KR100510053B1 - Pump shaft - Google Patents

Pump shaft Download PDF

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Publication number
KR100510053B1
KR100510053B1 KR19980004387A KR19980004387A KR100510053B1 KR 100510053 B1 KR100510053 B1 KR 100510053B1 KR 19980004387 A KR19980004387 A KR 19980004387A KR 19980004387 A KR19980004387 A KR 19980004387A KR 100510053 B1 KR100510053 B1 KR 100510053B1
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KR
South Korea
Prior art keywords
impeller
shaft
pump
pump shaft
main coolant
Prior art date
Application number
KR19980004387A
Other languages
Korean (ko)
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KR19980071346A (en
Inventor
프란쯔 스타들러
Original Assignee
안드리츠-파텐트페르발퉁스-게젤샤프트 엠.베.하.
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Application filed by 안드리츠-파텐트페르발퉁스-게젤샤프트 엠.베.하. filed Critical 안드리츠-파텐트페르발퉁스-게젤샤프트 엠.베.하.
Publication of KR19980071346A publication Critical patent/KR19980071346A/en
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Publication of KR100510053B1 publication Critical patent/KR100510053B1/en

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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
    • F04D29/18—Rotors
    • F04D29/20—Mounting rotors on shafts
    • 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
    • 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
    • F04D29/18—Rotors
    • F04D29/181—Axial flow rotors
    • 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
    • F04D29/18—Rotors
    • F04D29/181—Axial flow rotors
    • F04D29/183—Semi axial flow rotors
    • 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
    • F04D29/18—Rotors
    • F04D29/22—Rotors specially for centrifugal pumps
    • F04D29/2205—Conventional flow pattern
    • F04D29/2222—Construction and assembly
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00—Components
    • F05B2240/60—Shafts
    • F05B2240/61—Shafts hollow

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

본 발명은 주 냉각재 펌프용 임펠러를 구비하고 있는 펌프 축에 관한 것이다. 상기 임펠러의 기능이 상기 펌프 축에 통합되어 있는 것을 그 주된 특징으로 한다.The present invention relates to a pump shaft having an impeller for a main coolant pump. Its main feature is that the function of the impeller is integrated in the pump shaft.

Description

펌프 축{PUMP SHAFT}Pump Shaft {PUMP SHAFT}

본 발명은 주 냉각재 펌프용 임펠러(impeller)를 구비하고 있는 펌프 축에 관한 것이다.The present invention relates to a pump shaft having an impeller for a main coolant pump.

주 냉각재 펌프는 높은 온도에 견딜 수 있어야 하고 작동 시에 작동 안정성이 매우 높아야 한다. 일반적으로 임펠러 및 축은 페더 키(feather key)를 통하여 또는 중앙 볼트 및 반경 방향의 연결부 또는 세레이션(serration)을 구비하고 있는 연결자를 통하여 연결되어 있다. 임펠러를 안전하게 고정시켜야 할 뿐만 아니라 꽉 죄어 지지 않은 부품들이 핵발전소 주 루프(primary loop) 내측으로 들어가지 않도록 하여야 하기 때문에, 상기 연결 형태는 매우 복잡하다. 이 같은 연결에서의 몇몇 부분품들은 작동하는 동안 커다란 작동 응력을 받는다. 따라서, 안전을 위해서는 상기 축과 임펠러를 정기적으로 분해하여 비파괴 검사를 하는 것이 필요하다. 이는 부수적인 작업 중단을 필요로 한다.The main coolant pump must be able to withstand high temperatures and have very high operational stability in operation. In general, the impeller and shaft are connected via a feather key or through a connector having a central bolt and radial connection or serration. The connection form is very complicated because not only the impeller must be securely fixed but also the non-tight components must not enter inside the nuclear power plant primary loop. Some parts of this connection are subject to large operating stresses during operation. Therefore, for safety, it is necessary to periodically disassemble the shaft and the impeller to perform a non-destructive inspection. This requires an incidental outage.

