EP0121053B1 - Axial thrust reducing device for pumps - Google Patents

Axial thrust reducing device for pumps Download PDF

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Publication number
EP0121053B1
EP0121053B1 EP84101200A EP84101200A EP0121053B1 EP 0121053 B1 EP0121053 B1 EP 0121053B1 EP 84101200 A EP84101200 A EP 84101200A EP 84101200 A EP84101200 A EP 84101200A EP 0121053 B1 EP0121053 B1 EP 0121053B1
Authority
EP
European Patent Office
Prior art keywords
small gap
thrust
thrust disc
casing
reducing device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84101200A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0121053A1 (en
Inventor
Masahiro Yoshioka
Hiroshi Inoue
Eiichi Hazaki
Shiro Nakadaira
Akihisa Okada
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Priority to AT84101200T priority Critical patent/ATE27341T1/de
Publication of EP0121053A1 publication Critical patent/EP0121053A1/en
Application granted granted Critical
Publication of EP0121053B1 publication Critical patent/EP0121053B1/en
Expired legal-status Critical Current

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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
    • F04D29/04—Shafts or bearings, or assemblies thereof
    • F04D29/041—Axial thrust balancing
    • F04D29/0413—Axial thrust balancing hydrostatic; hydrodynamic thrust bearings
    • 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
    • F04D29/04—Shafts or bearings, or assemblies thereof
    • F04D29/041—Axial thrust balancing
    • F04D29/0416—Axial thrust balancing balancing pistons

