EP0313444A2 - Vorrichtung zur Feststellung der Unwucht einer rotierenden Maschine ab einem vorgegebenen Schwellenwert - Google Patents

Vorrichtung zur Feststellung der Unwucht einer rotierenden Maschine ab einem vorgegebenen Schwellenwert Download PDF

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Publication number
EP0313444A2
EP0313444A2 EP88402601A EP88402601A EP0313444A2 EP 0313444 A2 EP0313444 A2 EP 0313444A2 EP 88402601 A EP88402601 A EP 88402601A EP 88402601 A EP88402601 A EP 88402601A EP 0313444 A2 EP0313444 A2 EP 0313444A2
Authority
EP
European Patent Office
Prior art keywords
unbalance
pendulum
ring
mass
embedded
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.)
Withdrawn
Application number
EP88402601A
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English (en)
French (fr)
Other versions
EP0313444A3 (de
Inventor
Michel Serveau
Jean-Louis Fondin
Alain Dreno
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.)
Jouan SA
Original Assignee
Jouan SA
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 Jouan SA filed Critical Jouan SA
Publication of EP0313444A2 publication Critical patent/EP0313444A2/de
Publication of EP0313444A3 publication Critical patent/EP0313444A3/de
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B9/00—Drives specially designed for centrifuges; Arrangement or disposition of transmission gearing; Suspending or balancing rotary bowls
    • B04B9/14—Balancing rotary bowls ; Schrappers
    • B04B9/146—Unbalance detection devices

