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WO1992018841A1 - Systeme de commande pour instrument centrifugeur - Google Patents

Systeme de commande pour instrument centrifugeur Download PDF

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Publication number
WO1992018841A1
WO1992018841A1 PCT/US1991/009178 US9109178W WO9218841A1 WO 1992018841 A1 WO1992018841 A1 WO 1992018841A1 US 9109178 W US9109178 W US 9109178W WO 9218841 A1 WO9218841 A1 WO 9218841A1
Authority
WO
WIPO (PCT)
Prior art keywords
shaft
rotor
signal representative
predetermined
source
Prior art date
Application number
PCT/US1991/009178
Other languages
English (en)
Inventor
Michael Scott Gold
Victor William Miranda, Jr.
Original Assignee
E.I. Du Pont De Nemours And Company
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 E.I. Du Pont De Nemours And Company filed Critical E.I. Du Pont De Nemours And Company
Priority to CA002084899A priority Critical patent/CA2084899A1/fr
Priority to KR1019920703208A priority patent/KR930700210A/ko
Publication of WO1992018841A1 publication Critical patent/WO1992018841A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M99/00—Subject matter not provided for in other groups of this subclass
    • G01M99/004—Testing the effects of speed or acceleration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B13/00—Control arrangements specially designed for centrifuges; Programme control of centrifuges
    • B04B13/003—Rotor identification systems