Definitions

  • This invention relates to a thrust load reducing device in a pump unit comprising a pump section having a main impeller, a motor section for driving the main impeller, a thrust disc serving concurrently as an auxiliary impeller located at one end of a motor shaft in the motor section for supplying motor cooling water flowing in circulation to the motor section, and thrust bearings mounted on an inner surface of a casing in positions in which they are juxtaposed against a front surface of the thrust disc located on its suction side and a rear surface of the thrust disc located on its discharge side, respectively.
  • Such a pump unit of the type driven by a wet motor as disclosed in the US-A-3 947 153 comprises a main impeller and guide vanes mounted in a pump chamber, and a motor mounted in a motor chamber.
  • a hydrodynamic thrust load directed axially of the pump is produced by the main impeller. All the thrust load is borne by thrust bearings located in the motor chamber.
  • thrust load bearing means of this construction is because the pump chamber lacks enough space to mount the thrust bearings in the vicinity of the main impeller.
  • the thrust bearings of this type inevitably become large in size and high in cost because they have to bear all the thrust load produced by the main impeller, as described hereinabove. Such thrust bearings are unable to have a long service life because they operate under severe load conditions.
  • This invention has as its object the provision of a thrust load reducing device capable of effectively lessening a thrust load applied to the thrust bearings.
  • the thrust load reducing device of the generic kind comprises a first small gap defining member located on the inner surface of the casing and cooperating with an outer peripheral surface of the thrust disc to define therebetween a first small gap constituting a passage for a fluid discharged by the thrust disc and returning thereto in return flow and a second small gap defining member secured to the inner surface of the casing and cooperating with an inner peripheral surface of the thrust disc on the suction side to define therebetween a second small gap, and a pressure control chamber defined by the first small gap defining member, the second small gap defining member, the front surface of the thrust disc on the suction side and the inner peripheral surface of the casing.
  • the present invention enables a thrust load applied to the thrust bearings provided to the thrust disc serving concurrently as an auxiliary impeller to be reduced. This enables a compact size to be obtained in a thrust bearing and allows the service life of the thrust bearings to be prolonged. As a result, the reliability of the pump unit can be greatly increased.
  • the first small gap defining member has a large axial length to thereby increase the resistance offered by the first small gap to the flow of a fluid therethrough.
  • the second small gap defining member is constituted by a cylindrical member connected to the casing and juxtaposed against the inner peripheral surface of the thrust disc on its suction side to define axially therebetween the second small gap.
  • the second small gap defining member is constituted by a cylindrical body connected to the thrust disc on its suction side, and another cylindrical body connected to the casing and juxtaposed against the first-mentioned cylindrical body to define the second small gap therebetween.
  • the second small gap defining member is constituted by a cylindrical body connected to the thrust disc on its suction side, and two other cylindrical bodies connected to the casing and cooperating with the first-mentioned cylindrical body to define the second small gap therebetween by enclosing an end face and inner and outer peripheral surfaces of the first-mentioned cylindrical body.
  • the small gap defining members can each be formed with a labyrinth or a spiral groove at an inner surface facing the small gap.
  • Fig. 1 shows a pump unit comprising a pump section P, and a motor section M for driving the pump section P.
  • the pump section P comprises a main impeller 1 and guide vanes 2, and is located in a fluid passage L defined in a casing C for delivering a fluid in the direction of an arrow or downwardly in the plane of Fig. 1.
  • the motor section M which constitutes a wet motor is secured to the casing C as a motor casing 3 is joined to the casing C.
  • the motor section M comprises a motor shaft 4, a rotor 5 located on the motor shaft 4, and a stator 6 supported on the motor casing 3 and juxtaposed against the rotor 5.
  • the motor shaft 4 has its one end attached to a thrust disc 7 serving concurrently as an auxiliary impellerfor circulating motor cooling water and is connected to the main impeller 1 of the pump section P at the other end thereof.
  • the thrust disc 7 is formed with a multiplicity of ducts 8 for performing a pumping action.
  • the motor shaft 4 is journalled by radial bearings 9A and 98.
  • Thrust bearings 10A and 10B are located in positions in which they are juxtaposed against a front surface of the thrust disc 7 or auxiliary impeller located on its suction side and a rear surface thereof located on its discharge side, respectively.
  • the thrust bearings 10A and 10B and thrust disc 7 perform the function of bearing a hydrodynamic thrust load applied by the main impeller 1 and acting upwardly in the plane of Fig. 1. Cooling water pressurized by the thrust disc 7 or auxiliary impeller cools the stator 6 of the motor section M and flows through a heat exchanger 11 located outside the pump unit before returning to the suction side of the thrust disc 7 serving as
  • a first small gap defining member 12 cooperating with an outer peripheral surface of the thrust disc 7 for defining a first small gap G 1 serving as a passage for a back flow of the water discharged by the auxiliary impeller and flowing to its suction side is located on an inner surface of the motor casing 3.
  • a second small gap defining member 13 extends from the inner surface of the pump casing 3 along an inner peripheral surface of the thrust disc 7 to define therebetween a second small gap G 2 .
  • the first and second small gap defining members 12 and 13 which are each in the form of a cylinder define a pressure control chamber 14 between the front surface of the thrust disc 7 on its suction side and the inner surface of the pump casing 3.
  • the pressure control chamber 14 has its pressure set at a predetermined level by a drop. in pressure caused by a loss of pressure by the fluid due to the presence of the first and second small gaps G 1 and G 2 .
  • the pressure in the pressure control chamber 14 acts on the front surface of the thrust disc 7 on its suction side and, combined with the pressure of a fluid acting on the rear surface of the thrust disc 7 on its discharge side, performs the functions of reducing the thrust load produced by the main impeller 1.