본 발명의 목적은, 많은 구성 부분품들을 정확히 조립해야만 하고 설치 작업시의 가설 및 용접 작업이 상대적으로 복잡하다는 기존 기술의 문제점을 해결하는 것이다.It is an object of the present invention to solve the problems of the prior art that many components must be assembled correctly and the construction and welding work in the installation work is relatively complex.

따라서, 임펠러의 기능이 펌프 축에 통합되어 있는 것을 특징으로 한다. 상기 임펠러와 펌프 축을 분해될 수 없는 하나의 부품으로 합체시킴으로써, 연결자들의 복잡한 구조가 더 이상 필요치 않고 연결자들이 고정될 필요가 없다.Thus, the function of the impeller is characterized in that it is integrated in the pump shaft. By combining the impeller and pump shaft into one inseparable part, the complex structure of the connectors is no longer needed and the connectors do not need to be fixed.

본 발명의 장점은, 임펠러/축 유니트가 하나의 단조 가공된 블랭크(forged blank)로 제조되는 것을 특징으로 한다. 상기 유니트의 제작에 있어서 특별한 형상의 블랭크를 사용하는 것이 특히 유리하다.An advantage of the present invention is that the impeller / shaft unit is made from one forged blank. It is particularly advantageous to use blanks of special shape in the manufacture of the unit.

본 발명의 유리한 변형예는 상기 축이 허브(hub) 상에 있는 임펠러 날개의 견부를 지나서 축 방향으로 연장되어 있는 중앙 홀을 가지고 있는 것을 특징으로 한다. 상기 임펠러/축 유니트의 축 부분 및/또는 임펠러 부분은 상기 홀을 통하여 비파괴 초음파 검사를 수행할 수 있다. 그렇게 함으로써, 더 이상 축을 분해시킬 필요가 없다.An advantageous variant of the invention is characterized in that the shaft has a central hole extending in the axial direction beyond the shoulder of the impeller blade on the hub. The shaft portion and / or the impeller portion of the impeller / shaft unit may perform nondestructive ultrasound examination through the hole. By doing so, it is no longer necessary to disassemble the shaft.

이하, 예시된 도면들을 참조하여 본 발명을 상세히 설명한다.Hereinafter, the present invention will be described in detail with reference to the illustrated drawings.

도 1은 종래 기술에 의한 주 냉각재 펌프의 임펠러/축 연결 상태를 도시하고 있다. 축(1)과 임펠러 날개(3)들을 구비하고 있는 임펠러 허브(2)는 이 경우에 중앙 스크류(4)에 의해서 연결되어 있다. 상기 중앙 스크류(4)는 너트(5) 및 그 내측에 결합되는 탄성 슬리브로 유압식으로 미리 조여진다. 상기 임펠러(2)의 두부(頭部)는, 중앙 볼트(7)에 의해서 다시 조여지는 임펠러 캡(cap)(6)으로 덮여 있다. 임펠러 캡(6)의 고정 볼트(7)는 잠금 요소(8)에 의해 고정되며, 상기 잠금 요소는 설치 작업 동안 임펠러 캡(6)에 용접된다.1 shows an impeller / shaft connection of a main coolant pump according to the prior art. The impeller hub 2 with the shaft 1 and the impeller blades 3 is in this case connected by a central screw 4. The central screw 4 is pre-tightened hydraulically with an elastic sleeve which is coupled to the nut 5 and its inside. The head of the impeller 2 is covered with an impeller cap 6 which is tightened again by the central bolt 7. The fastening bolt 7 of the impeller cap 6 is fastened by a locking element 8, which is welded to the impeller cap 6 during the installation operation.