Definitions

  • the present invention relates to a centrifuge instrument having a system for automatically verifying whether a rotor is present on the rotor shaft.
  • a centrifuge instrument is a device adapted to expose a liquid sample carried in a rotating member, called a rotor, to a centrifugal force field.
  • the centrifuge instrument has a motive source that includes a drive shaft.
  • the shaft is adapted to receive any one of a predetermined plurality of rotors thereon.
  • the shaft is an elongated member having a cone-shaped adapter, typically termed a "spud", disposed at the upper end thereof.
  • a spud cone-shaped adapter
  • the ratio of the moment of inertia of the spud with a rotor mounted thereon about the axis of rotation with respect to the moment of inertia of these members about an axis perpendicular to the axis of rotation should be greater than one.
  • the present invention relates to a control system for a centrifuge instrument which is adapted to determine whether a rotor is present on the shaft.
  • the centrifuge instrument includes a motive source having a shaft adapted to receive a rotor thereon.
  • Means such as a tachometer, is adapted to generate a signal representative of the actual velocity of the shaft at predetermined measurement time(s) following initiation of the source.
  • a respective first and second predetermined measurement times t m ⁇ and tm2 is provided for generating a signal representative of the actual acceleration of the shaft.
  • the signal representative of the actual acceleration of the shaft is compared to a reference acceleration value thereby to determine whether a rotor is present on the shaft.
  • the measurement times occur within a predetermined time window immediately following initiation of a power source and the application of power to the motive source of the instrument.
  • the value of the difference in actual shaft velocities may be compared to a signal representative of a reference velocity difference thereby to determine whether a rotor is present on the shaft.
  • the predetermined measurement times t ⁇ and tm2 may be selected in any convenient fashion.
  • the time at which the source is energized to initiate rotation of the shaft may be selected as the first predetermined measurement time tmi > such that the calculation of a velocity difference actually degenerates into a comparison of the actual velocity at a predetermined measurement time following initiation of a power source and the application of power to the motive source of the instrument to cause rotation with a predetermined reference velocity.
  • the value of the actual acceleration may be otherwise derived, as by direct measurement and this actual acceleration value compared to a reference acceleration to determine the presence of a rotor on the shaft.
  • the Figure is a highly stylized pictorial representation of a centrifuge instrument with which a control system in accordance with the present invention may be used.
  • FIG. 10 Shown in the Figure is a stylized pictorial representation of a centrifuge instrument generally indicated by reference character 10 with which a control system generally indicated by the reference character 50 embodying the teachings of the present invention may be used.
  • the instrument 10 includes a framework schematically indicated at 12.
  • the framework 12 supports a bowl 14.
  • the interior of the bowl 14 defines a generally enclosed chamber 16 in which a rotating element, or rotor, 18 may be received. Access to the chamber 16 is afforded through a door 20.
  • the bowl 14 may be provided with suitable evaporator coils (not shown) in the event that it is desired to refrigerate the bowl 14, the rotor 18 and its contents.
  • One or more energy containment members, or guard rings, 22 is(are) carried by the framework 12.
  • the guard ring 22 is arranged concentrically with respect to the bowl 14 and serves to absorb the kinetic energy of the rotor 18 or fragments thereof should a catastrophic failure of the rotor 18 occur.
  • the guard ring 22 is movably mounted within the framework 12, as schematically indicated by the rollers 24, to permit free rotation of the ring 22 to absorb any rotational component of the energy of the rotor fragments. It is important to absorb the energy of the rotor and to contain the possible fragments which if permitted to exit the instrument may cause injury to an operator.
  • a motive source 30 is mounted within the framework 12.
  • the motive source 30 may be any one of a well-known variety of sources, such a brushless DC electric motor, an induction motor, or an oil turbine drive.
  • a power source 32 is connected to the motive source 30.
  • the motive source 30 is connected to or includes as an element thereof a drive shaft 34.
  • the drive shaft 34 projects into the chamber 16.
  • the upper end of the shaft 34 is provided with a mounting spud 36 which receives the rotor 18. Any one of a predetermined number of rotor elements may be received on the spud 36.
  • a tachometer generally indicated by the reference character 38 is arranged to monitor the rotational speed (i. e., angular velocity) of the shaft 34. Any convenient form of tachometer arrangement 38 may be utilized and remain within the contemplation of the present invention.
  • An electrical signal representative of the actual angular velocity of the shaft 34 (and of a rotor, if the same is mounted thereon) is carried by an output line 38L from the tachometer 38.
  • control system 50 serves this end.
  • the control system 50 in accordance with the present invention includes means 52 associated with the tachometer 38.
  • the means 52 may, for example, sample the tachometer signal representative of the actual velocity ⁇ a of the shaft at one or more predetermined measurement tim ⁇ (s) following initiation of the power source 32 and the application of a predetermined power level to the motive source 30.
  • the measurement times occur within a predetermined time window immediately following initiation of the source 32 and the application of power to the motive source 30.
  • the time window is on the order of a few seconds (e.g., three seconds) following initiation of the source 32 and the application of power to the motive source 30.
  • a predetermined limited power level is applied from the power source 32 to the motive source 30.
  • the measurement time window occurs early in the centrifugation run to insure that the shaft 34 does not reach a potentially destructive velocity before the presence (or absence) of a rotor is verified.
  • signals representative of the actual velocity co a 1 and the actual velocity ⁇ a 2 of the shaft 34 at at least a respective first predetermined measurement time tmi and a second predetermined measurement time t m 2 following energization of the motive source 30 are used by the means 52 to generate a signal on an output line 52L thereof representative of the actual acceleration of the shaft 34.
  • the actual acceleration signal on the line 52L is applied to a comparator 56.
  • the actual acceleration signal is compared to a reference acceleration signal carried on a line 58L.
  • the reference acceleration signal on the line 58L may be derived from a suitable reference source, as a memory 58.
  • the results of the comparison are output on a line 56L and provide an indication as to whether a rotor is mounted to the spud.
  • the output on the line 56L may be used to represent this error condition and may be applied to interrupt power applied to the power source 32 to the motive source 30.
  • the signal on the line 52L may represent merely the difference between the signal representative of the actual velocity ⁇ a ⁇ of the shaft 34 at the first predetermined measurement time tmi and the signal representative of the actual velocity ⁇ 3 2 of the shaft at the second predetermined measurement time tm2 both immediately following initiation of the source 32 and the application' of power to the motive source 30.
  • the velocity difference signal on the line 52L may likewise be applied to the comparator 56 where it is compared to a reference velocity difference signal, again derived from the memory 58 over the line 58L. In a manner similar to that earlier discussed the results of the comparison provide an indication as to whether a rotor is mounted to the spud and the appropriate action taken.
  • the actual value of the acceleration may be calculated in any convenient fashion.
  • One technique is to include a calculation of acceleration as part of the instrument speed control program.
  • the acceleration is calculated every 0.10 second, over a preceding one second period.
  • a speed reading is derived from the tachometer and stored in a buffer-the "Alpha" buffer- at 0.1 second intervals. At each interval, when a new speed reading is available, the value of the speed at one second in the past is recalled. Since the speed readings are spaced one second apart, an acceleration value in units of "revolutions/minute-second" is equal to the difference between the two speed readings.
  • the following subroutine uses the acceleration value "Alpha” to determine whether a rotor is disposed on the shaft. The determination is performed following a three second interval (implemented by lines 1 to 13) during which a predetermined constant current (one ampere) is applied to the electric motor drive. At the end of this time interval the acceleration "Alpha” (derived from the speed control routine as discussed above) is loaded to a buffer (line 14) and is compared (line 15) to a reference acceleration value (225 revolution/minute-seconds, line 15). The reference acceleration value is determined empirically and corresponds to one-half of the acceleration of the shaft with no rotor disposed thereon when the shaft is driven by the motor at reduced current (one amp).
  • the acceleration of a shaft having no rotor acceleration of the shaft with a rotor of known inertia is first measured.
  • the acceleration of the shaft with no rotor is then computed by dividing the inertia of the rotor and shaft by the inertia of the shaft alone and multiplying this quotient by the measured acceleration of the shaft having the rotor mounted thereon.
  • the reference acceleration is one-half of this value.
  • control system 50 may include means 60 that is directly or indirectly associated with the motive source 30, the power source 32 or the shaft 34 to generate a signal representative of the actual acceleration of the shaft.
  • the actual acceleration signal may be applied to the means 60 on an input line 60I.
  • an accelerometer may be mechanically coupled to the shaft 34 and used to generate a signal representative of the actual acceleration thereof.
  • the signal representative of the actual acceleration, as otherwise derived, is applied to the comparator 56 on the line 60L. Again a comparison between the actual acceleration signal on the line 60L and a reference acceleration signal on the line 58L is effected. The results of the comparison are again used to provide an indication as to whether a rotor is mounted to the shaft.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Centrifugal Separators (AREA)