  • Actuation of the motor section M causes the main impeller 1 and the thrust disc 7 serving as an auxiliary impeller to rotate, so that the main impeller 1 delivers a fluid in the passage L downwardly in the plane of Fig. 1 as indicated by the arrow, while the thrust disc 7 functions as an auxiliary impeller to draw cooling water through the suction side as shown in Fig. 2 and discharge same after pressurizing same by the pumping action performed through the ducts 8.
  • the major portion of the discharged cooling water flows through the thrust bearing 10B on the rear surface of the thrust disc 7 to cool same and then along an outer periphery of the motor shaft 4, from which it flows further upwardly to cool the stator 6 of the motor section M, before flowing into the heat exchanger 11 located outside the pump unit as shown in Fig. 1.
  • the cooling water that has performed cooling is cooled by heat exchange performed in the heat exchanger 11 and returns to the suction side of the thrust disc 7 serving as an auxiliary impeller.
  • a pressure P 3 in the pressure control chamber 14 is intermediate between a suction pressure P 1 of the auxiliary impeller and a discharge pressure P 2 thereof due to a loss of pressure in the first and second small gaps G 1 and G 2 .
  • the pressure P 3 can be controlled as desired by arbitrarily setting the dimensions of the first and second small gaps G 1 and G 2 or their widths and lengths.
  • the main impeller 1 usually produces an upwardly directed thrust load W 1 as shown in Fig. 2.
  • the load W 1 which is borne by the thrust bearing 10B can be reduced by varying the pressure P 3 in the pressure control chamber 14. More specifically, the pressure P 3 in the pressure control chamber 14 acts on the front surface of the thrust disc 7 and the discharge pressure P 2 of the thrust disc 7 acts on the rear surface of the thrust disc 7.
  • the pressure P 3 in the pressure control chamber 14 acts on a level below the discharge pressure P 2 and close to the suction pressure P i , it is possible to produce a downwardly directed thrust W 2 at the thrust disc 7 by the relative pressures acting on the front surface and the rear surface of the thrust disc 7.
  • the thrust W 2 acts in a direction opposite to the direction in which the thrust load W, produced by the main impeller 1 acts, so that it is possible to reduce the thrust load W 1 borne by the thrust bearing 10B. This is conductive to prevention of damage which might otherwise be caused to the thrust bearing 10B, and the service life of the thrust bearing 10B can be prolonged.
  • the thrust load W 1 has been assumed to be higher than the thrust W 2 .
  • the thrust W 2 might become higher than the thrust load W 1 depending on the conditions under which the main impeller 1 operates.
  • the load acting on the thrust bearing 10B would become zero or too small to allow positioning of the motor shaft 4 in the axial direction to be performed stably, thereby causing the motor shaft 4 to vibrate.
  • An excessively high load would be applied to the thrust bearing 10A which is designed to have an ability to bear a load substantially of the same level as the weight of a rotary member from the point of view of reducing a mechanical loss, thereby causing damage to the thrust bearing 10A.
  • the damage caused to the thrust bearing 10A can be avoided by adjusting the pressure P 3 in the pressure control chamber 14 by varying the dimensions of the first and. second small gaps G 1 and G 2 .
  • the pressure P 3 in the pressure control chamber 14 would become equal to the discharge pressure P 2 of the thrust disc 7 if the first small gap defining member 12 did not exist in Fig. 2, so that no thrust tending to reduce the thrust load W1 produced by the main impeller 1 would not be produced at the thrust disc 7. Therefore, it would be impossible to reduce the thrust load W1 unless the first small gap G 1 is provided.
  • the first fine gap G 1 is essential for reducing the thrust load W 1 .
  • Fig. 3 shows another embodiment, in which the thrust disc 7 serving as an auxiliary impeller is formed with a multiplicity of oblique ducts 8A which are directed obliquely upwardly in going from the center of the thrust disc 7 toward its outer periphery, to enable the length of the first small gap G 1 to be increased.
  • the thrust disc 7 serving as an auxiliary impeller is formed with a multiplicity of oblique ducts 8A which are directed obliquely upwardly in going from the center of the thrust disc 7 toward its outer periphery, to enable the length of the first small gap G 1 to be increased.
  • Fig. 4 shows still another embodiment in which the second small gap G 2 is modified.
  • a first cylindrical body 15 extends downwardly from a lower end of the thrust disc 7 in such a manner that inner peripheral surfaces of the first cylindrical body 15 and the thrust disc 7 form a straight line, and a second cylindrical body 16 located outwardly of the first cylindrical body 15 is secured to the motor casing 3.
  • the axiatly extending second small gap G 2 is defined between an outer peripheral surface of the first cylindrical body 15 and an inner peripheral surface of the second cylindrical member 16 and, at the same time, a first radial small gap G 21 and a second radial small gap G 22 are defined between an end face of the first cylindrical body 15 and an inner peripheral surface of the motor casing 3 and between an end face of the second cylindrical body 16 and the lower end of the thrust disc 7, respectively.
  • the pumping efficiency of the auxiliary impeller is improved because leaks of the fluid in the pressure control chamber 14 to the suction side of the thrust disc 7 can be minimized by the centrifugal pumping action performed by the end portions of the cylindrical bodies 15 and 16.
  • Fig. 5 shows a further embodiment in which the second small gap G 2 is further modified.
  • a first cylindrical body 17 extends downwardly from a lower end of the thrust disc 7 in such a manner that inner peripheral surfaces of the first cylindrical body 17 and the thrust disc 7 form a straight line
  • a second cylindrical body 18 and a third cylindrical body 19 are secured to the motor casing 3 to define a small gap G 23 between inner and outer peripheral surfaces and an end face of the first cylindrical body 17 and inner peripheral surfaces of the second and third cylindrical bodies 18 and 19.
  • the length of the small gap G 23 can be increased and a thrust load of reverse direction produced by the thrust disc 7 can be controlled.
  • an increase in the size of the gap prevents the cylindrical body 17 from coming into contact with the cylindrical bodies 18 and 19, and the pumping efficiency of the auxiliary impeller can be improved.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
  • Control Of Non-Positive-Displacement Pumps (AREA)
EP84101200A 1983-03-04 1984-02-06 Axial thrust reducing device for pumps Expired EP0121053B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84101200T ATE27341T1 (de) 1983-03-04 1984-02-06 Axialschubausgleichsvorrichtung fuer pumpen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP58034508A JPS59160093A (ja) 1983-03-04 1983-03-04 サブマ−ジブルポンプの軸スラスト荷重低減装置
JP34508/83 1983-03-04

