Electricity: measuring and testing – Determining nonelectric properties by measuring electric...
Reexamination Certificate
1999-09-22
2001-09-04
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Determining nonelectric properties by measuring electric...
C324S691000, C324S693000, C420S900000
Reexamination Certificate
active
06285179
ABSTRACT:
DETAILED EXPLANATION OF THE INVENTION
1. Field of the Invention
This invention relates to a detecting method and a detecting apparatus for detecting an absorbed hydrogen amount in a hydrogen absorbing tank.
2. Related Background Art
Conventionally, an absorbed hydrogen amount in a hydrogen absorbing tank filled with hydrogen absorbing alloy powder is detected as shown in Japanese Unexamined (Koukai) Patent No.5-10211, for example. In this prior art, an amount of a hydrogen gas coming in a hydrogen absorbing tank and going out therefrom is detected by a gas flow-amount sensor, and the detected results are accumulated.
However,the hydrogen gas flow-amount sensor inevitably has a measuring error. So, when occludes (absorption) and desorption of the hydrogen to or from the hydrogen absorbing tank are repeated, the accumulated error of the absorbed hydrogen amount becomes large, so that a detecting accuracy by the hydrogen gas flow-amount sensor will be deteriorated. This deterioration of the detecting accuracy may cause some problems in a vehicle and the like which use the hydrogen gas as a fuel.
SUMMARY OF THE INVENTION
The present invention is made in view of the above circumstances, and accordingly has an object to provide the detecting method and the detecting apparatus of absorbed hydrogen amount in the hydrogen absorbing tank, which can detect the hydrogen occlude condition in the hydrogen absorbing tank accurately, irrespective of repeating the absorption and desorption of the hydrogen to and from the hydrogen absorbing tank.
In order to achieve the above object, the detecting method of the absorbed hydrogen amount in the hydrogen absorbing tank of the present, and the detecting apparatus used therefor invention use the following principle. That is, when expansion of the hydrogen absorbing alloy powder occurs with a change of an absorbed hydrogen amount, a contact area and a contact condition of adjacent hydrogen absorbing alloy powders change, so that electrical resistance between electrodes also changes. In view of the above, a relation between the absorbed hydrogen amount of the hydrogen absorbing alloy powder in the hydrogen absorbing tank and the electrical resistance between the both electrodes is mapped in advance, and this relation is used together with a detected electrical resistance value to calculate the absorbed hydrogen amount.
According to these detecting methods and the detecting apparatus, even if the absorption and desorption or the hydrogen to and from the hydrogen absorbing tank are repeated in many times, the measuring error will not be accumulated, different from the above mentioned conventional art. Thus, the high accuracy detection of the absorbed hydrogen amount in the hydrogen absorbing tank can be realized.
The hydrogen absorbing tank preferably has rigidity to generate a compress stress in the hydrogen absorbing alloy powder in increasing the absorbed hydrogen amount thereof, in other words, to restrict a volume expansion of the hydrogen absorbing alloy powder in occluding the hydrogen. By usage of such hydrogen absorbing tank, since a change rate of the contact area and contact condition between the adjacent hydrogen absorbing alloy powders due to a change of the absorbed hydrogen amount becomes larger, the electrical resistance value between both electrodes can be changed larger, so that a detecting sensitivity of the absorbed hydrogen amount by the detecting method and the detecting apparatus can be further improved.
In the detecting apparatus of a preferred embodiment, the hydrogen absorbing tank contains a predetermined amount of hydrogen absorbing alloy powder which the electrical resistance value changes suddenly when the absorbed hydrogen amount substantially corresponds to a saturated occlude amount. According to this detecting apparatus, the hydrogen occlude saturated condition of the hydrogen absorbing tank is judged by detecting the sudden change of the electrical resistance value.
In the detecting apparatus of the other preferred embodiment, the hydrogen absorbing tank contains a predetermined amount of the hydrogen absorbing alloy powder which the electrical resistance value changes suddenly when the absorbed hydrogen amount substantially corresponds to an absorbed non-hydrogen amount. According to this detecting apparatus, the non-hydrogen occlude condition of the hydrogen absorbing tank is judged by detecting the sudden change of the electrical resistance value.
In the detecting apparatus of the other preferred embodiment, the determining means determines the absorbed hydrogen amount in the hydrogen absorbing tank by substituting the detected electrical resistance value to a map which shows the relation between the electrical resistance value and the absorbed hydrogen amount. According to this detecting apparatus, the present or newest absorbed hydrogen amount can be detected without accumulation of the measured errors.
In the detecting apparatus of the other preferred embodiment, the hydrogen absorbing tank is comprised of a capsule for detecting the absorbed hydrogen amount contained in a main tank which contains a large amount of hydrogen absorbing alloy powder to allow the come-in and go-out of the hydrogen gas relative to the hydrogen absorbing tank. In this detecting apparatus, the problem that when the main tank has small rigidity, the volume thereof expands due to increase of the absorbed hydrogen of the hydrogen absorbing alloy powder contained in the main tank, so that increase of the contact area between the hydrogen absorbing alloy powders in the main tank is restricted irrespective of volume expansion of such hydrogen absorbing alloy powder, is taken into consideration. In view of the above, a hydrogen absorbing tank (capsule) which has an extremely smaller volume than an inner space of the main tank is provided for detecting the absorbed hydrogen amount in the hydrogen absorbing tank accurately. As a result, a large size main tank can be manufactured easily and weight thereof can be reduced to half.
In the detecting apparatus of the other preferred embodiment, the same advantage described above can be obtained.
In the detecting apparatus of the other embodiment, the hydrogen absorbing tank includes a first hydrogen absorbing tank containing the amount of the hydrogen absorbing alloy powder which the electrical resistance value changes suddenly when the absorbed hydrogen amount corresponds to a saturate amount substantially, and a second hydrogen absorbing tank containing the amount of the hydrogen absorbing alloy powder which the electrical resistance value changes suddenly when the absorbed hydrogen amount corresponds to zero substantially. As a result, both of two important conditions i.e. hydrogen occlude saturated condition and non-hydrogen occlude condition for the hydrogen absorbing tank can be accurately detected.
Finally, in the detecting apparatus of the other embodiment, the main tank can be used for one of the first and second hydrogen absorbing tanks, so that the number of capsules contained in the main tank can be reduced.
REFERENCES:
patent: 4233127 (1980-11-01), Monahan
patent: 4788491 (1988-11-01), Ayers
patent: 5668301 (1997-09-01), Hunter
patent: 6155099 (2000-12-01), Kobayashi
patent: 5-10211 (1993-01-01), None
patent: 6-206701 (1994-07-01), None
Journal of Alloys and Compounds 231 (1995), pp. 182-187.
Kubo Hidehito
Yamaguchi Masuhiro
Deb Anjan K
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Metjahic Safet
Morgan & Finnegan , LLP
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