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
  • 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
  • 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
  • F04D29/60—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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2260/00—Function
  • F05D2260/30—Retaining components in desired mutual position
  • F05D2260/36—Retaining components in desired mutual position by a form fit connection, e.g. by interlocking

Definitions

• Locking device for locking the stator pack of motor-driven pumps
• the present invention relates to a locking device for locking the stator pack of submersible centrifugal pumps.
• Said device is suitable for locking the pack of the diffusers preventing the pack from moving inside the cylindrical shell of the pump, particularly along an axial direction.
• Italian patent IT 1005473 filed in the name of the same applicant, discloses a locking device comprising a pair of end crowns each of which is fixed inside the cylindrical shell, respectively upstream and downstream the stator pack, by means of an elastic ring having circular section and toroidal shape inserted into a corresponding groove obtained inside said shell.
• Each crown is provided with threaded holes suitable for receiving respective screws passing through closing flanges arranged at opposite ends of the shell and centred thereon.
• the crown arranged downstream the stator pack acts as an axial stop for the pack, while the crown arranged upstream the pack acts as a fastening element for the upper flange.
• the upper flange abuts on a collar provided with a step centring and abutting the collar on a peripheral region of the first diffuser of the pack. In this manner, when the upper flange is fixed to the respective crown by means of the screws, the stator pack is tightened between the collar and the crown arranged at the opposite end.
• said device comprises a crown which is welded at an end of the pump shell and is not fixed to the shell by means of elastic ring.
• a drawback of the devices of this type is that, when the flanges are fixed to the shell by means of the screws, the tightening torque has to be limited to a pre-established value for preventing the elastic ring from being extruded into the space existing between the crown and the shell so as to deform the groove and bend the shell, or even exiting from the groove. While the pump is working, then, the elastic ring is stressed not only by the stresses caused by the tightening of the screws, but also by the pressure of the liquid, so that such locking device is may be applied only to pumps having limited head and small number of stages.
• the tightening torque of the screws must have a limited value for preventing dangerous ejection of the ring from the seat thereof in condition of maximum clearance .
• a locking device comprising two rows of slots punched in the outer cylindrical shell of the pump on two planes parallel to each other and orthogonal to the axis of the pump, arranged respectively upstream and downstream the stator pack.
• nibs may be introduced into the shell, said nibs being provided on nuts which are capable of engaging the threaded ends of tie rods arranged parallelly to the axis of the pump and passing through holes obtained in the closing flanges of the pump.
• the above-mentioned nibs act as stops for the end diffusers of the stator pack so allowing said diffusers to be locked.
• the pump may comprise a flange welded at one end thereof and a device analogous to the above-described device at the other end.
• a drawback of such devices consists in that punching or shearing the slots on the external shell produces out-of-round deformations of the shell which makes it difficult to introduce the pack into the shell and requires onerous operations of adjustment.
• the tightening stress is not uniformly distributed on the circumferential edge of the shell, but is concentrated in regions from which cracks and corrosion under fatigue start.
• a locking device comprising a pair of flanges, each arranged at one of the ends of the shell, which protrude from said shell and are provided with holes arranged externally with respect to the diameter of the shell and suitable for allowing tie rods to be housed.
• tie rods On the threaded ends of such tie rods nuts are engaged which tighten the shell, and consequently the stator pack, between the flanges of the pump.
• a variation consists in the absence of an external metallic shell and the use of diffusers each provided with its own shell. Devices of this type are very bulky and considerably increase the radial overall dimensions due to the presence of the tie rods, which are sized according to the maximum pressure exerted by the pump during working.
• a locking device comprising a pair of flanges threaded on their external diameter and each arranged at one of the ends of the shell. The threads of said flanges engage a respective threaded section obtained on the internal surface of the shell. The- stator pack of the diffusers is locked by screwing to the shell the two treaded flanges.
• the shell comprises a first flange welded at one end thereof and suitable for acting as a stop for the first diffuser of the pack and a second threaded flange screwed at the other end.
• pumps provided with such devices are difficult to be disassembled due to the presence of encrusting material, such as sludge or slime, which may accumulate at the threaded coupling.
• An object of the present invention is to improve the known locking devices.
• Another object of the present invention is to provide a device for locking the stator pack of a pump comprising an elastic ring which is easy to be inserted into and extracted from a respective seat.
• a further object of the invention is to provide a locking device comprising an elastic ring which is substantially free from deformations during working, so that the risk of an ejection of the ring from the groove in which it is housed is reduced.
