WO1999008026A1

WO1999008026A1 - Mechanical seal for rotating shaft

Info

Publication number: WO1999008026A1
Application number: PCT/IB1997/000984
Authority: WO
Inventors: Bernard Leonetti
Original assignee: John Crane Inc.
Priority date: 1997-08-11
Filing date: 1997-08-11
Publication date: 1999-02-18
Also published as: AU3632597A

Abstract

The invention concerns a mechanical seal for a rotating shaft (1), comprising a fixed sealing ring (4), in sealing relationship with a support (2) traversed by the shaft (1), a mobile sealing ring (6) rotating with the shaft (1) and in sealing surface contact (7) with the fixed sealing ring (4), a mobile sleeve (8), integral with the shaft and axially spaced from the mobile sealing ring, and elastic means (9) co-operating with the mobile ring (4) and the mobile sleeve (8) and which are arranged to urge elastically in the axial direction the mobile ring against the fixed ring and to transmit to the mobile ring the rotating movement of the shaft and the mobile sleeve. The invention is characterised in that the elastic means comprise: a radial washer (11); linking means (12), at least in a rotating relationship, between the washer and one and the first of said mobile ring and bush; and axial branches (13) borne by the axial washer, forming undulations (15) in the axial direction and arranged to co-operate by their free end (16) with the other and second of said mobile ring and bush at least in a rotating relationship.

Description

MECHANICAL SEALING FOR A ROTATING SHAFT

The present invention relates to mechanical seals for rotating shafts.

Such seals are used to seal between a rotating shaft and a fixed support through which it passes.

Among these seals, the invention relates to those which comprise a fixed sealing ring, integral with the support and in sealing relationship with it, a mobile sealing ring, rotating with the shaft and in facial contact with sealing with the fixed ring, a movable bush, integral with the shaft and axially distant from the movable sealing ring, and elastic means which cooperate with the movable ring and the movable bush and which are arranged, on the one hand, to elastically urge the movable ring in the axial direction against the fixed ring and, on the other hand, to transmit to the movable ring the rotational movement of the shaft and of the movable bush. Such a mechanical seal is described for example in document FR-A-2,594,519. In this document, the elastic means consist of an axial bellows comprising annular mounting ends. In two embodiments described in this document, the annular ends of the bellows are secured, respectively, to the movable bushing and the movable ring, sealing means being provided at the ends of the bellows, respectively between the bellows and the shaft. , at the movable sleeve, and between the bellows and the movable ring, at the other end. In operation, this seal is satisfactory, but it is of a relatively complex structure and manufacture, and therefore costly.

EP-A-365 138 also discloses a seal of the same type, in which the elastic means consist of one or two wavy washers forming an axial spring and carrying drive studs which cooperate with complementary cavities provided in the radial faces opposite the movable ring and the movable bush.

Document US-A-4,389,051 also discloses a seal of the same type, in which separate means are used to drive the movable ring in rotation from the shaft. and one resilient axial spacing of the movable ring and the movable sleeve fixed on the shaft.

The object of the invention is to improve and simplify these fittings without harming their functional characteristics.

To this end, the gasket according to the invention is characterized in that the elastic means comprise: a radial washer; connecting means, at least in a rotational drive relationship, between the washer and one, first, of said movable ring and sleeve; and axial branches, carried by the radial washer, forming corrugations in the axial direction and arranged to cooperate by their free end with the other, second, of said ring and bush movable at least in a rotational drive relationship.

Preferably, the radial washer and the axial branches are made of sheet metal, in particular stainless steel, machined for example by wire EDM or press.

According to a preferred embodiment, the elastic means comprise at least two regularly distributed branches, and preferably three branches at 120 °. For example, the branches start from the contour of the washer, preferably from the outer contour of the latter.

To receive the free ends of said branches, said second of said movable ring and bush has for example an annular groove on its radial face turned towards said first of said movable bush and bush. The groove advantageously has a shoulder or axial retaining rim of the free end of the branches folded back.

In this embodiment, the movable sleeve is secured to the rotating shaft by at least one screw which interferes with said groove to cooperate with the free end of at least one of the branches in a rotational drive relationship.

