Oil separator arrangement

Abstract

The oil separator (4') comprises a hub (5) mounted on the vent shaft (1) and a cover (8') mounted on the hub (5) between two thrust faces (3, 14) which allow it to not be attached by welding or bolting.

Description

[0001] The subject of the invention is an oil separator arrangement, located at the end of the turbine shaft of a turbomachine.

[0002] Such an oil separator (a description of a model of which can be found in document EP 0 780 546 A) is placed at the outlet of an air flow maintained in the machine to transport the oil which lubricates bearings or other parts, in order to separate the air from the oil which is dispersed therein in mist before discharging the air to the outside, and returning the oil to the inlet of the lubrication device. The recovery of the oil prevents pollution from the outside, drying out of the lubrication circuit or even fires due to deposits on hot external parts.The model of the oil separator considered here comprises three main parts: a hub used for mounting and positioning the oil separator on a vent shaft, concentric with the turbine shaft and projecting from it at the rear of the machine, and extending in front of the end of the turbine shaft; a cover delimiting a housing with the hub; and a filter, which may be a honeycomb network, contained in the housing, retained by the cover and responsible for the separation of air and oil, which is deposited on the walls of the honeycomb when the vent shaft rotates the oil separator.

[0003] In EP 0 780 546 A, the cover is bolted to the hub to hold it in place, but the use of bolts makes the assembly heavier and complicates assembly. Another solution is to weld the cover to the hub. This solution has the disadvantage that the cover can no longer be removed.

[0004] In document FR 2 696 655 A, the cover and a housing closure flange are provided with circular hubs allowing them to be successively threaded onto the vent shaft. The cover is held axially both by pins passing through its hub and the vent shaft, and by stop faces belonging to the turbine shaft and the closure flange. The closure flange appears to be held axially by a nut screwed onto the vent shaft. The arrangement is complicated.

[0005] And in document FR 2 299 898 A, the hub and the cover are held axially on the vent shaft between abutment faces belonging to a bearing and a nut. In addition, the cover abuts against a conical shoulder of the shaft. Here again the arrangement is complicated, the vent shaft having to ensure the separate abutment of the two elements of the oil separator and being shaped accordingly.

[0006] The subject of the invention is an improved oil separator arrangement, also lighter than the bolted oil separator, more easily dismantled than the welded oil separator, and also which offers very good cohesion between the hub and the cover, while allowing simple mounting on the vent shaft.

[0007] In general form, the invention relates to an oil separator arrangement according to claim 1.

[0008] The cover is held by the abutment faces, excluding any means of fixing. This achieves significant weight reduction.

[0009] Another important original feature of the invention is that the cover is no longer mounted on the vent shaft after the hub, but on the hub: the vent shaft carries the means for abutting only one of the two elements of the oil separator and is therefore simplified; by being held on the hub by its two opposite ends, the cover is assembled with much better cohesion to the hub; finally, it is easy to arrange the sleeve of the hub to make it carry one of the abutment faces of the cover flange, or both.

[0010] The first thrust face may be a cleat on the sleeve; the second thrust face may be one end of the turbine shaft, or perhaps better, a ring engaged on the sleeve.

[0011] The invention will now be described by means of the following figures: THE figures 1 and 2represent a first embodiment of the invention, in perspective and in longitudinal section respectively; and the figures 3 and 4 are analogous to figures 1 and 2 , for a second embodiment of the invention.

[0012] We first refer to the figures 1 and 2. The arrangement comprises an oil separator 4, a vent shaft 1, a turbine shaft 2 concentric with the previous one and surrounding it; the shafts 1 and 2 extend in a longitudinal direction of the machine to which they belong, the vent shaft 1 projecting beyond one end 3 of the turbine shaft 2 towards the rear of the machine. The oil separator 4 comprises a hub 5 essentially composed of a cylindrical sleeve 16, mounted on the vent shaft 1 and abutting on a shoulder 15 of the turbine shaft 2, and a hub flange 6, flat, perpendicular to the shafts 1 and 2 and extending outside the sleeve 16 in a single piece with it. A tightening nut 7 screwed onto the vent shaft 1 holds the hub 5 in abutment against the shoulder 15. The oil separator 4 also comprises a cover 8, delimiting with the hub 5 a housing 9 in which a filter 10 is contained.The housing 9 is delimited by the sleeve 16, the hub flange 6, a cover flange 11 parallel to the previous one, and a spacer 12 belonging to the cover 8, cylindrical and surrounding the sleeve 16 in a concentric state with it and with the vent shaft 1. The spacer 12 is in one piece with the cover flange 11. One end of the spacer 12 opposite the cover flange 11 extends under a rim 13 of the hub flange 6.

