revolving bearing 15 and is provided to this end on the side of the transmission 5 with a collar which forms the revolving bearing house 16 around the bearing 15.
On the side of the revolving element 3, the opening between the outside of the moving bearing house 16 and the inside of the main bearing house 6 is sealed by means of a seal consisting of a ring 17 whose circumference, as represented in figure 2, has a changing width. This ring 17 is fixed by means of three protruding bolts 18 on a radially extending part 19 of the main shaft 11 which extends radially to up against the main bearing house 6.
The ring 17 is, both on its outer edge which is situated opposite the inside of the main bearing house 6 and on its inner edge which is situated opposite the outside of the moving bearing house 16, provided with screw thread 20, as represented in detail in figure 3. This screw thread 20 is directed such that oil flowing from the main bearing house 6 in the direction of the element 3 is automatically returned.
As the main shaft 11 rotates, the secondary shaft 13 carries out a circular movement around the axis 7. As a result, via the revolving bearing 15, also the revolving element 3, which is prevented among others by the crankshafts 8 from rotating on itself, carries out a circular movement in the housing 1 around the axis 7.
Consequently, air between the moveable scroll 4 and the fixed scroll 2 is displaced and compressed. Also the bearing house 16 standing fixed on the element 3 carries out the same circular movement around the axis 7, whereby the secondary shaft 13 carries out a rotation around its geometrical axis in relation to the bearing house 16.
The inner edge of the ring 17 also carries out a circular movement around the axis 7 and simultaneously turns around the geometrical axis 14 and thus also around the moving bearing house 16 which carries out the same circular movement as the inner edge of the ring 17. Thus, the inner edge of the ring 17 only makes a rotating movement in relation to the outside of the bearing house 16 around the centre of this bearing house 16.
The ball bearings 12 and especially the revolving bearing 15 are lubricated by means of oil which is situated in the main bearing house 6. Thanks to the ring 17, the oil cannot leave the main bearing house 6 at the side of the revolving element 3.
The embodiment of the transmission 5 to which the figures 4 and 5 are related merely differs from the above-described embodiment in that the seal formed by the ring 17 is provided with screw thread 20 only on the inside of the ring opening, i.e. on the side directed towards the main bearing house 16, and in that the outer screw thread 20 is not provided in the outside of the ring 17 but opposite said outside, in the inside of the main bearing house 6 or more in particular in an insert ring 21 which is cased in the inside of the main bearing house 6 in a fixed way.
Naturally, this embodiment offers the same advantages as the first-described embodiment.
Thanks to the screw thread 20, no contact is required between the ring 17 and the bearing houses 6 and 16. By making use of the rotation, both of the outside of the ring 17 in relation to the inside of the main bearing house 6, as of the inside of the ring 17 in relation to the inside of the moving bearing house 16, in combination with a suited screw thread 20 on one of the opposite sides, a contact-free seal is obtained. Consequently, the wear and tear and heat development are minimal. Thanks to the good lubrication, the main shaft 11 can be driven at a high speed.
The embodiments according to the figures 6 to 8 differ from the above-described embodiments in that the seal, apart from an actual ring 22, has at least one sealing lip 23, for example made of synthetic material. The ring 22 coincides with the ring 17 and is fixed in a similar manner by means of bolts 18 on the part 19 of the main shaft 11.
In the embodiment according to figure 6, both on the outer circumference and on the inner circumference of the ring 22 is provided a sealing lip 23 which is cased in the ring 22. The two sealing lips 23 are connected elastically against the inside of the main bearing house 6 and the outside of the moving bearing house 16 respectively.
In the embodiment according to figure 7, only one sealing lip 23 is fixed on the ring 22, for example on the inner circumference, whereas the second sealing lip 23 is connected onto the ring 22 and is cased in a ring 24 which is fixed on a bearing house, for example the main bearing house 6.
