EP0051382B1 - Mischer - Google Patents

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Publication number
EP0051382B1
EP0051382B1 EP81304879A EP81304879A EP0051382B1 EP 0051382 B1 EP0051382 B1 EP 0051382B1 EP 81304879 A EP81304879 A EP 81304879A EP 81304879 A EP81304879 A EP 81304879A EP 0051382 B1 EP0051382 B1 EP 0051382B1
Authority
EP
European Patent Office
Prior art keywords
agitator
current
vessel
motor
output
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
EP81304879A
Other languages
English (en)
French (fr)
Other versions
EP0051382A3 (en
EP0051382A2 (de
Inventor
Robert William English
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.)
Netzsch Mastermix Ltd Te Walsall Groot-Britta
Original Assignee
MASTERMIX 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 MASTERMIX Ltd filed Critical MASTERMIX Ltd
Publication of EP0051382A2 publication Critical patent/EP0051382A2/de
Publication of EP0051382A3 publication Critical patent/EP0051382A3/en
Application granted granted Critical
Publication of EP0051382B1 publication Critical patent/EP0051382B1/de
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/05—Stirrers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F35/00—Accessories for mixers; Auxiliary operations or auxiliary devices; Parts or details of general application
    • B01F35/20—Measuring; Control or regulation

Definitions

  • This invention relates to a development in the mixing apparatus disclosed in our prior published EP-A-0 000 827 (equivalent to GB-A-2 002 246).
  • the object of the present invention is to overcome the above mentioned drawback.
  • mixing apparatus comprising a vessel for receiving liquid and other materials to be mixed, a rotary agitator for immersion into the contents of the vessel, an electric motor for rotatably driving said agitator and means responsive to the noise level emitted by the contents of the vessel during agitation for automatically adjusting the vertical position of the agitator, characterised by means for monitoring the drive motor so as to sense a significant reduction in current of the motor driving the agitator, and when so sensed to cause automatic lowering of the agitator irrespective of the noise level detected.
  • the drive system comprises an electric motor, as in the apparatus described in EP-A-0 000 827 and the monitoring means is responsive to the motor current which, it will be appreciated, will decrease significantly when the rotor rises above the liquid surface level because the drag on the rotor exerted by a layer of powder or air is considerably less than that exerted by the liquid.
  • the monitoring means in response to significant reduction in motor current, generates a signal to cause lowering of the rotor automatically and this signal at least temporarily overrides the controls which position the rotor according to the noise levels prevailing.
  • the monitoring means senses motor current and may convert it into voltage so that when the motor current drops below a predetermined minimum value, the logic state of the output channel of the monitoring means changes to provide the above mentioned signal.
  • the control circuitry of the apparatus may be designed to provide, in essence, three output channels corresponding to the raise, lower and motor detector conditions with appropriate gating to derive an output signal consistent with the desired operating conditions.
  • the output derived from the monitoring means in response to reduced current will override those signals produced by the apparatus during normal operation.
  • control circuitry illustrated in the accompanying drawing may for the most part be generally similar to that disclosed in our EP-A-0 000 827 and the description herein will therefore be confined to the modifications provided by the present invention.
  • the control circuits depicted by the blocks 10 and 12 respectively correspond to circuitry illustrated in Figures 2a and 2b of EP-A-0 000 827 and reference should be made to the prior application for detailed description.
  • the circuits 10, 12 serve to process the output from the microphone 14 in order to produce control signals governing the vertical positioning of the rotary agitator of the mixing apparatus.
  • the circuit 10 provides two outputs 16, 18 such that a signal appears either at output 16 or 18 depending on whether the noise level is below or above a predetermined range. If the noise level is below the predetermined range, the circuit 12 will produce a control signal to effect raising of the agitator and vice versa.
  • the modification introduced by the invention involves the use of means for sensing the current drawn by the electric motor for rotatably driving the mixing agitator.
  • Such means may comprise a current transformer 20 connected in circuit with the motor and interface circuitry 22 for providing an output 24 representing the motor current.
  • the outputs 16, 18 are gated with the outputs 24 in gating circuitry 26 in accordance with the following conditions. If the output 24 corresponds to normal motor current levels, the output 16, 18 are coupled by the gating circuitry 26 to inputs 28, 30 respectively of the control circuitry 12. In these circumstances, the apparatus operates in the manner described in EP-A-0 000 827.
  • the output 24 corresponds to a low motor current such as occurs if the agitator is withdrawn from the body of liquid within the mixing vessel then the output 16 is decoupled from input 28 and the output 24 is coupled to the input 30 so as to cause the circuit 12 to generate an output resulting in lowering of the agitator.
  • the motor current will return to a normal level with resumption of normal control of the agitator by the outputs 16, 18 which will once again be connected to the inputs 28, 30 respectively. It will be seen that the output 24 is effective to override normal operation of the apparatus in circumstances where the motor control current falls substantially and will therefore overcome any tendency for the apparatus to continue raising the agitator through failure to detect a change in noise level due to the presence of a blanketing layer of solids on the liquid surface.
  • lowering of the agitator in response to fall in motor current may be sustained for longer than is strictly necessary to re-introduce the agitator back into the liquid.
  • the circuitry 22 may, in response to detection of a substantial fall in motor current, produce a corresponding signal at output 24 for a predetermined time interval sufficient to re-immerse the agitator to a desired depth before allowing resumption of control in accordance with the noise level detected by the microphone.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Accessories For Mixers (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)