도 2는 본 발명에 의한 임펠러/축 유니트(10)를 관통하는 단면도이다. 상기 유니트는 축 부분(11) 및 임펠러 날개(13)들을 구비하고 있는 임펠러 부분(12)으로 이루어져 있고, 일체로 제조되어 있다. 바람직하게는 상기 유니트(10)는, 원통형의 단조 가공된 블록에서 임펠러 날개(13)들을 절삭하여 연마함으로써, 단조 가공된 블랭크(forged blank)로부터 제조된다. 상기 축 부분(11)은 일반적으로, 작은 직경을 가지고 있는 단조 가공된 블랭크의 원통형 부분으로부터, 예를 들면, 선반 작업에 의해서 제조될 수 있다. 절삭 가공의 대안으로서, 상기 임펠러 날개(13)들은 침식(浸蝕) 가공에 의해서 제조될 수 있다. 축 부분(11) 및 임펠러 부분(12)의 전이부(transition)는 응력을 피할 수 있도록 설계되는 것이 특히 바람직하다.2 is a cross-sectional view through the impeller / shaft unit 10 according to the present invention. The unit consists of an impeller portion 12 having a shaft portion 11 and impeller blades 13 and is manufactured integrally. Preferably, the unit 10 is manufactured from a forged blank by cutting and polishing impeller blades 13 in a cylindrical forged block. The shaft portion 11 can generally be produced from a cylindrical portion of a forged blank having a small diameter, for example by lathe work. As an alternative to cutting, the impeller blades 13 may be manufactured by erosion. It is particularly preferred that the transitions of the shaft portion 11 and the impeller portion 12 are designed to avoid stress.

도 3은 본 발명의 다른 실시예를 도시하며, 동일한 구성 요소들은 동일한 도면 부호로 표시된다. 도 2는 축류(axial-flow) 펌프의 임펠러를 도시하고 있지만, 도 3은 임펠러/축 유니트(10)가 일체형으로 제조되어 있는 혼합류(mixed-flow) 펌프를 도시하고 있다.3 shows another embodiment of the invention, in which like elements are denoted by like reference numerals. While FIG. 2 shows an impeller of an axial-flow pump, FIG. 3 shows a mixed-flow pump in which the impeller / axial unit 10 is made in one piece.

도 4는 완전한 임펠러/축 유니트(10)를 나타내고 있다. 축 부분(11)의 전체 길이에 걸쳐서 임펠러 부분(12) 내의 임펠러 날개(13)들의 견부(15)를 넘어서 연장되어 있는 중앙 홀(14)이 도시되어 있다. 상기 홀은, 특히 임펠러 부분(12)을 향하는 축 부분(11)과 임펠러 부분(12) 상의 임펠러 날개들의 견부(15) 사이에 있는 전이부 내에, 초음파 비파괴 검사를 위한 검사 헤드를 삽입할 수 있도록 해준다. 종래에는 분해, 검사 및 재설치를 위하여 몇 일간의 작업 중단을 계획해야 하는 데에 반하여, 본 발명의 경우는 상기 유니트를 분해하지 않고도 짧은 시간에 검사를 할 수 있다.4 shows a complete impeller / axis unit 10. The central hole 14 is shown extending over the shoulder 15 of the impeller vanes 13 in the impeller portion 12 over the entire length of the shaft portion 11. The hole allows insertion of a test head for ultrasonic nondestructive testing, in particular in the transition between the shaft portion 11 facing the impeller portion 12 and the shoulder 15 of the impeller wings on the impeller portion 12. Do it. Whereas conventional work has to be planned for a few days for disassembly, inspection and reinstallation, in the case of the present invention the inspection can be performed in a short time without disassembling the unit.

본 발명은 임펠러와 펌프 축을 일체로 제조하여, 연결자의 복잡한 구조가 필요 없고 펌프 축의 조립 및 설치 작업을 단순화하는 효과가 있다.The present invention is manufactured integrally with the impeller and the pump shaft, there is no need for a complicated structure of the connector and has the effect of simplifying the assembly and installation of the pump shaft.