Abstract

Système de commande (50) pour instrument centrifugeur (10). Il échantillonne la vitesse de l'axe (34) à un premier et à un second instants de mesure afin de générer un signal indiquant l'accélération effective de l'axe. Le signal d'accélération effective est comparé à une accélération de référence de manière à déterminer si un rotor (18) est présent sur l'axe.
PCT/US1991/009178 1990-04-11 1991-12-18 Systeme de commande pour instrument centrifugeur WO1992018841A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CA002084899A CA2084899A1 (fr) 1991-04-11 1991-12-18 Systeme de commande pour instrument centrifuge
KR1019920703208A KR930700210A (ko) 1990-04-11 1991-12-18 원심 분리기

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US68392991A 1991-04-11 1991-04-11
US683,929 1991-04-11

Publications (1)

Publication Number Publication Date
WO1992018841A1 true WO1992018841A1 (fr) 1992-10-29

Family

ID=24746043

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1991/009178 WO1992018841A1 (fr) 1990-04-11 1991-12-18 Systeme de commande pour instrument centrifugeur

Country Status (4)

Country Link
EP (1) EP0540696A1 (fr)
JP (1) JPH05508346A (fr)
CA (1) CA2084899A1 (fr)
WO (1) WO1992018841A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008002094A1 (fr) * 2006-06-30 2008-01-03 Medikan Inc. Centrifugeuse

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4193005A (en) * 1978-08-17 1980-03-11 United Technologies Corporation Multi-mode control system for wind turbines
DE3222020A1 (de) * 1981-07-01 1983-01-20 Magyar Optikai Müvek, 1525 Budapest Schaltungsanordnung bei ultrazentrifugen zum schutz des anlassens ohne rotor
US4827197A (en) * 1987-05-22 1989-05-02 Beckman Instruments, Inc. Method and apparatus for overspeed protection for high speed centrifuges
US4848142A (en) * 1987-10-15 1989-07-18 Nissan Motor Sales Co., Ltd. Motor vehicle performance test apparatus
US4942493A (en) * 1988-11-02 1990-07-17 Sundstrand Corporation Method and apparatus for detecting prime mover start malfunction

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5753262A (en) * 1980-09-17 1982-03-30 Hitachi Koki Co Ltd Monitor for operation of centrifuge

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4193005A (en) * 1978-08-17 1980-03-11 United Technologies Corporation Multi-mode control system for wind turbines
DE3222020A1 (de) * 1981-07-01 1983-01-20 Magyar Optikai Müvek, 1525 Budapest Schaltungsanordnung bei ultrazentrifugen zum schutz des anlassens ohne rotor
US4827197A (en) * 1987-05-22 1989-05-02 Beckman Instruments, Inc. Method and apparatus for overspeed protection for high speed centrifuges
US4848142A (en) * 1987-10-15 1989-07-18 Nissan Motor Sales Co., Ltd. Motor vehicle performance test apparatus
US4942493A (en) * 1988-11-02 1990-07-17 Sundstrand Corporation Method and apparatus for detecting prime mover start malfunction

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0540696A4 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008002094A1 (fr) * 2006-06-30 2008-01-03 Medikan Inc. Centrifugeuse

Also Published As

Publication number Publication date
CA2084899A1 (fr) 1992-10-12
EP0540696A4 (fr) 1994-04-13
JPH05508346A (ja) 1993-11-25
EP0540696A1 (fr) 1993-05-12

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