• a locking device for locking the stator pack of a pump comprising shell means suitable for containing pumping stages suitable for pumping a fluid, crown means provided with connecting and fixing means arranged for connecting flange means of said pump to said crown means, said flange means being suitable for hermetically closing said shell means, elastic ring means arranged between said shell means and said crown means, suitable for preventing said crown means from sliding in an axial direction inside said shell means, characterised in that said elastic ring means comprises wedge means provided with a friction surface suitable for being coupled with a respective conjugate surface of said crown means .
• said elastic ring means comprises tooth means suitable for engaging respective groove means obtained in said shell means. In such manner, a pre-established axial position in said shell for said elastic ring means is provided.
• said friction surface is a conical surface.
• the ring means is broken in a section of the peripheral edge thereof, which allows a limited circumferential deformation, however sufficient to allow the tooth means to firmly engage the groove means obtained in the shell.
• said flange means is associated with support means provided with a support step which engages the first of the diffusers of the pack of the pump. Therefore, when the screws are tightened, the flange means presses the support means which locks the stator pack of the pump so preventing any movement thereof.
• Figure 3 is a further enlarged detail of Figure 1 which shows an elastic ring inserted into a respective seat;
• Figure 4 is a section taken along the plane IV-IV of Figure 2 which shows the elastic ring in the region in which it is broken.
• a pump 1 comprising an external shell 2 consisting of a steel tubular element into which a crown 3 is housed. Between the crown 3 and the shell 2 an elastic ring 4 is arranged comprising a protruding portion 5 arranged for being housed into a groove 6 obtained in the shell 2.
• the elastic ring 4 comprises a conical surface section 7 suitable for being coupled with a respective conjugate surface 7a of the crown 3.
• the pump 1 further comprises a closing flange 8 suitable for closing the shell 2 which is fixed to the crown 3 by means of screws 9 engaging threaded holes obtained in the above- mentioned crown 3. While the screws 9 are tightened, the ring means 4 are kept firmly connected to the shell 2 because the protruding portion 5 couples with the groove 6, while the crown 3 moves towards the flange 8 bringing the conjugate surfaces 7 and 7a to keep in contact with each other.
• a closing flange 8 suitable for closing the shell 2 which is fixed to the crown 3 by means of screws 9 engaging threaded holes obtained in the above- mentioned crown 3. While the screws 9 are tightened, the ring means 4 are kept firmly connected to the shell 2 because the protruding portion 5 couples with the groove 6, while the crown 3 moves towards the flange 8 bringing the conjugate surfaces 7 and 7a to keep in contact with each other.
• an inclined cut 15 breaking the circumference of the ring 4 is shown; the above-mentioned cut 15 allows the ring 4 to be the quickly removed using a standard flat-
• the cut 15 allows the ring 4 to deform so as to allow the protruding portion 5 to be housed into the groove 6. Since during working the ring 4 does not lock the crown 3 owing to an elastic deformation, but rather locks the crown 3 by substantially acting as a body rigidly fixed to the shell 2, advantageously the ring 4 is made of steel for a better stress strength.
• impellers 10 keyed onto the shaft 11 and fixed thereto through a further screw 16, and the diffusers 12 are further arranged internally to the shell 2.
• the flange 8 comprising the valve body of the pump 1 abuts on a support 13 provided with a step 14 which engages the first diffuser 12 so locking said diffuser 12 and the whole stator pack of the pump 1 and, therefore, preventing the stator pack from sliding in an axial direction.
• the pump 1 is provided, in the not-shown portion arranged downstream the stator pack, with a further crown, provided with a further ring similar to the above-described ring, said crown acting as a supporting and stopping element for the stator pack.
• the crown arranged downstream the stator pack is not fixed to the shell by means of an elastic ring, but is directly welded to said shell.
• the pump is assembled in the way described hereinafter.
• the impellers 10 and the diffusers 12, alternated in a suitable sequence, are inserted on the shaft 11 abutting, at the bottom, on the driving joint of the shaft 11, not shown, and being tightened, at the top, with the screw 16 which engages a threaded hole obtained in the upper end of the shaft 11.
• the pack so assembled is then inserted into the shell 2 until it abuts on the lower crown, not shown, fixed to the shell by elastic ring 4, or by welding. Subsequently, the sub-group of the support 13 is inserted into the shell 2 and then the crown 3 is introduced and pushed until it contacts the shoulder of the support 13 for allowing the groove 6 obtained in the shell 2 to become accessible. Then the elastic ring 4 is inserted into the shell 2 until the protruding portion 5 thereof engages the groove 6 obtained in the shell 2.
• the flange 8 comprising the stop valve, is placed on the upper end of the shell 2, so that the holes present on the flange 8 are properly aligned with the threaded holes present on the crown 3 previously inserted into the shell 2.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Motor Or Generator Frames (AREA)
• Lock And Its Accessories (AREA)
• Iron Core Of Rotating Electric Machines (AREA)
• Motor Or Generator Cooling System (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=11450454

Family Applications (1)

Country Status (7)

Cited By (5)

Families Citing this family (2)

Citations (3)

• 2000
  • 2000-05-02 IT IT2000MO000088A patent/IT1314627B1/it active
• 2001
  • 2001-04-30 EP EP01925772A patent/EP1280999B1/de not_active Expired - Lifetime
  • 2001-04-30 WO PCT/IB2001/000716 patent/WO2001083996A1/en active Application Filing
  • 2001-04-30 AU AU2001252453A patent/AU2001252453A1/en not_active Abandoned
  • 2001-04-30 CN CNB018089240A patent/CN1177148C/zh not_active Expired - Fee Related
  • 2001-04-30 DE DE60140607T patent/DE60140607D1/de not_active Expired - Fee Related
  • 2001-04-30 AT AT01925772T patent/ATE449914T1/de not_active IP Right Cessation

Patent Citations (3)

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