또한 본 발명은, 펌프 축과 임펠러의 분해, 검사 및 재설치를 위하여 상당 기간 동안 작업을 중단할 필요 없이, 펌프 축과 임펠러를 분해하지 않고도 짧은 시간 내에 검사를 할 수 있는 효과가 있다.In addition, the present invention, there is an effect that can be inspected within a short time without disassembling the pump shaft and the impeller, without having to interrupt the operation for a considerable time for the disassembly, inspection and reinstallation of the pump shaft and the impeller.

도 1은 종래 기술에 의한 축과 임펠러 사이의 연결 상태를 도시한 도면.1 is a view showing a connection state between the shaft and the impeller according to the prior art.

도 2는 본 발명의 일 실시예를 도시한 도면.2 illustrates an embodiment of the present invention.

도 3은 본 발명의 다른 실시예를 도시한 도면.3 illustrates another embodiment of the present invention.

도 4는 중앙 홀이 형성되어 있는 본 발명의 일 실시예를 도시한 도면.4 is a view showing an embodiment of the present invention in which a central hole is formed.

** 도면의 주요 부분에 대한 부호의 설명 **** Description of symbols for the main parts of the drawing **

1 : 축 2 : 임펠러 허브1: shaft 2: impeller hub

3 : 임펠러 날개 4 : 중앙 스크류3: impeller wing 4: center screw

5 : 너트 6 : 캡5: nut 6: cap

7 : 고정 볼트 8 : 잠금 요소7: fixing bolt 8: locking element

10 : 임펠러/축 유니트 11 : 축 부분10 impeller / shaft unit 11 shaft portion

12 : 임펠러 부분 13 : 임펠러 날개12 impeller part 13 impeller wing

14 : 중앙 홀 15 : 임펠러 날개의 견부14: central hole 15: shoulder of the impeller wing

Claims (4)

펌프 축(11)과 임펠러(12)가 일체로 합체되어 단일 유닛(10)으로 형성된 것을 특징으로 하는 핵발전 설비용 주 냉각재 펌프(main coolant pump)를 위한 임펠러를 구비한 펌프 축.A pump shaft having an impeller for a main coolant pump for a nuclear power plant, characterized in that the pump shaft (11) and the impeller (12) are integrally integrated to form a single unit (10). 제1항에 있어서,The method of claim 1, 펌프 축(11)과 임펠러(12)가 합체된 상기 단일 유닛(10)은 하나의 단조 가공된 블랭크(forged blank)로 제조되는 것을 특징으로 하는 핵발전소의 주 냉각재 펌프를 위한 임펠러를 구비한 펌프 축.The pump with impeller for the main coolant pump of a nuclear power plant, characterized in that the single unit 10, in which the pump shaft 11 and the impeller 12 are incorporated, is made of one forged blank. shaft. 제1항 또는 제2항에 있어서,The method according to claim 1 or 2, 펌프 축(11)에는 중앙 홀(hole)(14)이 형성되어 있는 것을 특징으로 하는 핵발전소의 주 냉각재 펌프를 위한 임펠러를 구비한 펌프 축.A pump shaft having an impeller for the main coolant pump of a nuclear power plant, characterized in that the pump shaft (11) is formed with a central hole (14). 제3항에 있어서,The method of claim 3, 상기 중앙 홀(14)은 축의 허브 부분에 있는 견부(15)를 지나도록 축방향으로 연장되는 것을 특징으로 하는 핵발전소의 주 냉각재 펌프를 위한 임펠러를 구비한 펌프 축.The central hole (14) is a pump shaft with an impeller for the main coolant pump of the nuclear power plant, characterized in that extending axially past the shoulder (15) in the hub portion of the shaft.
KR19980004387A 1997-02-14 1998-02-13 Pump shaft KR100510053B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ATA244/97 1997-02-14
AT0024497A AT410827B (en) 1997-02-14 1997-02-14 PUMP SHAFT