Definitions

  • the present invention relates to a device for detecting unbalance in rotating machines, and in particular in centrifuges, from a threshold which is considered to be detrimental to the safety of personnel or to the life of the machine.
  • the object of the invention is not to determine the value of the unbalance, nor especially the position of the unbalance on the rotating members of the rotary machine, with a view to providing a corrective action, such as balancing machines can do this.
  • the sole aim of the invention is to detect an unbalance threshold which would be detrimental to the machine and to stop the operation of the latter before this threshold has been reached, this detection having to be carried out at the lowest cost.
  • the device which it is proposed to make must therefore be simple and inexpensive, and therefore of a lower technological level than the detection devices which could be made with magnetic sensors, accelerometers or optoelectronic means.
  • the detection device of FIG. 1 is constituted by a microswitch 10 fixed on the casing 12 of a rotating machine, which rests, by means of an elastic suspension 14 ensuring good damping, on a rigid chassis 16, considered therefore as not being unbalanced.
  • the imbalance existing in the rotating assembly 18 of the machine is represented schematically by two weights 20, 22 of slightly different masses and which are fixed to the ends of two radial arms integral with the motor shaft and arranged in the extension of each other.
  • the machine casing is subjected to an unbalance, which results in vibrations of the casing in the horizontal plane.
  • a fixed stop 24 secured to the chassis 16 and which, when the motor is at rest, is at a predetermined distance from the pallet 26 of the microswitch. As soon as the unbalance component in the direction of the stop 24 becomes equal to said distance, the microswitch is engaged and the operation of the machine is interrupted.
  • the microswitch is sensitive only along one axis; it therefore does not take into account the transverse components of movement which are always present during the increase in speed; - due to the dispersion of manufacturing tolerances, each microswitch must be set to the factory position until tripping takes place for the value corresponding to the desired detection threshold; - at each imbalance detection, the pallet of the microswitch is subjected to mechanical forces which cause successive deformations of the pallet and which require frequent adjustments of the microswitch and sometimes even its replacement; - after a certain period of use, the suspensions of the machine degrade and modify the relative positions between the chassis and the microswitch; - detection depends on the horizontal setting of the machine. If, for any reason, the horizontality of the machine varies, the microswitch must be adjusted again.
  • the second known detection system is based on the principle of inertia. As shown in Figure 2, it consists of a bulb 28, partially filled with a liquid 30 conductive of electricity and having a high inertia. For this purpose, the bulb has a small volume and a liquid having a high density will be chosen, for example mercury.
  • the bulb is fixed integral with the casing 12 of the rotary machine. Its upper wall is crossed by two electrodes 32 which, when the machine is at rest, are not in contact with the mercury. During the movements of the casing, if the unbalance reaches a certain threshold, the mercury establishes a contact between the two electrodes and thus closes an electrical circuit which triggers an alarm or the stopping of the machine.
  • This detection device no longer has some of the faults reported for the previous device. Indeed, the detection does not depend on the relative position between the machine housing and the fixed chassis. No mechanical adjustment should be made. Unlike the previous one, this device is not very sensitive to aging. In addition, detection is independent of horizontality.
  • the detection is done only along the vertical axis.
  • the rotating assembly generates an unbalance having movement components also along two horizontal axes, perpendicular to each other.
  • the mercury bulb is unable to detect the unbalance components along said horizontal axes; - It is shown that the detection condition depends on the mass of the mercury and the distance between the surface of the mercury and the end of the electrodes. If the manufacturers can guarantee the precision of the mass, it is not the same with regard to the aforementioned distance for which the desired precision is of the order of a few tenths of a millimeter.
  • the present invention aims to remedy the drawbacks of the prior art and therefore proposes an imbalance detection device which does not require adjustment in the factory or in customers, the detection of which is very little dependent on the horizontality, which is insensitive with aging, which has good reproducibility from one device to another, and finally that allows unbalance to be detected along two horizontal axes.
  • the detection device is characterized in that it consists of a pendulum formed of a vertical rod, of an elastically deformable metal, the upper end of which is embedded in an insulating support, rigidly attached to the housing.
  • the rotary machine and which carries a metal mass at its lower end, the latter being received concentrically and with a predetermined peripheral clearance inside a metal ring, also integral with the casing and electrically insulated from the latter, said ring and said recessed end of the pendulum being electrically connected to an electric alarm or safety circuit which closes as soon as the mass comes into contact with the ring, as a result of the appearance of an unbalance whose horizontal component transmitted to said mass by the rod is equal to the value of said peripheral clearance, the physical characteristics of said pendulum being chosen so that its resonant frequency is lower than that of the parts of the rotating machine subject to unbalance.
  • FIGS. 1 and 2 having already been described previously, we will pass directly to the description of FIG. 3.
  • the rotating machine shown in this figure is a centrifuge 40, but it goes without saying that this example was chosen only to fix ideas.
  • the centrifuge comprises a casing 42 in which is housed the drive motor. It has at its upper part an annular flange 44 by which it rests on the edge of an opening 46 formed in a horizontal wall of a frame 48 assumed to be rigidly secured to the ground and therefore not subject to unbalance.
  • the casing crosses the opening coaxially and with a large clearance, so that it is supported only by the flange.
  • the rotating assembly of the centrifuge is represented diagrammatically in the form of a shaft 50, provided with two radial arms 52, 54 carrying at their ends two weights 56, 58 whose masses are supposed to be slightly different, the difference of the masses, ⁇ m being the imbalance.
  • a U-shaped support 62 On the side wall of the casing 42 is rigidly fixed by its central branch 60, a U-shaped support 62, made of electrically insulating material.
  • a vertical rod 66 In the upper branch 64 of said support is embedded the upper end of a vertical rod 66 of an elastically deformable metal, preferably steel.
  • the rod is vertical and carries at its lower end a metallic mass 68 of cylindrical shape, but which can have any other geometric shape, for example prismatic or spherical.
  • the cylindrical mass 68 is received inside a metal ring 70 of larger section and which is crimped inside an opening drilled through the lower arm 72 of the insulating support.
  • a metal ring 70 of larger section When the rotating assembly is at rest, the cylindrical mass is exactly in the axis of the ring, a constant peripheral clearance remaining between it and the ring. This play corresponds to the maximum value ⁇ o which is imposed on the angle of movement of the pendulum, when it starts to vibrate during the increase in speed of the rotating crew.
  • the rod 66 and the ring 70 are connected by electrical conductors 74, 76 to an electrical or electronic alarm or security circuit, capable of triggering an alarm or of stopping the operation of the drive motor of the moving assembly. , as soon as the mass comes to touch the ring, that is to say as soon as the vibrations of the pendulum are about to exceed the limit amplitude ⁇ o that one has set.
  • the elastic pendulum behaves like a damped mechanical oscillator, the casing being the exciting system and the pendulum being the excited system.
  • - ⁇ e is the instantaneous excitation angle communicated by the casing (see figure 3). It is the angle whose casing pivots around its center of gravity G under the action of the unbalance; - ⁇ s is the angle of travel of the pendulum under the effect of this excitation; - ⁇ o is the natural oscillation frequency of the pendulum and - ⁇ is the speed of rotation of the rotating crew.
  • the frequency ⁇ o is a constant which only depends on the following parameters: - the coefficient of elasticity of the steel rod, - the length of the steel rod, - the value of the suspended mass.
  • the frequency ⁇ o increases with the coefficient of elasticity of the rod and, it decreases with the length of the rod and with the value of the suspended mass.
  • the damping at a given frequency ⁇ o depends only on the ratio between a viscous friction term and the elasticity coefficient of the rod, said viscous coefficient term being constituted by the friction of the mass of the pendulum in air and by mechanical losses at the attachment of the pendulum to the insulating support.
  • the curve of FIG. 4 also shows that when the mobile assembly turns and there is an imbalance of the rotating masses, it generates an excitation angle ⁇ e whose module
  • the rotating crew behaves itself as a second order system with a natural frequency of oscillation. The amplitudes then decrease when the speed of rotation exceeds the value corresponding to said natural frequency.
  • the condition under which detection will occur will therefore be A ⁇ e ⁇ ⁇ o (1) - ⁇ o being the maximum amplitude allowed for the pendulum, that is to say the angle of deviation of the pendulum when the mas se 68 is in contact with the ring 70, and - A being the amplification coefficient obtained thanks to the elastic pendulum.
  • condition (1) we obtain the complete detection condition:
  • the unbalance detection device must be optimized so that the unbalance detection occurs under conditions such that the excitation amplitude ⁇ e (t) never reaches values detrimental to the service life and the operational safety of the rotating machine.
  • the device according to the invention does not require any factory or customer adjustment. It is insensitive to aging and allows detection which practically does not depend on the horizontality of the rotating machine. In addition, it can detect an imbalance along two perpendicular horizontal axes.

