| 摘要 |
A safety device for a closed battery capable positively preventing a rupture due to a rapid internal pressure rise at over-packing and short-circuiting and being produced inexpensively, a positive electrode lid (<HIL><PDAT>16</BOLD><PDAT>) attached to one end of an outer covering can (<HIL><PDAT>11</BOLD><PDAT>) comprises a pressure receiving plate (<HIL><PDAT>18</BOLD><PDAT>) forming the innermost lid and connected to positive electrode (<HIL><PDAT>13</BOLD><PDAT>) of an electrode unit (<HIL><PDAT>12</BOLD><PDAT>) via positive electrode lead (<HIL><PDAT>17</BOLD><PDAT>), a shielding plate (<HIL><PDAT>20</BOLD><PDAT>) forming a middle lid and electrically connected to the pressure receiving plate (<HIL><PDAT>18</BOLD><PDAT>) via a center contact (<HIL><PDAT>19</BOLD><PDAT>), and a sealing plate (<HIL><PDAT>21</BOLD><PDAT>) forming the outermost lid and electrically connected to the shielding plate (<HIL><PDAT>20</BOLD><PDAT>). The center contact (<HIL><PDAT>19</BOLD><PDAT>) is formed of a projection (<HIL><PDAT>28</BOLD><PDAT>) having a first flat contact surface (<HIL><PDAT>27</BOLD><PDAT>) of the pressure receiving plate (<HIL><PDAT>18</BOLD><PDAT>) and a second flat contact surface (<HIL><PDAT>29</BOLD><PDAT>) of the shielding plate (<HIL><PDAT>20</BOLD><PDAT>), and a plurality of annular grooves (<HIL><PDAT>31, 33</BOLD><PDAT>) are alternately provided around the second flat contact surface (<HIL><PDAT>29</BOLD><PDAT>) so as to face each other at 180° intervals, the annular grooves (<HIL><PDAT>31, 33</BOLD><PDAT>) being covered with a metal foil (<HIL><PDAT>34</BOLD><PDAT>) to form valve membranes (<HIL><PDAT>35, 36</BOLD><PDAT>).</PTEXT>
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