Claims (2)

1. Mischvorrichtung, enthaltend ein Gefäß zur Aufnahme von flüssigen oder sonstigen zu mischenden Stoffen, ein Rührwerk, das in den Gefäßinhalt eintaucht, einen Elektromotor zum Drehantrieb des Rührwerkes sowie eine Einrichtung, die auf den vom Gefäßinhalt bei der Rührbewegung erzeugten Geräuschpegel anspricht und die vertikale Lage des Rührwerkes automatisch einstellt, dadurch gekennzeichnet, daß eine Einrichtung vorgesehen ist, die den Antriebsmotor derart überwacht, daß eine merkliche Verringerung des Motorstromes festgestellt wird, woraufhin eine automatische Absenkung des Rührwerkes unabhängig von dem festgestellten Geräuschpegel bewirkt wird.
2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß die Überwachungseinrichtung einen Stromtransformator zur Feststellung von Stromänderungen enthält.
EP81304879A 1980-11-04 1981-10-20 Mischer Expired EP0051382B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8035429 1980-11-04
GB8035429 1980-11-04

Publications (3)

Publication Number Publication Date
EP0051382A2 EP0051382A2 (de) 1982-05-12
EP0051382A3 EP0051382A3 (en) 1983-03-30
EP0051382B1 true EP0051382B1 (de) 1985-10-09

Family

ID=10517081

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81304879A Expired EP0051382B1 (de) 1980-11-04 1981-10-20 Mischer

Country Status (2)

Country Link
EP (1) EP0051382B1 (de)
DE (1) DE3172624D1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3220453A1 (de) * 1982-05-29 1983-12-01 Janke & Kunkel GmbH & Co KG Ika - Werk, 7813 Staufen Ruehrgeraet insbesondere fuer den laborbetrieb

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1118659A (de) * 1954-04-30
US3373823A (en) * 1965-09-20 1968-03-19 Jr Hal B Fullerton Well drilling control system
US3480212A (en) * 1967-02-23 1969-11-25 Reserve Mining Co Control apparatus
US3460812A (en) * 1968-03-25 1969-08-12 Robert R Kaufman Concrete mixing control apparatus for concrete mixing trucks
GB1237290A (en) * 1969-02-24 1971-06-30 Cox S Machinery Ltd Mixing apparatus
US3720135A (en) * 1971-02-01 1973-03-13 Kearney & Trecker Corp Feed rate controller
GB1564201A (en) * 1975-11-27 1980-04-02 Boots Co Ltd Determining end point of agitating processes

Also Published As

Publication number Publication date
EP0051382A3 (en) 1983-03-30
DE3172624D1 (en) 1985-11-14
EP0051382A2 (de) 1982-05-12

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