Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D1/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
  • F04D1/06—Multi-stage pumps
  • F04D1/063—Multi-stage pumps of the vertically split casing type
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/40—Casings; Connections of working fluid
  • F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
  • F04D29/426—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for liquid pumps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/60—Mounting; Assembling; Disassembling
  • F04D29/62—Mounting; Assembling; Disassembling of radial or helico-centrifugal pumps
  • F04D29/628—Mounting; Assembling; Disassembling of radial or helico-centrifugal pumps especially adapted for liquid pumps

Definitions

• the present invention relates to a locking device of the stator pack of pump diffusers, in particular centrifugal submersible pumps.
• Such a device is suitable for locking the pack of the diffusers thus preventing any movement thereof, in particular in an axial direction, inside the cylindrical casing of the pump.
• Locking devices comprising a pair of flanges provided on their external diameter with threading and each one of which is arranged at an end of the casing. Such threading engages in a corresponding threaded area obtained on the internal surface of the casing.
• the stator pack is locked by screwing the two threaded flanges and tightening the pack of diffusers between these flanges.
• a flange is provided that is welded to an end of the casing and another flange screwed to the casing using similar methods to those disclosed above .
• the flange in order to be able to effectively tighten the pack of diffusers, the flange must be screwed to the casing by using high tightening moments.
• the thread comes into contact with the threaded area on a significant portion of the respective threads, which generates resistant torques, which, owing to the friction, can reach considerably high values.
• Another drawback of such devices is that they are difficult to dismantle.
• Another drawback of the known devices is that they can be used only for pumps having a casing with a relatively high thickness.
• the threaded area obtained on the casing constitutes a zone of weakness of the casing and, if the casing has a limited thickness, the threaded area undergoes plastic deformation during operation, namely when the pump is crossed by fluid having high pressure.
• One object of the present invention is to improve the locking devices of the stator pack of pumps.
• Another object is to obtain a locking device of the stator pack of pumps that can easily be fitted to and dismantled from a body of the pump.
• a further object is to obtain a locking device of the pack of the pump diffusers that is sufficiently resistant not to be damaged when subjected to the pressure exerted by the pumped fluid, even when the device is applied to pumps operating at high pressure.
• a further object is to limit the depositing of encrusting matter on a locking device of the stator pack of pumps .
• a locking device of the stator pack of a pump comprising casing means arranged to contain pumping stages of a fluid to be pumped, flange means suitable for closing said casing means, screw means provided with thread means and cooperating with nut screw means provided with further thread means for fixing together said flange means and said casing means, characterised in that said thread means has contour that is substantially non-complementary to a further contour of said further thread means.
• the mechanical clearance enables, during a phase of dismantling of the device, axial shifting of the flange means in relation to the casing means, such as to remove any encrusting matter that may be present between the screw means and the nut screw means.
• a locking device of the stator pack of a pump comprising casing means suitable for containing the pumping stages of a fluid to be pumped, flange means suitable for closing said casing means, and connecting means arranged for fixing together said flange means and said casing means, characterised in that it further comprises seal means arranged to insulate said connecting means from said fluid.
• connecting means comprises threaded coupling means it is possible to prevent encrusting matter to deposit between screw means and nut screw means that define the above mentioned threaded coupling means .
• Figure 1 is a fragmentary section taken along a longitudinal plane of a locking device according to the invention.
• Figure 2 is an enlarged detail of Figure 1;
• Figure 3 is a detail like the one in Figure 2 in which flange means of the device are shifted axially in relation to casing means.
• Figure 1 shows a locking device 1 of the stator pack of a pump.
• the locking device 1 comprises a flange 2 of circular shape, in metal material, provided with threading on one of its external surfaces.
• the threading defines a screw element 3 arranged to engage in a corresponding nut screw element 5 defined by a threaded area obtained inside a casing 4 arranged to contain the stator pack of the diffusers - not shown - of the pump.
• the casing 4 comprises a tubular element in steel, at an end 6 of which the nut screw element 5 is obtained.
• a further nut screw element can be provided arranged to engage with a further screw element of a further flange similar to the flange 2 disclosed above.
• stator pack is tightened against the flange 2 and the further flange.
• the screw element 3 has a contour that is different from a further contour of the nut screw element 5.
• the nut screw element 5 comprises a further thread 14 that defines a helicoidal groove 7 that has a further axial height S.
• the nut screw element 5 can be obtained through plastic deformation of the end 6 of the casing 4.
• the further thread 14 is obtained in a portion of metal material having a constant thickness. .
• the further axial height S of the further thread 14, and consequently of the groove 7, is greater than the axial height C of the thread 8 that is received inside it. In this way, between the groove 7 and the thread 8 - when they are coupled - there is defined a mechanical clearance Gl of a preset amount.
