GB2431440A

GB2431440A - A non-contacting sealing device with integral self-adjusting orifice cover

Info

Publication number: GB2431440A
Application number: GB0521257A
Authority: GB
Inventors: Alan James Roddis; Andrew Colverson
Original assignee: AES Engineering Ltd
Current assignee: AES Engineering Ltd
Priority date: 2005-10-19
Filing date: 2005-10-19
Publication date: 2007-04-25
Anticipated expiration: 2025-10-19
Also published as: GB0521257D0; GB2431440B

Abstract

A non-contacting seal device 30 comprises a stator housing 31, the stator housing including a multitude of orifices 37 spaced around its circumference which provide communication between the innermost stator circumferential surface 38 and the outermost stator circumferential surface 39. The orifices 37 are designed to accommodate angular rotational variance in the stator 32 of a piece of rotation equipment. The orifices 37 are substantially covered by an orifice cover plate 40 except at a predetermined circumferential location (i.e. 6 o'clock position). The orifice cover plate 40 may have an innermost circumferential discontinuity 43 and, preferably, adjacent material weighting (40 in Figs 6 & 8), so that the discontinuity 43 self-adjusts to the 6 o'clock position given rotational stator variance. The device may be used, for example, as a bearing protector or isolator.

Description

* 2431440 MRH/O11O iSsuez

NON CONTACTING BEARING PROTECTOR WITH INTEGRAL

SELF-ADJUSTING ORIFICE COVER

Field of the Invention

This invention relates to non-contacting seals and their use in rotating equipment, especially devices, which prevent the ingress or egress of a fluid or solid to a cavity, which results in deterioration of equipment life. Such devices are often referred to as bearing protectors, bearing seals or bearing isolators. However, the use of such rotary seals extends well beyond the protection of a bearing in rotating equipment. Accordingly, while reference will be made below to bearing protectors, it should be understood that this term is used, as far as the invention is concerned, in connection with such having wider uses.

Background to the Invention

The purpose of a bearing protector is to prevent the ingress of fluid, solids and/or debris from entering a bearing chamber. Equally, bearing protectors are employed to prevent the egress of fluid or solids from a bearing chamber. Essentially, their purpose is to prevent the premature failure of the bearing.

Bearing protectors generally fall into two categories: repeller or labyrinth bearing protectors; and mechanical seal bearing protectors. Reference is made to our co-pending labyrinth seal bearing protection application GBO4I 5548.7 which defines a substantially non-contacting bearing protector I 25 with static shut off device. 2III I's's

1 i The rotating component typically has a complex outer profile which is 1 located adjacent and in close radial and axial proximity to a complex inner profile of the stationary component. Ideally, advanced stators have at least .1k * : 30 one orifice, which is orientated at the 6 o'clock position. Any foreign debris and/or water which enters the radial gap between the rotor and stator is thus MRH/01 10 Issue 2 encouraged to be expelled, via gravity and/or centrifugal effect if the rotor, out of the stator orifice.

By its nature, the labyrinth seal stator is rotationally fixed to the pump/bearing housing stator, by either the radial squeeze on the stator elastomer seal and/or a radial interference fit between the two stator parts.

Unfortunately, some modern designs of rotating equipment, such as the Flowserve, Mark Ill pumps, are designed so that the bearing housing stator, rotates when making impeller adjustments. This means that it is not guaranteed that the labyrinth seal stator, specifically the stator orifice port(s) will remain in the 6 o'clock orientation once the equipment is set to its final running position.

If said stator orifice ports are not set at 6 o'clock, debris/water is not naturally encouraged to exit via said orifice.

Conventional labyrinth technology overcomes this by either not providing an stator orifice or providing a multitude of stator orifice ports which are typically equi-spaced around the circumference of the stator.

