GB2390398A

GB2390398A - Fluid pump with pumping chamber dividing shroud

Info

Publication number: GB2390398A
Application number: GB0324293A
Authority: GB
Inventors: Stephen Walker Tebby
Original assignee: Concentric Pumps Ltd
Current assignee: Concentric Pumps Ltd
Priority date: 1999-03-30
Filing date: 2000-03-28
Publication date: 2004-01-07
Anticipated expiration: 2020-03-28
Also published as: GB2390398B; GB0324293D0

Abstract

A fluid pump 10 includes a body housing 14, a fluid pumping chamber having a rotatable pumping member 16, a drive shaft 12 which passes through an aperture in the body 14 into the pumping chamber to rotate the pumping member 16 , and a seal 18 between the pump body 14 and the shaft 12 to inhibit fluid moving along the shaft 12 out of the pumping chamber. A dividing shroud 32 is located between the seal 18 and the pumping member 16 to divide the pumping chamber 30 and create a pressure gradient across a fluid inlet 36 and a first portion of the divided pumping chamber, such that fluid flows into the first portion. The dividing shroud 32 may be stationary in use, and may be attached to a lip on the pump body 14 by a resilient clip.

Description

1 2390398

I'3lH1367r;RnlV1 Improvements in Pumps I his invention relates to improvements in pumps and in particular but not cxcJusi>'el,, to improved performance and reliability of shaft fluid seals as used in impeller pumps.

The reader is refened to the applicant's co-pending CrB patent application nr.mler 0007340.3 (publication nunbcr GB2348997).

In the field of impeller pumps which incorporate a single impeller on an

overhung sliest, the shaft seal is often provided with a suitably shaped annular space around it commonly referred to as a seal chamber or balance chamber.

()ne purpose of the seal chamber is to assist in conducting await heat generated by the sl:aft seal. The seal chamber must be of adequate capacity and of suitable slave to promote a sufficient degree of swirling to enable a necessary proportion of the heat generated by the shaft seal to be transferred into the pumped media (iurill<r the passage of that pumped media from wearing ring to impeller balance holes. '->metimes the swirling action in the seal chamber is assisted by a duct or iltiplicty of duets which permit a portion of the outlet pumped media to be directed into the seal chamber in a manner conducive to the cooling of the shaft sea I. l ypicalJy the ducts may be dril]in.gs or pairs of drillings each of which also Am need to be tapped or plugged, or one or more external tubes or pipes to pipe con.eclors which require drilling and tapping and may be also plugging. The ducked pumped media is typically circulated back to the main pumped flow tl,rougl conventional impeller balance holes.

I-lowever many impeller pumps are called upon to be axially compact.

As such there may be insufficient space for an effectively proportioned seal C.ilOWilCr. Also there!nay be insui^cien space for weariest is Jo altci natively no wearing rings may be fitted as a cost saving.

in such arrangements it is thought that fluid circulation is impeded because the whole mass of fluid between the impeller and pump head tends to rotate as a whole in the manner associated with a liquid annular seal. The resulting pressure differential available across each of the impeller balance holes is insufficient to promote the flow rate which is required for adequate shaft seal Coolidge. Accordingly the present invention seeks to avoid or at least mitigate certain problems in the prior art including the lack of cooling of the shaft seal in

tall example an axially reduced pump arrangement. One object of the invention is to increase fluid recirculation back into the main Pow path of the pump thereby to effect cooling and/or recirculation of fluid in the region of the shaft seal. fine. specs of talc present invention provides a fluid pump comprising a primp body housing a fluid pumping chamber having a rotatable pumping member Judith a first radius a drive shaft which passes through an aperture in the pump body into the pumping chamber to effect rotation of the pumping member in also. -cl a seal between the pump body and drive shaft to inhibit fluid moving along the Aloft out ofthe pumping chamber characterized by a dividing shroud

cperabl!oca+ed he+.x.een the sea! and the rotatable pumping member to divide the fluid pumping chamber between the seal and the rotatable pumping member, wherein a fluid inlet is provided into a first portion of the divided fluid pumping clanler. which first portion is adjacent the seal and the Pius inlet is provicieci at a radially outer portion of the dividing shroud at a second radius substantially -!-1 n the first radius exposing the fluid inlet to substantially the outlet or essure enerated by the pump in use, and wherein the dividing shroud operably creates a pressure gradient across the fluid inlet find first portion of the d,> Ted fluid pumping chamber, thereby to effect fluid flow into the first portion.