• the thread 8 comprises an active side 15 and a non- active side 16.
• the active side 15 is configured in such a way as to be more tilted, at least at a crest 27 of the thread 8, than the non-active side 16, in relation to a longitudinal axis Z of the device 1.
• the further thread 14 comprises a further active side 18 and a further non-active side 19.
• the further active side 18 is configured in such a way as to be more tilted, at least at a further crest 28 of the further thread 14 that the further non- active side 19, in relation to the Z axis.
• the active side 15 and the further active side 18 are arranged substantially perpendicularly to the axis (Z) .
• the contour of the thread 8 and the further contour of the further thread 14 are substantially complementary in correspondence of the active side 15 and of the further active side 18 and substantially non-complementary in correspondence of the non-active side 16 and of the further non-active side 19.
• the screw element 3 and the nut screw element 5 are movable between an active configuration, indicated by X in Figure 2, in which the operative side 15 interacts with the further active side 18, and a non- operative configuration, indicated by Y in Figure 3, in which the active side 15 is distant from the further active side 18.
• a gap 29 having a width A and such dimensions as to allow the passage of particles of solid matter dispersed in the fluid between the screw element 3 and the nut screw element 5.
• the active side 15 interacts with the further active side 18 along a contact zone 17 of limited surface extent.
• the thread 8 and the further thread 14 are such that the reaction that occurs in the contact zone 17 has a line of action directed substantially parallel to the
• the screw element 3 and the nut screw element 5 are subjected during use to a substantially axial load.
• the limited surface extent of the contact zone 17 enables the phase of fitting the locking device 1 to be facilitated inasmuch as the contact reaction has a limited friction component.
• the external diameter of the nut screw element 5 is greater than the external diameter of the screw element 3.
• the thread 8 has a depth h greater than the depth of the further thread 14 and, therefore, than the depth
• the pump is assembled in the manner disclosed below.
• the diffusers which form the stator pack, and the impellers, are arranged in the correct sequence to form a preassembled pack, which is inserted inside the casing 4 till making it to rest against said closing cover arranged at the further end of the casing 4.
• the flange 2 presses the stator pack as the screw element 3 is screwed onto the corresponding nut screw element 5, until a preset preload value is reached.
• fitting of the flange 2 can be achieved by using a pusher tool that is not shown, comprising an anchoring element that engages in projections 22 of the nut screw element 5 and a push rod arranged in contact with internal zones of the stator pack.
• the projections 22 are obtained in an external surface 23 of the casing 4, at the groove 7 defined by the further thread 14 in the nut screw element 5.
• This pusher tool is pressed on the stator pack in such a way as to compress it and facilitate screwing of the flange 2, which occurs without further pressure on the pack of the diffusers.
• the flange 2 can be subjected to axial shifts towards the inside of the casing 4, in a direction indicated by the arrow F.
• the axial shifts enable any encrustation of matter to be broken up that has formed through depositing of residues or slime present in the fluid that has infiltrated between the screw element 3 and the nut screw element 5, causing sticking of the coupling.
• portions of the encrustation may be removed from the contact zone 17 through the gap 29 defined between the screw element
• the flange 2 can easily be unscrewed without having to apply high torsional moments.
• the locking device 1 enables the dismantling phase to be significantly facilitated, considerably limiting seizure or sticking of the coupling, even in the presence of polluted fluids.
• the locking device 1 furthermore comprises seal means
• the seal means 24 comprises a first gasket 9 and a second gasket 10, arranged respectively above and below the threaded coupling.
• the first gasket 9 is received in a cavity 12 obtained on the flange 2 upstream of the thread 8 and the second washer 10 is received in a housing 13 obtained on the flange 2 downstream of the thread 8.
• the first gasket 9 and the second gasket 10 are such as to cooperate with internal surfaces 11a, lib of the casing 4 to ensure a seal against fluid and substantially insulate the coupling zone between the flange 2 and the casing 4 from encrusting material, such as for examples residues or slime conveyed by the fluid.
• the first gasket 9 comprises an appendage 25 arranged to partially envelop an edge zone 26 of the casing 4.
• the second gasket 10 is placed in direct contact with the pumped fluid.
• the pumped fluid thus presses the second gasket 10 against the flange 2 and the casing 4, such as to ensure its seal.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Lock And Its Accessories (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Infusion, Injection, And Reservoir Apparatuses (AREA)
• Motor Or Generator Frames (AREA)
• Motor Or Generator Cooling System (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=30012825

Family Applications (1)

Country Status (8)

Families Citing this family (1)

Citations (6)

Family Cites Families (1)

• 2003
  • 2003-07-31 IT IT000225A patent/ITMO20030225A1/it unknown
• 2004
  • 2004-07-30 DK DK04763665T patent/DK1649171T3/da active
  • 2004-07-30 ES ES04763665T patent/ES2318316T3/es active Active
  • 2004-07-30 AT AT04763665T patent/ATE415562T1/de not_active IP Right Cessation
  • 2004-07-30 DE DE602004017996T patent/DE602004017996D1/de not_active Expired - Fee Related
  • 2004-07-30 WO PCT/EP2004/008585 patent/WO2005015027A1/en active Application Filing
  • 2004-07-30 EP EP04763665A patent/EP1649171B1/de not_active Not-in-force
  • 2004-07-30 CN CNB2004800213093A patent/CN100451350C/zh not_active Expired - Fee Related

Patent Citations (6)

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