If the stator has no orifice ports, any debris/water entering the seal, is unable to exit and thus travels into the sealed media, which is often an oil.

i: 8 25 If the stator has a multitude of stator orifice ports, debris/water can easily enter the labyrinth seal, therefore exasperating the entry situation making the work-load on the exit situation a many fold increase. 111*1

It deemed advantageous if a non-contacting labyrinth-type seal bearing protector can effectively discourage the entry of debris/fluid in such modern items of rotating equipment and/or encompass an orifice feature which MRH/O110 Issue 2 automatically compensates for rotational movement of the equipment housing, thereby permitting said orifice to orient itself at the 6 o'clock position no matter what the respective rotational travel of the stators.

Statements of the Invention

According to the present invention there is provided a non-contacting sealing device comprising of a labyrinth seal with at least one stationary surface and one rotary surface, substantially adjacent to one another.

Preferably, the invention incorporates a third member, which is nonrotationally secured to the stator member, thereby free to rotate about its own accord.

Preferably said third member is axially restrained and a clearance fit, within the stator member.

Preferably said third member is substantially of tubular construction with an inner most circumference and an outer most circumference, said inner most circumference has a discontinuity.

Preferably said third member is weighted around its circumference, so that the heaviest circumferential segment of said member corresponds to the discontinuity in said member. Is

I 25 Preferably said third member is a circumferentially split member. Is Ills

Embodiments of labyrinth seals in accordance with the present invention $ may be such that the arrangement, specifically the sum of the three members provides a self-adjusting outlet orifice, in the stator assembly, which is self-adjusted by gravitation forces thus moving the discontinuity 1 orifice to the 6 o'clock position when looking on the end view.

MRH/O110 Issue 2

Description of the drawings

The accompanying drawings are as follows: Figure 1 is a longitudinal section view of a prior art labyrinth seal bearing protector mounted on a shaft.

Figure 2 is a longitudinal section view of said prior art labyrinth seal bearing protector mounted on a shaft and installed in a bearing plate, adjacent to a bearing of an item of rotating equipment.

Figure 3 corresponds to Figure 2 and is an end view on Figure 2's 1 0 Arrow "A" Figure 4 corresponds to Figure 3 and illustrates rotational movement of the bearing housing stator and labyrinth seal stator, of a conventional

prior art design.

Figure 5 is a longitudinal section view of a labyrinth seal bearing protector mounted on a shaft, of the first embodiment.

Figure 6 corresponds to Figure 5 and is an end view on Arrow "B" of Figure 5.

Figure 7 is an isometric exploded assembly view the labyrinth seal stator and stator cover, of the first embodiment.

Figure 8 corresponds to Figure 5 and is a radial section view on Section "C-C" of Figure 5.

Figure 9 corresponds to Figure 8 and illustrates rotational movement of the bearing housing stator and labyrinth seal stator, of a design of the invention.

Figure 10 is a longitudinal section view of a labyrinth seal bearing I I S I protector mounted on a shaft, of the second embodiment.

Figure 11 is an end view of a labyrinth seal bearing protector I " I mounted on a shaft, of the third embodiment. :s'

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MRH/O11O Issue 2

Detailed description of the Invention

The invention will now be described, by way of examples only, with reference to the accompanying drawings.

In general rotary seals in accordance with the present invention may be used not only in the case where the shaft is a rotary member and the housing is a stationary member but also the reverse situation, that is to say, in which the shaft is stationary and the housing is rotary.

Furthermore, the invention may be embodied in both rotary and stationary arrangements, cartridge and component seals with metallic components as well as non-metallic components.

Referring to Figure 1 of the accompanying drawings, there is illustrated the prior art bearing protector assembly 10 mounted on a rotating shaft 12 and a fitted to a stationary housing 13.

Figure 2 illustrates said prior art bearing protector 10 position on the rotating equipment 11, with respect to the bearing 9 and stationary equipment housing 13.

Area "X" at one axial end of the bearing protector assembly 10 could partially contain fluid and/or solids and/or foreign debris and/or atmosphere, however for clarity it will herewith be termed "product substance", being used to 25 describe the single or mixed medium. Ills $ S Ills

Area "Y" at the other axial end of the bearing protector assembly 10 could also partially contain fluid and/or solids and/or foreign debris and/or atmosphere, however for clarity it will herewith be termed "atmospheric i S substance" being used to describe the single or mixed medium.