Beneficially, the dividing shroud is found to increase circulation of the pump fluid, especially around the seal.

Preferably, fluid inlet into the first portion of the divided seal chamber, which first portion is adjacent the seal, is provided. Beneficially, a pressure 'radict exists across the fluid inlet, and indeed across the whole first portion of the divided seal chamber, thereby to cifect fluid {low into the first portion of the seal chamber.

Preferably, the dividing shroud comprises a central aperture which o; cra'oly surrounds the rotatable shaft in use. Prcierab]y, the radius of the aperture is slightly greater than the radius of the shaft thereby to provide a fluid passageway between the first and second divided portions of the seal chamber.

I'referably, the circular rim of the central aperture can comprise a lip. The lip Carl extend axially along the rotatable shaft. Preferably, the lip extends away front the seal.

Prcterably, means for attaching the dividing shroud to the pump body are l roilcd. For example. the shroud can comprise one or more apertures to enable co-operating locking means such as a threaded bolt and threaded sockets in We Pusan hndv to be used to attach the shroud to the pump body. Of course, threaded bolts can protrude fiom the pump body and nuts can be used to fasten the shroud onto the pump body in this reverse configurations.

Phe dividing shroud can comprise an attachment or retaining device for c moderating with part of the pump body. For example, the shroud can comprise an annular resilient clip which engages a lip on the pump body thereby to Or ovidc a mechanical/frictional attachment.

I'he fluid inlet to the first portion can comprise a series of fluid passageways in the pump body around the dividing shroud. For exanp]c, a series of passageways can be provided between a series of bosses, castellations, - crenallations in the pump body itself.

Another aspect of the invention provides a dividing shroud for a seal chandler of pump. Another aspect provides a flow or recirculation enhancer for ic-zasii recirculation of the fluid or pumped medium past a shaft seal in a p:llllp hack into the main flow path between pump inlet and outlet. A further aspect peroxides a pressure enhancer for increasing fluid pressure in the vicinity oftile scale preferably talking it close to the fluid outlet pressure for the pump.

s F.mbodiments of the invention will now be described, by way of example only. with reference to the accompanying drawings' in which: !2' RF 1 in schematic sectional side elevation view of a first e mI:odiment of part of a pump according to the invention; FIGURE 2 is a schematic side elevation view of part of a second embodiment of a pump according to the invention; FIGURE 3 is a schematic perspective view of part of the pump shown in Fire viewed Corn the right hand side of Figure 2; FIGURE 4 is a schematic sectional side elevation view of part of a pump according to a third embodiment ofthc invention; I--TGl]RE 5 is a schematic side elevation view of a fourth embodiment; and Is IGURE 6 is a schematic side elevation view of part of a fifth cnbodicnt of the invention.

Referring to Figure 1 there is shown part of a pump 10 according to the ie:tio comprising a rotatable shaft 19, a pump body 14 and an impeller 16.

Inleller 16 comprises a series of blades for effecting fluid flow along the axial direction indicated lay arrow l through to a radial outlet direction indicated by arrow ().

Primp 10 comprises a seal 1 Pi comprising an annular stepped clip 20 for encraiig part oi the pump body id adjacent line cenrai aperture for sllalr if.

( lip 20 carries an annulus 22 having a seat portion 24 for engaging and cn-}cratino with a second seat portion 26 which in turn is attached to a sleeve S which is located to effect abutment between seats 24 and 26 in a rotationally fast position on shaft] 2.

Pump 10 further comprises a dividing shroud 32 which is substantially disk shaped, having a radially outer Cup portions 34 for gripping part of pump body 14 and a central aperture through shaft 12, which aperture is defined by a lip 38 wlicl extends axially along shaft 12 away from seal 18. Shroud 32 farther comprises a series of apertures 36 in a radial outer position.

Shroud 32 divides the seal chamber 30 forming part of the pumping clamber within pump 10, which seal chamber 30 is defined by seal 18 and part ol else pump body 14 as well as the face of impeller 16. Shroud 32 acts to divide the seal chamber 30 into a first portion 31 a adjacent seal 18 and a second portion 31 b NNIh jCIF in this embodiment is between shroud 39 and in.pcller 16.