Finally, in the embodiment according to figure 8, one of the sealing lips 23, for example that on the outside, is replaced by screw thread 20 on the circumference of the ring 22 or on the opposite side of a bearing house 6 or 16.
Also in the embodiments according to figures 6 to 8, the seal formed by the ring 22 and one or two sealing lips 23 prevents the oil from leaving the main bearing house 6.
The invention is by no means limited to the above-described embodiments represented in the figures; on the contrary, such a transmission with revolving bearing and the seal used hereby can be made in all sorts of variants while still remaining within the scope of the invention.
In particular, the transmission should not necessarily be designed to drive a scroll compressor. The invention is applicable in any case where the opening between a first bearing house surrounding a shaft and a second bearing house surrounding a bearing revolving eccentrically in relation to the above-described shaft needs to be sealed.
In the embodiments with screw thread on the inside of the ring, this screw thread can be provided on the outside of the revolving bearing house instead of on the inside of the ring.
Insofar that screw thread is provided in the main bearing house or in the revolving bearing house, said screw thread does not necessarily need to be provided in an insert ring. It might also be provided directly in the wall of the bearing house.

Claims

Transmission with revolving bearing (15) containing a main shaft (11), a main bearing house (6) in which said main shaft (11) is supported on bearings (12), a secondary shaft (13) connected to the main shaft (11) and revolving around the geometrical axis (7) of the main shaft (11), whose geometrical axis (14) is parallel to but eccentrically in relation to the geometrical axis (7) of the main shaft (11), and a revolving bearing house (16) in which the secondary shaft (13) revolving together with the bearing house (16) is supported on the revolving bearing (15) in a revolving manner around its geometrical axis, characterized in that the transmission contains a seal (17; 22,23) which is situated between the inside of the main bearing house (6) and the outside of the revolving bearing house (16), seals the opening between these bearing houses (6 and 16) and is fixed in relation to the whole consisting of the main shaft (11) and the secondary shaft (12).
Transmission according to the above claim, characterized in that the seal (17; 22,23) contains a ring (17, 22) which is fixed on a radially protruding part (19) which extends into or opposite the opening between the inside of the main bearing house (6) and the outside of the revolving bearing house (16) and which stands on the whole consisting of the main shaft (11) and the secondary shaft (13).
Transmission according to any of the above claims, characterized in that a screw thread (20) is provided on one of the sides formed by the inside of the main bearing house (6) opposite the seal (17; 22,23) and the opposite outside of the seal (17; 22,23).
Transmission according to any of the above claims, characterized in that screw thread (20) is provided on one of the sides formed by the outside of the revolving bearing house (16) opposite the seal (17; 22,23) and the opposite inside of the seal (17).
Transmission according to claim 3 and 4, characterized in that the seal (17) is provided with screw thread (20) both on the inside opposite the revolving bearing house (16) and on the outside opposite the main bearing house (6).
Transmission according to any of claims 3 and 4, characterized in that the bearing house (6, 16) is provided with a screw thread (20) opposite the seal (17; 22,23).
Transmission according to the above claim, characterized in that the screw thread (20) is provided in a bearing house (6,16) in an insert ring (21) which is cased on the side of the seal (17; 22,23) in the bearing house.
Transmission according to claim 2, characterized in that the seal (22,23) contains a sealing lip (23) which is provided on one of the sides formed by the inside of the main bearing house (6) opposite the ring (22) and the opposite outside of the ring (22).
Transmission according to any of claims 2 and 8, characterized in that the seal (22,23) contains a sealing lip (23) which is provided on one of the sides formed by the outside of the revolving bearing house (16) opposite the ring (22) and the opposite inside of the ring (22).
Seal for sealing the opening between a main bearing house (6) in which a main shaft (11) is supported on bearings (12) and a moving bearing house (16) moving inside said main bearing house according to a circular path in which a secondary shaft (13) is supported by a bearing (15), characterized in that it contains a ring (17, 22) with a width which increases from a minimum at one place to a maximum at a diametrically opposite place.