According to a first embodiment of said connecting means, these consist of a second series of branches, shorter than the previous ones, preferably alternated with these, and cooperating with axial notches formed at the periphery of said first said movable ring and socket; the branches of this second series advantageously have a free end which is folded for the axial retention between the elastic means and said first of said movable ring and bush.

According to a second embodiment of said connecting means, said first of said movable ring and sleeve has, on its face of cooperation with the elastic means, radial notches for receiving the feet of said axial branches forming undulations. Advantageously, in this embodiment, the radial washer comprises, in its plane and on its outer periphery, axial retaining projections arranged to be housed behind a shoulder of said first of said movable ring and sleeve. Advantageously, to avoid axial play between the elastic means and the movable ring or bushing which receives them, the bottom of said radial notches and the retaining face of said shoulder are axially spaced apart by a distance substantially equal to the thickness of the radial washer.

The radial washer and the axial branches can be constituted either by a single piece, or by separate pieces made integral.

According to a preferred embodiment, the radial washer cooperates with the movable ring, while the free ends of the axial branches cooperate with the movable sleeve.

In a particular embodiment, an annular seal is placed between the fixed ring and the support through which the shaft passes, and an annular seal is placed between the movable ring and the shaft, so that exemption from sealing means at the movable sleeve or at the end of the elastic means cooperating with the latter. In addition, the operating liquid surrounds the mobile ring, except in the area of the fixed ring and the shaft, which allows cooling and possibly lubrication of the mobile ring.

The invention will be clearly understood on reading the additional description which follows and with reference to the appended drawings which form part of the description and in which:

Fig. 1 is an axial section, taken along the line I-I of FIG. 2, a mechanical seal established according to a first embodiment of the invention;

Fig. 1A and 1B show, on a larger scale, two details of FIG. 1; Fig. 2 is a cross-sectional view of the packing of FIG. 1, taken along the broken line II-II of this Figure;

Fig. 3 is an axial view of a single piece forming a spring and means for driving in rotation, this piece being considered flat before its conformation;

Fig. 4 shows, on a larger scale, another detail of FIG. 1;

Fig. 5 is an axial view of the movable sealing ring of a mechanical sealing gasket established according to a second embodiment of the invention;

Fig. 6 is an exploded axial section showing, on the one hand, the movable ring of FIG. 5, in the cutting plane VI-VI and, on the other hand, a single piece also forming a spring and means for driving in rotation;

Fig. 7 is an axial view of the single part used with the movable ring of FIGS. 5 and 6, this single piece being considered flat before its conformation;

Fig. 8 is a view similar to FIGS. 3 and 7, relative to a third embodiment of the elastic means;

Fig. 9 shows, in section along the line IX-IX of FIG. 8, the structure of the radial washer of FIG. 8;

Fig. 10 is a plan view of an axial branch of FIG. 8, before it is fixed to the radial washer and before it is folded; and Fig. 11 shows, in section along the line XI-XI of FIG. 10, a detail of the axial strip.

There is shown in Figs. 1, 1A, 1B and 2 a rotating shaft 1 which passes through a fixed support 2. The space 3 inside the support 2 contains a fluid, for example of lubrication or of operation, and the lining is intended to seal the passage from shaft 1 through support 2.

The mechanical seal has, in known manner, a fixed ring 4, in sealing relation with the support 2 by an annular seal 5 disposed between the fixed ring and the support, a movable seal ring 6, rotating with the shaft 1 and in facial sealing contact with the fixed ring, by cooperation at 7 of the planar radial faces of the fixed ring and of the movable ring, a movable bush 8, integral with the shaft 1 and axially distant from the movable ring 6, and elastic means 9 which cooperate with the movable ring 6 and the sleeve 8 and which are arranged, on the one hand, to elastically urge the movable ring in the axial direction against the fixed ring and, on the other hand , to transmit to the movable ring the rotational movement of the shaft 1 and of the sleeve 8.

The shaft 1 passes through the support 2, the fixed ring 4 and the movable ring 6 with a functional radial clearance, and an annular seal 10 is placed between the movable ring 6 and the shaft 1. This seal is for example placed in a groove, which allows the radial face of the movable ring 6 to be released for its cooperation with the elastic means 9.

