Fluid handling – Destructible or deformable element controlled – Destructible element
Reexamination Certificate
1999-02-08
2001-07-10
Rivell, John (Department: 3753)
Fluid handling
Destructible or deformable element controlled
Destructible element
C220S089200, C361S521000
Reexamination Certificate
active
06257267
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to especially safety valve elements for condenser use which can be broken off at the low prescribed presser and release the internal presser, condenser case lids provided with safety valves and condensers produced by employing such safety valve elements and condenser case lids.
PRIOR ARTS
Conventionally, a condenser which uses an organic solvent as an electrolyte sometimes suffers rupture when the pressure in the condenser is abnormally elevated. To prevent the occurrence of such rupture when the pressure in the condenser is excessively increased, various safety valves with different mechanisms have been proposed in the request of safety valves capable of releasing inner pressure outside. The safety valves need to be operated particularly at a low pressure of not more than 2 to 5 kgf/cm
2
so as to assure the safety for fear that broken pieces or contents of the condenser would scatter outside to thereby hurt human body, if the condenser ruptures by a chance.
The condenser which uses an organic solvent as the electrolyte requires to have high sealability. A Japanese laid-open publication SHO 63-285859 discloses a safety valve used in the condenser required of such a high realability, which can release the inner pressure of such condenser outside when its inner pressure is excessively elevated.
In this condenser, a part of the wall of the condenser vessel is thinned by cold rolling using a press device until the thickness of the rolled part becomes half of the initial thickness thereof. Accordingly, when the inner pressure is elevated and reaches a predetermined pressure, the thinned wall part is ruptured and the inner pressure is released outside.
To release the inner pressure at a low pressure of not more than 30 kg/cm
2
, the thinned wall part should be made considerably thin. And, during press working to obtain an extremely thin wall part, fine or minute cracks may occur in the thinned wall part, and once such cracks occur, sealability of the vessel is spoiled. Although the thinned wall part is hardened by such press working, it is not uniformly hardened.
Accordingly, the release valve as mentioned above has another drawback that even if the thinned wall part is pressed to have a uniform thickness, it does not always rupture at a constant pressure.
Furthermore, an etching method has been proposed to make thinner a part of the wall of the condenser vessel, however, it is extremely difficult to control the thickness of the thinned wall part at a prescribed thickness after etching. Besides the thinned wall part is apt to suffer pinholes, which needs a pinhole test for detecting the pinholes of all the thinned wall parts after etching.
Thus, when using the above mentioned method, it is extremely difficult to obtain a thinned wall part having a uniform thickness. Especially in a case that the safety valve is to be operated for the pressure releasing at a low pressure of not more than 30 kgf/cm
2
a reliable reproductivity of the pressure releasing operation cannot be achieved.
There is another method for releasing inner pressure outside proposed. For instance, Japanese laid-open publication HEI 2-304861 discloses a valve chest provided at a part of an outer vessel with a valve aperture to be communicated with the inside of the condenser and an outlet to be communicated with outside of it, in which a valve element at least whose one surface facing the valve aperture is made of rubber, and an elastic element for pressing the above mentioned rubber surface of the valve element to the valve aperture.
According to this method, the releasing pressure of the safety valve is naturally determined from the elastic modulus of the elastic element and the area of the valve element exposed to pressure, and it can be easily selected in an optional range from a low pressure of 10 kgf/cm
2
down to 1 kgf/cm
2
to a high pressure of 50 kgf/cm
2
. This method, however, cannot provide such high sealability as required for the condenser which uses organic solvent as the electrolyte.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide safety valve elements for condenser use, which stably operates especially in a low pressure range and rupture precisely at a predetermined pressure for releasing inner pressure outside and can be manufactured readily, and provide a condenser which incorporates the safety valve elements.
The safety valve elements for condenser use according to the present invention comprises a metal substrate which is provided with a perforated opening and a metal foil laid over the metal substrate so as to close the perforated opening.
Such safety valve elements for condenser use may preferably be provided with a plurality of perforated openings. The metal substrate may be made of an aluminum sheet or aluminum alloy sheet and the metal foil is desirably made of an aluminum foil. The condenser case lid is produced by forming a perforated opening in the metal substrate, pressure welding the metal foil to the metal substrate so as to close the perforated opening and molding the metal substrate into a case lid form. The condenser employs the above mentioned safety valve elements for condenser use, and the condenser employs the above mentioned condenser case lid with the safety valve elements.
REFERENCES:
patent: 2203902 (1940-06-01), Georgiev
patent: 3688162 (1972-08-01), Willy et al.
patent: 3852647 (1974-12-01), Ishii
patent: 3878440 (1975-04-01), Ando
patent: 4115629 (1978-09-01), Dey et al.
patent: 4245010 (1981-01-01), Golz
patent: 4495147 (1985-01-01), Fricker et al.
patent: 4550743 (1985-11-01), McFarlane et al.
patent: 4612739 (1986-09-01), Wilson
patent: 6150037 (2000-11-01), Saijo et al.
patent: 0068836 (1983-01-01), None
patent: 887396 (1943-11-01), None
Isobe Yoshihiko
Saijo Kinji
Yoshida Kazuo
Yoshimoto Nobuyuki
Browdy and Neimark
Rivell John
Toyo Kohan Co. Ltd.
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