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  • Testing Of Balance (AREA)
EP19880402601 1987-10-22 1988-10-13 Vorrichtung zur Feststellung der Unwucht einer rotierenden Maschine ab einem vorgegebenen Schwellenwert Withdrawn EP0313444A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8714612A FR2622290B1 (fr) 1987-10-22 1987-10-22 Dispositif pour la detection du balourd d'une machine tournante, a partir d'un seuil predetermine
FR8714612 1987-10-22

Publications (2)

Publication Number Publication Date
EP0313444A2 true EP0313444A2 (de) 1989-04-26
EP0313444A3 EP0313444A3 (de) 1990-10-03

Family

ID=9356073

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880402601 Withdrawn EP0313444A3 (de) 1987-10-22 1988-10-13 Vorrichtung zur Feststellung der Unwucht einer rotierenden Maschine ab einem vorgegebenen Schwellenwert

Country Status (3)

Country Link
US (1) US4910502A (de)
EP (1) EP0313444A3 (de)
FR (1) FR2622290B1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0455878A2 (de) * 1990-05-05 1991-11-13 Heraeus Sepatech GmbH Laboratoriums-Zentrifuge
DE102004049100B4 (de) 2003-10-09 2020-04-23 Koki Holdings Co., Ltd. Zentrifuge

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5415026A (en) * 1992-02-27 1995-05-16 Ford; David Vibration warning device including mercury wetted reed gauge switches
US5375282A (en) * 1993-09-20 1994-12-27 General Electric Company System and method for detecting and interrupting an out-of-balance condition in a washing machine
US5375437A (en) * 1993-09-20 1994-12-27 General Electric Company Out-of-balance condition detecting system with lid actuated switching assembly
DE4335119C2 (de) * 1993-10-15 1997-11-20 Eppendorf Geraetebau Gmbh Laborzentrifuge mit Unwuchtabschaltung
US5685038A (en) * 1995-05-18 1997-11-11 U.S. Controls Corporation Out-of-balance control for washing machine
JP3710001B2 (ja) * 1995-06-16 2005-10-26 日立工機株式会社 遠心分離機
KR100274470B1 (ko) * 1997-05-20 2000-12-15 구자홍 드럼 세탁기의 편심 감지방법과 그 제어장치
CA2242994C (en) * 1997-07-14 2008-09-16 Lg Electronics Inc. Method for detecting cloth amount in drum washing machine
SE512770C2 (sv) * 1998-02-19 2000-05-08 Alfa Laval Ab Stödanordning
US6354988B1 (en) * 1999-06-17 2002-03-12 Kendro Laboratory Products, Llp Centrifuge gyro diaphragm capable of maintaining motor shaft concentricity
US6422047B1 (en) 2000-05-04 2002-07-23 Maytag Corporation Washing machine with unbalance detection and control system
US6635007B2 (en) * 2000-07-17 2003-10-21 Thermo Iec, Inc. Method and apparatus for detecting and controlling imbalance conditions in a centrifuge system
US6350224B1 (en) * 2000-07-17 2002-02-26 Westinghouse Savannah River Company, Llc Centrifugal unbalance detection system
DE10125808A1 (de) * 2001-05-26 2002-12-12 Westfalia Separator Food Tec G Zentrifugalseparator
ATE552909T1 (de) * 2002-08-02 2012-04-15 Harvest Technologies Corp Dekantierzentrifuge mit vibrationsisolierung
JP5263570B2 (ja) * 2007-10-31 2013-08-14 日立工機株式会社 遠心機