:1 use, shaft 19 is caused to rotate thereby to effect rotation of impeller 16 t]erely causing fluid flow along the direction of arrow I into pump 10 and out alcn> flee direction of arrow 0. Shaft 17 further effects rotation of sleeve 78 and Ala rotational seat 96. The frictional contact between seats 24 and 26 causes heating of the seal. The pumped media between the impeller] 6 and stationary stepped annular disc or shroud 32 typically will rotate at approximately half the

impel ler speed thereby effecting a radial pressure imbalance between the impeller periphery and the shaft seal. No such pressure i.mba]ance is generated het\veen the stationary pump head 14 and shroud 32. A circulation of fluid cosistig of a sunsantiaiIy rauiai inward flow DiW;! ills; biaijullai-y p-Uil-p Scald 14 and shroud 32 and a radially outwardly spiralling fluid movement let\ecn shroud 32 and the rotating impeller 16 is thus promoted by the impeller thereby enhancing the cooling of the shaft seal 18.

llencc, in accordance with the present invention, impeller 16 increases fluid flows past seal 18 along a path through apertures 36 in shroud 32 down to Aloft 12 via the portion 31a of chamber 30 between shroud 39 and seal 18 tlerel:'y to effect some cooling of seal 18. The fluid is further recirculated back into the second potion of the seal chamber between shroud 32 and impeller 16 via the annulus hctwcen lip 38 on shroud 32 and shaft 19. The fluid is then drawls up towards outlet arrow O between shroud 32 and impeller]6 and or drawn through the axial bores or balance holes 17 in impeller 16. Accordingly, shroud 39 acts to divide chamber 30 and disrupts the otherwise isolated novenent of fluid within chamber 30, and effects recirculation of fluid about seal 1 8 thereby to provide better cooling of the seal.

Moreover, in impeller pumps where tile fluid pressure at the pump inlet is close to the vapour pressure of the pumped medium, it is preferable that the pres.surc in the seal chamber should be maintained at a level sufficiently remote fi-on the vapour pressure to prevent the pumped medium from boiling and, in the case of coolant pumps in the I.C. engine field, to prevent the well-known

phenomenon of filming of the shaft seal surfaces from occurring which leads to coolant leakage.

In prior art pump arrangements, the pressure of the pumped medium in

file seal chamber 3u can ve Diode io 1vv r-,ui-,;lu;;I,e. prcss-a;-c and it 'lllCr rressurc is close to the vapour pressure of the pumped medium then the additional heat generated by the shaft seal] 8 may cause the pumped medinn1 to boil at- the seal and/or advance the rate of filming at the shaft seal mating s.'rJ:aces as just described.

1 the arrangement of the prcscut invention, the fluid pressure in portion 3 1 a of seal chamber 30 is raised to be closer to the higher outlet pressure and hence shroud 30 helps to mitigate the problems in the prior art arrangement by

reducing the possibility of boiling and/or filming at the seal 18. This effect is chanced by ensuring a smal1 running clearance between the internal diameter of lip 3S' and Aloft 12' and by arranging a series of apertures or slots 36 in the shroud 3Q clear to the outlet of the pump. Accordingly, the seal clamber Or essure self ad lusts to a value appreciably closer to the pressure at the impeller lcriphery than to the pump inlet pressure thereby reducing the possibility of the sla:tl seal to film over and lealc.

In another embodiment of the invention, a pump] JO is provided as shown in part in 'inures and 3. In this embodiment, components having identical or like functions to those shown in the first embodiment arc given the same two digit reference number prefixed with the number 1. Accordingly, IMP 1 O comprises a shaft l 19, pump body 1 14 and seal 1] 8. Shroud 130 comprises a inner stepped annulus 149 which extends down to rim 138. The shroud l:Q further comprises a series of apertures 140 for receiving bolts 147.

Rcterring in particular to Figure 3, it can be seen that the pump body 114 in this embodiment comprises fluid communication passageways which lead into seal chamber 130 and in particular portion 131a. In this embodiment, the fluid t;tiliL;di;'it)Jasaag'vaia CvOi^l'.luiJac slots 1 4 CC-v'iCCl, hc SC1,CS via lA,vSSeS' ca.stellations or crenallations 144. The castel]ations 144 each comprise a threaded lore 146 for co-operating with bolts 147 thereby to locate shroud 132 in lilac.

lt should be noted that shroud 132 shown in Figure 3 differs slightly from float shown in Figure 2 in that stepped inner annular portion 142 is not shown.

