Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Reexamination Certificate
2001-11-09
2004-01-13
Walsh, Donald D. R. (Department: 3653)
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
Reexamination Certificate
active
06677547
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns a method and an apparatus for classifying and recovering the main components of used batteries. More specifically, it concerns a method and an apparatus by which the batteries are conveyed on a conveyor while an alternating magnetic field is applied to each. A detection means detects what sort of induced magnetic field has resulted from the eddy current induced in the battery and in this way determines what sort of battery it is. The batteries being conveyed on the conveyor are brought to within a fixed distance of the detection means, and their travel path is constrained so as to maintain highly accurate detection.
BACKGROUND OF THE INVENTION
In order to prevent environmental pollution, make the fullest possible use of natural resources and aid recycling, it is desirable to classify used batteries according to their main components.
Devices have therefore been developed which can be used to classify used batteries without destroying them. Such apparatus apply an alternating magnetic field to a used battery to generate an eddy current. By measuring the magnetic field induced by this eddy current, one can classify the battery according to its main components.
However, the exterior of a battery is usually covered with an ornamental steel jacket which has a tendency to influence the magnetic characteristics.
In Japanese Patent Publication 6-215802, a design was proposed in which an alternating magnetic field was applied to the used battery and a very large magnetostatic field (a quasi-magnetostatic field) was also applied. The magnetostatic field would magnetically saturate the steel jacket.
The battery separator proposed in Japanese Patent Publication 6-215802 is characterized by the following features. It has at least one excitation coil (
20
), which is connected to three excitation means (
21
,
22
and
23
) and which generates an alternating magnetic field; a positioning means to position the battery or storage battery (
10
) in the alternating magnetic field; three detection means (
30
,
31
and
32
), which measure the induction while the battery or storage battery (
10
) is in the alternating magnetic field; and four means (
41
,
42
,
24
and
34
) to induce a quasi-magnetostatic field in the battery whose properties are being measured via the induction. The quasi-magnetostatic field will virtually saturate at least a part of the ferromagnetic portion of the battery or storage battery (
10
).
The numbers given above are those used in the drawings appended to Patent Publication 6-215802.
As is explained in the Patent Publication 6-215802, when the jacket of the battery is magnetically saturated, the magnetic characteristics of the used battery are no longer influenced by the jacket, but are now determined by the main components constituting the battery within the jacket. Thus by measuring the field created by the eddy current induced by the alternating field, one can determine what the main components of the battery are.
However, in the prior art technique, when the steel jacket of the used battery is magnetically saturated, an attraction force is generated between the jacket and the coil. Thus this method is not suitable for continuous sorting of batteries.
If the batteries are positioned one by one inside the coil and a magnetic field is applied to them, the method described above can be used successfully to sort the batteries by composition. However, if a very large magnetostatic field is applied while a large number of batteries are being continuously fed or dropped into the coil, the batteries will be attracted to the coil when the field is applied and the feed will be interrupted. This makes continuous sorting problematical.
When an alternating magnetic field is applied to the used batteries so that the induced magnetic field which is generated can be measured, the batteries, which are being conveyed on a belt, must be prevented from shifting up, down, left or right on the belt. When they are in position to be detected by the detection means, the distance between the battery and the detection means must remain fixed; and the batteries must be transported smoothly, without getting hung up.
However, because the prior art technique makes use of a saturation field, the field strength is extremely large. In practical terms, this means that it is difficult to achieve a smooth movement of the batteries on the belt.
SUMMARY OF THE INVENTION
In view of the shortcomings of the prior art, the object of this invention is to enable continuous bulk sorting of batteries, to assure a smooth feed, and to improve the accuracy with which the induced magnetic field generated in the battery is detected.
To address the aforementioned shortcomings in the prior art, the present invention is designed as follows. The method of sorting batteries according to the invention entails inducing in a battery being continuously conveyed a weak magnetic field and an alternating magnetic field containing numerous frequency components. The induced magnetic field created by the eddy current induced in the battery is then detected to determine what sort of battery it is. The strength of the induced magnetic field and the phase-shift are detected with respect to the alternating field. Based on the relationship between the classification/the size of the battery with respect to the strength/the phase-shift of the induced magnetic field which were previously obtained, the battery is then sorted according to type and size.
A further refinement of the method of sorting batteries according to the invention is characterized by the fact that the strength of the magnetostatic field is between 0.01 T (Teslas) and 0.3 T.
Another embodiment of the method of sorting batteries according to the invention entails inducing in a battery being continuously conveyed an alternating magnetic field containing numerous frequency components. The induced magnetic field created by the eddy current induced in the battery is then detected to determine what sort of battery it is. The strength of the induced magnetic field and the phase-shift are detected with respect to the alternating field. Based on the relationship between the classification/the size of the battery with respect to the strength/the phase-shift of the induced magnetic field which were previously obtained, the battery is then sorted according to type and size.
A further development of the foregoing method of sorting batteries is further characterized by the fact that the relationship between the type and size of the battery, and the strength and phase of its induced magnetic field has a tolerance range for every frequency component of the alternating field. From the set of tolerance ranges, the type and size of the battery can be determined.
Another refinement of the method of sorting batteries according to the invention is further distinguished by the fact that the strength of the magnetostatic field should be set at a level such that the feed of the batteries is not hindered.
With this invention, an eddy current is generated in batteries which differ in their main constituents. The induced magnetic field resulting from this eddy current causes characteristic changes depending on the materials which constitute the battery. By detecting these changes, the batteries can be sorted by their main ingredients.
In particular, if a weak magnetostatic field is superposed on an alternating field, the differences between the variations in eddy current which are observed with different sorts of batteries will be enhanced. Reducing or not applying the magnetostatic field allows the batteries to be conveyed at high speeds.
Using signals of multiple frequencies allows batteries to be sorted by composition with greater accuracy. Combining a number of sorting apparatuses allows batteries to be sorted by composition even though they may be of different sizes or shapes.
In a preferred embodiment of the invention, the strength of the magnetostatic field is between 0.01 T (Teslas) and 0.3 T, or {fraction (1/10)} the field strength in the
Hirai Takahiko
Honnmura Shiro
Kamimura Takeo
Kurokawa Masaaki
Miyauchi Reizou
Crowell & Moring LLP
Mitsubishi Heavy Industries Ltd.
Rodriguez Joseph C
Walsh Donald D. R.
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