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1256550A (fr) * 1960-02-05 1961-03-24 Dispositifs de sécurité pour machines centrifugeuses et analogues
US3053949A (en) * 1959-11-18 1962-09-11 Harold K Johnson Intermittent electrical switch
US3790727A (en) * 1972-12-13 1974-02-05 Sealectro Corp Inertia switch with resilient conductive support arm immersed in silicone base viscous fluid medium
GB2119574A (en) * 1982-04-28 1983-11-16 Sentrol Systems Ltd Detection device
US4455461A (en) * 1982-09-29 1984-06-19 E. I. Dupont De Nemours And Company Adjustable imbalance detector for a centrifuge

Family Cites Families (9)

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Publication number Priority date Publication date Assignee Title
US2081604A (en) * 1935-02-01 1937-05-25 Fletcher Works Inc Centrifugal circuit breaker
US2807950A (en) * 1951-09-14 1957-10-01 Borg Warner Gyration suppression control device for a washing machine
DE1298045B (de) * 1962-04-03 1969-06-19 Goedecker B J Maschf Einrichtung an Schleudertrommeln zum Kompensieren der Unwucht
US3226016A (en) * 1962-07-09 1965-12-28 Monsanto Chem Australia Ltd Industrial centrifuges
FR1357002A (fr) * 1963-02-18 1964-04-03 Hotchkiss Brandt Dispositif de sécurité pour machine à laver automatique ou semi-automatique
US3209561A (en) * 1963-11-21 1965-10-05 Westinghouse Electric Corp Unbalance control for washing machines
US3227835A (en) * 1964-10-06 1966-01-04 Borg Warner Combination out-of-balance and safety spin switch
US3583182A (en) * 1968-10-23 1971-06-08 Hitachi Ltd Washing machine
NL7304620A (en) * 1973-04-03 1974-10-07 Imbalance cutout switch for rotating bodies - of compact design and assembled close to the objective

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3053949A (en) * 1959-11-18 1962-09-11 Harold K Johnson Intermittent electrical switch
FR1256550A (fr) * 1960-02-05 1961-03-24 Dispositifs de sécurité pour machines centrifugeuses et analogues
US3790727A (en) * 1972-12-13 1974-02-05 Sealectro Corp Inertia switch with resilient conductive support arm immersed in silicone base viscous fluid medium
GB2119574A (en) * 1982-04-28 1983-11-16 Sentrol Systems Ltd Detection device
US4455461A (en) * 1982-09-29 1984-06-19 E. I. Dupont De Nemours And Company Adjustable imbalance detector for a centrifuge

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0455878A2 (de) * 1990-05-05 1991-11-13 Heraeus Sepatech GmbH Laboratoriums-Zentrifuge
EP0455878A3 (en) * 1990-05-05 1992-01-22 Heraeus Sepatech Gmbh Laboratory centrifuge
DE102004049100B4 (de) 2003-10-09 2020-04-23 Koki Holdings Co., Ltd. Zentrifuge

Also Published As

Publication number Publication date
US4910502A (en) 1990-03-20
FR2622290B1 (fr) 1990-03-30
EP0313444A3 (de) 1990-10-03
FR2622290A1 (fr) 1989-04-28

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