Publications (2)

Publication Number Publication Date
EP0121053A1 EP0121053A1 (en) 1984-10-10
EP0121053B1 true EP0121053B1 (en) 1987-05-20

Family

ID=12416197

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84101200A Expired EP0121053B1 (en) 1983-03-04 1984-02-06 Axial thrust reducing device for pumps

Country Status (4)

Country Link
EP (1) EP0121053B1 (enrdf_load_stackoverflow)
JP (1) JPS59160093A (enrdf_load_stackoverflow)
AT (1) ATE27341T1 (enrdf_load_stackoverflow)
DE (1) DE3463824D1 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7785082B2 (en) 2004-09-15 2010-08-31 Mitsubishi Heavy Industries, Ltd Sealless pump

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6389309U (enrdf_load_stackoverflow) * 1986-11-29 1988-06-10
JPH088319Y2 (ja) * 1988-07-18 1996-03-06 株式会社荏原製作所 遠心ポンプのバランスデイスク式軸推力平衡装置
DE3929750A1 (de) * 1989-03-04 1990-09-06 Klein Schanzlin & Becker Ag Axialschubentlastungseinrichtung
US5340272A (en) * 1992-08-19 1994-08-23 Bw/Ip International, Inc. Multi-stage centrifugal pump incorporating a sealed thrust bearing
FI940630L (fi) * 1994-02-11 1995-08-12 Ahlstroem Oy Keskipakopumppu
US6071091A (en) * 1998-02-12 2000-06-06 Lemieux; Guy B. Integral motor/generator and pump/turbine with hydrostatic bearings
US7820761B2 (en) 1999-08-04 2010-10-26 Hybrid Plastics, Inc. Metallized nanostructured chemicals as cure promoters
US7612143B2 (en) 1999-08-04 2009-11-03 Hybrid Plastics, Inc. Metallized nanostructured chemicals alloyed into polymers
JP4119815B2 (ja) * 2003-09-30 2008-07-16 三菱重工業株式会社 圧縮機
DE102006011613A1 (de) * 2006-03-14 2007-09-20 Ksb Aktiengesellschaft Kreiselpumpe mit Axialschubausgleichseinrichtung
CN103195745B (zh) * 2013-04-24 2015-08-19 东风汽车公司 一种新能源汽车的冷却水泵
CN110454509A (zh) * 2019-08-30 2019-11-15 福建福清核电有限公司 一种唧送型轴承推力盘
CN111998005B (zh) * 2020-08-25 2022-02-18 南京工程学院 一种水润滑推力轴承的冷却冲洗结构

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB518428A (en) * 1937-10-06 1940-02-27 Sulzer Ag Improvements in or relating to rotary immersion pumps
DE922807C (de) * 1945-03-06 1955-01-24 Aeg Einrichtung zum Ausgleich des Axialschubes mehrstufiger Kreiselpumpen
FR1276208A (fr) * 1960-12-14 1961-11-17 Pompe sans bourrage ni presse-étoupe avec passage du liquide par une section intérieure du palier d'entrée
US3420184A (en) * 1967-05-17 1969-01-07 Julius L Englesberg Pump employing magnetic drive
GB1351826A (en) * 1971-11-29 1974-05-01 Carter Co J C Lubricating cooling and balancing of pump and motor units
JPS5825876B2 (ja) * 1980-02-18 1983-05-30 株式会社日立製作所 軸推力平衡装置
JPS5788288A (en) * 1980-11-21 1982-06-02 Hitachi Ltd Internal pump

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7785082B2 (en) 2004-09-15 2010-08-31 Mitsubishi Heavy Industries, Ltd Sealless pump

Also Published As

Publication number Publication date
EP0121053A1 (en) 1984-10-10
JPS59160093A (ja) 1984-09-10
DE3463824D1 (en) 1987-06-25
ATE27341T1 (de) 1987-06-15
JPS626119B2 (enrdf_load_stackoverflow) 1987-02-09

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