Publications (2)

Publication Number Publication Date
KR19980071346A KR19980071346A (en) 1998-10-26
KR100510053B1 true KR100510053B1 (en) 2005-10-19

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JP (1) JPH10227298A (en)
KR (1) KR100510053B1 (en)
CN (1) CN1190705A (en)
AT (1) AT410827B (en)
DE (1) DE19802115C2 (en)
FR (1) FR2760795B1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007044646A1 (en) 2007-09-18 2009-03-26 Ksb Aktiengesellschaft wheelmounting
FR3057626A1 (en) * 2016-10-19 2018-04-20 Saint Jean Industries NOISE ROTOR MOTOR PUMP AND METHOD FOR MANUFACTURING SUCH MOTOR PUMP
CN107022919B (en) * 2017-05-27 2019-04-05 安德里茨（中国）有限公司 Runner and fiberizer

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62131996U (en) * 1986-02-14 1987-08-20
JPS63309798A (en) * 1987-06-11 1988-12-16 Seiko Epson Corp Run-out prevented impeller
JPH0626495A (en) * 1992-07-09 1994-02-01 Toshiba Corp Manufacture of hydraulic pump
JPH06300885A (en) * 1993-04-19 1994-10-28 Toshiba Corp Inspection tool for internal pump

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH423490A (en) * 1965-03-03 1966-10-31 Sulzer Ag Turbo engine
US3431860A (en) * 1967-07-14 1969-03-11 Atomic Energy Commission Centrifugal pump of the free surface type
DE2259832C2 (en) * 1972-12-07 1974-02-28 Klein, Schanzlin & Becker Ag, 6710 Frankenthal Cooled radial bearing within a support tube
DE2345635A1 (en) * 1973-09-10 1975-03-27 Stork Koninklijke Maschf Bladed rotor production method - involves trimming mechanically produced hub and blades by electro-chemical and finally mechanical means
FR2394700A1 (en) * 1977-06-17 1979-01-12 Commissariat Energie Atomique CIRCULATION PUMP, ESPECIALLY FOR LIQUID METAL COOLING THE CORE OF A NUCLEAR REACTOR WITH QUICK NEUTRON
DE2921704A1 (en) * 1979-05-29 1980-12-11 Kloeckner Humboldt Deutz Ag RUNNER FOR TURBO MACHINES
FR2474744A2 (en) * 1980-01-25 1981-07-31 Electricite De France Sodium cooling circuit for nuclear reactor - where sodium heats steam generator, and is pumped through circuit contg. de-surging reservoir and gas equalising sodium pressure
GB2074662A (en) * 1980-04-23 1981-11-04 Rolls Royce Rotary Impeller for a Centrifugal Pump
JPH01201193A (en) * 1988-02-05 1989-08-14 Toshiba Corp Impeller container built-in type non-shaft sealing pump
JPH04296698A (en) * 1990-12-21 1992-10-21 Gebr Sulzer Ag Runner imparting pump action for high-temperature liquid of nuclear reactor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62131996U (en) * 1986-02-14 1987-08-20
JPS63309798A (en) * 1987-06-11 1988-12-16 Seiko Epson Corp Run-out prevented impeller
JPH0626495A (en) * 1992-07-09 1994-02-01 Toshiba Corp Manufacture of hydraulic pump
JPH06300885A (en) * 1993-04-19 1994-10-28 Toshiba Corp Inspection tool for internal pump

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AT410827B (en) 2003-08-25
ATA24497A (en) 2002-12-15
JPH10227298A (en) 1998-08-25
DE19802115C2 (en) 2002-02-07
KR19980071346A (en) 1998-10-26
DE19802115A1 (en) 1998-08-20
FR2760795A1 (en) 1998-09-18
CN1190705A (en) 1998-08-19
FR2760795B1 (en) 2002-01-11

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