Weighing scales – With lock or seal
Reexamination Certificate
2000-02-18
2001-12-11
Gibson, Randy W. (Department: 2859)
Weighing scales
With lock or seal
C177S238000, C177S243000, C073S862381, C073S862621
Reexamination Certificate
active
06329611
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for measuring a weight and/or a force caused by a substance which is subjected to severe circumstances.
2. Related Art Statement
Upon measuring a weight of a substance, an electronic weighing apparatus has been widely used. In general, a substance whose weight is to be measured is placed in a same environment as that in which an electronic weighing apparatus is installed. However, in some cases, substances are placed in severe environments such as poisonous gas atmospheres and corrosive gas atmosphere. In such a case, when the electronic weighing apparatus is installed in the same environment as that in which the substance whose weight is to be measured, the weighing apparatus and a measuring sensor are also subjected to the severe environment and are liable to be damaged. When the electronic weighing apparatus is kept in such a severe environment for a long time, the apparatus might be corroded or broken and the accurate measurement could not be carried out any more.
In order to mitigate the above mentioned problem, there has been proposed a known weight/force measuring apparatus, in which a part of an electronic weighing apparatus is placed in a substance space in which a substance is existent, and the remaining parts of the weighing apparatus are installed in a measuring space which is completely separated from the substance space. For instance, a permanent magnet is coupled with a member which is moved up and down in response to a weight of a substance and is placed in the substrate space, and a position sensor which detects a position of the permanent magnet and an electromagnetic coil within which said permanent magnet is inserted are installed within the measuring space which is separated from the substance space by means of a partition wall. In such a weight measuring apparatus, a position of the permanent magnet is detected by the position sensor and an electric current passing through the electromagnetic coil is controlled in accordance with an output signal of the position sensor such that the permanent magnet is always positioned at a predetermined position with respect to the electromagnetic coil. In this manner, a weight of the substance can be measured by monitoring the electric current passing through the electromagnetic coil.
In this known weight measuring apparatus, since almost all parts except for the permanent magnet is arranged within the safe measuring space, even if the substance space is subjected to severe conditions, the measuring could be performed. However, the permanent magnet is not directly coupled with the electromagnetic coil, but is separated from the main parts of the measuring apparatus, and therefore an accurate measurement could not be attained.
SUMMARY OF THE INVENTION
The present invention has for its object to provide a novel and useful apparatus for measuring weight/force of a substance in an accurate manner without being influenced by a severe environment within which the substrate is placed.
According to the invention, an apparatus for measuring weight/force of a substance comprises:
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 connected to 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.
In a preferable embodiment of the weight/force measuring apparatus according to the invention, 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. In this case, although either one of the substance space and measuring space may be arranged above the other, it is preferable to arrange the measuring space above the substance space.
In a preferable embodiment of the weight/force measuring apparatus according to the invention, 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. In this case, the ring shaped permanent magnet is magnetized in an axial direction, i.e. a central axial direction of the hole.
REFERENCES:
patent: 3444943 (1969-05-01), Tytus
patent: 4072049 (1978-02-01), Miller
patent: 4320809 (1982-03-01), Knothe et al.
patent: 4884645 (1989-12-01), Knothe et al.
patent: 5052505 (1991-10-01), Naito et al.
patent: 5587698 (1996-12-01), Genna
patent: 5895894 (1999-04-01), Zumbach
patent: 6166336 (2000-12-01), Odiet
Abe Tetsuya
Terunuma Kozo
Gibson Randy W.
Japan Atomic Energy Research Institute
Vardnell & Varndell, PLLC
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