Magnetic stirrer

• US 4,080,663 A
• Filed: 03/07/1977
• Issued: 03/21/1978
• Est. Priority Date: 03/09/1976
• Status: Expired due to Term

• Current Assignee: Gunnar Wik
• Original Assignee: Gunnar Wik
• Inventors: Wik, Gunnar
• Primary Examiner(s): Jenkins, Robert W.
• Application Number:
  US05/775,153
• Time in Patent Office: 379 Days
• Field of Search: 259/1 R, 259/DIG. 46, 259/27, 259/21, 259/22, 259/23, 259/24, 259/40, 259/41, 259/43, 259/44, 259/5-8, 259/64, 259/65, 259/66, 259/67, 259/102, 259/107, 259/108, 310/103, 310/104
• US Class Current: 366/274
• CPC Class Codes: B01F 33/452 using independent floating stirring elements
• CPC Class Codes: B01F 35/20 Measuring; Control or regulation

Abstract

A magnetic stirrer for stirring a fluid in a vessel where a stirring rotor in form of a permanent bar magnet is easily movable for rotation by means of an externally applied rotating magnet field. Said field is set up by four magnet coils arranged in a parallel relationship to form a square configuration and fed by respective phase-shifted a.c. currents, the common center axis of the coils being aligned with the rotor in the overlying vessel. A plate of mu-metal is arranged in said center axis and adjacent the bottom of the vessel to concentrate the longitudinal magnet flow lines of the coils for interaction with the flow lines of the rotor to maintain the rotor centered.

Claims

1. A magnetic stirrer comprising a stirring rotor in form of a permanent bar magnet which is easily movable in a vessel containing a fluid to be stirred, at least one pair of parallelly disposed magnet coils, supplied with respective phase-shifted a.c. currents to induce opposite magnetomotive forces in said coils, resulting in a rotating magnet field, said vessel being positioned near the top plane of said coils and having the rotor substantially aligned with the common centre axis of the coils, so that the rotor is rotated by said rotating magnet field, a plate of a soft-magnetic material having magnetic shielding properties, such as mu-metal, being positioned adjacent the bottom of said vessel and substantially in said common centre axis of the coils.

2. A magnetic stirrer according to claim 1, comprising two pairs of coils arranged in a substantially square formation, each pair being supplied from a different phase line of an a.c. voltage source, the plate of mu-metal being provided in the common centre area of the four coils and located adjacent the bottom of said vessel.

3. A magnetic stirrer according to claim 2, comprising an additional pair of coils forming, together with one of the two remaining pairs, another square formation, said additional pair of coils having a phase supply line common with the other of these coil pairs, a second plate of mu-metal being positioned in the central area of said additional square formation to act upon a rotor in a second overlying vessel.

4. A magnetic stirrer according to claim 1, wherein disks of mu-metal also are placed over each of the coils, said disks being of a size to cover the top surface of said coils.