MRH/0110 Issue 2 The bearing protector assembly 10 includes a rotor member 14, which is radially and axially adjacent to stator member 15.

The stator elastomer 16 provides a radial seal between the housing 13 and stator 15. The shaft elastomer 17 provides a radial seal between the shaft 12 and rotor 14.

The operation of the prior art design is defined in our co-pending labyrinth seal bearing protection application GB0415548.7 and will not be further described.

From Figure 2, the experienced reader will note that it is preferred that the seal stator 15 and the housing stator 13, are rotationally secured.

Furthermore it is preferred that the orifice holes 18 and/or 19, of the seal 10, are orientated at the 6 o'clock position when looking on the end view of the equipment at Arrow "A". For clarity, this is shown in Figure 3.

For orifice 18, this orientation allows any or foreign debris which gets into the seal, to be discharged, via gravity out of the orifice 18, before travelling to the inboard side "X". For orifice 19, this orientation allows any sealed media, which gets into the seal, to be discharged, via gravity out of the orifice 19, before travelling to the outboard side "Y".

Referring back to Figure 2, in some types of rotating equipment, such as the Mark Ill design offered by a USA company called Flowserve, the adjustment : : 25 of the equipment's impeller (not shown) necessitates a possible rotational *: :: : movement of the equipment's housing stator 13.

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Since the seal stator 15 is rotationally secured to the equipment housing stator 13, any such rotational movement is transferred to said seal stator 15 S. 5 30 and results in a displacement of the orientation of the orifice 18 and/or 19 a from the ideal 6 o'clock position. This is shown in Figure 4.

MRH/01 10 Issue 2 Figure 5 is a longitudinal section view of a labyrinth seal bearing protector 30, mounted on a shaft, of the first embodiment.

From Figure 5, the seal stator 31 is preferably rotationally connected to equipment housing 32 and is sealed by stator elastomer 33. The rotor 34 is rotationally connected to the equipment shaft 35 and sealed by rotor elastomer 36.

The stator housing 31, preferably has a multitude of orifices 37 spaced around its circumference. Said orifices 37 provide a communication between the inner most stator circumferential surface 38 and the outer most stator circumference surface 39.

Around the circumference of said outer most stator surface 39, is a cover 40.

Said cover 40 is not rotationally connected to seal stator 31 and thereby it is allowed to rotate independently of said seal stator 31.

Preferably, said cover 40 is axially restrained, yet free to circumferentially rotate, by one or more radially extending seal stator surfaces 41 and/or 42.

The purpose of said cover 40, is to block the multitude of stator orifices 37 in the upper most segment (12, 3 and 9 o'clock position) of the stator 31 yet allow any water/foreign debris to drain away under gravitation effects by maintaining a communication orifice 43 in the lower stator segment or better termed 6 o'clock position. 1 $ I.,

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* * Figure 6 corresponds to Figure 5 and is an end view on Arrow "B" of Figure and clearly shows the communication orifice 43 in cover 40. From Figure s 6, preferably, cover 40 i*ssI MRH/0110 Issue 2 Figure 7 is an isometric exploded assembly view the labyrinth seal stator 31 and stator cover 40, of the first embodiment. From Figure 7, the stator cover inner most diameter is preferably smaller than the outer most diameter of the stator 31, but slightly oversize of the stator groove 50. In order to assemble the cover 40, over an oversized stator 31, the cover is preferably made from a flexible material such as plastic and/or is of substantially small and elastically deformable construction that it can be temporally circumferentially stretched over the largest stator diameter before fitting snugly in the stator groove 50.

Figure 8 corresponds to Figure 5 and is a radial section view on Section "c- c,, of Figure 5. As shown, in its ideal orientation, at least one of the communication orifices 37 in stator 31 aligns with communication orifice 43 in cover 40 at the 6 o'clock position.

Figure 9 corresponds to Figure 8 and illustrates circumferential rotational movement of the bearing housing stator 13 and thus labyrinth seal stator 31.