Sealing is thus ensured, when the shaft 1 passes through the support 2, by the seal 5, the fixed ring 4, the cooperation at 7 of the fixed ring and of the mobile ring, the mobile ring itself and seal 10. According to a first type of embodiment, the elastic means 9 consist of a single piece and are made of sheet metal, for example of stainless steel cut by wire EDM, which avoids crack initiation. Alternatively, this unique piece could be worked with the press. There is shown in Figs. 3 and 7, according to two embodiments, the single piece 9 as obtained after cutting, that is to say flat and before its final conformation.

In the embodiment of Figs. 1-4, the unique piece

9 comprises a circular radial washer 11 and two series of radial branches 12, 13 which, after shaping by folding, extend in the general axial direction of the shaft 1. The radial washer 11 is intended to come into facial contact with the movable ring 6 or the movable sleeve 8; in the adopted embodiment, the washer 11 is in contact with the movable ring 6. As a variant, the washer it could rest against the seal 10 projecting axially relative to the ring 6. The branches 12 are short and are intended, after a first 90 ° folding, to cooperate with axial notches 14 formed at the periphery of the movable ring 6 and, after a second 90 ° folding at their free end, to cooperate with the opposite radial face of the ring 6 to ensure axial retention and centering between the single part 9 and the ring 6 (Fig. 1B). The branches 13 are much longer than the branches 12 and are intended, after folding at 90 ° relative to the washer 11, and in the axial direction opposite to that of the first folding of the branches 12, to form corrugations 15 in the direction axial, their ends 16, which preferably end with a narrowed finger 17, being received in an annular groove 18 formed on the radial face of the sleeve 8 which is turned towards the movable ring 6. As best shown in FIG. 4, the groove 18 has, near its outlet on the radial face of the sleeve 8, a shoulder or rim 19 for axial retention of the finger 17 folded back and radially outwards, substantially at 45 ° with respect to 1 axis of 1 shaft 1. In the adopted embodiment, the branches 12, 13 start from the external contour of the washer 11 and, consequently, the notches 14 are formed on the external periphery of the movable ring 6.

The branches 12 and 13 of the two series are alternated, preferably regularly, and each series comprises at least two regularly distributed branches, and preferably three branches at 120 °, as shown in the drawings.

Because the washer 11 is in facial contact with the movable ring 6, the branches 12 are housed almost completely in the notches 14.

For clarity, in Figs. 1A and 1B, the washer 11 and the short branches 12 have been shown at a distance from the movable ring 6 when, in reality, they are in contact with the latter.

The sleeve 8 is immobilized on the shaft 1 by at least one radial screw 20 which, preferably, interferes with the groove 18 so as to constitute a stop in rotation for the ends 16 of the branches 13 and thus to transmit to the part 9 the rotational movement of the shaft 1. In general, two screws 20 are provided at 120 ° for two of the branches 13, but a third screw 20 can also be provided for the other branch 13.

In operation, the single part 9, by its corrugations 15, biases the movable ring 6 axially against the fixed ring 4, allowing it to float slightly in the radial direction and driving it in rotation by the branches 12 and 13, to from shaft 1 and bush 8.

The embodiment shown in Figs. 5 to

7 does not differ from that of FIGS. 1 to 4 only by means of cooperation between the single part 9 and the movable ring 6. We will therefore not repeat the description of the cooperation of the axial branches 13 with the movable sleeve 8, the latter not being shown in FIGS. 5 and 6.

In this second embodiment, the rotational connection means between the single part 9 and the movable ring 6 are constituted by the feet 21 of the axial branches 13 themselves. These feet are the connecting part of the branches 13 with the radial washer 11.

To cooperate with the feet 21, the movable ring 6 has, on its face for cooperating with the single piece, radial notches 22, of the same width as the branches 13. Because the feet 21 of the branches 13 are housed in the notches 22, the rotational drive of the movable ring 6 is thus carried out by the single piece 9 by the branches 13 themselves without it being necessary, as in the embodiment of FIGS. 1 to 4, to provide additional branches.