Beneficially, stepped portion 142 increases the size of the first portion of cavity 13() adjacent seal I 1 thereby enabling greater Iluid movement in the vicinity of the seal.

Of course, the nature and number of fluid passageways, in this embodiment slots 148 can be varied. Similarly, the number of castellations 144 can be varied such that any number can be provided and not just the four shown in the present embodiment.

Referring to Figure 4, there is shown part of a third embodiment of a pump _lO according to the invention. Here, like components with the earlier eboclients are given the same two digit reference number prefixed with the Abet 3. Accordingly, pump 210 comprises a shaft 712, pump body 214, seal 2 I and seal chamber 230. A dividing shroud 232 is provided which engages a series of castellations 244 at an intermediate radial position. In this enlodiient, shroud 232 comprises a radially outer curved portion 250 for

guiding fluid down towards castellations 244. Shroud 232 further comprises an annular stepped portion 252 which grips the radially outer surfaces of castel]atios 244 thereby to fix the shroud 232 in position. Of course, further il;CCIlaMICal C-ttLCAlCJli-l-ICilt LlC'v'iCCS Ccli} 1_; iSC SUCK US,J ttt' Cl' "..',,':,e.l.,+ as.shon in the previous embodiment. Shroud 232 further comprises an inner stepped annulus 244 and finally a lip 238. Accordingly, stepped annulus 252 Evicts to secure the shroud 232 in position whilst stepped annulus 244 acts to increase tle area around seal 18.

A yet further embodiment of the invention is slown in Figure 5 Herein a shroud 332 comprises a radially outer portion 350 for guiding fluid hetwce shroud 332 and pump body 314 down towards apertures 336 in the shroud. Shroud 332 comprises a. stepped portion 354 which engages part of pump body 314 thereby to locate the shroud in position. In this embodiment, shroud 330 further carries amu]us 320 which forms part of the seal 318 (not shown). Accordingly, amulus 320 carries a further annuls 322 and stationary circular seat 324. Beneficially, shroud 332 acts, in particular through outer portion 3SO, to increase fluid flow down towards shaft 12 through apertures 336 thereby to effect cooling ofthe sear 1 a lirther embodiment of the invention shown in Figure 6, a shroud 432 comprises a stepped radially outer portion 460 for engaging crenallations in the pushup body 414. The S-shaped central portion of shroud 432 extends *om stepped portion 460 to apertures 436 which can be provided IM a circular series around the shroud 439. Accordingly, the central portion of shroud 436 acts to Aide fluid between slots located between the series of bosses or castel]ations 444 in the pump and the apertures 436. Shroud 439 further comprises an inner

annular clip 490 for engaging part of pump body 4] 4. Annulus 420 forms part of a seal 418 (not shown), and therefore carries a further annulus and seat for engaging the r otatable part of the seal as shown in earlier embodiments.

Claims

Claims

I. A fluid pump comprising a pump body housing a fluid pumping chamber c' in c.,.,ict,a'.-,,e lu-ui,^,ii;, ili-l'el- -a-.', a,C,isL 1"UIU:,, a i'iVC Sllalc;'V-l,C Assess through an aperture in the pump body into the pumping chamber to effect r otation of the pumping member in use, and a seal between the pump body and drive shaft to inhibit fluid moving along the shaft out of the pumping chamber, cl.laracteri,:cd by a dividing shroud operably located between the sea] and the rotatab]c pumping member to divide the fluid pumping chamber between the seal arid the rotatable pumping member, wherein a fluid inlet is provided into a first portion of the divided fluid pumping chamber, which first portion is adjacent the seal and the fluid inlet is provided at a radia]]y outer portion of the clividig shroud at a. second radius substantially equal to the first radius exposing bloc fluid inlet to substantially the outlet pressure generated by the pump in use, find;\;herein the dividing shroud operably creates a pressure gradient across the :I:l'id Clot and first portion of the divided fluid pumping chamber, thereby to ci [c-et t].id flow into the first portion.

