Apparatus for measuring weight and force with magnetic fluid seal

• US 6,329,611 B1
• Filed: 02/18/2000
• Issued: 12/11/2001
• Est. Priority Date: 02/22/1999
• Status: Expired due to Fees

• Current Assignee: Shinko Denshi Co. Ltd. (Ishida Company Limited), Japan Atomic Energy Research Institute (Japan Atomic Energy Agency)
• Original Assignee: Shinko Denshi Co. Ltd. (Ishida Company Limited), Japan Atomic Energy Research Institute (Japan Atomic Energy Agency)
• Inventors: Terunuma, Kozo, Abe, Tetsuya
• Primary Examiner(s): Gibson, Randy W.
• Application Number:
  US09/506,331
• Time in Patent Office: 662 Days
• Field of Search: 177/229, 177/238, 177/239, 177/243, 177/124, 738/623.81, 738/625.41, 738/626.21
• US Class Current: 177/124
• CPC Class Codes: G01G 1/22 for precision weighing
• CPC Class Codes: G01G 21/244 combined with flexure-plate fulcrums flexure-plate fulcrums G01G21/07
• CPC Class Codes: G01G 21/28 Frames, Housings

Abstract

An apparatus for measuring weight of a substance placed within a substrate space which is subjected to sever conditions, including a measuring unit having a transducer and placed within a measuring space, a partition member provided between the measuring space and the substance space and having hole through which said measuring space is communicated with said substance space, a rod-like member extending through said hole formed in the partition member such that a first end of said force transferring member situates within said substance space and a second end of said force transferring member situates within said measuring space, a parallel link mechanism arranged within the measuring space and connected with the rod-like member, a magnetic fluid provided in a space within said hole such that said substance space and measuring space is isolated from each other in a liquid tight manner by means of said magnetic fluid, and a magnetic force generating unit producing a magnetic force such that said magnetic fluid is kept in position by said magnetic force.

Claims

1. An apparatus for measuring weight/force of a substance comprising:

a measuring unit having a transducer;

a partition member provided between a measuring space in which said measuring unit is arranged and a substance space in which the substance whose weight/force is to be measured is placed, said partition member having a hole formed therein, said measuring space being communicated with said substance space through said hole;

a force transferring member extending through said hole formed in the partition member such that a first end of said force transferring member situates within said substance space and a second end of said force transferring member situates within said measuring space and is coupled with said transducer;

a magnetic fluid provided in a space within said hole such that said substance space and measuring space is isolated from each other in a liquid tight manner by means of said magnetic fluid; and

a magnetic force generating means for producing a magnetic force such that said magnetic fluid is kept in position by said magnetic force.

2. An apparatus according to claim 1, wherein said partition member is arranged horizontally, said substance space and measuring space are separated vertically by means of the horizontally arranged partition member, and said force transferring member is arranged vertically.

3. An apparatus according to claim 2, wherein said force transferring member is a rod.

4. An apparatus according to claim 3, wherein said rod is supported within said measuring space by a parallel link mechanism such that the rod can be resiliently moved in the vertical direction.

5. An apparatus according to claim 4, wherein said rod and parallel link mechanism are formed as an integral single body.

6. An apparatus according to claim 5, wherein said rod and parallel link mechanism are formed by cutting a stainless steel plate.

7. An apparatus according to claim 1, wherein said magnetic force generating means includes a ring shaped permanent magnet, a ring shaped magnetic yoke arranged to surround the permanent magnet except for an inner side of the permanent magnet, and a nonmagnetic ring provided on the inner side of the permanent magnet, said permanent magnet, magnetic yoke and nonmagnetic ring being arranged concentrically to surround the hole formed in the partition member, and the ring shaped permanent magnet is magnetized in an axial direction.

8. An apparatus according to claim 7, wherein said force transferring member is made of a nonmagnetic material.