Preferably, in this second embodiment of the invention, means are also provided for ensuring the axial retention between the movable ring 6 and the single part

9. For this, the movable ring 6 has, on the side of the single part 9, a rim 23 projecting radially inwards which defines, in the ring 6, an internal radial shoulder 24 intended to cooperate with projections 25 which are provided in the plane of the washer 11 and on the outer periphery thereof, on each side of the legs 21. The flange 23 has an inner diameter slightly smaller than the outer diameter of the projections 25, these coming to be housed behind the rim 23, against the shoulder 24, by elastic deformation.

Preferably, the bottom of the radial notches 22 and the retaining face of the shoulder 24 are axially spaced by a distance substantially equal to the thickness of the washer 11 so that it is received without play and therefore does not float.

In this embodiment, the washer 11 is not in facial contact with the movable ring 6. It is radially set back relative to the notches 22 which receive the feet 21 of the axial branches 13. It is therefore the feet 21 which communicate to the movable ring 6 both the axial biasing forces against the fixed ring 4 and the rotational driving forces.

There is shown in Figs. 8-11 a third embodiment of the elastic means 9.

By analogy with the above, the same reference numerals have been adopted in these Figures as in Figs.

I to 7 for identical, similar or equivalent elements.

This embodiment differs from the previous ones essentially by the fact that the elastic means 9 are not constituted by a single piece, but by separate pieces which are joined together.

The radial washer 11 is for example constituted by the superposition and the assembly of two identical elementary washers (Fig. 9). Furthermore, the washer

It can be split, as shown in 26.

At their free end 16 of cooperation with the movable sleeve (not shown), the axial branches 13 comprise, as previously, a narrowed finger 17 which ends in teeth 27 favoring the axial retention of the branches in the groove 18 (Fig. 1 ).

At their other end of connection with the washer 11, the branches 13 have a narrowed finger 28 assembly intended to be folded at 180 ° to trap the washer 11 in the U thus formed by overlapping its inner edge. At a distance from the finger 28, each branch 13 carries a stop 29, for example a stamping puncture, intended to cooperate with the outside edge of the washer 11. The latter is thus trapped between the finger 28 and the stop 29.

The narrowed fingers 17 cooperate with the movable sleeve 8 as described with reference to Figs. 1 to 4.

For the cooperation of the washer 11 - branches 13 assembly with the movable ring 6, the latter is similar to that of FIGS. 5 and 6, that is to say that it has radial notches 22 for the reception of the feet 21 of the branches 13 and that the washer 11 is radially set back relative to the notches 22, without facial contact with the movable ring 6. As in the embodiment of Figs. 5 to 7, the washer 11 therefore only serves to connect the branches 13.

In the embodiment, there is no axial retention between the movable ring 6 and the assembly 11, 13. However, to obtain such an axial retention, the feet 21 of the branches 13 could have projections, such as the projections 25 of FIG. 7, which is housed elastically behind a shoulder of the movable ring 6.

It follows from the above that the mechanical seal according to the invention has many advantages, mainly due to its simplicity, and in particular the following: the manufacturing tolerances are very wide for all the components, without the the effectiveness of the packing is affected; the sleeve 8 having no direct sealing role, it can be obtained by simple turning; the lining is preferably in one piece, which avoids the risk of breakage and release during assembly; the packing works for both directions of rotation of the shaft 1, due to the fact that, after a possible vacuum movement, the branches 13 abut against another screw 20; the elastic arms 13 allow axial movement of the movable ring without any risk of jamming; the fact that the movable ring 6 is almost entirely surrounded by the fluid, its cooling and possibly its lubrication are ensured, in particular at the level of the zone of cooperation 7 with the fixed ring 4; the packing is completely open, which eliminates the risk of blockage by the fluid; and the movable ring 6, because it can float radially, does not necessarily have an axis of symmetry.

Of course, the invention is not limited to the embodiments which have been described; on the contrary, we could conceive of various variants without going beyond its scope.