[0013] The cover 8 is retained axially by a double stop of the cover flange 11: against a cleat 14 standing on the hub 5 by its face inside the housing 9 and towards the rear of the machine, and against the end 3 of the turbine shaft 2 by its external face and towards the front. Longitudinal play is however provided, mainly in order not to compress the thin, perforated spacer 12 subjected to significant centrifugal forces in service. This double stop arrangement makes it possible to retain the cover 8 without any means of fixing other than the interlocking of parts. It is obtained by placing the hub flange 6 at the rear of the sleeve 16, unlike the usual designs. It is obtained by placing the hub flange 6 including that of the prior patent, where this flange is adjacent to the end 3.The cohesion of the assembly is improved by the radial interlocking of the cover 8 in the hub 5, the cover flange 11 being engaged around the sleeve 16 and the rim 13 surrounding the spacer 12 at the other opposite end of the cover 8. The cover 8 is completely separated from the vent shaft 1.

[0014] The vent shaft 1, the hub 5 and the spacer 12 are perforated to allow a centripetal flow of air through the oil separator 4. The filter 10 is a honeycomb network whose channels are oriented radially; its function is to collect the oil suspended in the flow by deposition on the walls of the honeycomb and to force it outwards thanks to the centrifugal forces caused by the rotation of the oil separator 4, and therefore to allow only perfectly dry air, having completed its centripetal movement, to pass into the vent shaft 1. Other details of the environment of the oil separator, which are not, however, part of the invention, can be found in the document EP 0 780 546 A. Other seals, such as balls, have been used and could still be suitable.

[0015] We now move on to the comments of the figures 3 and 4 .

[0016] A number of elements are similar to those of the previous embodiment and bear the same numbers; the hub flange, now referenced by 6', and the cover, now referenced by 8', are however interchanged along the oil separator 4 while retaining the same shape: the hub flange 6' is now adjacent to the end 3, and the cover flange, now 11', is at the front of the oil separator.

[0017] The cleat, now 14', remains while being in front of the hub 5, and it still abuts against the internal face of the cover flange 11'. An elastic ring 17 is added in a groove 18 in front of the external face of the cover flange 11', and abuts against this external face, so that the cover 11' is still retained without rigid attachment to the hub 5. The advantages of lightness and ease of assembly of the oil separator are still obtained in this embodiment which takes up the essential characteristics of the previous one: a mounting of the cover on the hub, and by a double stop and an interlocking of parts, without rigid attachment to the hub by a connecting element.

[0018] The same comments apply. This embodiment, where the cover 11' is assembled exclusively to the hub 5, is of an even simpler design than the previous one.

[0019] One improvement, common to both embodiments described here, must still be mentioned. The spacer 12 is not only thin but perforated to allow the flow of oil by centrifugation and therefore consists of a group of straps 19 along its circumference between the hub flange 6 or 6' and the cover flange 11 or 11'. These straps 19 are subject to significant bending due to centrifugal forces, which is likely to create stress concentrations at the point where they connect to the cover flange 11 or 11'. To overcome this drawback, it is advantageous to provide the cover flange 11 or 11' with a border 20 at its outer circumference, where the cover flange 11 or 11' connects to the spacer 12, which projects on the side opposite the spacer 12, i.e. towards the front of the machine in the embodiment of the figures 1 and 2 and backward in the realization of the figures 3 and 4, while extending the spacer 12. The overhang of the edge 20 combined with the centrifugal forces it undergoes produces a bending of the end of the cover flange 11 or 11' which contributes to balancing that which it undergoes from the spacer 12 and therefore reduces the stress concentrations at its outer edge.

Claims

1. Turbine deoiler arrangement (4, 4') comprising: a turbine shaft (2), a vent shaft (1) surrounded by the turbine shaft, the deoiler comprising a hub (5) with a sleeve (16) of cylindrical shape mounted on the vent shaft and with a hub plate (6) extending beyond the sleeve (16), and a cover (8, 8') with a cover plate (11, 11') and a cylindrically shaped spacer (12) surrounding the sleeve (16), wherein the hub plate comprises a rim (13) in which the spacer is engaged at one end, characterised in that the cover plate (11, 11') is mounted around the sleeve and engaged on the sleeve, the sleeve being retained in an elongation direction of the shafts by an element (7) of the vent shaft and an element (15) of the turbine shaft, and the cover plate (11, 11') being retained in the elongation direction of the shafts between a first stop face belonging to the sleeve and a second stop face either secured to the sleeve or belonging to the turbine shaft, without any fastening element of the cover to the hub, the second stop face belonging to a ring (17) engaged on the sleeve (16) when the second stop face is secured to the sleeve.

2. Deoiler arrangement according to claim 1, characterised in that the first stop face is formed by a cleat (14, 14') of the sleeve (16).

3. Deoiler arrangement according to claim 1 or 2, characterised in that the second stop face is an end (3) of the turbine shaft (2).

4. Deoiler arrangement according to any one of claims 1 to 3, characterised in that the cover plate (11, 11') comprises a projecting rim (20), opposite the spacer (12) and extending it.

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