2. A fluid pump according to Claim 1 wherein the dividing shroud is st'tioary in use.

3. A fluid pump according to Claim I or 2 wherein a fluid inlet is provided into - first portion of the divided fluid pumping chamber, which first portion is d Scent the seal.

4. A fluid pump according to Claim 3 wherein dividing shroud operably cries pressure gradient. across the fluid inlet and first portion oi the divided fluid piping chamber, thereby to effect fluid flow into the first portion.

. fluid pump according to any preceding claim wherein the dividing shroud comprises an aperture which operably surrounds the drive shaft in use.

A I..:.. At- t 1;. Shim the raids of the lr in \). (} I]LllJ UlIl.._,..n,, _,. ^. __._.

slightly greater than the radius of the drive shaft thereby lo provide a fluid passageway between the divided portions of the pumping chamber.

7 A fluid pump according to Claim 5 or 6 wherein the rim of the aperture is circular. 8. A fluid pump according to Claim 5, 6 or 7 wherein the aperture comprises a protruding lip.

9. A fluid pump according to Claim 8 wherein the lip extends co-axially along the drive shaft.

i (). A fluid pump according to Claims 6, 7, 8, or 9 wherein the lip extends away fi ore the seal.

11. fluid pump according to any preceding claim comprising means lor attaching the dividing shroud to the pump body.

12. A fluid pump according to Claim I 1 wherein the shroud comprises an annular resilient clip which engages a lip on the pump body thereby to provide a r e chan ical/frictional attachment.

13 A timid pump according to any preceding claim comprising a livid inlet to bloc first portion having a series of fluid passageways in the pump body around the dividing shroud.

14. A fluid pump according to claim 13 wherein the series of fluid passageways comprises a series of castellations, in the pump body.

!..,A, '!".".'-A - so Af^r sari!..her of a f4.lli r,.l! - A. i hi. A i7'w enhancer for increasing recirculation or fluid, or pumped neclium, past a shaft seal in a pump back into a main fluid flow path between a pump inlet and outlet.

Annendments to the claims have been filed as follows ! 5 1. A fluid pump comprising a pump body housing a fluid pumping chamber having a rotatable, nun.ping member with a first radius, a drive shaft which passes through an aperture in the pump body into the pumping chamber to effect Oil. of the planning member in use. and a seal between the pump body and drive shaft to inhibit fluid moving along the shaft out of the pumping chamber, characterized by a dividing shroud operably located between the seal and the rotatable pumping member to divide the fluid pumping chamber between the seal and the rotatable pumping member, wherein a fluid inlet is provided into a first portion of the divided fluid pumping chamber, which first portion is adjacent the seal and the fluid inlet is provided at a radially outer portion of the dividing shroud at a second radius substantially equal to the first radius exposing the fluid inlet to substantially the outlet pressure generated by the pump in use, and wherein the dividing shroud operably creates a pressure gradient across the fluid inlet and first portion of the divided fluid pumping chamber, thereby to effect fluid flow into the first portion.

2. A fluid pump according to Claim 1 wherein the dividing shroud is stationary in use.

3. A fluid pump according to any preceding claim wherein the dividing shroud comprises an aperture which operably surrounds the drive shaft in use.

4. A fluid pump according to Claim 3 wherein the radius of the aperture is slightly greater than the radius of the drive shaft thereby to provide a fluid passageway between the divided portions of the pumping chamber.

5. A -mid purlp according to Claire 3 or a herein a rim of the aperture is circular. 6. A fluid pump according to claim a, or wherein a aperture corrlprii<;s;a protruding lip.

7. A fluid pump according to Claim 6 wherein the lip extends co-axially along the drive shaft.

8. A fluid pump according to Claims 4, S. 6, or 7 wherein the lip extends away from the seal.

9. A fluid pump according to any preceding claim comprising means for attaching the dividing shroud to the pump body.

10. A fluid pump according to Claim 9 wherein the shroud comprises an 4 annular resilient clip which engages a lip on the pump body thereby to provide a mechanical/frictional attachment.

11. A fluid pump according to any preceding claim comprising a fluid inlet to the first portion having a series of fluid passageways in the pump body around the dividing shroud.

12. A fluid pump according to claim 11 wherein the series of fluid passageways comprises a series of castellations, in the pump body.