Claims

1. Mechanical seal for a rotating shaft (1), comprising a fixed sealing ring (4), in sealing relation with a support (2) through which the shaft (1) passes, a ring mobile seal (6) rotating with the shaft (1) and in facial contact (7) sealing with the fixed ring (4), a movable bush (8), integral with the shaft and axially distant from the ring d mobile seal, and elastic means (9) which cooperate with the movable ring (4) and the movable bush (8) and which are arranged, on the one hand, to elastically bias the movable ring against the ring in the axial direction fixed and, on the other hand, for transmitting to the movable ring the rotational movement of the shaft and of the movable bushing, characterized in that the elastic means (9) comprise: a radial washer (11); connecting means (12, 21), at least in a rotational drive relationship, between the washer and one, first, of said movable ring and bush; and axial branches (13), carried by the radial washer, forming corrugations (15) in the axial direction and arranged to cooperate by their free end (16,17) with the other, second, of said ring and sleeve movable at less in a rotational drive relationship.

2. A fitting according to claim 1, characterized in that the radial washer (11) and the axial branches

(13) are made of metal, of sheet, in particular of cut stainless steel, by wire EDM or worked in the press.

3. A fitting according to one of claims 1 and 2, characterized in that the free ends of said branches (13) and / or said connecting means (12,21) are arranged to also ensure an axial retention between the elastic means ( 9) and the movable sleeve (8) and / or the movable ring (6).

4. Trim according to one of claims 1 to 3, characterized in that the elastic means comprise at least two axial branches regularly distributed, and preferably three branches at 120 °.

5. A fitting according to one of claims 1 to 4, characterized in that the axial branches depart from the contour of the washer (11), preferably from the outer contour thereof.

6. A fitting according to one of claims 1 to 5, characterized in that, to receive the free ends of said branches, said second of said movable ring and sleeve has an annular groove (18) on its radial face facing the other of said movable ring and sleeve.

7. A fitting according to claim 6, characterized in that the groove (18) has a shoulder or flange (19) for retaining the free end (17) of said branches folded backwards.

8. A fitting according to one of claims 6 and 7, characterized in that the movable sleeve (8) is secured to the shaft (1) by at least one screw (20) which interferes with the groove (18) to cooperate with the free end (16,17) of at least one of said branches (13) in a rotational drive relationship.

9. A fitting according to one of claims 1 to 8, characterized in that said connecting means consist of a second series of branches (12), shorter, preferably alternating with said branches (13), and cooperating with axial notches (14) formed at the periphery of said first of said movable ring and bush.

10. A fitting according to claim 9, characterized in that the branches (12) of the second series have a folded free end for the axial retention between the elastic means and said first of said movable ring and bush.

11. A fitting according to one of claims 1 to 8, characterized in that said first of said movable ring and sleeve has, on its face of cooperation with the elastic means, radial notches (22) for receiving the feet (21) of said branches (13).

12. A fitting according to claim 11, characterized in that the radial washer (11) comprises, in its plane and on its outer periphery, projections (25) of axial retention arranged to be housed behind a radial shoulder (24) of said first of said mobile ring and sleeve.

13. A fitting according to claim 12, characterized in that the bottom of said radial notches (22) and the retaining face of said shoulder (24) are axially spaced by a distance substantially equal to the thickness of the radial washer (11) .

14. Fitting according to one of claims 1 to 13, characterized in that the elastic means (9) are in one piece.

15. Trim according to one of claims 1 to

13, characterized in that the elastic means (9) consist of separate and assembled parts.

16. A fitting according to claim 15, characterized in that the axial branches (13) comprise at one end means (28, 29) for fixing on the washer (11).

17. A fitting according to claim 16, characterized in that said fixing means consist of a finger (28) folded in a U and enclosing the washer (11) and by a stop (29) cooperating with a song of the washer.

18. Trim according to one of claims 1 to

17, characterized in that the radial washer (11) cooperates with the movable ring (6) and the free ends of the axial branches (13) cooperate with the movable bush (8).

19. Trim according to one of claims 1 to

18, characterized in that an annular seal (5) is arranged between the fixed ring (4) and the support (2), and an annular seal (10) is arranged between the movable ring (6 ) and the tree (1).