PURPOSE: To realize a valve device with a high safety which can absorb the thermal expansion of a valve body by forming the upper side form of an elastic valve body used for the safety valve of a sealed type battery, in a square form, and the thickness of the opposite side edges smaller than the center part.
CONSTITUTION: A cap form positive electrode terminal 5 is provided to a sealing plate 2 so as to form a valve chest 6. An elastic valve body 7 housed in the valve chest 6 is formed in a square in the form of the upper side, while the thickness is reduced gradually in a curve form toward a pair of opposite side edges. And in the side edges, notches are provided at the upper side and the lower side in a step form, so as to form a flange form. By forming the elastic valve body 7 in such a form, a sufficient space can be formed in the valve chest 6 without increasing the capacity of the valve chest 6. And, even though the elastic valve body 7 is thermal-expanded by the heating following a rapid charging and discharging and the like, the increasing amount of the valve body can be absorbed sufficiently. Consequently, the battery can be protected from a deformation and a crack, and a damage and the like of the using apparatus can be prevented.
MARUYAMA HIROMI
OKAMI KAICHI