The reader will note that the cover 40 remains positioned in the 6 o'clock position since the mass of the cover is distributed and preferentially equally surrounds the cover orifice 43. Preferentially, at least one stator orifice 37 overlaps the cover orifice no matter what circumferential rotation of the stator 31 takes place.

Figure 10 is a longitudinal section view of a labyrinth seal bearing protector 60 mounted on a shaft 61, of the second embodiment. From this embodiment, a similar cover 62 is positioned on the inboard side of the labyrinth seal 60 offering the similar level of orifice protection to the $ ISIf * aforementioned first embodiment. From Figure 10, it is clear that more than * one orifice covers can be applied to a seal assembly.

MRH/0110 Issue 2 Figure 11 is an end view of a labyrinth seal bearing protector 70 mounted on a shaft 71, of the third embodiment. From Figure 11, by way of example only, the cover 72 is circumferentially split 73 to allow its easy installation into a stator groove (not shown).

Furthermore, by way of example, cover 72 incorporates an inserted member 74 and/or 75, such as to help to increase the mass to help the distribution and/or orientation of the cover to the 6 o'clock position. Said inserted member 74 and/or 75 may be permanently or non-permanently secured to the orifice cover 72 and preferably made from a material with a high mass such as stainless steel.

Clearly, the experienced reader will relate to the advantages that such embodiments offer to labyrinth and/or bearing seals which are installed on items of rotating equipment which are prone to rotational circumferential movement of the stator members, specifically in times of equipment impeller adjustment.

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Claims

1. An isolator device comprising of - a stator which locates into the stator of a piece of rotating equipment - a rotor which locates onto a rotary shaft of a piece of rotating equipment, at least one orifice cover member which is non-rotationally connected to neither stator or rotor and which is substantially adjacent to one or more communication orifices between the inner circumference and outer circumference of either stator or rotor member.

2. An isolator device as defined in claim 1, where preferably the orifice cover has is substantially of tubular construction with an inner most circumference and an outer most circumference, said inner most circumference has a discontinuity. ::

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3. An isolator device as defined in claims 1 and/or 2, where preferably said orifice cover has an uneven mass distribution around its circumference. * S...

4. An isolator device as defined in claim 3, where preferably the largest circumferential mass segment of said orifice cover member corresponds to the discontinuity in said member.

5. An isolator device as defined in any aforementioned claim where preferably said orifice cover is axially restrained and a clearance fit, within the stator member.

6. An isolator device as defined in any aforementioned claim where preferably said orifice cover is circumferentially split.

7. An isolator device is defined in any aforementioned claim where preferably said orifice cover is weighted by the incorporation of one additional members.

Amendments to the claims have been filed as follows

1. An isolator device comprising a stator for location into the stator part of a piece of rotating equipment having a rotary shaft, a rotor for location on to said rotary shaft, said stator and / or rotor being provided with one or more communication orifices, there being mounted on said device, in a rotationally independent relationship with both said rotor and said stator, an orifice cover member having means for covering the or each orifice except at a predetermined circumferential location 2. An isolator device as defined in Claim 1, wherein the orifice cover is of substantially tubular construction with an innermost circumference and an outermost circumference, said innermost circumference having a discontinuity.

3. An isolator device as claimed in Claim 1 or Claim 2, wherein said orifice cover has an uneven mass distribution around its circumference, 4. An isolator device according to Claim 3, wherein the largest circumferential mass segment of said orifice cover member corresponds to the discontinuity in said member.

5. An isolator device according to any of the proceeding claims, wherein said orifice cover is axially restrained, within the stator with which it has a clearance fit.

*S. 25 I *SS * . . s 6. An isolator device as according to any of the proceeding claims wherein said orifice cover is circumferentially split. SS*

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7. An isolator device according to any of the proceeding claims, wherein said orifice cover is weighted by the incorporation of one additional

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members.

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MRH/O11O Issue 2 8. An isolator device as defined in claim I and substantially as herein described.

9. An isolator device as described herein with reference to Figures 5 to 9, Figure 10 or Figure 11 of the accompanying drawings * * ***S *S** S... **SS *.S*

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